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

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 ). 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.Keywords: semiarid, soil fauna, environmental variables, insects. Abundância e estratificação de macroartrópodes de solo em uma Caatinga do Nordeste do Brasil ResumoEm ambientes áridos e semiáridos, a sazonalidade geralmente exerce forte influência sobre a composição e dinâmica da comunidade do solo. , com 35 e 18 táxons registrados, respectivamente. A abundância de indivíduos e a riqueza de táxons foram significativamente maiores na estação chuvosa. Isoptera (57,8%) foi o táxon mais abundante, seguido por Hymenoptera: Formicidae (17,2 %), larva de Coleoptera (7,3%) e Araneae (3,5%). Na estação chuvosa, a abundância da camada A (576 ± 138 ind.m ). Também não houve diferença entre as abundâncias das camadas B e C. Na estação seca, a abundância da camada B (232 ± 120 ind.m -2 ) não apresentou 737 Braz. J. Biol., 2010, vol. 70, no. 3 (suppl.), p. 737-746 Araújo, VFP., Band...

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