Large delay in flowering in continental versus coastal populations of a Mediterranean shrub, Globularia alypum.

8 páginas, 5 figuras.t Mediterranean ecosystems are water limited and the current general circulation Models (GCM) and ecophysiological models forecast a warming and a further increase of drought in the next decades. A stronger water stress can decrease the capacity for nutrient absorption by plants. We conducted a field experiment to simulate forecasted drought and warming in a Mediterranean calcareous shrubland to assess the performance of rootsurface phosphatase activities of the dominant shrub Globularia alypum. These enzyme activities were higher in autumn and spring, when the climate conditions were optimal for plant activity, than in summer or winter, when there was either lack of water or cold temperatures. A decrease in soil moisture in drought plots decreased rootsurface phosphatase activity (29% in summer and 25% in autumn). The decrease in root-surface phosphatase activity in drought plots coincided with a decrease in P leaf concentrations and P accumulation in aboveground biomass and loss of photosynthetic capacity of some dominant shrub species of this ecosystem, and with a tendency to increase total soil-P. These results suggest that the expected drier conditions in this Mediterranean shrubland in the next decades will slow down the P uptake by plants, thereby, diminishing the P contents in biomass and increasing total P contents in soil in non-available forms and that this can be, in part, attributable to a result of the decrease in rootsurface phosphatase activityThis research was supported by Spanish Government grants REN2003-04871/GLO, CGL2004-01402/BOS, and CGL2006-04025/BOS, the Catalan government grant SGR2005- 00312, the EC Integrated FP6 ALARM (GOCE-CT-2003-506675) Project, and a Fundación BBVA 2004 grant.Peer reviewe