Data from: Edge influence on vegetation at natural and anthropogenic edges of boreal forests in Canada and Fennoscandia

1. Although anthropogenic edges are an important consequence of timber
harvesting, edges due to natural disturbances or landscape heterogeneity
are also common. Forest edges have been well-studied in temperate and
tropical forests, but less so in less productive, disturbance-adapted
boreal forests. 2. We synthesized data on forest vegetation at edges of
boreal forests and compared edge influence among edge types (fire, cut,
lake/wetland; old vs. young), forest types (broadleaf vs. coniferous) and
geographic regions. Our objectives were to quantify vegetation responses
at edges of all types and to compare the strength and extent of edge
influence among different types of edges and forests. 3. Research was
conducted using the same general sampling design in Alberta, Ontario and
Quebec in Canada, and in Sweden and Finland. We conducted a meta-analysis
for a variety of response variables including forest structure, deadwood
abundance, regeneration, understorey abundance and diversity, and
nonvascular plant cover. We also determined the magnitude and distance of
edge influence using randomization tests. 4. Some edge responses (lower
tree basal area, tree canopy and bryophyte cover; more logs; higher
regeneration) were significant overall across studies. Edge influence on
ground vegetation in boreal forests was generally weak, not very extensive
(distance of edge influence usually < 20 m) and decreased with
time. We found more extensive edge influence at natural edges, at younger
edges and in broadleaf forests. The comparison among regions revealed
weaker edge influence in Fennoscandian forests. 5. Synthesis. Edges
created by forest harvesting do not appear to have as strong, extensive or
persistent influence on vegetation in boreal as in tropical or temperate
forested ecosystems. We attribute this apparent resistance to shorter
canopy heights, inherent heterogeneity in boreal forests and their
adaptation to frequent natural disturbance. Nevertheless, notable
differences between forest structure responses to natural (fire) and
anthropogenic (cut) edges raise concerns about biodiversity implications
of extensive creation of anthropogenic edges. By highlighting universal
responses to edge influence in boreal forests that are significant
irrespective of edge or forest type, and those which vary by edge type, we
provide a context for the conservation of boreal forests.