Uso del agua y productividad de los bosques nativos e implantados en el NO de la Patagonia: aproximaciones desde la ecohidrología y la ecofisiología

there is a concern about the potential excessive water used of forest plantations with fast growing exotic species compared to the native vegetation systems they replace in nw patagonia. for this reason, several studies have being conducted focused on the productivity, water consumption and water use efficiency of the different systems, in areas with different precipitation levels. the studies were carried out from ecohydrological and ecophysiological approaches. the objective of this paper was to analyze and synthesize the available knowledge about these topics. both at the individual tree level or at forest with complete cover systems, the exotic species (pinus ponderosa and pseudotsuga menziesii) have a higher water consumption than all native individual tree-vegetation systems they replace (grassland- austrocedrus chilensis forests, and mixed forests with nothofagus antarctica, lomatia hirsuta, and other native woody species, respectively). however, in all cases, an increase in water use efficiency was observed in exotic species compared to native species. our results suggest that differences in productivity and water use are mainly due to a higher resistance to water flow, both in liquid (lower wood conductivity) and vapor (higher stomatal sensitivity to vapor pressure deficit) phases in native species compared to exotic ones. at least in the case of ponderosa pine, water use of plantations may be decreased managing leaf area of the system by means of green pruning and thinning. moreover, in the native mixed forest water use and water use efficiency are able to be managed through selective extraction of individuals of certain species and sizes. on the other hand, the higher differences in water use between native and exotic systems were observed in the most xeric areas, between native grasslands and high density ponderosa pine plantations. on the other hand, rain interception was higher in native forests than in forests plantations in the xeric area, resulting