Termite flights seasonally promote nutrient pulses in the Caatinga dry forest in northeastern Brazil

Abstract

Termites have a high biomass in tropical ecosystems, exerting a marked influence on the populations of their predators and on the processes of decomposition and formation of soils. During seasonal dispersion flights, colonies release a large number of alate individuals, however, the nutrient pools involved in this process are not known. The present study estimated the nutrient yields transferred at ground level from termite dispersion flights in an area of dry forest Caatinga, in the semiarid region of Brazil. For this purpose, trays employed on the ground for 12 months collected the alates. The annual biomass of the alates at ground level was estimated at 0.588 g (dry mass) m−2, corresponding to a density of 164 individuals m−2. Annual transfers of C and N were estimated at 0.280 g m−2 and 0.039 g m−2, respectively. The C and N represented 54.11 and 8.11% of the alates dry mass, respectively, with an average C:N ratio of 6.8:1. An annual yield of protein 2.3 kg ha−1 and fat 2.7 kg ha−1 was estimated, corresponding to 39,365 kcal ha−1. Alates flights transfer nutrients to the soil, which can be deposited in its surface layer or incorporated to the upper trophic levels, acting as a seasonal pulse of nutrients. This happens, basically in sync with the reproductive period of several of its predators in the Caatinga, including birds and lizards, which are in greater demand for food resources to feed their young. Anthropogenic disturbances and changes in the Caatinga's climate, especially those related to their rainfall pattern, may lead to a decrease of termite populations, affecting the seasonal pulses of nutrient release from the colonies via flights of alates.