PS 28-139
The influence of a shore-normal gradient on soil microarthropod-community dynamics in a Mediterranean ecosystem
The distinctive feature of coastal sand-dune fields is a shore-normal gradient of decreasing physical stress and increasing complexity in the ecosystem landwards. The influences of this environmental gradient, set up by the proximity to the sea, were shown in many macrofaunal species, from insects and arachnids to vertebrates such as mammals and birds. The soil mesofauna is often neglected and there are not much data available on its composition in sandy shore areas in general and the effect of the environmental gradient on it in particular. Microarthropods are a vital component in soils, especially in semi-arid areas, and they play an important role in many biological and physical processes going on under our feet. The Israeli coastal sand dunes are characterized by Mediterranean climatic conditions but this environment has relatively harsh conditions that turned it into a xeric habitat. This is a unique ecosystem in the Mediterranean region that is constantly decreasing in size due to the heavy stress of urbanization. We examined the seasonal effect of distance from the sea on the soil microarthropod community. The microarthropods were extracted from soil samples collected from six stations, i.e., open sandy areas along a 4-km transect from the sea landwards.
Results/Conclusions
The soil microarthropod - community diversity and density in coastal sand dunes were found to be affected both temporally and spatially along the environmental gradient. The community was dominated mostly by Acari when, during the winter season, high numbers of collembolans were present. Some mite families appeared only at certain distances from the sea, where the abiotic conditions were favorable. The highest microarthropod density was found during the winter season, due to the interplay between soil moisture and soil surface temperature, with a continuous increase in population density from the sea-shore toward inland. The lowest microarthropod density was found during the summer season, when the differences in soil physico-chemical soil properties along the gradient disappeared. The present study suggests that the shore-normal environmental gradient affects not only the invertebrates above the sand but also the smaller ones – the microarthropods – beneath it. The intensity of this influence is determined by the season of the year.