Fire as mediator of pine invasion: evidence from Patagonia, Argentina

Abstract

Fire has been found to promote or halt biological invasions. Pine trees (genus Pinus) are highly invasive in the southern hemisphere and the effect of fire on their invasion ability is not clear. An analysis of Pinus spreading after wildfires in Patagonia reveals that there is a high risk of pines becoming invasive if ignition frequency increases in Patagonia. Also plantations could increase fire intensity and/or frequency in Patagonia, creating a potential positive feedback between invasion and wildfires. The effect of fires on pine invasion was modulated by precipitation. In areas where precipitation was lower than 800 mm fires did not promote pine invasion. However, in areas with higher precipitation there was a strong promotion of pine invasion by fire, after a lag time. These results show that fire, a disturbance more frequent now in the region, can promote pine invasion.