Can unproductive sites function as refuges for Austrocedrus chilensis against fire?

LANDESMANN, J.B.; GOWDA, J.H.; KITZBERGER, T.

Concepción

Congreso; IUFRO Forests, Society and Global Change; 2012

IUFRO Landscape Ecology

Fire is a disturbance that modulates forests dynamics around the world. Sites with low biomass and humidity could have less probability of being burned or could be affected by less severe fires. Furthermore, thicker trees could be more fire resistant, thus reinforcing the pattern. Austrocedrus chilensis forests of northwestern Patagonia are expanding since the early 20th century due to fire suppression. We hypothesized that this expansion has been triggered from specific sites in the landscape that, because of their biophysical characteristics are less affected by fire, allowing the survivorship of obligate seeder trees. To test this hypothesis we surveyed 9 rocky outcrops in SW Rio Negro, Argentina and found that Austrocedrus trees with fire scars where older and larger in diameter than the rest of the trees. Some of the larger individuals had up to three fire scars, indicating the survival to several past fires. In eight of the nine study sites, we found female trees with fire scars. However, soil depth and slope, two of the physical variables we studied, could not explain the survivorship of these individuals to fire. While our results suggest that these groups of surviving trees could have acted as seed sources of present post-fire Austrocedrus forests, we still could not identify the physical site attributes which explain higher persistence of trees in the landscape.