Experimental drought and warming decrease diversity and slow down post-fire succession in a Mediterranean shrubland

14 páginas, 12 figuras, 2 tablas.Plant community recovery (species richness, diversity and composition) of a post-fire Mediterranean shrubland was monitored over a seven year period (1998 2005) under experimental drought and warming that simulated the environmental conditions forecast for this area in the coming decades. Species richness and Shannon’s index were positively correlated with accumulated precipitation in the growing season and both variables were negatively affected by reduced water availability in drought plots. The relative abundance of the different species in both treatments was linearly correlated with their relative abundance in control plots. Moreover, we found species-specific responses to treatments. Drought and warming treatment reduced the competitive ability of the obligate seeder tree Pinus halepensis against native resprouter shrubs and consequently, the transformation from shrub to pine tree dominated vegetation was slowed down. Conversely, the water use strategy of Globularia alypum may allow this species to maintain a dominant position in drought plots. Therefore, future drier and warmer conditions in Mediterranean areas may severely affect plant community recovery after a disturbance, due to the existence of both abundance-dependent and species-specific responses that may change inter-specific competitive relationships.This research was funded by EU under the projects CLIMOOR (Contract ENV4-CT97-0694) and VULCAN (Contract EVK2- CT-2000-00094) and we also received financial help from the Spanish Government (grants CGL2006-04025/BOS and Consolider MONTES CSD2008-00040), the Catalan Government (grant SGR2005-00312), the European project ALARM (Contract 506675), and the Fundacio´n Banco Bilbao Vizcaya 2004 grant.Peer reviewe