Dissecting the hydrological niche: soil moisture, space and lifespan

Questions: Are communities structured on a hydrological (soil moisture) gradient? Is there spatial segregation into hydrological niches? What is the shape of the hydrological niches of individual species? Controlling for spatial autocorrelation, how much of the spatial structure in the community is due to variation in hydrology? Do annuals and perennials behave alike with respect to the above questions? Locations: La Mina in Moscosa Farm, Salamanca, western Spain (dehesa community) and Laguna Larga in the Urbión Peaks, Soria, central-northern Spain (alpine grassland). Methods: The presence of plant species was sampled in two contrasting field sites, for which we also built hydrological models. First, we reduced the dimensionality of the plant distribution data (non-metric multidimensional scaling) and measured the correlation between the resulting ordination and the hydrological gradient. Then we defined hydrological niches and tested niche segregation of plant species against null mo...