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

Aila Soares Ferreira,Alexandre Vasconcellos,Bruno Cavalcante Bellini

doi:10.1590/s1984-46702013005000009

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.

Highlights

Collembola are abundant representatives of the pedofauna (CASSAGNE et al 2003) and have important roles in soil formation and decomposition of organic material (HOPKINS 1997, ZEPPELINI & BELLINI 2004)
The abundance and richness of Collembola species are influenced by various biotic and abiotic factors (CULIK & ZEPPELINI 2003, ZEPPELINI et al 2009), and the abundances of individuals in numerous insect orders are known to be related to temporal variations in climatic conditions in both temperate and tropical ecosystems (WOLDA 1988)
Seasonal variations in insect abundances are a common phenomenon, with accentuated reductions in abundance being common during the dry seasons in tropical regions or during the winter in temperate regions (WOLDA 1988, PINHEIRO et al 2002, VASCONCELLOS et al 2010)

Summary

Introduction

Collembola are abundant representatives of the pedofauna (CASSAGNE et al 2003) and have important roles in soil formation and decomposition of organic material (making it more degraded by fungi and bacteria) (HOPKINS 1997, ZEPPELINI & BELLINI 2004). Seasonal variations in insect abundances are a common phenomenon, with accentuated reductions in abundance being common during the dry seasons in tropical regions or during the winter in temperate regions (WOLDA 1988, PINHEIRO et al 2002, VASCONCELLOS et al 2010). The present study sought to evaluate the Collembola fauna in a semiarid area of Caatinga vegetation in northeastern Brazil and identify the climatic variables that influence species richness, individual abundances, and the structural composition of that guild. This represents one of the few studies undertaken in the Caatinga biome that has evaluated the effects of temporal variations in climatic elements on invertebrates at the species level

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Conclusion