Forest edge density in a gradient of boreal landscapes in Sweden
(English)Manuscript (Other academic)
The boreal forests in Fennoscandia are strongly fragmented by intensive forestry and other land use resulting in high amount of edge habitat. Detailed data on edge quantity is critical to assess fragmentation effects on biodiversity. We estimated the density of sharp forest edges in 28 landscapes, each 4 km × 4 km, along a 830 km gradient in northern Sweden. Data was collected from colour infrared aerial photographs using line intersect sampling and 20-m radius plots. Forest edge density was 54 ± 4.6 m ha-1 land area (mean ± SE) but variation was high among landscapes (12-102 m ha-1). Natural edges constituted 38% but created edges dominated (36% maintained and 26% regenerating). Thirty percent of edges adjoined narrow (5-19 m) open landscape elements (corridor edges) and seventy percent adjoined more exposed patches (≥20 m, patch edges). We found 34 types of patch edges, with the highest density recorded for edges in mature forest. Edge density increased with proportion of landscape disturbed by forestry and agriculture, and decreased with latitude and altitude, but natural and created edges showed contrasting patterns. The high density of sharp edges and the variability among landscapes implies that edges may have strong and diverse effects on the structure, function and biodiversity of boreal forest ecosystems. This variability must be taken into account when formulating strategies for sustainable forest management.
line intersect sampling, aerial photographs, forest fragmentation, edge influence, edge length, edge types
Research subject Ecological Botany
IdentifiersURN: urn:nbn:se:umu:diva-21660OAI: oai:DiVA.org:umu-21660DiVA: diva2:211433