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

Abstract

Composition of functional groups of ground vegetation differ between planted stands of non-native Pinus contorta and native Pinus sylvestris and Picea abies in northern SwedenBäcklund S., Jönsson M.T., Strengbom J., Thor G. (2015). Composition of functional groups of ground vegetation differ between planted stands of non-native Pinus contorta and native Pinus sylvestris and Picea abies in northern Sweden. Silva Fennica vol. 49 no. 2 article id 1321. 10 p. Highlights• Differences in ground vegetation patterns can be linked to tree species, forest stand age and differences in canopy cover.• Vascular plant cover was higher in stands of P. contorta than in stands of both native tree species.• The overall differences and similarities between P. contorta and the two native conifers were not consistent over the different age classes. AbstractIntensified forestry increases the interest in replacing native tree species with fast growing nonnative 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 quantified the ground cover of lichens, bryophytes, vascular plants and ground without vegetation (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. contorta as an alternative tree species in Fennoscandian forestry will influence native ground vegetation patterns. This influence is likely to change with time and future research should consider both temporal and landscape-scale effects from shifting tree-species dominance to Pinus contorta and other non-native tree species.

A Pine Is a Pine and a Spruce Is a Spruce – The Effect of Tree Species and Stand Age on Epiphytic Lichen Communities

“…Although studies of mature stands are lacking, younger stands of introduced P . contorta are not “biological deserts” from the perspective of epiphytic species (this study), understory species [ 61 , 62 , 63 ], or epigaeic beetles [ 62 ]. The higher growth rate of the non-native P .…”

The tree species matters: Biodiversity and ecosystem service implications of replacing Scots pine production stands with Norway spruce

“…Overstory effects on understory vascular plants is largely dictated by interspecific competition, mediated by soil and light conditions (Kuusipalo 1985a). The most distinct difference between pine and spruce stands is lower understory light levels beneath the later (see Table 1 ;Kuusipalo 1985b;Bäcklund et al 2015). As a result, the field layer abundance of spruce stands is generally lower than in pine (Bäcklund et al 2015) and declines rapidly as stem density increases (Hedwall et al 2013;Tonteri et al 2016).…”

“…The most distinct difference between pine and spruce stands is lower understory light levels beneath the later (see Table 1 ;Kuusipalo 1985b;Bäcklund et al 2015). As a result, the field layer abundance of spruce stands is generally lower than in pine (Bäcklund et al 2015) and declines rapidly as stem density increases (Hedwall et al 2013;Tonteri et al 2016). Understory light levels can be particularly low in southern Sweden due to high-stem densities of spruce, which may cause vascular plants to be replaced by bryophytes or patches lacking vegetation (Esseen et al 1997).…”

“…In contrast, light is rarely limiting in pine stands, and understory composition is primarily determined by competition (Tonteri et al 1990). In dry and high light conditions, ground-living species of lichens benefit (Okland 1995), but tend to decline with increased stand age and stem densities (Bäcklund et al 2015). At later successional stages, competitive dwarf shrubs such as bilberry (Vaccinium myrtillus) and cowberry (V. vitis-idaea) can dominate and prevent other species from establishing (Tonteri et al 1990), thereby lowering species richness (Widenfalk and Weslien 2009).…”

Consequences for bird diversity from a decrease in a foundation species—replacing Scots pine stands with Norway spruce in southern Sweden

“…differences in the resources and environments provided are in turn linked to differences in the species communities and biodiversity supported. For example, differences between Norway spruce and Scots pine stands have been found in the community composition or diversity of epiphytic lichens (Bäcklund et al 2016;Marmor et al 2013), macrofungal communities (Ferris et al 2000), and bryophytes (Augusto et al 2003;Bäcklund et al 2015). Concerns may thereby be raised that the conversion of Scots pine stands to Norway spruce may lead to changes to forest biodiversity in southern Sweden, though the specific nature of such impacts and their extent remains largely unknown.…”