Os bosques higrófilos Ibero-atlânticos

Abstract

Floristic composition, community structure and ecological functioning of freshwater wetland woods were studied along the Atlantic coastal belt of the Iberian Peninsula in a multi-scaled study. The determinant environmental factors of floristic variability along the transition from Temperate to Mediterranean climate were analysed. The interaction between edaphic and hydrological variables in the regeneration modes, growth and productivity of the main tree species were examined. Nutrient cycling and their interplay with lateral and longitudinal hydrological gradients over space and time were studied. Five floristic types were found, 86% of them dominated by Alnus glutinosa and Salix atrocinerea, with transitional phases in between. Hydromorphological factors had a higher contribution than climatic in the explanation of latitudinal variation, contrary to main terrestrial vegetation patterns. Periodicity and intensity of water flow resulted determinant for the differences between alder and willow woods ecological functioning. Duration of waterlogging seems to promote a persistence strategy in trees by the dominance of shrubbiness and vegetative regeneration. The maintenance of a sufficiently-developed mosaic of hydrological conditions within the stand was found to be the main driver underlying natural community dynamics and appears crucial for the preservation of wetland woods integrity in times of increasing climatic uncertainties and human pressures.