How does prescribed burning in temperate and boreal forests affect biodiversity?

Abstract

Image credit: Dmytro Gilitukha, from iStockphoto

Forests set aside from productive forestry are often considered best conserved by non-intervention. However, biodiversity can be maintained in natural forests by a background level of disturbance, which, in some forests, takes the form of forest fires.

While the effects of prescribed burning on tree regeneration and on pyrophilous and/or saproxylic species in some regions are well known, effects on other organisms are less clear and/or consistent. The primary aim of this systematic review was to clarify how biodiversity is affected by prescribed burning in temperate and boreal forests, and how it may be useful as a means of conserving or restoring biodiversity, beyond that of pyrophilous and saproxylic species. A separate review, almost complete at the time of writing, focuses on the impacts of dead wood (e.g. by prescribed burning or addition of dead wood) on forest biodiversity. This review avoids overlap by excluding saproxylic species; those most impacted by dead wood changes.

Relevant studies were taken from a recent systematic map of the evidence on biodiversity impacts of active management in forests. Additional searches and a search update were undertaken using a search string targeted to identify studies focused on prescribed burning interventions. Studies were assessed for internal and external validity and data was extracted, using critical appraisal and data extraction tools, specifically developed for this review. Studies were presented in a narrative synthesis and interactive map, and those which were suitable were combined in meta-analyses.

After screening for relevance, 244 studies were included in this review, 82 were included in the quantitative synthesis. We describe the geographical spread, study characteristics and heterogeneity of the evidence base. We find no evidence for a general trade-off between improving conditions for fire dependent species and the biodiversity of non-target species groups. We discuss the knowledge gaps in study scope identified by this review. We also identify evidence needs, such as appropriate and consistently applied study designs, long-term data sets and more detailed reporting by authors.

Image credit: Dmytro Gilitukha, from iStockphoto