Post-fire salvage logging versus non-intervention polices: Old facts, new questions

Background/Question/Methods

A current controversial issue among restoration ecologists and forest managers is appropriate management of dead burnt trees after forest fires. Post-fire salvage logging (i.e. the felling and removal of the burnt tree trunks, also often including the elimination of the remaining woody debris such as branches, logs, and snags by chipping, mastication, fire, etc.) historically has been routinely practiced by forest managers worldwide, but there is increasing evidence that salvage logging may have negative impacts on ecosystem function and structure, affecting a wide array of ecosystems processes. We manipulated a burnt forest area on a Mediterranean mountain to experimentally analyze the effect of salvage logging on several aspects related to post-fire regeneration such as plant and animal diversity and community assemblage, natural tree species regeneration, nutrient cycling, or carbon exchange. In addition, all the works conducted by the forest services since the fire were monitored, which allowed to make an economical balance of the management costs. Three replicates of three treatments differing in post-fire burnt wood management were established in four plots previously dominated by pines: “Salvage logging” (SL), “Non-intervention” (NI), and an intermediate degree of intervention (felling and lopping most of the trees but leaving all the biomass in situ; “Partial cut plus lopping”, PCL). Treatments have been monitored for five years

Results/Conclusions

The results show that burnt logs and branches acted as nurse structures that improved the natural regeneration of tree species as they reduced water stress during the summer, as determined by both growth parameters and leaf isotopic analysis. Burnt logs and branches also increased the abundance and diversity of birds and plants, and even provided a way for natural oak colonization given that the main acorn disperser (the European jay) used the non-salvaged areas as an habitat for caching the acorns. Burnt logs and branches were also a relevant source of nutrients, an allowed the increase in soil microbial biomass and nutrients and, altogether, the nutrient cycling in the system. In addition, the non-salvage area acted as a sink of atmospheric carbon (estimated with eddy covariance technique), whereas the salvaged area acted as a source of carbon. Salvage logging also increased the cost of reforestation operations by ca. two times. In conclusion, salvage logging had a negative effect on several key aspects related to ecosystem regeneration and services, and the results strongly support that less aggressive intervention policies should be implemented in burnt forest.