Helping society to mitigate logging impacts on biodiversity and ecosystem services of burned forests

Abstract

Over the last decades, an average of 213,000 ha of European forest has been affected by fire every year, with 90% of this area corresponding to Mediterranean countries. The timber of the burned forests is harvested by clearcutting over large areas. Whole trees are then chipped to be used as bioenergy, so that very little coarse woody debris remains in the ecosystem. In recent years, scientific evidence has shown the strong impact that these practices of “salvage logging” have on the soil, the ecosystem regeneration and the conservation of biodiversity. Academic debate is therefore centered in the convenience of harvesting burnt forests based on the trade-off between environmental impacts and practical reasons of logging. However, forest owners and companies largely ignore this debate, and salvage logging decisions are usually taken for other reasons, including economic and emotional aspects, immediately after fire. Instead of demonizing postfire logging, our approach has been to look for best forestry practices to protect biodiversity and services provided by the regenerating ecosystem. Based on bibliographic review and feedback with practitioners, authorities and the forest sector, in 2016 we published a “Handbook of good management practices in burnt Mediterranean forests” (pdf available at http://anifog.wixsite.com/anifog/blank). The handbook contains the fundamentals of management (based on the measured effects of salvage logging), a decision-making tool to help management decisions, and the recommendations for sustainable forestry (depending on the managers’ objectives and on the environmental context). The next step is to experimentally test alternative management practices. Using 3-4 plots/treatment we are currently measuring the effects of non-intervention (NI), conventional (CL) and sustainable logging (SL) on ecosystem and biodiversity indicators in a mixed pine-oak forest burnt in 2016. Selected indicators will give us information about soil fertility and erosion, woody biomass, plant regeneration, invertebrate diversity (ants, beetles and spiders), vertebrate occupancy, seed removal and the economic yield of each treatment. NI and SL plots are being monitored since 2017, whereas CL plots will be studied from 2018. The total wood biomass was 88 and 98 m3/ha in NI and SL plots, respectively. Harvested wood biomass in SL plots was 69 m3/ha, while 28 m3/ha remained as coarse woody debris (piles of branches and scattered logs) and 11 m3/ha as burnt living trees. Provisional results for biodiversity found in the burnt forest include 29 spider, 13 ant and 123 beetle species (70% of them being saproxylic). At the end of the study in 2020 we expect to provide practitioners with quantitative evaluation of three main postfire management options taking into account biodiversity and the ecosystem resilience. We will also provide authorities with ecological assessment protocols to be used before and after the management of burnt forests.