Individual study: Levels of thinning in upland Scottish plantations are insufficient to permit the development of shrub layers that might enhance breeding bird populations
Calladine J., Humphreys E.M., Strachan F. & Jardine D.C. (2009) Forestry thinning in commercial conifer plantations has little effect on bird species richness and breeding abundance. Bird Study, 56, 137-137
This study is summarised as evidence for the intervention(s) shown on the right. The icon shows which synopsis it is relevant to.
Thin trees within forests
A replicated, paired site study from April-June in 2006 in 20 conifer plantation sites in Moray Firth, Scotland (Calladine et al. 2009), found that bird species richness and abundance was similar between thinned and unthinned plantations. Sites were in first-rotation and 18-32 years since planting and consisting of ten thinned sites paired with ten unthinned (average of 11 and 16 trees within a 5 m radius around count stations). Average species richness was 19 (range 13–24) at the thinned sites and 19 (range 15–22) at control sites. No significant differences between treatments were found in occurrence rates or abundance for any bird species. As the authors did not find any difference in species richness, they concluded that thinning within the study areas was also unlikely to have influenced the breeding populations of the scarcer species. No significant differences in ground cover, the presence of shrubs or stem diameter at breast height were found between treatments.