@article {1514911, title = {Feedback loops between 3D vegetation structure and ecological functions of animals}, journal = {Ecology Letters}, year = {2023}, abstract = {Ecosystems function in a series of feedback loops that can change or maintain vegetation structure. Vegetation structure influences the ecological niche space available to animals, shaping many aspects of behaviour and reproduction. In turn, animals perform ecological functions that shape vegetation structure. However, most studies concerning three-dimensional vegetation structure and animal ecology consider only a single direction of this relationship. Here, we review these separate lines of research and integrate them into a unified concept that describes a feedback mechanism. We also show how remote sensing and animal tracking technologies are now available at the global scale to describe feedback loops and their consequences for ecosystem functioning. An improved understanding of how animals interact with vegetation structure in feedback loops is needed to conserve ecosystems that face major disruptions in response to climate and land-use change.}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/ele.14272}, author = {Russo NJ and Davies AB and Blakey RV and Ordway EM and Smith TB} } @article {1520371, title = {Soil carbon in tropical savannas mostly derived from grasses}, journal = {Nature Geoscience}, volume = {16}, year = {2023}, pages = {710{\textendash}716 }, abstract = {Tropical savannas have been increasingly targeted for carbon sequestration by afforestation, assuming large gains in soil organic carbon (SOC) with increasing tree cover. Because savanna SOC is also derived from grasses, this assumption may not reflect real changes in SOC under afforestation. However, the exact contribution of grasses to SOC and the changes in SOC with increasing tree cover remain poorly understood. Here we combine a case study from Kruger National Park, South Africa, with data synthesized from tropical savannas globally to show that grass-derived carbon constitutes more than half of total SOC to a soil depth of 1 m, even in soils directly under trees. The largest SOC concentrations were associated with the largest grass contributions (\>70\% of total SOC). Across the tropics, SOC concentration was not explained by tree cover. Both SOC gain and loss were observed following increasing tree cover, and on average SOC storage within a 1-m profile only increased by 6\% (s.e. = 4\%,\ n = 44). These results underscore the substantial contribution of grasses to SOC and the considerable uncertainty in SOC responses to increasing tree cover across tropical savannas}, author = {Y, Zhou and B, Bomfim and WJ, Bond and TW, Boutton and MF, Case and C, Coetsee and AB, Davies and EC, February and EF, Gray and LCR, Silva and JL, Wright and AC, Staver} } @article {1514866, title = {Impacts of large herbivores on terrestrial ecosystems}, journal = {Current Biology}, volume = {33}, year = {2023}, abstract = {Large herbivores play unique ecological roles and are disproportionately imperiled by human activity. As many wild populations dwindle towards extinction, and as interest grows in restoring lost biodiversity, research on large herbivores and their ecological impacts has intensified. Yet, results are often conflicting or contingent on local conditions, and new findings have challenged conventional wisdom, making it hard to discern general principles. Here, we review what is known about the ecosystem impacts of large herbivores globally, identify key uncertainties, and suggest priorities to guide research. Many findings are generalizable across ecosystems: large herbivores consistently exert top-down control of plant demography, species composition, and biomass, thereby suppressing fires and the abundance of smaller animals. Other general patterns do not have clearly defined impacts: large herbivores respond to predation risk but the strength of trophic cascades is variable; large herbivores move vast quantities of seeds and nutrients but with poorly understood effects on vegetation and biogeochemistry. Questions of the greatest relevance for conservation and management are among the least certain, including effects on carbon storage and other ecosystem functions and the ability to predict outcomes of extinctions and reintroductions. A unifying theme is the role of body size in regulating ecological impact. Small herbivores cannot fully substitute for large ones, and large-herbivore species are not functionally redundant {\textemdash} losing any, especially the largest, will alter net impact, helping to explain why livestock are poor surrogates for wild species. We advocate leveraging a broad spectrum of techniques to mechanistically explain how large-herbivore traits and environmental context interactively govern the ecological impacts of these animals.}, url = {https://www.cell.com/current-biology/pdf/S0960-9822(23)00472-4.pdf}, author = {RM, Pringle and JO, Abraham and MT, Anderso and TC, Coverdale and AB, Davies and CL, Dutton and A, Gaylard and JR, Goheen and RM, Holdo and MC, Hutchinson and DM, Kimuyu and RA, Long and AL, Subalusky and MP, Veldhuis} } @article {1498161, title = {Monitoring the online ant trade reveals high biological invasion risk}, journal = {Biological Conservation}, volume = {282}, year = {2023}, abstract = {Ants are traded as pets across the globe, but if introduced outside of their native ranges they could become invasive with dire environmental and economic consequences. We demonstrate how geotagged e-commerce information can be utilized for\ biosecurity\ risk assessment. We monitored online pet\ ant\ sales in China and found that 58,937 ant colonies from 209 species were sold by 206 sellers in 89 cities across the country in six months. More than a quarter of the traded species were not native to China. Trait-based analysis revealed that the most sought-after ants have higher invasive potential than less popular species. Climate-based distribution models suggest that 24.7\ \% of the non-native species could find suitable climatic conditions in the cities from which they were sold. If released, pet ants could interfere with urban ecosystems, rural agriculture, and spill over to threaten back-country habitats with high biodiversity. Based on our analysis we offer guidelines on wildlife trade policy and management: (1) we provide a list of potentially invasive ants sold in each Chinese city; (2) we identify the highest risk of a non-native ant introduction at the Greater Bay area of subtropical southern China; (3) we highlight the absence of within-country permitting requirements which resulted in\ invasive species\ being transported across Chinese provincial lines. Worldwide, similar wildlife trade records are only accessible to conservation practitioners cognizant of local languages and customs. We encourage grassroot web scraping of under-monitored, fast-developing economies to gather information crucial for guiding regional policy decisions.}, url = {https://www.sciencedirect.com/science/article/pii/S0006320723001398?via\%3Dihub}, author = {Z, Wang and J, Zeng and H, Ran and W, Meng and S, Zhou and AB, Davies and C, Liu} } @article {1514886, title = {Effects of long- term fixed fire regimes on African savanna vegetation biomass, vertical structure and tree stem density}, journal = {Journal of Applied Ecology}, year = {2023}, abstract = {
  1. Fire plays an integral role in shaping the vegetation structure of savanna ecosystems. However, the effects of fire regime characteristics, such as frequency and season of burn, on savanna vegetation structure, biomass and tree abundance across landscape types are largely unknown.
  2. We used high-resolution airborne light detection and ranging (LiDAR) to investigate the long-term effects of fire manipulation on savanna vegetation in Kruger National Park, South Africa. We analysed the effects of fire exclusion and experimental burns every 1, 2, 3, 4 and 6 years and during different seasons on aboveground biomass (AGB), tree stem densities and vegetation vertical height profiles across a rainfall gradient and on contrasting geologies.
  3. Across savanna types, and especially in drier savannas, fire season was more influential for constraining AGB than fire frequency. Plots experiencing fires during the late- and mid-dry season had 44.50\% and 43.60\%, respectively, lower AGB relative to unburnt plots than wet-season fires. However, in mesic savannas, fire frequency interacted with fire season to influence AGB: plots subjected to high frequency, dry-season fires had 55.35\% lower AGB than unburnt plots, whereas plots burnt in the wet season at lower frequencies had lower AGB (24.40\% lower than unburnt plots) than plots subjected to high frequency, wet-season fires (13.74\% lower AGB than unburnt plots).
  4. Fire regimes had variable effects on tree densities, and effects varied with the savanna type. Woody vertical vegetation profiles showed the largest differences in response to dry-season fires, with the greatest divergence in vegetation height classes \<5 m.
  5. Synthesis and applications. Understanding the influence of fire regimes on vegetation structure has important implications for the management of savanna heterogeneity and for predicting trajectories of change in savanna vegetation as fire regimes vary with climate change. We show that the magnitude of the effect of fire on woody vegetation structure varies with savanna context. Our results suggest that heterogeneous vegetation structure can be achieved by applying fires in the dry season in mesic savannas, whereas in dry savannas, variation in fire regimes is less consequential for constraining biomass accumulation and altering vegetation structure.
}, url = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2664.14435}, author = {Singh J and Boucher PB and Hockridge EG and Davies AB} } @article {1514901, title = {Are hippos Africa{\textquoteright}s most influential megaherbivore? A review of ecosystem engineering by the semi-aquatic common hippopotamus}, journal = {https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12960}, year = {2023}, abstract = {Megaherbivores perform vital ecosystem engineering roles, and have their last remaining stronghold in Africa. Of Africa{\textquoteright}s remaining megaherbivores, the common hippopotamus (Hippopotamus amphibius) has received the least scientific and conservation attention, despite how influential their ecosystem engineering activities appear to be. Given the potentially crucial ecosystem engineering influence of hippos, as well as mounting conservation concerns threatening their long-term persistence, a review of the evidence for hippos being ecosystem engineers, and the effects of their engineering, is both timely and necessary. In this review, we assess, (i) aspects of hippo biology that underlie their unique ecosystem engineering potential; (ii) evaluate hippo ecological impacts in terrestrial and aquatic environments; (iii) compare the ecosystem engineering influence of hippos to other extant African megaherbivores; (iv) evaluate factors most critical to hippo conservation and ecosystem engineering; and (v) highlight future research directions and challenges that may yield new insights into the ecological role of hippos, and of megaherbivores more broadly. We find that a variety of key life-history traits determine the hippo{\textquoteright}s unique influence, including their semi-aquatic lifestyle, large body size, specialised gut anatomy, muzzle structure, small and partially webbed feet, and highly gregarious nature. On land, hippos create grazing lawns that contain distinct plant communities and alter fire spatial extent, which shapes woody plant demographics and might assist in maintaining fire-sensitive riverine vegetation. In water, hippos deposit nutrient-rich dung, stimulating aquatic food chains and altering water chemistry and quality, impacting a host of different organisms. Hippo trampling and wallowing alters geomorphological processes, widening riverbanks, creating new river channels, and forming gullies along well-utilised hippo paths. Taken together, we propose that these myriad impacts combine to make hippos Africa{\textquoteright}s most influential megaherbivore, specifically because of the high diversity and intensity of their ecological impacts compared with other megaherbivores, and because of their unique capacity to transfer nutrients across ecosystem boundaries, enriching both terrestrial and aquatic ecosystems. Nonetheless, water pollution and extraction for agriculture and industry, erratic rainfall patterns and human{\textendash}hippo conflict, threaten hippo ecosystem engineering and persistence. Therefore, we encourage greater consideration of the unique role of hippos as ecosystem engineers when considering the functional importance of megafauna in African ecosystems, and increased attention to declining hippo habitat and populations, which if unchecked could change the way in which many African ecosystems function.}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/brv.12960}, author = {Voysey DM and de Bruyn PJN and Davies AB} } @article {1498126, title = {Trophic rewilding can expand natural climate solutions}, journal = {Nature Climate Change}, year = {2023}, abstract = {Natural climate solutions are being advanced to arrest climate warming by protecting and enhancing carbon capture and storage in plants, soils and sediments in ecosystems. These solutions are viewed as having the ancillary benefit of protecting habitats and landscapes to conserve animal species diversity. However, this reasoning undervalues the role animals play in controlling the carbon cycle. We present scientific evidence showing that protecting and restoring wild animals and their functional roles can enhance natural carbon capture and storage. We call for new thinking that includes the restoration and conservation of wild animals and their ecosystem roles as a key component of natural climate solutions that can enhance the ability to prevent climate warming beyond 1.5 {\textdegree}C.}, url = {https://www.nature.com/articles/s41558-023-01631-6}, author = {Schmitz OJ and Sylv{\'e}n M and Atwood TB and Bakker ES and Berzaghi F and Brodie JF and Cromsigt JP and Davies AB and Leroux SJ and Schepers FJ and Smith FA} } @article {1458011, title = {Species-level termite methane production rates}, journal = {Ecology}, volume = {104}, year = {2023}, pages = {e3905}, abstract = {Termites consume substantial amounts of plant material across tropical and subtropical ecosystems. During the process of lignocellulose digestion, the symbiotic methanogenesis within termites{\textquoteright} guts produces the potent greenhouse gas methane (CH4). Termites contribute an estimated 1-5\% of global CH4 emissions, with these estimates derived from the product of termite biomass and termite CH4 production rate per unit of termite biomass. However, termite CH4 production rates vary significantly across species, genus, family, and feeding group, yet our understanding of this variation remains poor. Here, we reviewed papers published from 1975 to 2021 to create a single consistently derived list of species-level termite CH4 production rates. We searched the Google Scholar using two key words: termite AND methane. We only included studies that had measured termite CH4 production rates using the incubation method. For each eligible study, we extracted and tabulated termite CH4 production rates and other relevant variables (e.g., feeding groups). We used μg CH4 g-1(termite) h-1 as the standardized unit, and if other units were presented, we converted them into this standardized unit. Overall, these data include 134 termite species from 65 genera and 5 families. Termite CH4 production rates ranged from 0 to 25.26 μg CH4 g-1(termite) h-1, with an average rate of 3.74 (standard deviation = 4.08, n = 251). Reported CH4 production rates were largely concentrated in the family Termitidae. Across feeding groups, soil feeders tended to have higher CH4 production rates than wood feeders. However, published data represent fewer than 5\% of described termite species, and therefore we hope that our study will initiate a community-wide effort to fill data gaps and advance our understanding of the role of termites in critical biogeochemical cycles and other ecosystem processes. The data set is in the public domain under a Creative Commons Zero (CC0) license waiver.}, url = {https://doi.org/10.1002/ecy.3905}, author = {Y, Zhou and AC, Staver and AB, Davies} } @article {1490691, title = {Flying high: Sampling savanna vegetation with UAV-lidar}, journal = {Methods in Ecology and Evolution}, volume = {n/a}, year = {2023}, note = {https://doi.org/10.1111/2041-210X.14081}, month = {2023/03/16}, publisher = {John Wiley \& Sons, Ltd}, abstract = {Abstract The flexibility of UAV-lidar remote sensing offers a myriad of new opportunities for savanna ecology, enabling researchers to measure vegetation structure at a variety of temporal and spatial scales. However, this flexibility also increases the number of customizable variables, such as flight altitude, pattern, and sensor parameters, that, when adjusted, can impact data quality as well as the applicability of a dataset to a specific research interest. To better understand the impacts that UAV flight patterns and sensor parameters have on vegetation metrics, we compared 7 lidar point clouds collected with a Riegl VUX???1LR over a 300???300?m area in the Kruger National Park, South Africa. We varied the altitude (60?m above ground, 100?m, 180?m, and 300?m) and sampling pattern (slowing the flight speed, increasing the overlap between flightlines and flying a crosshatch pattern), and compared a variety of vertical vegetation metrics related to height and fractional cover. Comparing vegetation metrics from acquisitions with different flight patterns and sensor parameters, we found that both flight altitude and pattern had significant impacts on derived structure metrics, with variation in altitude causing the largest impacts. Flying higher resulted in lower point cloud heights, leading to a consistent downward trend in percentile height metrics and fractional cover. The magnitude and direction of these trends also varied depending on the vegetation type sampled (trees, shrubs or grasses), showing that the structure and composition of savanna vegetation can interact with the lidar signal and alter derived metrics. While there were statistically significant differences in metrics among acquisitions, the average differences were often on the order of a few centimetres or less, which shows great promise for future comparison studies. We discuss how these results apply in practice, explaining the potential trade-offs of flying at higher altitudes and with alternate patterns. We highlight how flight and sensor parameters can be geared toward specific ecological applications and vegetation types, and we explore future opportunities for optimizing UAV-lidar sampling designs in savannas.}, keywords = {active remote sensing, canopy cover, canopy height, Kruger National Park, lidar, savanna, UAS, UAV, unoccupied aerial systems, unoccupied aerial vehicles, vegetation survey}, isbn = {2041-210X}, url = {https://doi.org/10.1111/2041-210X.14081}, author = {PB, Boucher and EG, Hockridge and J, Singh and AB, Davies} } @article {1490696, title = {High-intensity fires may have limited medium-term effectiveness for reversing woody plant encroachment in an African savanna}, journal = {Journal of Applied Ecology}, volume = {n/a}, year = {2023}, note = {https://doi.org/10.1111/1365-2664.14362}, month = {2023/02/15}, publisher = {John Wiley \& Sons, Ltd}, abstract = {Abstract Woody thickening or ?bush encroachment? is a growing concern in savannas worldwide, and can reportedly be reversed by applying high-intensity fires. Preliminary findings following experimental fires in 2010 and 2013 indicated that woody plant cover declined 1?year after high-intensity fires, but increased after low-intensity fires. However, the longer-term outcomes of high-intensity fires are largely unknown. To establish longer-term outcomes, we re-assessed sites subjected to low, medium and high-intensity fire treatments 10?years after the initial experimental fires. We compared woody vegetation structure in 2010 with that in 2020 using both ground surveys and airborne LiDAR. Ground surveys revealed increases in the number of stems and individual shrubs (\<10\ m tall) over 10?years, and decreases in shrub height, with no significant differences between treatments. Large trees (>=10\ m) declined by about 65\% in number due to ongoing high mortality across treatments over 10?years. LiDAR surveys revealed significant but very small differences in woody plant height and cover between treatments after 10?years. Median height was around 2\ m in all treatments, and 90th percentile tree height was moderately taller in the low fire treatment. Mean canopy cover was about 55\% in all treatments. The treatments therefore did not result in a meaningful reversal of woody encroachment with no discernible difference between the treatment sites after 10?years. Synthesis and applications. The application of high-intensity fires did not reverse woody encroachment in the longer term. In addition, the application of such treatments would be impractical at a large scale. Within a framework of strategic adaptive management, the next logical step would be to attempt a different approach. In this case, it is intended to use early or late wet season burns to increase the mortality of shrubs when they are in a more vulnerable phenological state. This study illustrates the importance of ongoing long-term monitoring, review and adaptation for finding practical ways to achieve desired ecological outcomes.}, keywords = {bush encroachment, drought, fire intensity, global change, Kruger National Park, lidar, South Africa, strategic adaptive management}, isbn = {0021-8901}, url = {https://doi.org/10.1111/1365-2664.14362}, author = {T, Strydom and IPJ, Smit and N, Govender and C, Coetsee and J, Singh and AB, Davies and BW, van Wilgen} } @article {1487356, title = {Unravelling the relationship between plant diversity and vegetation structural complexity: A review and theoretical framework.}, journal = {Journal of Ecology}, volume = {00}, year = {2023}, pages = {1-18}, abstract = {

1. Vegetation structural complexity (VSC){\textemdash}the three-dimensional distribution of plants within an ecosystem{\textemdash}is an important ecological trait. To date, research has focused primarily on the effects of VSC on ecological patterns and processes, but comparatively little is known about what drives variation in VSC.

2. Recent advances in active remote sensing technology, particularly light detection and ranging and radio detection and ranging, have allowed the measurement of VSC at unprecedented spatial scales and resolutions. Out of this and earlier work has emerged evidence that VSC is typically associated with greater ecosystem functioning (especially microclimate regulation, productivity, faunal diversity and habitat provisioning), making restoration of vegetation complexity a potentially powerful restoration tool.

3. Recent studies of VSC across natural and experimental gradients of plant diversity have also revealed that more diverse plant communities tend to be more structurally complex. However, the shape and generality of this relationship{\textemdash}and the mechanism(s) by which phytodiversity might contribute to structural complexity{\textemdash}remain poorly understood.

4. Here, we review how active remote sensing has facilitated recent VSC research and shaped our understanding of the relationship between vegetation complexity and ecosystem function. We then present a theoretical framework for the relationship between phytodiversity and VSC based on classic biodiversity-ecosystem functioning principles. Finally, we evaluate the evidence for the notion that diverse plant assemblages tend to be more structurally complex and explore the shape of the relationship between phytodiversity and VSC using data from 13 recent remote sensing studies.

5. Synthesis. The relationship between phytodiversity and VSC appears to be almost universally positive. Preliminary evidence further suggests that the most common relationships between phytodiversity and VSC are linear or saturating, indicating that the extent of functional redundancy between species varies across plant communities and ecosystems. In contrast, we find little evidence for exponential or negative relationships between plant diversity and VSC, suggesting that even\ 
modest increases in plant diversity could markedly increase structural complexity. Additional investigations of phytodiversity-VSC relationships are necessary to establish whether the observed positive relationships are causal (and, if so, in which direction) and to clarify the potential impact of plant community restoration on structural complexity and broader ecosystem function.

}, url = {https://besjournals.onlinelibrary.wiley.com/doi/abs/10.1111/1365-2745.14068}, author = {TC, Coverdale and AB, Davies} } @article {1432710, title = {Limited increases in savanna carbon stocks over decades of fire suppression}, journal = {Nature}, year = {2022}, pages = {445{\textendash}449}, abstract = {Savannas cover a fifth of the land surface and contribute a third of terrestrial net primary production, accounting for three-quarters of global area burned and more than half of global fire-driven carbon emissions1,2,3. Fire suppression and afforestation have been proposed as tools to increase carbon sequestration in these ecosystems2,4. A robust quantification of whole-ecosystem carbon storage in savannas is lacking however, especially under altered fire regimes. Here we provide one of the first direct estimates of whole-ecosystem carbon response to more than 60 years of fire exclusion in a mesic African savanna. We found that fire suppression increased whole-ecosystem carbon storage by only 35.4 {\textpm} 12\% (mean {\textpm} standard error), even though tree cover increased by 78.9 {\textpm} 29.3\%, corresponding to total gains of 23.0 {\textpm} 6.1 Mg C ha-1 at an average of about 0.35 {\textpm} 0.09 Mg C ha-1 year-1, more than an order of magnitude lower than previously assumed4. Frequently burned savannas had substantial belowground carbon, especially in biomass and deep soils. These belowground reservoirs are not fully considered in afforestation or fire-suppression schemes but may mean that the decadal sequestration potential of savannas is negligible, especially weighed against concomitant losses of biodiversity and function.}, url = {https://www.nature.com/articles/s41586-022-04438-1}, author = {Y, Zhou and J, Singh and JR, Butnor and C, Coetsee and PB, Boucher and MF, Case and EG, Hockridge and AB, Davies and AC, Staver} } @article {1458001, title = {Resistance of termite mounds to variation in long-term fire regimes across semi-arid African savannas}, journal = {Journal of Animal Ecology}, year = {2022}, abstract = {\ \  \ 1.\ \  \ Fire regimes are expected to change with climate change, resulting in a crucial need to understand the specific ways in which variable fire regimes impact important contributors to ecosystem functioning, such as mound-building termites. Termite mounds and fire are both important agents of savanna ecosystem heterogeneity and functioning, but there is little understanding of how they interact across savanna types.
\ \  \ 2.\ \  \ We used very high-resolution LiDAR remote sensing to measure the size and distribution of termite mounds across approximately 1300 ha of experimental burn plots in four South African savanna landscapes representing a wide range of fire treatments differing in seasonality and frequency of burning.
\ \  \ 3.\ \  \ In nutrient-poor granitic savannas, fire had no impact on termite mound size, densities and spatial distributions. In nutrient-rich basaltic savannas with high mammalian herbivore abundance and intermediate rainfall, very frequent fires caused a decrease in termite mound size, whereas in arid nutrient-rich basaltic savannas, fires that occurred at intermediate frequencies and in transitional seasons (i.e. late dry season and late wet season) decreased the degree of spatial overdispersal exhibited by mounds.
\ \  \ 4.\ \  \ Overall, our results suggest that termite mounds are resistant to variation in fire seasonality and frequency, likely indicating that ecosystem services provided by mound-building termites will be unaffected by changing fire regimes. However, consideration of changes to termite mound size and distribution could be necessary for land managers in specific savanna types, such as nutrient-rich soils with high mammalian herbivore abundance.
\ }, url = {https://doi.org/10.1111/1365-2656.13830}, author = {EG, Hockridge and J, Singh and PB, Boucher and AB, Davies} } @article {1434779, title = {The first sub-meter resolution digital elevation model of the Kruger National Park, South Africa}, journal = {Koedoe}, volume = {63}, year = {2021}, pages = {a1679}, abstract = {

The use of digital elevation models has proven to be crucial in numerous studies related to savanna ecosystem research. However, the insufficient spatial resolution of the chosen input data is often considered to be a limiting factor when conducting local to regional scale ecosystem analysis. The elevation models and orthorectified imagery created in this study represent the first wall-to-wall digital elevation data sets produced for the Kruger National Park (KNP), South Africa, at very high spatial resolution. Using colour-infrared (CIR) aerial imagery from the archives of the Chief Directorate: National Geo-spatial Information (CDNGI), Department of Agriculture, Land Reform and Rural Development (DALRRD) aerial acquisition programme, we created digital surface models (DSMs), digital terrain models (DTMs) and CIR orthomosaics covering the entire KNP with a nominal ground sampling distance of 0.25 m. Elevation information was derived using state-of-the-art stereo matching algorithms that utilised semi-global matching (SGM) as a cost aggregation function throughout the image pairing, using the Enterprise software from CATALYST. The final products were validated against reference products, and showed excellent agreement with\ R{\texttwosuperior} values of 0.99. Further, the validation of the DTM and DSM revealed median absolute vertical height error (LE90) across all sites of 1.02 m and 2.58 m, respectively. The orthomosaics were validated with in situ ground control points (GCPs) exhibiting a horizontal Circular Probable Error (CPE) of 1.37 m. The data resulting from this work will be distributed freely with the aim of fostering more scientific studies in the African science community and beyond.

Conservation implications:\ Accurate information about terrain and surface height are crucial inputs to a variety of scientific analysis, which are essential in protected areas, such as flood prediction or fire hazard estimation. Elevation data sets and orthomosaics in very high resolution can therefore serve as a crucial tool to improve park management and foster positive implications on conservation efforts.

}, url = {https://koedoe.co.za/index.php/koedoe/article/view/1679}, author = {Kai Heckel and Marcel Urban and Jean-S{\'e}bastien Bouffard and Jussi Baade and Peter Boucher and Andrew Davies and Evan G Hockridge and Wolfgang L{\"u}ck and Jonas Ziemer and Izak Smit and Bernhard Jacobs and Mark Norris-Rogers and Christiane Schmullius} } @article {1380859, title = {Environmental controls on African herbivore responses to landscapes of fear}, journal = {Okios}, volume = {130}, year = {2021}, pages = {171-186}, abstract = {Herbivores balance forage acquisition with the need to avoid predation, often leading to trade-offs between forgoing resources to avoid areas of high predation risk, or tolerating increased risk in exchange for improved forage. The outcome of these decisions is likely to change with varying resource levels, with herbivores altering their response to predation risk across heterogeneous landscapes. Such contrasting responses will alter the strength of non-consumptive predation effects, but are poorly understood in multiple-predator/multiple-prey systems. We combined fine-scaled spatial information on two predator and 11 herbivore species with remotely-sensed measurements of forage quantity and vegetation structure to assess variation in herbivore response to predation risk with changing environmental context, herbivore body size, herbivore foraging strategy (browsers\ vs.\ grazers), predator type (ambush\ vs.\ coursing hunters) and group size across a South African savanna landscape. Medium-sized herbivore species were more likely to adjust their response to risk with a changing resource landscape: warthog, nyala and wildebeest tolerated increased long-term predator encounter risk in exchange for abundant (warthog and nyala) or preferred (wildebeest) forage, and nyala selected areas with higher visibility only in landscapes where food was abundant. Impala were more likely to be observed in areas of high visibility where wild dog risk was high. In addition, although buffalo did not avoid areas of high lion encounter risk, large buffalo groups were more frequently observed in open areas where lion encounter risk was high, whereas small groups did not alter their space use across varying levels of risk. Our findings suggest that risk effects are not uniform across landscapes for medium-sized herbivores and large buffalo groups, instead varying with environmental context and leading to a dynamic landscape of fear. However, responses among these and other prey species were variable and not consistent, highlighting the complexities inherent to multi-predator/multi-prey systems.}, url = {https://onlinelibrary.wiley.com/doi/10.1111/oik.07559}, author = {AB, Davies and JPGM, Cromsigt and CJ, Tambling and E, le Roux and N,Vaughn and DJ, Druce and DG, Marneweck and GP, Asner} } @article {1384105, title = {A global review of termite sampling methods}, journal = {Insectes Sociaux}, volume = {68}, year = {2021}, pages = {3-14}, abstract = {Termites are globally dominant and functionally important soil organisms. While their role in ecosystems is being increasingly recognised and understood, methods that adequately sample termite communities across habitats can be challenging and have not advanced at the same pace as studies of termite ecology. Moreover, the appropriateness of sampling methods varies with habitat and biogeographic region due to differences in termite communities. Focusing largely on tropical systems where the majority of termites occur, we review currently available termite sampling methods and provide recommendations for sampling across different biomes and biogeographic regions. Active searching transects are most effective in rainforest habitats, whereas reduced transects, baiting and mound surveys are more appropriate in grassy systems and seasonally dry forests. Baiting is recommended for deserts. Recent advances in termite sampling, such as the use of remote sensing and DNA metabarcoding, and outstanding challenges, such as sampling episodic grass-feeding termites, are also discussed. Improved use of standardised termite sampling methods, as we recommend, should lead to increased knowledge of the patterns and drivers of termite diversity, which will, in turn, facilitate the quantification of the influence termites have on ecosystems and lead to new insights into the functioning of tropical systems.}, url = {https://link.springer.com/article/10.1007/s00040-020-00797-y}, author = {AB, Davies and CL, Parr and P, Eggleton} } @article {1401141, title = {Mammalian herbivore movement into drought refugia has cascading effects on savanna insect communities}, journal = {Journal Of Animal Ecology}, year = {2021}, abstract = {
  1. Global climate change is predicted to increase the frequency of droughts, with major impacts on tropical savannas. It has been suggested that during drought, increased soil moisture and nutrients on termite mounds could benefit plants but it is unclear how such benefits could cascade to affect insect communities.
  2. Here, we describe the effects of drought on vegetation structure, the cascading implications for invertebrates and how termite mounds influence such effects. We compared how changes in grass biomass affected grasshopper and ant diversity on and off\ Macrotermes\ mounds before (2012) and during a drought (2016) at two locations that experienced large variation in drought severity (Skukuza and Pretoriuskop) in the Kruger National Park, South Africa.
  3. The 2013{\textendash}2016 drought was not ubiquitous across the study site, with rainfall decreasing at Skukuza and being above average at Pretoriuskop. However, grass biomass declined at both locations. Grasshopper abundance decreased at droughted Skukuza both on and off mounds but decreased on mounds and increased off mounds at non-droughted Pretoriuskop. Ant abundance and species richness increased at Skukuza but remained the same on mounds and decreased off mounds at Pretoriuskop.
  4. Our results demonstrate the spatially extensive effects of drought. Despite above average rainfall in 2016 at Pretoriuskop, grass biomass decreased, likely due to an influx of large mammalian herbivores from drought-affected areas. This decrease in grass biomass cascaded to affect grasshoppers and ants, further illustrating the effects of drought on invertebrates in adjoining areas with higher rainfall. Our grasshopper results also suggest that increased drought in savannas will contribute to overall declines in insect abundance. Moreover, our recorded increase in ant abundance was primarily in the form of increases in dominant species, illustrating how drought-induced shifts in relative abundance will likely influence ecosystem structure and function.
  5. Our study highlights the phenomenon of spill-over drought effects and suggests rather than mitigating drought, termite mounds can instead become the focus for more intense grazing, with important consequences for insect communities.

}, author = {MO,Trisos and CL, Parr and AB, Davies and M, Leitner and EC, February} } @article {1384106, title = {Spatial heterogeneity facilitates carnivore coexistence}, journal = {Ecology}, volume = {102}, year = {2021}, pages = {e03319}, abstract = {Competitively dominant carnivore species can limit the population sizes and alter the behavior of inferior competitors. Established mechanisms that enable carnivore coexistence include spatial and temporal avoidance of dominant predator species by subordinates, and dietary niche separation. However, spatial heterogeneity across landscapes could provide inferior competitors with refuges in the form of areas with lower competitor density and/or locations that provide concealment from competitors. Here, we combine temporally overlapping telemetry data from dominant lions (Panthera leo) and subordinate African wild dogs (Lycaon pictus) with high-resolution remote-sensing in an integrated step selection analysis to investigate how fine-scaled landscape heterogeneity might facilitate carnivore coexistence in South Africa{\textquoteright}s Hluhluwe-iMfolozi Park, where both predators occur at exceptionally high densities. We ask whether the primary lion avoidance strategy of wild dogs is spatial avoidance of lions or areas frequented by lions, or if wild dogs selectively use landscape features to avoid detection by lions. Within this framework, we also test whether wild dogs rely on proactive or reactive responses to lion risk. In contrast to previous studies finding strong spatial avoidance of lions by wild dogs, we found that the primary wild dog lion-avoidance strategy was to select landscape features that aid in lion avoidance. This habitat selection was routinely used by wild dogs, and especially when in areas and during times of high lion encounter risk, suggesting a proactive response to lion risk. Our findings suggest that spatial landscape heterogeneity could represent an alternative mechanism for carnivore coexistence, especially as ever-shrinking carnivore ranges force inferior competitors into increased contact with dominant species.}, author = {Davies, AB, and Tambling and Marneweck and Druce and Le Roux and Asner and Cromsigt and Ranc} } @article {1270462, title = {Natural and anthropogenic drivers of Bornean elephant movement strategies}, journal = {Global Ecology and Conservation}, volume = {22}, year = {2020}, pages = {Article e00906}, abstract = {Endangered Bornean elephants are severely threatened by ongoing habitat transformation and increasing levels of human-elephant conflict. Understanding how elephants move across intact and transformed landscapes, as well as within them, is therefore of vital importance for the successful implementation of conservation management initiatives. We combined remote sensing and GPS telemetry data to identify broad habitat utilization and key movement areas to aid elephant management and conflict mitigation in three spatially-isolated populations in central and eastern Sabah, Malaysian Borneo. Home ranges were estimated using Brownian Bridge Movement Models and specific behavioral movement traits were identified by pathway analyses. These behavioral traits enabled a fine-scale evaluation of movements between and adjacent to forest patches and the role of large-scale agriculture in shaping elephant movements. Both natural (topological) and anthropogenic (agricultural) landscape features were found to have a broad influence on elephant movements. All elephant populations exhibited human-mediated behavioral responses, regardless of disturbance level. Throughout their range, elephants appeared to actively select relatively degraded forests, as measured by aboveground carbon density. However, elephants actively avoided urbanized areas, including roads and villages. Throughout the elephant range, high-speed, low-trajectory movements were found at low aboveground carbon locations, with 27\% of all such movements located in large-scale agriculture. Our results suggest that agriculture impacts movement strategies of elephants, with evidence of repeat agricultural use pointing towards an active rationale for this behavior. Elephants were also found to use ridgelines as movement pathways, providing further context for the protection of such forested areas. The Lower Kinabatangan population, located in small remnant forests, travelled further to meet their ecological needs, suggesting the population is under added strain. Our work represents the broadest landscape assessment of Bornean elephant movements to-date and has important implications for both future work and habitat-level protected area management strategies.}, url = {direct.com/science/article/pii/S2351989419306018?via\%3Dihub}, author = {Evans LJ and B, Goossens and AB, Davies and G, Reynolds and GP, Asner} } @article {1277261, title = {Opportunistic feeding by lions: non-preferred prey comprise an important part of lion diets in a habitat where preferred prey are abundant}, journal = {Mammal Research}, year = {2020}, abstract = {Optimal foraging theory predicts less diverse predator diets with a greater availability of preferred prey. This narrow diet niche should then be dominated by preferred prey, with implications for predator{\textendash}prey dynamics and prey population ecology. We investigated lion (Panthera leo) diets in Hluhluwe{\textendash}iMfolozi Park (HiP), South Africa, to assess whether lions in a site with a high density of preferred prey (prey species weighing 92{\textendash}632\ kg as estimated from a published meta-analysis) have a narrow diet, consisting primarily of preferred prey. HiP is a useful study site to investigate this prediction because it is a productive landscape (with a high density of prey) where lion-preferred prey constitutes up to 33\% of the prey available to lions. Furthermore, to investigate whether lions in HiP exhibit sex-specific diets as documented in other southern African populations, we estimated male and female lion diets separately. We were specifically interested in testing whether traditional approaches of estimating lion diets at the population level mask sex-specific predation patterns, with possible implications for management of lions in small to medium-sized fenced reserves. Lions in HiP preferred larger prey species (63{\textendash}684\ kg) and had diets with a larger proportion of preferred prey than reported in an African-wide meta-analysis. However, despite the high density of preferred prey species, 36\% of lion diets still consisted of typically non-preferred species such as nyala (Tragelaphus angasii). This finding suggests that lions in HiP maintain a degree of opportunism even when preferred prey are abundant. Therefore, abundant, non-preferred prey are likely to be an important resource for lion populations. Sex-specific differences in lion diets were evident in HiP, suggesting that estimation of lion resource use and carrying capacity should consider opportunistic hunting and sex-specific differences in lion diets.}, url = {https://link.springer.com/article/10.1007\%2Fs13364-020-00481-3}, author = {T, Barnardo and CJ, Tambling and AB, Davies and S, Klein-Snakenborg and GP, Asner and E, Le Roux and JPGM, Cromsigt and DJ, Druce and GIH, Kerley} } @article {1363952, title = {Resistance of mound-building termites to anthropogenic land-use change}, journal = {Environmental Research Letters}, volume = {15}, year = {2020}, pages = {094038}, abstract = {Humans pose a major threat to many species through land-use change in virtually every habitat. However, the extent of this threat is largely unknown for invertebrates due to challenges with investigating their distributions at large scales. This knowledge gap is particularly troublesome for soil macrofauna because of the critical roles many of these organisms perform as ecosystem engineers. We used a combination of high-resolution airborne Light Detection and Ranging and deep learning models to map the distribution of the ecologically important termite genus Macrotermes across a South African savanna land-use gradient, quantifying the effects of land-use change on patterns of mound densities, heights and spatial patterning. Despite significant anthropogenic alteration to landscapes, termite mounds persisted and shared a number of similarities to mounds in untransformed areas. Mean mound height was not substantially reduced in transformed landscapes, and over-dispersion of mounds at localized scales was conserved. However, mound densities were partially reduced, and height distributions in transformed areas differed to those in protected areas. Our findings suggest that mound-building termites persist even in areas of relatively high human disturbance, but also highlight important differences in termite distributions that could lead to reductions in ecosystem services provided by termites in human-modified landscapes. The persistence of at least half of mounds in human-modified landscapes could serve as starting points for savanna restoration.}, url = {https://iopscience.iop.org/article/10.1088/1748-9326/aba0ff/meta}, author = {AB, Davies and PG, Brodrick and CL, Parr and GP, Asner} } @article {1274501, title = {Termite mounds create heterogeneity in invertebrate communities across a savanna rainfall gradient}, journal = {Biodiversity and Conservation}, year = {2020}, pages = {1-15}, abstract = {Termite mounds create nutrient hotspots that serve as key resource areas for savanna vegetation and mammalian herbivores. However, despite the key ecological roles performed by termite mounds, few studies have investigated their influence on invertebrate communities, and none have examined such effects across environmental gradients. We hypothesised that termite mounds would support greater numbers of invertebrates than the surrounding savanna matrix and that assemblages would differ in composition due to the enhanced nutritional quality of vegetation on mounds. We also predicted that the differences between on-mound and off-mound invertebrate diversity would be more pronounced in areas where the difference in nutritional value between mounds and the savanna matrix vegetation was most prominent. We tested these hypotheses in Kruger National Park, South Africa, by sampling ground- and grass-dwelling invertebrate herbivores, omnivores and detritivores on and at various distances away from termite mounds at three savanna sites of varying vegetation quality across a rainfall gradient. All invertebrate groups sampled responded to termite mounds, but mound influence varied across trophic groups (Orthoptera showed the clearest patterns), diversity measures (changes in abundance rather than species richness) and with mean annual rainfall (strongest effects at the highest rainfall site). Orthoptera were more abundant on mounds, particularly at the wettest site, and there was a positive relationship between mound size and Orthoptera species richness. Ant assemblage composition on mounds differed from that off mounds and beetle abundance was greater on mounds, possibly as a result of concentrated mammalian herbivore activity and faecal deposition on mounds. Our results suggest that termite mounds are not only important nutrient and foraging hotspots for vertebrates, but that they also introduce heterogeneity in invertebrate communities, especially in nutrient-poor savannas.}, url = { https://doi.org/10.1007/s10531-020-01943-5}, author = {M, Leitner and AB, Davies and MP, Robertson and CL, Parr and van Rensburg BJ} } @article {1176049, title = {Uncovering ecological patterns with convolutional neural networks.}, journal = {Trends in Ecology and Evolution}, volume = {34}, year = {2019}, pages = {734-745}, abstract = {Using remotely sensed imagery to identify biophysical components across landscapes is an important avenue of investigation for ecologists studying ecosystem dynamics. With high-resolution remotely sensed imagery, algorithmic utilization of image context is crucial for accurate identification of biophysical components at large scales. In recent years, convolutional neural networks (CNNs) have become ubiquitous in image processing, and are rapidly becoming more common in ecology. Because the quantity of high-resolution remotely sensed imagery continues to rise, CNNs are increasingly essential tools for large-scale ecosystem analysis. We discuss here the conceptual advantages of CNNs, demonstrate how they can be used by ecologists through distinct examples of their application, and provide a walkthrough of how to use them for ecological applications.}, url = {https://www.sciencedirect.com/science/article/pii/S0169534719300862}, author = {PG, Brodrick and AB, Davies and GP, Asner} } @article {1176050, title = {Elephants limit aboveground carbon gains in African savannas.}, journal = {Global Change Biology}, volume = {25}, year = {2019}, pages = {1368-1382}, abstract = {Understanding the drivers of vegetation carbon dynamics is essential for climate change mitigation and effective policy formulation. However, most efforts focus on abiotic drivers of plant biomass change, with little consideration for functional roles performed by animals, particularly at landscape scales. We combined repeat airborne Light Detection and Ranging with measurements of elephant densities, abiotic factors, and exclusion experiments to determine the relative importance of drivers of change in aboveground woody vegetation carbon stocks in Kruger National Park, South Africa. Despite a growing elephant population, aboveground carbon density (ACD) increased across most of the landscape over the 6-year study period, but at fine scales, bull elephant density was the most important factor determining carbon stock change, with ACD losses recorded only where bull densities exceeded 0.5 bulls/km2. Effects of bull elephants were, however, spatially restricted and landscape dependent, being especially pronounced along rivers, at mid-elevations, and on steeper slopes. In contrast, elephant herds and abiotic drivers had a comparatively small influence on the direction or magnitude of carbon stock change. Our findings demonstrate that animals can have a substantive influence on regional-scale carbon dynamics and warrant consideration in carbon cycling models and policy formulation aimed at carbon management and climate change mitigation.}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/gcb.14585}, author = {AB, Davies and GP, Asner} } @article {1197709, title = {Are Termite Mounds Always Grazing Hotspots? Grazing Variability with Mound Size, Season and Geology in an African Savanna.}, journal = {Ecosystems}, volume = {22}, year = {2019}, pages = {125-136}, abstract = {Foraging site selection by large herbivores is influenced by multiple factors varying across landscapes and spatial scales. Termite mounds harbour highly nutritious plants compared with the savanna matrix, making them preferred foraging patches in many savannas. However, it is unknown whether termite mounds equally influence herbivore grazing intensity across geological substrates and mound sizes. These knowledge gaps hamper our ability to draw general trans-ecosystem conclusions about the effect of termite mounds for savanna herbivores. We measured grazing intensity on mounds of three different size classes (small, medium and large) across two geologies with differing soil nutrition (granite and basalt) in Gonarezhou National Park, Zimbabwe. We recorded measurements across three seasons (hot wet, cool dry and hot dry), and at multiple distances from mounds. Grazing intensity on mounds was higher on nutrient-poor granite than nutrient-rich basalt, and termite mounds of all sizes had a significant effect on grazing on granite during the cool dry season. Grazing was highest on large mounds on both geologies throughout the year. Large mounds also had the largest spatial influence on grazing in the cool dry season, up to 8 m beyond the mound edge on granite and 2 m on basalt. When scaled up to the landscape level, mounds influenced about 15\% of the granite landscape, but only about 0.5\% of the basalt landscape. Our results show that the positive effects of mounds on grazing intensity were pronounced on nutrient-poor soils but negligible on nutrient-rich soils, and that the magnitude of these effects varied across seasons and with mound size.}, url = {https://link.springer.com/article/10.1007/s10021-018-0257-x}, author = {J, Muvengwi and F, Parrini and ETF, Witkowski and AB, Davies} } @article {1176052, title = {A checklist of the termites of Kruger National Park, South Africa}, journal = {Koedoe }, year = {2019}, pages = {a1531}, abstract = {The protection of biodiversity is critical to ecosystem function and is a primary management goal for conservation areas globally. Maintaining a current inventory of known diversity is a central component of achieving this goal and serves as an essential starting point for future research endeavours. Since the first published survey of termites in South Africa{\textquoteright}s Kruger National Park (KNP) over 55 years ago, our understanding of termite diversity has expanded sufficiently to merit an update and formal checklist. Here we revise the inventory of termite diversity in KNP and summarise the taxonomic and functional diversity of termites in the park. A thorough review of recent termite research in KNP added 6 new genera and 13 species to what was found in Coaton{\textquoteright}s original survey, with one genus, Anenteotermes, recorded for the first time in southern Africa. Based on the updated species checklist, the majority of genera in the park belong to Feeding Group II (39\%) and the Termitidae family (75\%). Conservation implications: In savannas, termites play crucial roles in nutrient cycling, water redistribution and plant dynamics. Systematically cataloguing termite diversity and assemblage composition in the park provides an essential baseline for scientific research, aids biodiversity conservation efforts and encourages scientists and managers to consider termites in ecosystem functioning and management. Having more detailed descriptions of genera, species and feeding groups allows for more tangible, ecologically relevant attributions of termite influence, facilitates enhanced inquiry and allows for more realistic quantification of termite roles in key ecosystem processes. Keywords: termite; Kruger National Park; feeding groups; diversity; savanna.}, url = {https://www.researchgate.net/publication/332302128_A_checklist_of_the_termites_of_Kruger_National_Park_South_Africa}, author = {BM, Lind and AB, Davies} } @article {1176053, title = {Combining behavioural and LiDAR data to reveal relationships between canopy structure and orangutan nest site selection in disturbed forests.}, journal = {Biological Conservation}, volume = {232}, year = {2019}, pages = {97-107}, abstract = {

Primary tropical forests are becoming increasingly disturbed and fragmented, making it critically important to understand the conservation value of degraded forests. Many populations of even the largest and most iconic species are now found outside of primary habitats, and the long-term survival of these and many other species depends on appropriate management of degraded areas, whether protected or not. However, for conservation in degraded habitats to be successful, an adequate understanding of the minimal ecological requirements necessary for species persistence within them is required. We combined ground and helicopter nest surveys of critically endangered Bornean orangutans with high-resolution measurements of forest canopy structure from airborne Light Detection and Ranging (LiDAR) to understand orangutan nest site selection across multiple spatial scales in degraded forests of the Lower Kinabatangan region, Malaysian Borneo. We found orangutans to be selective when choosing nest sites, with nests more likely to be observed in canopies of tall and uniform height and closer to full canopy gaps, which was consistent across spatial scales and orangutan age and sex classes. These sites likely offer orangutans an improved vantage point and/or shelter from wind and rain. In contrast, no discernible relationships between nest site selection and canopy complexity, or nest abundance and landscape forest structure or aboveground carbon density were recorded. Our findings suggest that although orangutans do nest across a range of forest conditions, their optimum requirement for nesting strongly depends on forest patches with sufficient tall canopy of uniform height. These results serve to inform degraded forest conservation strategies across Borneo, particularly where orangutans are a focal species.

}, url = {https://www.sciencedirect.com/science/article/pii/S0006320718312576}, author = {AB, Davies and F, Oram and M, Ancrenaz and GP, Asner} } @article {1197717, title = {Animals and the zoogeochemistry of the carbon cycle.}, journal = {Science}, volume = {362}, year = {2018}, pages = {eaar3213}, abstract = {Predicting and managing the global carbon cycle requires scientific understanding of ecosystem processes that control carbon uptake and storage. It is generally assumed that carbon cycling is sufficiently characterized in terms of uptake and exchange between ecosystem plant and soil pools and the atmosphere. We show that animals also play an important role by mediating carbon exchange between ecosystems and the atmosphere, at times turning ecosystem carbon sources into sinks, or vice versa. Animals also move across landscapes, creating a dynamism that shapes landscape-scale variation in carbon exchange and storage. Predicting and measuring carbon cycling under such dynamism is an important scientific challenge. We explain how to link analyses of spatial ecosystem functioning, animal movement, and remote sensing of animal habitats with carbon dynamics across landscapes.}, url = {https://science.sciencemag.org/content/362/6419/eaar3213/tab-article-info}, author = {OJ, Schmitz and CC, Wilmers and SJ, Leroux and CE, Doughty and TB, Atwood and M, Galetti and AB, Davies and SJ, Goetz} } @article {1207312, title = {No evidence of handling-induced mortality in Serengeti{\textquoteright}s African wild dog population}, journal = {Ecology and Evolution}, volume = {9}, year = {2018}, pages = {1110-1118}, abstract = {The disappearance of an endangered African wild dog population from Serengeti National Park (SNP) led to international debate centered around one question: were researchers to blame? The {\textquotedblleft}Burrows{\textquoteright} hypothesis{\textquotedblright} postulated that stress induced by research-related immobilization and handling reactivated a latent rabies virus, eliminating the population. Insufficient data inhibited hypothesis testing, but since wild dogs persisted alongside SNP and have been studied since 2005, the hypothesis can be tested 25\ years after its proposition. To be supported, wild dog immobilization interventions should have resulted in high mortality rates. However, 87.6\% of 121 handled wild dogs (2006{\textendash}2016) survived \>12\ months post-handling. Some argued that viral reactivation would necessitate long-term stress. Following immobilization, 67 animals were captured, transported, and held in a translocation enclosure. Despite the longer-term stress, 95.5\% survived \>12\ months. Furthermore, the stable number of wild dog packs in the ecosystem over the past decade, and lack of recolonization of SNP, strongly oppose Burrows{\textquoteright} hypothesis. Instead, factors such as heightened levels of interspecific competition are likely to have contributed to the wild dog disappearance and subsequent avoidance of the Serengeti plains. Handling and radio telemetry are invaluable when studying elusive endangered species, yielding information pertinent to their conservation and management, and had no effect on Serengeti wild dog survival.}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.4798}, author = {CR, Jackson and EH, Masenga and EE, Mjingo and AB, Davies and F, Foss{\o}y and RD, Fyumagwa and E, R{\o}skaft and RF, May} } @article {1197736, title = {Geology drives the spatial patterning and structure of termite mounds in an African savanna.}, journal = {Ecosphere}, volume = {9}, year = {2018}, pages = {1-17}, abstract = {Termite mounds perform important roles in savanna ecosystems, generating heterogeneity and influencing ecosystem processes across multiple trophic levels. However, the influence the environment and neighboring termite colonies have on mound spatial patterning and structure is poorly understood, despite the profound implications such dynamics can have on ecosystems. To better understand these drivers, we mapped the spatial distribution and size of active and inactive Macrotermes mounds in eight 1-km2 plots on contrasting geologies, nutrient-rich granite and nutrient-poor basalt, in a semi-arid Zimbabwean savanna. Although mound density was not significantly different between basalt (5.5 mounds/ha) and granite (6.1 mounds/ha), termite mound structural attributes and spatial distribution patterns varied greatly between geologies. Mound size distributions differed between the geologies and mounds were 2.6 times taller and 3.9 times wider and had 15 times greater lateral surface area on granite. Subsequently, 6\% of the total landscape was covered by mounds on granite compared with only 0.4\% on basalt. On granite, large mounds exhibited significant over-dispersion at scales below 30 m, signifying density-dependent thinning. Furthermore, small mounds were clustered around large mounds, likely a result of the budding of new colonies comprising fully fledged castes less vulnerable to competition. In contrast, random patterning was evident on comparably homogenous basalt. Our results demonstrate the powerful influence geological substrate has on mound spatial patterning and structure, suggesting that the importance of termite mounds for ecosystem functioning is more pronounced on nutrient-poor granitic substrates than basalts because of the pronounced over-dispersion, which maximizes mound production per unit area, and much larger mound sizes here.}, url = {https://esajournals.onlinelibrary.wiley.com/doi/10.1002/ecs2.2148}, author = {J, Muvengwi and AB, Davies and F, Parrini and ETF, Witkowski} } @article {1197720, title = {Woody encroachment slows decomposition and termite activity in an African savanna}, journal = { Global Change Biology}, volume = {24}, year = {2018}, pages = {2597-2606}, abstract = {Woody encroachment can lead to a complete switch from open habitats to dense thickets, and has the potential to greatly alter the biodiversity and ecological functioning of grassy ecosystems across the globe. Plant litter decomposition is a critical ecosystem process fundamental to nutrient cycling and global carbon dynamics, yet little is known about how woody encroachment might alter this process. We compared grass decay rates of heavily encroached areas with adjacent nonencroached open areas in a semi-arid South African savanna using litterbags that allowed or excluded invertebrates. We also assessed the effect of woody encroachment on the activity of termites- dominant decomposer organisms in savanna systems. We found a significant reduction in decomposition rates within encroached areas, with litter taking twice as long to decay compared with open savanna areas. Moreover, invertebrates were more influential on grass decomposition in open areas and termite activity was substantially lower in encroached areas, particularly during the dry season when activity levels were reduced to almost zero. Our results suggest that woody encroachment created an unfavourable environment for invertebrates, and termites in particular, leading to decreased decomposition rates in these areas. We provide the first quantification of woody encroachment altering the functioning of African savanna ecosystems through the slowing of aboveground plant decomposition. Woody encroachment is intensifying across the globe, and our results suggest that substantial changes to the carbon balance and biodiversity of grassy biomes could occur.}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/gcb.14118}, author = {M, Leitner and AB, Davies and CL, Parr and P, Eggleton and MP, Robertson} } @article {1197723, title = {Megafaunal effects on vegetation structure throughout a densely wooded African landscape}, journal = {Ecological Applications}, volume = {28}, year = {2018}, pages = {398-408}, abstract = {Megafauna strongly affect vegetation structure and composition, often leading to management concern. However, the extent of their influence across large scales and varying ecosystems remains largely unknown. Using high resolution airborne Light Detection and Ranging (LiDAR), we investigated landscape-scale changes in vegetation height and three-dimensional (3D) structure across landscapes of varying elephant densities and presence over time, and in response to surface water distribution and terrain variability in the heavily managed thicket biome of the Addo Elephant National Park, South Africa. Elephants caused up to a fourfold reduction in vegetation height and altered the vertical profile, but increased vegetation height variability. Vegetation height also increased with elevation and distance from water, particularly in areas that elephants had long occupied at high densities. Slope had opposing effects on vegetation height, with height increasing with slope in areas long exposed to elephants, but decreasing where elephants had only recently been granted access. Our results suggest that elephants are the primary agents of vegetation change in this ecosystem, but that the strength of their effects varies across the landscape, enabling management to use water and terrain as mitigation tools. We further highlight the necessity of landscape-level experimental studies on megafaunal effects to untangle mechanisms and establish causality.}, url = {https://europepmc.org/abstract/med/29178395}, author = {AB, Davies and A, Gaylard and GP, Asner} } @article {1197737, title = {Contrasting termite diversity and assemblages on granitic and basaltic African savanna landscapes}, journal = {Insectes Sociaux}, volume = {65}, year = {2018}, pages = {25-35}, abstract = {Termites are recognised soil ecosystem engineers in the tropics and sub-tropics, making the understanding of their distribution a priority. However, there is a poor understanding of how differences in soil properties and plant biomass productivity affect termite species diversity. We compared the diversity of termites between two soils of differing geological provenance (basalt and granite), and consequently contrasting nutrient content, but subject to similar climatic conditions in a semi-arid Zimbabwean savanna. Basaltic soils contained more dead wood, and were more nutrient-rich than granitic soils, with significantly higher exchangeable Ca and Mg, and available P, and a less acidic pH. However, despite this higher soil nutrient status on basalts, functional and taxonomic termite diversity was higher on granites, although termite abundance was similar between the geological formations. Termite assemblages differed between the geological formations, with very little overlap. We conclude that termite diversity is highly influenced by soil productivity, with nutrient-poor soils having higher diversity, potentially due to reduced competitive exclusion or differences in species adaptation to soil conditions.}, url = {https://link.springer.com/article/10.1007\%2Fs00040-017-0582-7}, author = {J, Muvengwi and AB, Davies and F, Parrini and ETF, Witkowski} } @article {1202053, title = {Effects of anthropogenic disturbance on bird diversity in Ethiopian montane forests}, journal = {The Condor}, volume = {119}, year = {2017}, pages = {416-430}, abstract = {

The Afromontane forests of Ethiopia are global biodiversity hotspots, known for their high biological diversity and endemism. However, conservation of these areas is challenging due to increasing human threats, including encroachment of agriculture and settlements, overgrazing of livestock, and selective logging. We examined the effects of forest disturbances on birds, and highlights the potential conservation value of unprotected tropical montane forests for birds in the dry evergreen Afromontane forests of the Bale Mountains, Ethiopia. We sampled birds across 2 yr in both protected forests (characterized by low levels of cultivation, overgrazing, and logging) and unprotected forests (higher levels of disturbance). Using functional traits of birds related to habitat type, diet, and foraging stratum, we characterized the differences between protected and unprotected forests in terms of avian species richness, abundance, and assemblage composition. Overall, species richness was 27\% higher and bird abundance was 19\% higher in unprotected forests. In contrast, species richness and abundance of forest specialists and canopy foragers were significantly higher in protected forests. These findings suggest that unprotected, disturbed tropical montane forests in Ethiopia help to achieve conservation aims in an area recognized for its global biodiversity importance. At the same time, intact forest ecosystems need continued protection to maximize functional heterogeneity associated with specialist tropical forest taxa.

}, url = {https://academic.oup.com/condor/article/119/3/416/5152916}, author = {A,Asefa and AB, Davies and AE, McKechnie and AA,Kinahan and BJ. van Rensburg} } @article {1197738, title = {Canopy structure drives orangutan habitat use in disturbed Bornean forests}, journal = {Proceedings of the National Academy of Sciences}, volume = {114}, year = {2017}, pages = {8307{\textendash}8312}, abstract = {Bornean orangutans are critically endangered, and their numbers continue to decline despite decades of conservation effort. Management strategies aimed at protecting primary forest are proving insufficient, and new approaches are required to ensure the species{\textquoteright} survival. Here, we use high-resolution laser remote sensing coupled with visual observations of wild orangutans to map canopy structure and quantify orangutan movement through disturbed forests in Borneo. Our findings provide crucial insights into the types of forest characteristics orangutans use in disturbed forests and are likely required for their continued survival in these fragmented landscapes, where most of the extant population occurs. Management and forest restoration efforts that foster these attributes are more likely to succeed at sustaining orangutan populations over the long term.}, url = {https://www.pnas.org/content/114/31/8307.short}, author = {AB, Davies and M, Ancrenaz and F, Oram and GP, Asner} } @article {1197739, title = {Riparian vegetation structure and the hunting behavior of adult estuarine crocodiles}, journal = {PLoS One}, volume = {12}, year = {2017}, pages = {1-12}, abstract = {Riparian ecosystems are amongst the most biodiverse tropical habitats. They are important, and essential, ecological corridors, linking remnant forest fragments. In this study, we hypothesised that crocodile{\textquoteright}s actively select nocturnal resting locations based on increased macaque predation potential. We examined the importance of riparian vegetation structure in the maintenance of crocodile hunting behaviours. Using airborne Light Detection and Ranging (LiDAR) and GPS telemetry on animal movement, we identified the repeated use of nocturnal resting sites by adult estuarine crocodiles (Crocodylus porosus) throughout the fragmented Lower Kinabatangan Wildlife Sanctuary in Sabah, Malaysia. Crocodile resting locations were found to resemble, in terms of habitat characteristics, the sleeping sites of long-tailed macaque; positioned in an attempt to avoid predation by terrestrial predators. We found individual crocodiles were actively selecting overhanging vegetation and that the protrusion of trees from the tree line was key to site selection by crocodiles, as well as influencing both the presence and group size of sleeping macaques. Although these findings are correlational, they have broad management implications, with the suggestion that riparian corridor maintenance and quality can have implications beyond that of terrestrial fauna. We further place our findings in the context of the wider ecosystem and the maintenance of trophic interactions, and discuss how future habitat management has the potential to mitigate human-wildlife conflict.}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0184804}, author = {Evans LJ and AB, Davies and B, Goossens and GP, Asner} } @article {1197741, title = {Termite mounds vary in their importance as sources of vegetation heterogeneity across savanna landscapes}, journal = {Journal of Vegetation Science}, volume = {28}, year = {2017}, pages = {1008-1017}, abstract = {

Questions
Termite mounds are known to host a suite of unique plants compared with the surrounding savanna matrix. However, most studies testing the significance of mounds for ecosystem heterogeneity have been conducted at single sites. Mound effects on savanna heterogeneity across varying landscapes are less well understood, and how effects might vary across geological types and mounds of different sizes is as yet unknown.

Location
Gonarezhou National Park, Zimbabwe.

Methods
We studied effects of termite mounds on vegetation spatial heterogeneity across two geologies (granite and basalt), including effects of mound size and the spatial extent of termite influence. Herbaceous vegetation was sampled on mounds and savanna matrix plots, and along distance transects away from mounds. Soil nutrients on mounds and in the matrix were also compared between geologies.

Results
Soil nutrients were more concentrated in large mounds compared with the matrix on granite, but not on basalt, with mounds therefore acting as nutrient hotspots only on nutrient-poor granite. Large- and medium-sized mounds hosted compositionally different grass species to the matrix on granite, but not on basalt. Large mounds on granite also had significantly lower grass and forb species richness compared with the matrix. However, small mounds on granite, and all mound size categories on basalt, did not have an effect on grass and forb species richness or assemblage composition, an observation attributed to a lack of difference in soil nutrients between the mounds and matrix.

Conclusion
Our study shows that the significance of termite mounds to ecosystem spatial heterogeneity is strongly influenced by geology and mound size, with mound effects on herbaceous plant species heterogeneity more pronounced in dystrophic geologies and around large mounds. Future studies should take greater cognisance of landscape context and mound size when seeking to understand the contribution of termite mounds to ecosystem structure and function.

}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/jvs.12560}, author = {J, Muvengwi and ETF, Witkowski and AB, Davies and F, Parrini} } @article {1202054, title = {Termites and trees. Response to comment on {\textquoteleft}Termite mounds alter the spatial distribution of African savanna tree species{\textquoteright}}, journal = {Journal of Biogeography}, volume = {44}, year = {2017}, pages = {952-955}, abstract = {In a recent correspondence article, Sileshi (2016) argues that several errors were made in our recent analysis of tree species distributions in relation to termite mounds in two African savanna sites (Davies et al., 2016). Specifically, he suggests that we used inappropriate analytical techniques and that our conclusions are not supported by the data, proposing alternative analyses. However, we show here that these criticisms are either erroneous or perhaps stem from misunderstandings of our work that are easily explained. Moreover, when Sileshi performs the suggested alternative analyses, our original conclusions are still supported. Below we present our response to each of Sileshi{\textquoteright}s critiques. We also explain why the statistical analyses performed are appropriate to the questions we sought to address and how our original conclusions are supported by the data.}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/jbi.12975}, author = {AB, Davies and CA, Baldeck and GP, Asner} } @article {1202055, title = {Communication: A few words can make a big impact}, journal = {Nature}, volume = {541}, year = {2017}, pages = {30}, url = {https://www.nature.com/articles/541030e}, author = {D, Del Giudice and AB, Davies} } @article {1202062, title = {No evidence for an elephant-termite feedback loop in Sand Forest, South Africa}, journal = {Biological Conservation}, volume = {203}, year = {2016}, pages = {125-133}, abstract = {Termites and mammalian herbivores might derive mutual benefit from each other through positive feedback loops, but empirical evidence is lacking. One suggested positive feedback loop is between termites and elephant, both ecosystem engineers. Termites, as decomposer organisms, contribute to nutrient cycling and soil enrichment, creating hotspots with increased forage quality. Elephant are known to select these high quality vegetation patches, depositing woody debris when foraging, but it is unknown whether elephant presence might affect termites, and if a feedback loop between these two taxa exists. We tested this hypothesis by measuring termite diversity and activity over three months in the summer wet season, inside and outside a long-term (eight years) elephant exclosure experiment in Sand Forest at Phinda Private Game Reserve, South Africa. Termites were sampled using cellulose baits and woody debris was quantified using line transects. Termite activity was not affected by eight years of elephant absence, despite a greater volume of woody debris where elephant were present. Termite assemblages were similarly unaffected by elephant absence. Apart from Schedorhinotermes, all other termite genera were sampled in both treatments. Therefore, the postulated positive feedback loop between termites and elephant is not supported in Sand Forest. However, this does not contradict findings that areas with high termite activity positively influence herbivore foraging, only that elephant foraging does not affect termite activity. This suggests that elephant disturbance (and elephant management policies) has little to no effect on termites and the fundamental roles they play in ecosystems over at least the short-term.}, url = {https://www.sciencedirect.com/science/article/pii/S0006320716303317}, author = {DDG, Lagendijk and AB, Davies and P, Eggleton and R, Slotow,} } @article {1202057, title = {Den site selection, pack composition, and reproductive success in endangered African wild dogs}, journal = {Behavioral Ecology}, volume = {27}, year = {2016}, pages = {1869-1879}, abstract = {Habitat quality is often assumed to be directly related to increased consumer density, but such assumptions cannot be made without supporting demographic data that indicate improved fitness. Habitat selection might be especially important for denning species, where vulnerable offspring are confined to a single location for extended periods, but the effect of den choice on the reproductive success of denning species is poorly understood. By combining airborne high-resolution Light Detection and Ranging (LiDAR) measurements with data on pack composition, we investigated den site selection by endangered African wild dogs in Hluhluwe-iMfolozi Park, South Africa, examining whether habitat selection based on ecological factors resulted in increased litter sizes and thus reproductive success compared with social factors known to be important. Although there was selection for den sites in areas of increased terrain ruggedness and vegetation density, only vegetation density was associated with larger litter sizes and translated into increased reproductive success. Moreover, pack size was only influential when a minimum vegetation density around den sites was achieved, indicating that although social variables have a powerful effect on reproductive success, they are mediated by ecological factors defining habitat quality. Our results demonstrate the importance of distinguishing between density- and fitness-based indicators of habitat quality, and how this can affect management actions, particularly for endangered species conservation.}, url = {https://academic.oup.com/beheco/article/27/6/1869/2453496}, author = {AB, Davies and DG, Marneweck and DJ, Druce and GP, Asner} } @article {1202897, title = {Termite mounds differ in their importance for herbivores across savanna types, seasons and spatial scales}, journal = {Oikos}, volume = {125}, year = {2016}, pages = {726-734}, abstract = {

Herbivores do not forage uniformly across landscapes, but select for patches of higher nutrition and lower predation risk. Macrotermes mounds contain higher concentrations of soil nutrients and support grasses of higher nutritional value than the surrounding savanna matrix, attracting mammalian grazers that preferentially forage on termite mound vegetation. However, little is known about the spatial extent of such termite influence on grazing patterns and how it might differ in time and space. We measured grazing intensity in three African savanna types differing in rainfall and foliar nutrients and predicted that the functional importance of mounds for grazing herbivores would increase as the difference in foliar nutrient levels between mound and savanna matrix grasses increases and the mounds become more attractive. We expected this to occur in nutrient-poor areas and during the dry season when savanna matrix grass nutrient levels are lower. Tuft use and grass N and P content were measured along transects away from termite mounds, enabling calculation of the spatial extent of termite influence on mammalian grazing. Using termite mound densities estimated from airborne light detection and ranging (LiDAR), we further upscaled field-based results to determine the percentage of the landscape influenced by termite activity. Grasses in close proximity to termite mounds were preferentially grazed at all sites and in both seasons, but the strength of mound influence varied between savanna types and seasons. In the wet season, mounds had a relatively larger effect on grazers at the landscape scale in the nutrient-poor, wetter savanna, whereas in the dry season the pattern was reversed with more of the landscape influenced at the nutrient-rich, driest site. Our results reveal that termite mounds enhance the value of savanna landscapes for herbivores, but that their functional importance varies across savanna types and seasons.

}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/oik.02742}, author = {AB, Davies and SR, Levick and MP, Robertson and van Rensburg BJ and GP, Asner and CL, Parr} } @article {1202065, title = {Limited spatial response to predation risk by African herbivores following predator reintroduction}, journal = {Ecology and Evolution}, volume = {6}, year = {2016}, pages = {5728-5748}, abstract = {Predators affect ecosystems not only through direct mortality of prey, but also through risk effects on prey behavior, which can exert strong influences on ecosystem function and prey fitness. However, how functionally different prey species respond to predation risk and how prey strategies vary across ecosystems and in response to predator reintroduction are poorly understood. We investigated the spatial distributions of six African herbivores varying in foraging strategy and body size in response to environmental factors and direct predation risk by recently reintroduced lions in the thicket biome of the Addo Elephant National Park, South Africa, using camera trap surveys, GPS telemetry, kill site locations and Light Detection and Ranging. Spatial distributions of all species, apart from buffalo, were driven primarily by environmental factors, with limited responses to direct predation risk. Responses to predation risk were instead indirect, with species distributions driven by environmental factors, and diel patterns being particularly pronounced. Grazers were more responsive to the measured variables than browsers, with more observations in open areas. Terrain ruggedness was a stronger predictor of browser distributions than was vegetation density. Buffalo was the only species to respond to predator encounter risk, avoiding areas with higher lion utilization. Buffalo therefore behaved in similar ways to when lions were absent from the study area. Our results suggest that direct predation risk effects are relatively weak when predator densities are low and the time since reintroduction is short and emphasize the need for robust, long-term monitoring of predator reintroductions to place such events in the broader context of predation risk effects.}, url = {https://onlinelibrary.wiley.com/doi/full/10.1002/ece3.2312}, author = {AB, Davies and CJ, Tambling and GIH, Kerley and GP, Asner} } @article {1202868, title = {Soil biota in a megadiverse country: current knowledge and future research directions in South Africa}, journal = {Pedobiologia}, volume = {59}, year = {2016}, pages = {129-174}, abstract = {Soils are integral to agricultural productivity, biodiversity, and the maintenance of ecosystem services. However, soil ecosystem research depends on foundational biological knowledge that is often missing. In this review, we present a comprehensive, cross-taxa overview of the soil biota of South Africa. We discuss the literature and sampling methods used to assess soil biota, the available taxonomic expertise and main collections within South Africa, the availability of identification guides and online resources, and the status and distribution of described species. We include species lists for all South African soil biota and, for groups with sufficient distribution records, species richness maps. Despite South Africa being only 0.8\% of the earth{\textquoteright}s terrestrial area, it contains nearly 1.8\% of the world{\textquoteright}s described soil species (mean per taxon 3.64\%, range 0.17{\textendash}15\%; n = 36 groups), with nematodes and earthworms showing a remarkable (6.4 and 7.7\%) proportion of globally described diversity. Endemism is high for most groups, ranging from 33{\textendash}92\%. However, major knowledge gaps exist for most soil biota groups. While sampling has been relatively comprehensive in some areas for a few groups (particularly those with direct socioeconomic impacts), the Nama-Karoo, Northern Cape and Eastern Cape are poorly sampled. Natural soils in biodiversity hotspots, such as the Fynbos Biome, are also understudied. We argue that a more integrative approach to acquiring foundational knowledge in soil biodiversity is needed if applied soil research is to be effective in ensuring sustainable soil health. Considerable investment will be required to bring our understanding of the soil biodiversity in this megadiverse region to a level where the Millennium Development Goals can be reached.}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0031405616300099}, author = {C, Janion-Scheepers and J, Measey and B, Braschler and SL, Chown and L, Coetzee and JF, Colville and J, Dames and AB, Davies and et al.} } @article {1202888, title = {Termite mounds alter the spatial distribution of African savanna trees}, journal = {Journal of Biogeography}, volume = {43}, year = {2016}, pages = {301-313}, abstract = {

Aim

Termite mounds form small islands of enhanced water and soil nutrient availability on otherwise dry and nutrient-poor hill crests, which can have important impacts on the plant community. However, the way in which termite mounds alter the spatial distribution of particular tree species across broad savanna landscapes is poorly understood. We aimed to understand the nature and extent of the relationship between termite mounds and key woody savanna species at landscape scales through the use of airborne remote sensing.

Location

Kruger National Park, South Africa.

Methods

We mapped 9894 termite mounds and 666,679 savanna trees from 15 species across two landscapes with contrasting rainfall regimes using airborne imaging spectroscopy and LiDAR data. We then examined changes in tree species densities and community composition with respect to distance from termite mounds.

Results

In both landscapes, termite mounds reduced overall tree densities over distances up to 10\ m from mound centres. However, the effect of termite mounds on tree density differed among species, with some species, typically associated with lowland and riparian habitats, showing increased density near termite mounds. Indeed, changes in overall tree community composition revealed that termite mounds harbour tree communities similar to lowland communities, with this similarity decreasing with increased distance from the nearest mound. Termite effects were more pronounced in the savanna landscape receiving higher annual rainfall, whereas a greater percentage of the landscape was affected in the drier landscape due to higher mound densities.

Main conclusions

Termite mounds mediate the spatial distribution of tree species in savanna landscapes, increasing the abundance of tree species typically associated with lowland habitats. This contributes to the spatial heterogeneity of savanna vegetation within landscapes and the maintenance of savanna biodiversity.

}, url = {https://onlinelibrary.wiley.com/doi/abs/10.1111/jbi.12633}, author = {AB, Davies and CA, Baldeck and GP, Asner} } @article {1202177, title = {Seasonal variation in the dominant herbivore consumer in an African savanna}, journal = {Ecology}, volume = {97}, year = {2016}, pages = {1618{\textendash}1624}, abstract = {

African savannas are highly seasonal with a diverse array of both mammalian and invertebrate herbivores, yet herbivory studies have focused almost exclusively on mammals. We conducted a 2-yr exclosure experiment in South Africa{\textquoteright}s Kruger National Park to measure the relative impact of these two groups of herbivores on grass removal at both highly productive patches (termite mounds) and in the less productive savanna matrix. Invertebrate and mammalian herbivory was greater on termite mounds, but the relative importance of each group changed over time. Mammalian offtake was higher than invertebrates in the dry season, but can be eclipsed by invertebrates during the wet season when this group is more active. Our results demonstrate that invertebrates play a substantial role in savanna herbivory and should not be disregarded in attempts to understand the impacts of herbivory on ecosystems.

}, url = {https://esajournals.onlinelibrary.wiley.com/doi/10.1890/15-1905.1}, author = {AB, Davies and BL, van Rensburg and MP, Robertson and SR, Levick and GP, Asner and CL, Parr} } @article {1202864, title = {Suppression of savanna ants alters invertebrate composition and influences key ecosystem processes}, journal = {Ecology}, volume = {97}, year = {2016}, pages = {1611-1617}, abstract = {In almost every ecosystem, ants (Hymenoptera: Formicidae) are the dominant terrestrial invertebrate group. Their functional value was highlighted by Wilson (1987) who famously declared that invertebrates are the {\textquotedblleft}little things that run the world.{\textquotedblright} However, while it is generally accepted that ants fulfil important functions, few studies have tested these assumptions and demonstrated what happens in their absence. We report on a novel large-scale field experiment in undisturbed savanna habitat where we examined how ants influence the abundance of other invertebrate taxa in the system, and affect the key processes of decomposition and herbivory. Our experiment demonstrated that ants suppressed the abundance and activity of beetles, millipedes, and termites, and also influenced decomposition rates and levels of herbivory. Our study is the first to show that top-down control of termites by ants can have important ecosystem consequences. Further studies are needed to elucidate the effects ant communities have on other aspects of the ecosystem (e.g., soils, nutrient cycling, the microbial community) and how their relative importance for ecosystem function varies among ecosystem types (e.g., savanna vs. forest).}, url = {https://esajournals.onlinelibrary.wiley.com/doi/full/10.1890/15-1713.1}, author = {CL, Parr and P, Eggleton and AB, Davies and TA, Evans and Holdsworth, S} } @article {1202865, title = {Effects of vegetation structure on the location of lion kill sites in African thicket}, journal = {PLoS ONE }, volume = {11}, year = {2016}, pages = {e0149098}, abstract = {Predator-prey relationships are integral to ecosystem stability and functioning. These relationships are, however, difficult to maintain in protected areas where large predators are increasingly being reintroduced and confined. Where predators make kills has a profound influence on their role in ecosystems, but the relative importance of environmental variables in determining kill sites, and how these might vary across ecosystems is poorly known. We investigated kill sites for lions in South Africa{\textquoteright}s thicket biome, testing the importance of vegetation structure for kill site locations compared to other environmental variables. Kill sites were located over four years using GPS telemetry and compared to non-kill sites that had been occupied by lions, as well as to random sites within lion ranges. Measurements of 3D vegetation structure obtained from Light Detection and Ranging (LiDAR) were used to calculate the visible area (viewshed) around each site and, along with wind and moonlight data, used to compare kill sites between lion sexes, prey species and prey sexes. Viewshed area was the most important predictor of kill sites (sites in dense vegetation were twice as likely to be kill sites compared to open areas), followed by wind speed and, less so, moonlight. Kill sites for different prey species varied with vegetation structure, and male prey were killed when wind speeds were higher compared to female prey of the same species. Our results demonstrate that vegetation structure is an important component of predator-prey interactions, with varying effects across ecosystems. Such differences require consideration in terms of the ecological roles performed by predators, and in predator and prey conservation.}, url = {https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0149098}, author = {AB, Davies and CJ, Tambling and GIH, Kerley and GP, Asner} } @article {1202174, title = {Integrating technologies for scalable ecology and conservation}, journal = {Global Ecology and Conservation}, volume = {7}, year = {2016}, pages = {262-275}, abstract = {Integration of multiple technologies greatly increases the spatial and temporal scales over which ecological patterns and processes can be studied, and threats to protected ecosystems can be identified and mitigated. A range of technology options relevant to ecologists and conservation practitioners are described, including ways they can be linked to increase the dimensionality of data collection efforts. Remote sensing, ground-based, and data fusion technologies are broadly discussed in the context of ecological research and conservation efforts. Examples of technology integration across all of these domains are provided for large-scale protected area management and investigation of ecological dynamics. Most technologies are low-cost or open-source, and when deployed can reach economies of scale that reduce per-area costs dramatically. The large-scale, long-term data collection efforts presented here can generate new spatio-temporal understanding of threats faced by natural ecosystems and endangered species, leading to more effective conservation strategies.}, url = {https://www.sciencedirect.com/science/article/pii/S2351989416300592}, author = {DC, Marvin and LP, Koh and AJ, Lynam and S, Wich and AB, Davies and R, Krishnamurthy and E, Stokes and R, Starkey and GP, Asner} } @article {1204127, title = {Afrotyphlops schlegelii: Termite mound access behaviour}, journal = {African Herp News}, volume = {62}, year = {2015}, pages = {16-22}, url = {http://africanherpetology.org/wp/wp-content/uploads/2018/12/AHN-62-2015.pdf}, author = {B, Bokhout and L, Verburgt and AB, Davies} } @article {1204126, title = {Habitat differences do not explain population declines of sable antelope in an African savanna}, journal = {Journal of Zoology }, volume = {297}, year = {2015}, pages = {225-234}, abstract = {Sable antelope, Hippotragus niger, populations have declined substantially in Kruger National Park, South Africa despite large-area protection from land use and poaching. Since Africa{\textquoteright}s large mammal populations are restricted to protected areas, understanding how to manage parks for biological diversity is critically important to the sustainability of faunal populations into the future. To better understand the drivers of sable decline, we analyzed landscapes where herds persist in the Pretoriuskop region of Kruger {\textendash} identified by GPS collar telemetry data from eight individuals in five herds remaining in this area, and compared them to landscapes where sable herds have recently disappeared. We mapped these landscapes with satellite-based spectral data on vegetation greenness and fire frequency and Carnegie Airborne Observatory LiDAR (Light Detection and Ranging) data on 3-D vegetation structure. Within their home ranges, sable herds consistently selected areas with high fire frequency, high tree cover and low shrub cover. However, there were no consistent differences in habitat features between the home ranges of current sable herds and areas formerly supporting herds. Locally deteriorating habitat conditions were therefore not responsible for the decline in sables in this region of the park. Our study also illustrates how multi-sensor, 3-D mapping of ecosystems provides a means to assess causes and consequences of changing animal habitats over time.}, url = {https://zslpublications.onlinelibrary.wiley.com/doi/full/10.1111/jzo.12269}, author = {GP, Asner and N, Owen-Smith and SR, Loarie and AB, Davies and E, Le Roux and SR, Levick} } @article {1204133, title = {Seasonal activity patterns of African savanna termites vary across a rainfall gradient}, journal = {Insectes Sociaux}, volume = {62}, year = {2015}, pages = { 157-165}, abstract = {Seasonal variations in temperature and moisture are strong drivers of biological activity and diversity. Termites are an important insect group previously shown to respond to seasonal variation, but results are mixed with unclear patterns across habitat types. We investigated seasonal variation in termite species density, activity levels and assemblage composition across three seasons (wet, transitional and dry) and four savanna types across a rainfall gradient (450{\textendash}900 mm year-1) in South Africa using cellulose baits. Termites responded to seasonality in all savannas investigated, with lower species density and activity levels during the dry season compared to the wet and transitional seasons. In the more arid sites (<=550 mm rainfall per year) activity levels were highest in the wet season, while at wetter sites (>=750 mm rainfall per year) the highest activity was recorded in the transitional season. Assemblage composition did not differ much between seasons across all sites, but differences in both composition and activity levels across seasons were more pronounced in wetter sites compared to drier ones. Our results demonstrate that seasonal patterns in termite diversity vary with mean annual rainfall, with larger variation in wetter habitats where climatic variation between seasons is greater.}, url = {https://link.springer.com/article/10.1007/s00040-014-0386-y}, author = {AB, Davies and P, Eggleton and van Rensburg BJ and CL, Parr} } @article {1204165, title = {Advances in animal ecology from 3D-LiDAR ecosystem mapping}, journal = {Trends in Ecology and Evolution~}, volume = {29}, year = {2014}, pages = {681-691}, abstract = {The advent and recent advances of Light Detection and Ranging (LiDAR) have enabled accurate measurement of 3D ecosystem structure. Here, we review insights gained through the application of LiDAR to animal ecology studies, revealing the fundamental importance of structure for animals. Structural heterogeneity is most conducive to increased animal richness and abundance, and increased complexity of vertical vegetation structure is more positively influential compared with traditionally measured canopy cover, which produces mixed results. However, different taxonomic groups interact with a variety of 3D canopy traits and some groups with 3D topography. To develop a better understanding of animal dynamics, future studies will benefit from considering 3D habitat effects in a wider variety of ecosystems and with more taxa.}, url = {https://www.sciencedirect.com/science/article/pii/S0169534714002249}, author = {AB, Davies and GP, Asner} } @article {1204170, title = {Spatial variability and abiotic determinants of termite mounds throughout a savanna catchment}, journal = {Ecography}, volume = {37}, year = {2014}, pages = {852-862}, abstract = {Termite mounds contribute to the spatial heterogeneity of ecological processes in many savannas, but the underlying patterns and determinants of mound distributions remain poorly understood. Using the Carnegie Airborne Observatory (CAO), we mapped the distribution of termite mounds across a rainfall gradient within a river catchment (\~{} 27 000 ha) of the Kruger National Park, South Africa. We assessed how different factors were associated with the distribution and height of termite mounds at three spatial scales: the entire catchment, among three broad vegetation types, and on individual hillslope crests. Abiotic factors such as the underlying geology and mean annual precipitation shaped mound densities at broad scales, while local hillslope morphology strongly influenced mound distribution at finer scales, emphasising the importance of spatial scale when assessing mound densities. Fire return period had no apparent association with mound densities or height. Mound density averaged 0.46 mounds ha-1, and exhibited a clustered pattern throughout the landscape, occurring at relatively high densities (up to 2 mounds ha-1) on crests, which are nutrient-poor elements of the landscape. Mounds exhibited significant over-dispersion (even spacing) at scales below 60 m so that evenly spaced aggregations of termite mounds are embedded within a landscape of varying mound densities. The tallest mounds were found in dry savanna (500 mm yr-1) and were positively correlated with mound density, suggesting that dry granitic savannas are ideal habitat for mound-building termites. Mound activity status also varied significantly across the rainfall gradient, with a higher proportion of active (live) mounds in the drier sites. The differential spacing of mounds across landscapes provides essential nutrient hotspots in crest locations, potentially sustaining species that would otherwise not persist. The contribution to biodiversity and ecosystem functioning that mounds provide is not uniform throughout landscapes, but varies considerably with spatial scale and context.}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/ecog.00532}, author = {AB, Davies and SR, Levick and GP, Asner and MP, Robertson and van Rensburg BJ and CL, Parr} } @article {1204167, title = {Variable effects of termite mounds on African savanna grass communities across a rainfall gradient}, journal = {Journal of Vegetation Science }, volume = {25}, year = {2014}, pages = {1405-1416}, abstract = {

Questions
Termite mounds of the genus Macrotermes are prominent features in African savannas, forming nutrient hotspots that support greater plant diversity, which is of higher nutritional value than the surrounding savanna matrix. However, little is known about grass communities on and around mounds or how the functional importance of mounds varies across sites. As mean annual rainfall increases, savannas in southern Africa become increasingly dystrophic through increased denitrification (including pyrodenitrification) and the leaching of soil nutrients. The functional importance of mounds is concomitantly expected to increase as the difference in foliar nutrient levels between mounds and the savanna matrix increases. We tested this prediction on grass communities across a rainfall gradient to: (i) determine the degree to which grass assemblages differ between termite mounds and the savanna matrix; (ii) determine the spatial extent to which mounds influence grass communities; and (iii) investigate whether these patterns differ across savanna types.

Location
Kruger National Park, South Africa.

Methods
Grass communities were surveyed at three savanna sites differing in mean annual rainfall (550{\textendash}750 mm{\textperiodcentered}yr-1). Grass diversity and tissue nitrogen concentrations were measured on and off termite mounds and along transects away from mounds in order to calculate the spatial influence of termite mounds on savanna grass communities. Using termite mound densities estimated from airborne LiDAR, we up-scaled field-based results to determine the percentage of the landscape influenced by Macrotermes termite activity.

Results
Although species richness of grasses was lower on mounds than in the savanna matrix, the assemblage composition varied significantly, with higher nutrient concentrations in grasses located on mounds. This pattern became more distinct with increasing rainfall. The spatial extent of these nutrient-rich grasses also differed across the rainfall gradient, with a larger sphere of influence around mounds in wetter areas. Mounds distinctly altered grass communities over ca. 2\% of the entire landscape. Conclusions
Our results show that Macrotermes mounds are important components of savanna heterogeneity, and reveal that the functional importance of mounds increases with increasing rainfall.

Nomenclature
van Oudtshoorn (1999)

}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/jvs.12200}, author = {AB, Davies and MP, Robertson and SR, Levick and GP, Asner and van Rensburg BJ and CL, Parr} } @article {1204172, title = {Assessing the relative efficiency of termite sampling methods along a rainfall gradient in African savannas}, journal = {Biotropica}, volume = {45}, year = {2013}, pages = {474-479}, abstract = {Although termites are ecosystem engineers in tropical and sub-tropical environments, the study of termite ecology is often constrained by sampling difficulties and a lack of established sampling protocols, particularly for savannas. The efficiency and relevance of different methods along climatic gradients, even within a single biome, is largely unknown. Here, we compare the relative contribution of two commonly used sampling methods, cellulose baits and active searching transects, in quantifying savanna termite diversity along a rainfall gradient in South Africa; sampling was conducted during the wet season across four markedly different savanna types. We also assessed the usefulness of different forms of baiting techniques. The relative efficiency of sampling method varied with annual rainfall. In arid savannas, baiting was as effective as active searching transects at sampling termite diversity and we recommend the use of baiting rather due to it being less labor intensive. In savannas of moderately low to intermediate rainfall, baiting and transects sampled different termite species and so both are deemed necessary for an accurate assessment of termite diversity. In contrast, in wetter savannas transects gave a better assessment of diversity, with cellulose baits not contributing much to diversity assessment. The efficiency of baiting techniques differed across the rainfall gradient, with baits needing to be left in the field for a longer period in more arid savannas. We conclude that habitat type, even within a single biome, will determine the sampling method or methods necessary to quantify termite diversity accurately.}, url = {https://onlinelibrary.wiley.com/doi/full/10.1111/btp.12030}, author = {AB, Davies and P, Eggleton and van Rensburg BJ and CL, Parr} } @article {1204171, title = {Interactive effects of fire, rainfall and litter quality on decomposition in savannas: frequent fire leads to contrasting effects}, journal = {Ecosystems}, volume = {16}, year = {2013}, pages = {866-880 }, abstract = {One of the many ecological processes expected to undergo alteration due to global change is the decomposition of organic matter, with little known concerning the effects that changing disturbance regimes may have. Fire, a critical process in many habitats, is expected to become more common. We measured the decomposition rates of four grass species that differed in litter quality, investigating them under different fire regimes across a savanna rainfall gradient in South Africa. We also collected data on the abundance and activity of fungus-growing termites and recorded measurements of temperature and canopy cover. Overall, decomposition rate followed global models, increasing under warmer and wetter conditions. Litter quality was also significant with higher quality grasses decomposing faster; however, this effect was less pronounced than expected. Fire regimes did not have a consistent effect on decomposition rate along the rainfall gradient. In the most arid savanna type examined, fire had no effect, whereas in the intermediate rainfall savanna burning increased decomposition rate under higher levels of fungus-growing termite activity. In the wetter savannas, fire slowed decomposition, possibly through modification of vegetation structure and potential effects on other invertebrates. Our results demonstrate that grass decomposition in African savannas varies significantly along precipitation gradients, with different factors becoming influential in different habitats. Importantly, we demonstrate that fire does not always act to slow decomposition and that it interacts with other factors to influence the process. These findings have important implications for decomposition in the light of global change models that predict wetter climates and a higher frequency of fires for southern African savannas.}, url = {https://link.springer.com/article/10.1007/s10021-013-9657-0}, author = {AB, Davies and van Rensburg BJ and P, Eggleton and CL, Parr} } @article {1204182, title = {Australia: no price on cutting fire risk}, journal = {Nature}, volume = {482}, year = {2012}, pages = {471}, abstract = {

David Bowman proposes that elephants should be introduced into Australia as a cost-effective way to control invasive gamba grass, a major source of wildfire fuel (Nature482, 30; 2012). But managing the elephants could be more expensive than, say, launching a fleet of harvesters every year to reduce fire risk. We should start by asking what is likely to work best, regardless of the cost. To combat the problems caused by invasive aliens, we should implement ecologically sound control mechanisms that have a reasonable probability of success. We can worry about the bill later.

}, url = {https://rdcu.be/bJEsw}, author = {PJN, de Bruyn and AB, Davies} } @article {1204181, title = {The pyrodiversity-biodiversity hypothesis: a test with savanna termite assemblages}, journal = {Journal of Applied Ecology}, volume = {49}, year = {2012}, pages = {422-430}, abstract = {

1. Fire is an important disturbance in African savannas where it is generally assumed that high levels of pyrodiversity (variation in aspects of the fire regime) are necessary to maintain high levels of biodiversity. There is, however, little empirical evidence in support of this hypothesis for animals. Furthermore, the relationship between pyrodiversity and biodiversity may vary with different savanna types, shaped by mean annual precipitation.

2. We made use of a long-term burning experiment to investigate the effect of interactions between precipitation and pyrodiversity on biodiversity. We sampled termites (major ecosystem engineers in savannas) within experimental plots involving a range of fire seasons and frequencies. Sampling was conducted in three distinct savanna types along a rainfall gradient in South Africa. We explored how termite diversity varied with mean annual precipitation and whether faunal responses to fire regimes varied with rainfall. Termites were sampled comprehensively during the wet season using cellulose baits and active searching in order to sample a variety of functional groups.

3. Assemblages differed significantly across savanna types with higher levels of diversity in the wetter site using the active searching method. Diversity was lowest at the most arid site but certain feeding groups (FGs) peaked in the savanna with intermediate rainfall. Differences between these savannas are attributed to broad underlying changes in net primary productivity and temperature, with mammalian herbivores thought to generate a peak in diversity of some faunal groups at the intermediate savanna through their role in facilitating nutrient cycling.

4. Overall, termites were highly resistant to fire in all savanna types with little difference between fire regimes (season and frequency), but assemblage composition and some FGs were affected by burning. Differences between fire regimes were more pronounced with increasing rainfall. These differences are likely to be linked to changes in vegetation structure caused by fire, which are more significant in wet savannas.

5. Synthesis and applications. Our findings, along with those for other insect taxa, indicate limited support for the pyrodiversity{\textendash}biodiversity hypothesis; this suggests that, at least for invertebrates, management regimes can be flexible, although more caution is advisable in wetter savannas.

}, url = {https://besjournals.onlinelibrary.wiley.com/doi/full/10.1111/j.1365-2664.2012.02107.x}, author = {AB, Davies and P, Eggleton and van Rensburg BJ and CL, Parr} } @article {1204183, title = {Termites and fire in Africa: current understanding and future research directions for improved savanna conservation}, journal = {Austral Ecology}, volume = {35}, year = {2010}, pages = {482-486}, abstract = {While tropical savannas and grasslands typically attract less attention than temperate systems (see, e.g. Gaston et al. 1998 and references therein indicating the general lack of biological data at low latitudes), they represent one of the dominant biomes of the southern hemisphere, and indeed the world, with savannas covering an estimated 12.5\% of global land area and over half of Africa and Australia, 45\% of South America and 10\% of India and Southeast Asia (Scholes \& Archer 1997). Fire is considered one of the most important disturbances in these grassy systems being both frequent and widespread across Australian, African and South American savannas (Bond \& Keeley 2005). The exceptional diversity and biomass of invertebrates has been long recognized, as has their functional importance in ecosystem services across the globe (Wilson 1987). Fire and invertebrates are thus key components determining the functioning and dynamics of savannas (Parr et al. 2004; van Wilgen et al. 2007), as well as other systems around the world (e.g. boreal forests {\textendash} McCullough et al. 1998). Yet, generally scientists, and more especially conservation managers, have a poor understanding and limited predictive capacity of the way in which invertebrate communities respond to fire and the implications for diversity and functioning in savanna systems. This was highlighted for the southern hemisphere by Parr and Chown (2003) who reviewed fire and invertebrate studies in southern Africa. A search on Web of Science using the keywords {\textquoteleft}insect*{\textquoteright} and {\textquoteleft}Africa{\textquoteright} with either {\textquoteleft}fire*{\textquoteright} or {\textquoteleft}burning{\textquoteright} revealed that since the review by Parr and Chown (2003) only three additional papers and one book chapter dealing with fire and invertebrates in Africa have been published (Parr et al. 2004; Axmacher et al. 2006; Uys et al. 2006; Underwood \& Christian 2009); this indicates little has changed since 2003. Similarly and for the same time period, work conducted at the global scale is also limited in its contribution to our broader understanding of the ecological processes involved when studying fire and invertebrate interactions. The lack of knowledge on invertebrates and fire is thus an important shortcoming to understanding how savanna systems are structured and function, and also when managing for the conservation of biodiversity, especially as savannas are often subject to intense fire management (van Wilgen et al. 2007). In tropical and subtropical areas, including savannas, termites are considered key ecosystem engineers, altering the mineral and organic composition of soils, their hydrology, drainage (Jones et al. 1994) and infiltration rates (Mando et al. 1996), as well as influencing decomposition, nutrient cycling and distribution (Holt \& Coventry 1990; Scholes 1990; Lepage et al. 1993; Konat{\'e} et al. 1999). Their vast biomass alone makes them an important consideration in tropical and subtropical ecology (Josens 1983) and they are considered the dominant arthropod decomposer in tropical forests and savannas (Collins 1981; Holt 1987; Schuurman 2005). Termites are also a diverse and varied group comprising of several functional groups, including wood feeders, grass harvesters and soil feeders (Josens 1983). Although it is somewhat surprising that relative to other invertebrate groups termite work is scarce with even basic natural history information lacking for many species (Dangerfield \& Schuurman 2000; DawesGromadzki 2003), this is likely because there are sampling and taxonomic difficulties associated with the group (Josens 1983). Here we use examples of studies conducted in savannas across the globe to highlight what we see as a critical research gap: the lack of published information on the interactions between termites specifically (Blattaria: Termitidae) and fire. Furthermore, we propose that if protected areas in savannas are to uphold their mandate of conserving biodiversity in its entirety, then a better ecological understanding of interactions between fire and termites is crucial for achieving this. The aims of this paper are therefore to highlight what we perceive as a paucity of studies on the topic, to demonstrate that critical information is still lacking, and to look towards potential future research directions.We compare studies from several continents and suggest ways in which the termite fauna of these continents could vary in their response to fire and some resultant ecological implications of this, particularly for the southern hemisphere.}, url = {https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1442-9993.2010.02124.x}, author = {AB, Davies and CL, Parr and van Rensburg BJ} }