The biodiversity of forests set aside from forestry is often considered best preserved by non-intervention. In many protected forests, however, remaining biodiversity values are legacies of past disturbances, e.g. recurring fires, grazing or small-scale felling. These forests may need active management to keep the characteristics that were the reason for setting them aside.
As a first step towards a more complete synthesis, we compiled a systematic map of impacts of interventions that could be useful for conserving or restoring biodiversity in boreal and temperate forests (1). Such a map gives an overview of the evidence base by providing a database with descriptions of relevant studies, but it does not synthesise reported results (2).
Searches for literature were made using online publication databases, search engines, specialist websites and literature reviews. We searched not only for studies of interventions in actual forest set-asides, but also for appropriate evidence from commercially managed forests, since some practices applied there may be useful for conservation or restoration purposes too.
The 798 articles found to be relevant included 812 individual studies, all of which were described in an interactive GIS application. Almost two thirds of the studies were conducted in North America, whereas most of the rest were performed in Europe. Of the European studies, 58% were conducted in Finland or Sweden. The interventions most commonly studied were partial harvesting, prescribed burning, thinning, and manipulation of grazing. The impacts most frequently reported were effects on trees, other vascular plants, dead wood, vertical stand structure and birds. Outcomes included e.g. abundance, species richness, diversity indices, and community composition based on ordinations.
The systematic map identified a wealth of evidence on impacts of active management practices that could be utilised to conserve or restore biodiversity in forest set-asides. As such, it should be of value to e.g. conservation managers, researchers and policymakers. Moreover, since the map also highlighted important knowledge gaps, it could inspire new primary research on topics that have so far not been well covered. Finally, it provided a foundation for systematic reviews on specific subtopics. Based on our map of the evidence, we identified four subtopics that were sufficiently covered by existing studies to allow full systematic reviewing. Three of the subtopics have now been subject to such reviews.
(1) Bernes, C., et al. 2015: “What is the impact of active management on biodiversity in boreal and temperate forests set aside for conservation or restoration? A systematic map.” Environmental Evidence 4:25
(2) Haddaway, N.R., et al. 2016: “The benefits of systematic mapping to evidence-based environmental management.” Ambio 45, 613-620