Losing your home: Temporal changes in forest landscape structure due to timber harvest accelerate Northern goshawk (Accipiter gentilis) nest stand losses

Abstract

In Finland, forests are both one of the main national economic resources and the main source of biodiversity. Lack of detailed empirical evidence of how forestry affects biodiversity limits the development of sustainable forest management. Previous studies have found that the Northern goshawk (Accipiter gentilis) is a keystone species in mature coniferous boreal forests, and that its presence is associated with high local biodiversity. To understand how timber harvest affect goshawk nest-stand constancy and nest occupancy, we analyzed changes in nine landscape classes in two buffer zones (100 m, 250 m) around goshawk nests in Western Finland during 2005-2013. Patterns of nest occupancy and nest stand loss during 2005-2013 was compared with corresponding data from 1999-2005 to investigate possible long-term changes in the same. We found a positive connection between the proportion of mature spruce forest and nest occupancy. Nest stand constancy was at a lower level during 2005-2013 than during 1999-2005. This was mainly because of forest loss due to cutting of nest stands. Given that the loss of goshawk nest stands has accelerated and because timber harvest in the area was found to be specifically targeted towards forest types favoured by goshawks, forestry may have an even larger negative effect on biodiversity locally than previously thought given that goshawk nest stands are associated with high biodiversity. To render the Finnish forestry ecologically sustainable, we propose that protection of goshawk nest stands should be an integrated part of standard forestry practices in the future.