Combined threats of climate change and land use to boreal protected areas with red-listed forest species in Finland

Protected areas (PAs) offer safe havens for threatened species, but their effectiveness is jeopardised due to climate change and habitat fragmentation in their surroundings. Species are forced into the unhospitable matrix in search of more favourable areas as climate conditions change, leading to negative effects on biodiversity. For red-listed forest species, the accelerating climate change can strengthen the negative effects of logging around PAs. In this work, we examine climate-change and land-use threats to biologically valuable PAs with red-listed species occurrences in Finland. Where the highest combined threats occur, do they coincide with accumulations of red-listed species, and how much do they vary between different boreal zones? This provides important knowledge for conservation planning in a managed matrix amid climate change. We use three spatial scales (100 m, 1 km, 10 km) to explore where the effects of clear-cutting have been the most intense during this millennium: right outside the PA border, exposing PAs to local-scale edge effects, or at landscape scales disrupting species movements due to degraded connectivity and increased fragmentation. For each PA, we also quantify how the January mean temperature (TJan), growing degree days (GDD5) and water balance (WAB) conditions are predicted to change by the end of the century under the RCP4.5 scenario. Additionally, for these variables, we estimate the velocity of the changes within valuable PAs. The proportion of forests which underwent clear-cutting was the highest in the more productive southern boreal zone and at the landscape scale of 10 km around the PAs. The combined threats of land use and climate change were evident, as there were positive correlations between logging levels around PAs with red-listed species and both the velocity values of GDD5 and TJan in the PAs. TJan is changing particularly fast in the northern boreal zone, where the coldest current climate conditions are projected to disappear by the end of the century. GDD5 in turn is changing fastest in the topographically flat southern boreal zone. GDD5 and TJan had generally a positive relationship with the magnitude of clear-cuts in a 10 km buffer zone. However, the direction of this relationship varied between the boreal zones. In climate-wise conservation planning for red-listed boreal forest species, multiple elements are needed. First and foremost, valuable sites for the red-listed species in the PA network should be identified and the climate change and land use-based threats to them measured. This information provides an elementary basis for additional threat analyses focusing on species habitat requirements and dispersal ecology. Together, this information can be used to assess the potential of different conservation measures to mitigate the combined climate-change and land-use risks, and ultimately to improve the conservation status of red-listed forest species.