Temporal variations of Collembola (Arthropoda: Hexapoda) in the semiarid Caatinga in northeastern Brazil

ABSTRACT

The richness and abundance of Collembola species can be influenced by many biotic and abiotic factors, mainly humidity. The semiarid region of Brazil is dominated by Caatinga dryland vegetation which experiences distinct seasonal alterations of its physiognomy linked to regional rainfall regimes. The present study evaluated the environmental factors affecting populations of Collembola in an area of Caatinga vegetation in Northeastern Brazil during a 12-months period. Specimens were collected by active searching in ten 20 x 20 m plots, with a sampling effort of 1 hour/person/plot. A total of 1231 specimens were collected, comprising 15 morphospecies, 12 genera, and nine families. Both species richness and individual abundances demonstrated oscillations during the year, with the highest values occurring during the rainy season; rainfall was the principal predictive variable for the observed temporal oscillations. Minimum temperatures and precipitation influenced the structural composition of the Collembola. Populations of Collembola demonstrated clustered distribution during the year. The direct and indirect effects of precipitation on the quality of microhabitats and resource availability were apparently responsible for the numerical and compositional alterations of the Collembola fauna observed in the Caatinga site.