Do vascular plants and bryophytes respond differently to coniferous invasion of coastal heathlands?

• Published in: Biological invasions Vol. 16; no. 4; pp. 775 - 791
• Main Authors: Saure, Heidi Iren, Vandvik, Vigdis, Hassel, Kristian, Vetaas, Ole Reidar
• Format: Journal Article
• Language: English
• Published: Cham Springer-Verlag 01.04.2014; Springer International Publishing; Springer; Springer Nature B.V
• Subjects: Aquatic plants; Biological and medical sciences; Biomedical and Life Sciences; Bryophyta; Bryopsida; Canopies; Community ecology; Coniferous trees; conifers; Developmental Biology; Ecology; ecosystems; Environmental changes; environmental factors; Environmental impact; Evergreen trees; forests; Freshwater & Marine Ecology; Fundamental and applied biological sciences. Psychology; heathlands; Indigenous species; Introduced species; Invasive species; Life Sciences; Microclimate; nitrogen; Nonnative species; Original Paper; Picea sitchensis; Pine trees; Pinus sylvestris; Plant cytology, morphology, systematics, chorology and evolution; Plant populations; Plant Sciences; Plant species introduction; species diversity; Species richness; stems; Terrestrial ecosystems; Trees; vascular plants; Europe; ANE, Europe; Ellenberg indicator values; Species turnover; Soil conditions; Species richness; Heathland and moor; Picea sitchensis; Bryophyta; Pinus sylvestris; Pteridophyta; Indicator; Invasion; Soils; Gymnospermae; Turnover; Coniferales; Spermatophyta
• ISSN: 1387-3547; 1573-1464
• DOI: 10.1007/s10530-013-0536-6

Invasion by non-native conifers may pose a threat to local biodiversity, but knowledge about introduced conifer effects on Northern Hemisphere ecosystems is scarce. The coastal heathlands of north-west Europe are threatened by invasion of native and introduced tree species. We assess how spread of the introduced conifer Sitka spruce (Picea sitchensis (Bong.) Carr.) into European coastal heathlands affect two major functional groups; vascular plants and bryophytes, and how these effects relate to the environmental changes imposed by the developing tree canopies. We compared the impact of introduced Sitka spruce and native Scots pine (Pinus sylvestris L.) by analysing effects on species richness and turnover of vascular plants and bryophytes along fine-scale transects from individual tree stems into open heathland vegetation. Environmental impacts were assessed by measured environmental variables, and the responses of the two species groups were assessed by calculating changes in their respective mean Ellenberg indicator values. Species richness decreased beneath both conifers, related to decreased light and increased nitrogen and pH. Whereas vascular plants responded negatively to poor light conditions beneath dense and low Sitka spruce canopies, bryophytes were more negatively affected by the warmer and drier microclimates beneath Scots pine. Introduced Sitka spruce impacts the sub-canopy environment differently from the native Scots pine, and the two functional plant groups responded differently to these impacts. This suggests that future forests are likely to differ in species richness and composition, depending on whether succession is based on native or introduced coniferous trees.