The role of termites in the decomposition of wood and leaf litter in the Southern Guinea savanna of Nigeria

Abstract

This is part of a study on the litter dynamics of Southern Guinea savanna, with special reference to the role of termites (Isoptera) as decomposers of wood and leaves. The biomass of accumulated wood litter on the 6 ha study area varied from 2.299 to 3.488 t ha^-1, with a mean of 2.821 t ha^-1 Leaf litter biomass varied from 0.290 to 1.643 t ha^-1, with a mean of 0.903 t ha^-1. The measured decomposition constant for wood of 51% a^-1 agreed well with a calculated value of 49% a^-1. Leaf decomposition was calculated as 264% a^-1. Termites removed an estimated 835.5 kg ha^-1a^-1 of wood litter (60% of annual wood-fall), and 68.4 kg ha^-1a^-1 of leaf litter (3% of annual leaf-fall), i.e. 24% of total annual litter production. Conversely, the annual bush-fire removed 1.173 t ha^-1a^-1 (49%) of annual leaf-fall but only 3 kg ha^-1a^-1 (0.2%) of annual wood-fall, i.e. 31% of total annual litter production. Baiting studies showed that the fungus-growing Macrotermitinae took 95% of the litter removed by termites (23% of annual litter production). The ability of the Macrotermitinae to utilise fresh litter is a diagnostic feature of decomposition processes in Southern Guinea and other savanna ecosystems. Their fungus combs produce a processed diet which allows the Macrotermitinae to feed in a seasonally arid environment where the curtailment of free fungal and microbial activity inhibits feeding by other decomposer invertebrates.