Termites and the Nitrogen Cycle

Desert termites are important for the microflora in their guts. Like mesquite trees, termites are simplistically seen as pests because they occasionally remove grass and other surface vegetation, particularly during drought (Plate 6). As in the case of mesquite, if termites are poisoned in an area of arid grassland, a pulse of grass productivity ensues as termite bodies release nutrients (Parker et al., 1982). This result is taken to indicate that termites are a negative factor for grass production.

Termites are important in the South Texas ecosystem, and caution should be used in interpreting and applying short term, narrowly focused experiments on termite removal. For one thing, desert termites, or rather their gut flora, are now known to fix atmospheric nitrogen (Schaefer and Whitford, 1981). Furthermore, they remove organic carbon from the surface, especially during drought, so that less of that resource is available to denitrifying bacteria near the soil surface when rains return. Termites also protect mesquite-fixed nitrogen from volatilization and/or leaching by moving it well underground where it is stored in termite biomass. In the short term, this nitrogen is not available to the shallow rooted grasses of the system (Parker et al., 1982) but in the long run it is, as the mating flights after rains put millions of termites into the food chain across the entire landscape (Schaefer and Whitford, 1981). Like shrub clumps, termites fix, accumulate, protect and slowly leak mineralized nitrogen into the system. We need to know much more about these and other desert detritivores (El-Ayouty et al., 1978: Crawford, 1979) before planning to remove or manipulate them.