Influence of landscape homogenization on the local diversity of spiders in eucalypt plantations settled in a grassland ecosystem

PAIRO P., PINTO C., BELLOCQ M. I.

Lisboa

Congreso; 15th European Ecological Federation (EEF) Congress y 18th National SPECO Meeting,; 2019

Grassland ecosystems traditionally replaced by agricultural and livestock fields have also currently being replaced by commercial tree plantations. To develop effective management strategies given the increasing extensions of forest landscapes in this biome, it is necessary to determine the best landscape arrangement that promotes native biodiversity. The objective of this study was to analyze the response of the diversity of spiders to the landscape homogenization due to commercial tree plantation. The study was conducted in the Pampean ecoregion of Argentina (Entre Rios province), originally dominated by grasslands. We selected seven areas of 5x5 km as landscape units, centered on a mature plantation of Eucalyptus sp. (sample site). Landscape units had increasing tree plantation cover, from 20% to 100%. At each sample site, spiders were collected using pitfall traps and garden-vacuum (G-vac) during spring and summer. To account for the landscape homogenization due to the forest plantations we estimated the Shannon?s Diversity Index within each landscape unit. We analyzed the relationship between Spider Richness and Abundance (response variables) and the Shannon?s Diversity (explanatory variable) using generalized linear models. In total 290 individuals were captured belonging to 15 families and 45 species. Both the species richness and spider abundance responded positively to Shannon?s Diversity. Our study shows that the diversity of spider assemblages in eucalypt plantations at the local scale is positively associated with the maintenance of a variety of land uses in the landscape, as they could act as a source of species.