Changes in Collembola richness and diversity along a land-use intensity gradient were studied in eight European countries (). In each country a set of six 1 km 2 land-use units (LUUs) were selected forming a gradient ranging from natural forest to agricultural dominated landscapes, passing through mixed-use ones. In addition to data on Collembola, detailed information regarding landscape diversity and structure was collected for each LUU. A total of 47,774 individuals were identified from 281 species. Collembola reacted not only to changes in the diversity of the landscape, but also to the composition of that diversity and the area occupied by each land-use type at each LUU. Although species richness patterns were not concordant among the different countries, the total number of species per LUU (landscape richness) was generally higher in natural forests and mixed-used landscapes, and lower in agricultural dominated landscapes. Moreover, high richness and diversity of ARTICLE IN PRESS www.elsevier.de/pedobi (J.P. Sousa).Collembola at each LUU were associated with a diverse landscape structure, both in terms of number of patches and patch richness. Despite this comparable species richness between mixed-use landscapes and those dominated by natural forests, average species richness on forested areas (local richness) decreased along the gradient, showing that forest patches on mixed-use landscapes support a lower richness than in landscapes dominated by forest. This aspect is important when addressing the role of native forests in structuring biodiversity in disturbed and fragmented landscapes. Although a diverse landscape can support a high biodiversity, the results suggest that intensive fragmentation should be avoided with the risk of collapsing local species richness with the consequent result for regional biodiversity.

Collembola communities were sampled along a gradient of soil-use intensification in a typical Mediterranen landscape dominated by cork-oak. This gradient ranged from a land-use unit (LUU1) dominated by closed oak forest with minimum intervention to an unit entirely composed of a monoculture crop submitted to frequent anthropogenic disturbances (LUU6), passing through LUUs with managed woodland (LLU2) or dominated by open cork-oak areas and pastures (LUU3 and LUU5). The Collembola community in the overall area was dominated by a few abundant species, mainly Isotomidae, present in almost all units. Abundance, diversity and species richness decreased along the gradient, with the agricultural site presenting an impoverished community. Diversity descriptors were positively and significantly correlated with habitat diversity, measured on the basis of the proportion of the different soil-use types present at each land-use unit. Multivariate analysis revealed changes in Collembola community composition between the LUUs, with LUU6 detaching from the rest. LUU1 and LUU2, despite the less diverse community of the latter, formed a separate group from the remaining two units (LUU3 and LUU5). Species composition in all these units was mainly determined by soil-use types present at each LUU (open cork-oak land and pastures vs. closed cork-oak areas), the proportion of the different soil-use types and the different management practices adopted for each soil use. Overall analysis revealed that Collembola reacted to changes in the landscape structure, with community composition giving a more robust response than diversity indices.

Avec 31 figures dans le texte. SOMMAIRE Revisiondieser Gattung, die der eine Autor (H. Gisin) vor Jahren in Angriff nahm und daruber verstorben ist. SUMMARY 18 new species of Pseudosinella from various European caves are described and their systematic position and phylogeny are considered. This work is part of a gênerai revision of the genus, which was begun several years before the untimely death of one of the authors (H. Gisin).

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