Are nests of Constrictotermes cyphergaster (Isoptera, Termitidae) important in the C cycle in the driest area of semiarid caatinga in northeast Brazil?

摘要

Termites play an important role in the carbon cycling of several ecosystems. Part of this C is directed to the formation of nests or mounds, but few published estimations have been made of the proportions of this C in relation to those in the vegetation and/or in the litter. The dynamics of C of Constrictotermes cyphergaster nests, in the driest part of caatinga, in semiarid northeast Brazil, was calculated considering all present, formed and abandoned nests in 1 ha, for two years. Carbon concentrations were determined from samples taken from the core and the external layer of nests. Total aboveground biomasses of trees and shrubs in the 1 ha were estimated by allometric equations. C concentrations were lower in the external layer (24-33 g kg(-1)) than in the nest cores (38-76 g kg(-1)). The stock of C in the nests of the sampled ha was 61.5 kg, which represents about 0.6% of that in the plant aboveground biomass (10.25 Mg C ha(-1)). The C in the annual formation and abandonment of nests (10.2 kg ha(-1) year(-1)) corresponded to 16% of the stock of C in the nests, 1.1% of the carbon in the annual litter production (925 kg C ha(-1) year-1) and 3.1% of the non-leaf litter. Although lower than the few values reported for more humid areas, these proportions indicate that C. cyphergaster nest formation contributes to C cycling in this very dry semiarid caatinga site. (c) 2010 Elsevier BM. All rights reserved.