Abundance and stratification of soil macroarthropods in a Caatinga Forest in Northeast Brazil

Vfp Araújo,Ag Bandeira,A Vasconcellos

doi:10.1590/s1519-69842010000400006

Vfp Araújo, Ag Bandeira + Show 1 more

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https://doi.org/10.1590/s1519-69842010000400006

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Abstract

In arid and semiarid environments, seasonality usually exerts a strong influence on the composition and dynamics of the soil community. The soil macroarthropods were studied in a Caatinga forest located in the Reserva Particular do Patrimônio Natural (RPPN) Fazenda Almas, São José dos Cordeiros, Paraíba, Brazil. Samples were collected during the dry and rainy seasons following the method proposed by the Tropical Soil Biology and Fertility Program (TSBF), with minor modifications. At each station, 15 soil blocks (20 × 20 × 30 cm: 12 L) were extracted and divided into three layers: A (0-10 cm), B (10-20 cm), and C (20-30 cm). In the rainy and dry seasons 1,306 ± 543(se) and 458 ± 212 ind.m-2 macroarthropods were found, respectively, with 35 and 18 respective taxa recorded. The abundance of individuals and taxa were significantly higher in the rainy season. Isoptera (57.8%) was the most abundant taxon, followed by Hymenoptera: Formicidae (17.2%), Coleoptera larvae (7.3%), and Araneae (3.5%). In the rainy season, abundance in layer A (576 ± 138 ind.m-2) was significantly higher than that of layer C (117 ± 64 ind.m-2), but was not different from layer B (613 ± 480 ind.m-2). There was also no difference between the layer B and C abundances. In the dry season, abundance in layer B (232 ± 120 ind.m-2) was not significantly different compared to layer A (182 ± 129 ind.m-2), but was significantly higher than abundance in layer C (44 ± 35 ind.m-2). During the rainy season, layer A (34 taxa) was significantly richer in taxa than layers B (19 taxa) and C (11 taxa). On the other hand, during the dry season the richness of layers A (12 taxa) and B (12 taxa) was equal, but significantly higher than that of layer C (6 taxa). Richness of taxa and abundance were positively correlated with soil organic matter and negatively correlated with soil temperature. The community of soil macroarthropods in the area of Caatinga studied has taxonomic and functional structures that are relatively complex and is therefore likely to exert an influence on ecosystem productivity due to its physical effects on soil profile and necromass fragmentation, as occurs in other arid and semiarid ecosystems throughout the world.

Highlights

Soil macroarthropods play an important role in most tropical terrestrial ecosystems, exerting a direct influence on the formation and stabilisation of soil structure and an indirect influence on the decomposition process, through strong participation in necromass fragmentation, and predation on the soil community (Lavelle et al, 1994; Decaëns et al, 2003)
This study aims to analyse the abundance and stratification of the soil macroarthropod community in dry and rainy seasons in a Caatinga forest located between the Northern Sertaneja Depression and Borborema Plateau Ecoregions
1,306 ± 543 macroarthropods.m–2 were found in the rainy season and 458 ± 212 macroarthropods.m–2 were found in the dry season, pertaining to 35 and 18 taxa, respectively (Table 1)

Summary

Introduction

Soil macroarthropods play an important role in most tropical terrestrial ecosystems, exerting a direct influence on the formation and stabilisation of soil structure and an indirect influence on the decomposition process, through strong participation in necromass fragmentation, and predation on the soil community (Lavelle et al, 1994; Decaëns et al, 2003). Several studies have shown a lack of correlation between soil abiotic factors and spatial distribution of various taxa of invertebrates (Rossi et al, 1997; Ettema et al, 1998) Despite their crucial role in ecosystem function, soil communities have been little studied in some neotropical ecosystems, such as the Caatinga and the Atlantic Forest (Silva and Bandeira, 1999; Souto et al, 2008). The Caatinga spans an area of about 800,000 km and covers most of Brazil’s Northeast (Andrade-Lima, 1981; Prado, 2003) It is characterised by high temperatures and high potential evapotranspiration, which exacerbates the effects of irregularity and low rainfall indices (Andrade‐Lima, 1981; Coutinho, 2006). The Caatinga has been severely altered by firewood cutting, agriculture, fires, hunting, and continuous movement of cattle and sheep herds, leaving only a few areas with primary vegetation (Santos and Tabarelli, 2002; Leal et al, 2005)

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