PARENT SESSION
Poster Session # 10: Soil Ecology.
Tuesday, August 5 Presentation from 5:00 PM to 6:30 PM. SITCC Exhibit Hall B.
Composition and distribution of belowground macroinvertebrates in a desert region of southern Spain.
Doblas-Miranda, Enrique1, Sánchez-Piñero, Francisco*,1, González-Megías, Adela1, 1 Dpto. Biología Animal y Ecología, Facultad de Ciencias, Univ. Granada, Granada, Granada, Spain
ABSTRACT- Belowground detrital food-webs are connected with ecological processes aboveground via the complex life cycles of many insects which use subterranean resources as larvae but are ground surface dwellers as adults. To investigate the connections between belowground and aboveground food webs, we are conducting a study in a desert region of SE Spain. Our first goal has been to describe the composition and distribution of the soil macroinvertebrate fauna. From April 2001 to March 2002, we have conducted a preliminary sampling using soil cores to extract the macrofauna up to 80 cm depth. Samples were taken monthly under the dominant shrub species, on bare soil areas and under ant-nests. A total of 1847 individuals belonging to 18 orders were collected. The assemblage was dominated by arthropods, which comprised 99.8% of the total number of macroinvertebrates. The most abundant groups were Hymenoptera (mostly Formicidae) Coleoptera (principally Tenebrionidae, Carabidae, Cebrionidae and Scarabaeoidea), Hemiptera (Margarodidae) and Embioptera (Oligotomidae). The fauna showed significant differences in vertical distribution , most families (85%) occurring in the more superficial level (0-13.5 cm). In general, abundance decreased with soil depth, except for Formicidae and Scarabaeoidea which showed higher number of individuals at deeper levels. Macroinvertebrates also differed in microhabitat distribution. Results show that diversity and abundance were significantly lower in bare ground areas and differed among shrub species. Holometabolous insects comprised most of the species and abundance in this desert region, contrasting with soil assemblages reported for other ecosystems. These results suggest an important role of these arthropods as ecosystem engineers and decomposers connecting below and above ground processes in these Mediterranean arid habitats.
Key words: Desert ecology, Soil macroinvertebrates, Vertical distribution, Microhabitat distribution