As consequence of global climate change, the rainfall decreased significantly in south-central Chile in the last decades and climate models anticipate a constant increment of this tendency in the future. At the same time, the demand for water supply for multiple uses is increasing continuously. In this scenario, a possible solution for reduce the effect of climate change over water supply is to manage the forest cover in watersheds for regulate the water yield. Because trees extract water from the soil and return it at the atmosphere they play an important, but not yet quantified, role in the forest water “production”. In this study, we evaluated the hydraulic properties of five tree species under drought conditions with the purpose of anticipate future changes in the forest structure as consequence of drought increasing, and propose an “ideal” forest cover (in composition) for water yield. We measured transpiration (T), specific hydraulic conductivity (Ks) in branches and leaf hydraulic conductivity (KL).
Results/Conclusions
Our results showed significant differences in transpiration rate and a differential response to sunny and cloudy days among species. The efficiency of hydraulic transport in branches (Ks) ranged between 3.5 to 0.1 Kg s-1 m-1 MPa-1 in Gevuina avellana and Nothofagus dombeyi respectively. Nothofagus dombeyi showed the highest drought tolerance, maintaining near to 20% of the leaf hydraulic conductivity at the most negative leaf water potential (-4 Mpa). On the contrary, Drimis winteri was the specie with highest KL (8 mmol m-2 S-1 Mpa -1) but less drought tolerance, losing the 50% of KL at -0.75 MPa. In general, the species with most drought tolerance have less hydraulic efficiency, but these species extract water from the soil continuously under drought conditions. The increment of water deficit in south central Chile could be an important factor that determines the competence among trees and the forest structure.
