How hot are retention patches as structural hotspots? : comparing key elements for biodiversity in retention patches and reference forest stands

Sammanfattning: Sweden’s historical and current forestry regime has created structurally simplified forest stands with little resemblance of boreal old-growth forests, leading to a decline in many forest dwelling species. Retention forestry was introduced to counteract the negative development by retaining biologically important forest elements. Retention patches are intact forest areas left to represent conditions in the pre-harvest stand for harbouring of threatened species and structurally enriching managed forests. However, many biodiversity preservation goals connected to forests remain unfulfilled, which indicate a need for evaluation of what is retained during harvest and possible influences on why. I used the Swedish Forest Agency method for inventorying woodland key habitats to evaluate differences in substrate supply, conservational quality and physical prerequisites in retention patches compared to structurally similar reference forest stands located in spruce�dominated boreal forests in Hälsingland, Sweden. My results showed how retention patches scored lower in the natural value assessment, contained less deciduous live conservation trees and less coarse deadwood. In general, substrate amounts are either lower or indifferent in retention patches compared to in reference forests, indicating that retention patches are not structural hotspots. If retention patches do not hold equal conservation values as the pre-harvest stand, the forest landscape would continuously be impoverished, and the threatened species disfavoured. The structure of retention patches, underlying causes of retention decisions, and following implications for biodiversity need further studying to ensure that areas with the highest conservational importance are preserved.