Composition of functional groups of ground vegetation differ between planted stands of non-native <i>Pinus contorta</i> and native <i>Pinus sylvestris</i> and <i>Picea abies</i> in northern Sweden

Intensifiedforestryincreasestheinterestinreplacingnativetreespecieswithfastgrowingnon- native species. However, consequences for native biodiversity and ecosystem functioning are poorly understood. We compared cover and composition of major functional groups of ground vegetation between planted stands of non-native Pinus contorta Dougl. var. latifolia Engelm. and native conifers Pinus sylvestris L. and Picea abies (L.) H. Karst. in northern boreal Sweden. We quantifiedthegroundcoveroflichens, bryophytes, vascularplantsandgroundwithoutvegeta- tion (bare ground) in 96 stands covering three different age classes (15, 30 and 85 years old). Our study revealed differences in ground vegetation patterns between non-native and native managed forests, and that these differences are linked to stand age and differences in canopy cover. Total vascular plant cover increased with increasing stand age for all tree species, with P. contorta stands having higher cover than both native conifers. The ground cover of lichens was, although generally low, highest in stands of Pinus sylvestris. P. abies stands had a lower cover of vascular plants, but bare ground was more common compared with P. contorta. Our results suggest that the use of P. contortaasanalternativetreespeciesinFennoscandianforestrywillinfluencenative groundvegetationpatterns. Thisinfluenceislikelytochangewithtimeandfutureresearchshould consider both temporal and landscape-scale effects from shifting tree-species dominance to Pinus contorta and other non-native tree species.