congresos y reuniones científicas
Regional-scale analysis of spatial fire occurrence in western Patagonia: Vegetation type, humans and feedbacks
PARITSIS, J.; HOLZ, A.; VEBLEN, T.T.; KITZBERGER, T.
Congreso; VII Southern Connection Congress; 2013
Although there is a growing recognition of the important role played by humans as drivers of wildfire activity globally, regional variations in the effects of humans on wildfire remain poorly understood. We evaluated the effects of biophysical and anthropogenic variables on fire activity at regional scales in western Patagonia, where most ignitions are due to humans. We used Landsat images to map fire perimeters in four extensive regions in western Patagonia from 43 to 53°S, and we modeled fire activity across space for each of these regions which differ in land use as well as biophysically. In the field, we characterized post-fire fuel structure and we recorded microclimatic parameters relevant to fire (i.e. temperature and relative humidity) in two key widespread vegetation types ?shrublands and Nothofagus pumilio forests. Our results show a significant and consistent association of differential probability of fire occurrence for particular vegetation types. We also found that human variables (i.e. proximity to roads and towns) had contrasting effects on fire activity depending on the region evaluated. While fire-prone shrublands regenerate to a similar fuel condition after burning, the relatively fire resistant N. pumilio forests tend to transform into more flammable shrublands after fire. This study highlights the complexity of fire responses to anthropogenic variables depending on predominant land-use and configuration of infrastructure, such as road and/or town density. Furthermore, our results suggest the presence of positive feedbacks among vegetation type, land use and fire, which may be driving these ecosystems into alternative states.