Agriculture causes homogenization of plant-feeding nematode communities at the regional scale

An emerging research line in conservation ecology addresses how environmental change drivers may cause the biotic homogenization of ecological communities by shifts in species diversity and community composition. While the drivers have been explored in unmanaged ecosystems and managed agricultural systems, this issue has received limited attention in regard to a key soil bioindicator organisms, soil nematodes. In this study, we evaluated the effect of land-use change and intensification on the diversity of plant-feeding nematodes (PFN) though taxonomic and functional measures of alpha and beta diversity. We selected olive tree farms in southern Spain as the study system, given the wide distribution of wild forms in unmanaged systems and cultivated forms in agricultural systems, thus providing the opportunity to assess the effects of land-use intensity. Notably, our study revealed that the conversion from natural to agricultural systems and even moderate increases in land-use intensity caused a significant biotic homogenization by enhancing the functional similarities of PFN communities. Our study emphasizes the key role of body size in structuring nematode communities in response to land-use type and intensity. Synthesis and applications. The importance of soil nematodes in soil processes is well known. We show that land-use intensification reduces soil nematode diversity. Our study has important implications for the development of management strategies that foster soil biodiversity conservation such as no or minimal tillage and logging, vegetative covers and the maintenance of natural habitat.

This research was supported by grant 219262 ArimNET-ERANET FP7 2012-2015 Project PESTOLIVE, grant AGL2012-37521 from Ministerio de Economía y Competitividad of Spain grant P12AGR 1486 Consejería de Economía, Innvovación y Ciencia of the Junta de Andalucía and Union Europea, Fondo Europeo de Desarrollo regional, ‘Una manera de hacer Europa'. A. Archidona-Yuste is a recipient of a Humboldt Research Fellowship for Postdoctoral Researchers at Helmholtz Centre for Environmental Research-UFZ, Leipzig, Germany. The authors thank J. Martín-Barbarroja and G. León Ropero (IAS-CSIC) for the excellent technical assistance. Moreover, we acknowledge support of iDiv funded by the German Research Foundation (DFG–FZT 118, 202548816).