High levels of browsing by alien mule deer may reduce survival of post-fire resprouting shrubs on Santa Catalina Island in southern
Results/Conclusions Browsed resprouts had greater levels of mortality compared to non-browsed resprouts (63.2% and 11.5%, respectively; P < 0.05). The average percentage of dead canopy for browsed resprouts was also greater than non-browsed resprouts (88% and 18%, respectively; P < 0.05). Stem elongation and plant canopy area for non-browsed resprouts were significantly greater compared to browsed resprouts (P < 0.05). Net carbon assimilation (Anmax) was higher for non-browsed resprouts (P < 0.05), but gs was not significantly different. Pre-dawn water potentials revealed that both browsed and non-browsed resprouting plants were well hydrated (Ypd > -0.9 MPa) indicating a lack of water stress for both groups. Lower values of Anmax, stem elongation, and canopy area for browsed resprouts suggesting decreased ability to capture CO2 that could lead to carbon starvation once reserves are depleted. Consistent with this, browsed plants had low lignotuber starch content. Alien deer appear to be drivers of a vegetation shift from native shrublands to alien grasses and forbs post-fire.