What is the impact of active management on biodiversity in forests set aside for conservation or restoration? A systematic review protocol

Abstract

Background: The traditional approach to limiting impacts of forestry on biodiversity is to set aside forest areas of particular conservation interest, either as formally protected reserves or on a voluntary basis. Many set-asides are left more or less untouched, but some of them have a history of disturbances such as wildfires, forest grazing, coppicing or small-scale felling. Such areas may gradually lose the qualities that were to be safeguarded unless the disturbances are re-introduced (e.g. by burning) or replaced with alternatives (e.g. gap-felling). Active management of forest set-asides may be particularly relevant in areas where the biota has been impoverished by intensive and large-scale harvesting. Here, biodiversity may not be able to recover adequately without restoration measures such as gap-felling or creation of dead wood. In recent years, interest in active management of forest set-asides has increased, but opinions differ among conservationists on how such management should be balanced against non-intervention. The topic of the proposed systematic review has therefore met approval among stakeholders in Sweden, where it is currently an issue of high concern. Methods: The review will examine primary field studies of how various forms of active management have affected biodiversity in boreal or temperate forests set aside for conservation or restoration. The primary focus will be on forest types represented in Sweden. In some cases, useful insights about management options may also be provided by studies of interventions in commercially managed forests. Non-intervention or alternative forms of active management will be used as comparators. Relevant outcomes include assemblage diversity (species richness, diversity indices), abundance of different functional or taxonomic groups of organisms, population viability of target species, and indicators of forest biodiversity such as forest structure and amounts of dead wood. The relevant scientific literature may turn out to be very heterogeneous, however. Numerous combinations of management forms and biodiversity outcomes can be conceived, and it remains to be seen whether any such combination is covered by sufficiently many studies to allow a meaningful meta-analysis. Nonetheless, it should be feasible to achieve a useful narrative synthesis of the available evidence.