Epsilon Archive for Student Projects

Abstract

Tree-related microhabitats (TreMs) provide crucial habitat structures for insects, birds and fungi, particularly in open landscapes where trees grow in isolation. This study examines the occurrence, richness and composition of TreMs in grazed and formerly grazed grasslands in Västerbotten, northern Sweden. A total of 1,445 trees were inventoried across 16 grazed sites and nearby ungrazed control areas. TreMs were recorded following a standardized European typology.
The results showed that trees in grazed sites hosted both more and a greater variety of TreMs compared to ungrazed areas. TreM richness was particularly high in deciduous species such as aspen (Populus tremula), alder (Alnus glutinosa) and rowan (Sorbus aucuparia). The interaction between light exposure and grazing pressure played a key role: in grazed sites, TreMs were more frequent in fully sunlit conditions, whereas in ungrazed sites, shaded conditions promoted higher TreM occurrence.
These findings suggest that grazing and light conditions jointly influence the structural development of trees and their potential to support biodiversity. Maintaining semi-open landscapes with diverse tree species may therefore be critical to preserving TreM-related species in boreal agricultural systems.