Fig 1.
Map of WKH in Sweden. The star in map A denotes the location of the study area in northwestern Sweden, with red dots illustrating the distribution of all deregistered WKH included in the map used in this study. Map B is a close-up of the study area, where all WKH are indicated in blue and deregistered WKH are indicated with red. All surveyed areas are marked with a label. Map C presents deregistered WKH D2 (now classified as production forest), in a landscape perspective. Boundaries of forests of high conservation value according to the County Administrative Board are delineated by a white line. [34–36-Base map from OpenStreetMap https://www.openstreetmap.org/].
Table 1.
Summary of results from the field survey.
Fig 2.
Conservation trees per hectare.
Mean number (± 1 SD), of conservation trees per hectare within each forest. The small box plots show the variation within each forest and the large box plots show the variation within the categories registered WKH (R) and deregistered WKH (D). Red line shows criteria for track 1 by the new inventory method, i.e., 20 conservation trees per hectare. It can be noted that all forests are well above the limit of 20 trees per hectare set as a criterium for WKH.
Fig 3.
Number of red-listed and signal species.
Mean number (± 1 SD), of the number of red-listed and signal species observed during survey within each forest. The box plots show the variation within the categories registered WKH (R1-9) and deregistered WKH (D1-9).
Fig 4.
Average number of deadwood objects.
Mean number (± 1 SD) for both standing and lying deadwood objects per hectare. With registered showed in purple and deregistered showed in red. The dead wood criteria are 50/hectare in Track 1 (dashed line) and 60/hectare in Track 2 (solid line).
Fig 5.
Number of living spruce trees of high age (> 250 years).
Mean number (± 1 SD) of living spruce trees of high age > 250 years per hectare and in the randomly assigned sample plot in studied forests. Criteria for Track 2 (black line) in the developed method is 10 trees per hectare.
Fig 6.
Harvested forest and forest reported for cutting per year.
Harvested forest area (left) and forest area reported for harvest (right) within the deregistered key habitats in Sweden.