ABSTRACT
Wildfires are able to kill large amounts of trees that can be recruited into the drainage network. Contrary to other large disturbances, most of these woody elements can be classified as “potential LW” since they are not necessarily recruited into the channels during or immediately after the disturbance. Our research deals with this topic, improving the understanding of post-fire recruitment. We analyzed the case of the Toro River, an Andean basin located in Chile. It was affected by two wildfires (2002 and 2015) that in both cases burned almost the entire basin. Repeated field surveys were carried out aiming at detecting fluctuations in wood-load along a 2 km-long reach during the period 2006-2019. Moreover, analyses of aerial photo and DEMs were carried out to detect changes in forest cover, connectivity and cascading processes at the basin scale.
Our results demonstrate that, after 17 years, LW recruitment has started, fluctuations were detected in the wood load along the channel. Anyway, distinctions are clear at the basin scale. The left side of the basin suffers from a clear change in connectivity, promoting potential cascading processes that may fasten the LW recruitment. On the other hand, in the valley bottom, the presence of living trees imposes a decoupling between hillslopes and channels. This holistic approach, not considering only the “wet” part of the basin, can improve the knowledge on the recruitment dynamics, supporting effective risk mitigation approaches.
