Spatial and temporal distribution of litter arthropods in different vegetation covers of Porto Santo Island (Madeira Archipelago, Portugal)

The main objective of this study is to assess the soil diversity and temporal and spatial distribution of litter macro-arthropods, captured with pitfall traps, on different vegetation covers from Porto Santo Island (Portugal) with different soil physical and chemical characteristics. The PCA clearly separated sampling areas geographically more exposed to winds and solar radiation, from the others that were not. In this analysis, seasons seemed to have no influence on this distribution. Non-exposed areas were characterized by high soil temperatures, water and organic matter contents. Among these areas, those that were covered by Pinus halepensis and Eucalyptus ficifolia showed the highest C/N ratios in winter, which may be explained by likely inhibitory effects of phenolic compounds of the leaves of both species on the decomposition process. The highest number of organisms was recorded on the exposed areas. Variance partitioning using CCA showed that the different vegetation covers and environmental variables explained 19% and 30%, respectively, of the variance in macro-arthropods distribution. Four environmental variables (exposure, temperature, C/N ratio and exchangeable K) were positively correlated with the taxa abundance matrix. The results showed that non-exposed areas with E. ficifolia and Cupressus macrocarpa seemed to favour the establishment of a high diversity of taxa, especially in the summer, when soil conditions tend to be extreme.