Padrões de distribuição e variação temporal de térmitas (Blattodea: Isoptera): uso como bioindicadores na amazônia central

Abstract

Termites are a group that has a recognized potencial as a bioindicator taxon. However, few studies aimed to understand their populational fluctuations, which is essential for the usage of any group in monitoring programs. For this reason, we evaluated the congruency of the taxonomic assemblages and the temporal pattern in the spatial distribution of termites assemblages collected in 2008 (rainy season), 2009 (less rainy season) and in 2014 (rainy season). The samplings were standardized and conducted in a “Terra Firme” tropical forest, in the Central Amazonia, in 30 plots of 250 m length each, distributed at 1 km of each other. Excluding the soldierless termites belonging to Apicotermitinae, the number of identified species for the 2008, 2009 and 2014 samplings are of 57, 53 e 44, respectively, totalizing 81 species. Using the 2014 assemblage with Apicotermitinae morphotyped, two multiple regression models were made. The soil clay content, terrain slope and the plant composition (live trees, palms and lianas) and litter depth were used as the independent variables. The taxonomic composition of total termite assemblage reduced to one axis using NMDS and the proportion of xylophage’s termite species were used as the dependent variables in regression models. The taxonomic composition of the total assemblage was correlated with the plant composition, while the geophagus termites were correlated with the plant composition and litter depth. The Apicotermitinae were excluded from the following analysis. Multiple regression analysis were made to each one of the three temporal assemblages, using the same environmental variables as independent variables. The assemblage captured in 2008 had significant correlation with soil clay content, while the one captured in 2009 did not have a significant correlation with any of the variables and the assemblage captured in 2014 had correlation with plant composition. MANOVA test did not detect any significant difference among the three temporal assemblages. Procrustes analysis demonstrated that all the assemblages were correlated. The similarity between the assemblages captured in different seasons (2008-2009) were of 0.49 and the six-year spaced assemblages (2008- 2014) was of 0.40. For the xylophage’s species subset, the similarity between different seasons was of 0.56, and for the six year-spaced assemblage was of 0.46. Therefore, even the assemblages collected in different seasons or spaced by a time gap had a similar congruency. The most abundant species, all classified as xylophages, kept their relative abundances stable along the years. Species compositions of the assemblages captured in the three periods in the plots were not correlated with the environmental variables. Although it is necessary to better understand which factors are regulating the spatial distribution of the termites, their temporal stability, coupled with their response to the environmental changes, which is documented in this study, strengthens their use as a bioindicator group, which should be used in monitoring programs.