Termites and fire in Africa: current understanding and future research directions for improved savanna conservation

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 – 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 ‘insect*’ and ‘Africa’ with either ‘fire*’ or ‘burning’ 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; Konaté 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.