Comparing ecophysiological traits and evapotranspiration of an invasive exotic, Pinus halepensis in native woodland overlying a karst aquifer

Invasion by exotic plant species into water-limited environments has the potential to change the ecosystem water balance and may further exacerbate water scarcity issues. Here, we compared ecophysiological traits related to tree water use (sap flux, sapwood density, leaf and soil water potentials) and actual evapotranspiration (ETa) of the invasive Pinus halepensis to native tree and shrub species. We hypothesized that the invasive pine species would possess traits that are consistent with the potential to use more water than native species, which would be supported by higher ETa in areas invaded by pine. We found higher rates of sap flux for the invasive P.halepensis (5.5cmh(-1)) per unit sapwood area compared with the native species (<3.5cmh(-1)). In addition, P.halepensis sapwood was significantly less dense than the sapwood of the native species, suggesting higher sapwood conductivity facilitated the faster sap flux. Comparison of remotely sensed ETa before and after P.halepensis removal within a Eucalyptus camaldulensis stand demonstrated a reduction in ETa by an average of 50(+/- 11 SE)mmyear(-1) in the 2years after removal, relative to the ETa from an undisturbed, intact E. camaldulensis stand. This study suggests that active management of this invasive species should reduce overall ETa losses and thereby exert a positive influence on the availability of soil moisture for groundwater recharge. Copyright (c) 2014 John Wiley & Sons, Ltd.