data

This dataset aimed to assess the relative importance of evolutionary distance, dispersal mechanism and environmental conditions as drivers of plant-plant interactions in semiarid environments. For doing this, we sampled 11 Stipa tenacissima grassland communities along a climatic gradient spanning from the center to the southeast of Spain. Our study sites have annual precipitation and temperature values ranging from 273 mm to 488 mm and from 13°C to 17°C, respectively. Four environmental variables were collected for each site: irradiance, mean temperature, annual rainfall (collected from available climatic models, Ninyerola et al. 2005-Atlas Climático Digital de la Península Ibérica. Metodología y aplicaciones en bioclimatología y geobotánica. Univ. Autónoma de Barcelona, Bellaterra, Spain), and altitude. At each site we also evaluated particular pairwise interactions for the two dominant nurses in the study area (Q. coccifera shrubs and S. tenacissima tussocks) by using 0.5 m x 0.5 m quadrats (see associated article for further details). With this data, we obtained two indices, the RII (Armas et al. 2004-Ecology 85: 2682–2686) to evaluate the intensity of the interaction, and the Iimp (Seifan et al. 2010-J. Ecol. 98: 356–361) to evaluate the importance of such pairwise interactions. To complement de dataset, phylogenetic distance between the two interacting species and the dispersal mechanism of the beneficiary species were also measured or obtained from available literature. More details from the dataset are given in the “metadata” spreadsheet and in the associated article). Related databases can be found in the dryad data package Data from: Environmental conditions and biotic interactions acting together promote phylogenetic randomness in semi-arid plant communities: new methods help to avoid misleading conclusions. Provisional DOI: doi:10.5061/dryad.d24c7. Gaps in the data are in blank. Field and dispersal mechanism data were collected by S. Soliveres and F.T. Maestre, the phylogenetic distances were calculated by R.Torices. Contact for further information: Dr. Santiago Soliveres (e-mail: [e-mail])