Environmental biotic predictors
Plots of 10 x 10 m2 were established in the middle of homogeneous grassland patches holding a given plant community (Canals & Sebastià 2000; Sebastiá 2004). Aboveground biomass was estimated from herbage harvested in four 50 x 50 cm quadrats placed in a 2 x 2 m subplot within the 100 m2 plot. Plant guild biomass was determined in one of the four quadrats per plot by hand separation. Four guilds were sorted: C3 grasses, sedges, legumes and non-legume forbs (the latter including some sub-shrubs), following Sebastià (2007). Guild biomass was then oven-dried at 60ºC to constant weight.