Abstract

Question: Ecological restoration has traditionally been evaluated by analyses focused on species identities and abundances. These analyses provide no ecological explanation to why certain species change in abundance. One solution to this may be a functional trait analysis. We asked whether shifts in functional traits could explain vegetation changes in fens restored through tree cutting and rewetting, and how the functional traits in the restored sites compare to those of the reference-site.

Location: Three former rich fens in east-central Sweden.

Methods: Tree cutting and rewetting were applied in a factorial design, and species and abundance data were recorded for 8 years. Abundance data and trait data of canopy height, specific leaf area (SLA) and diaspore mass were used to calculate functional richness (FRic), functional divergence (FDiv), functional dispersion (FDis) and community weighted mean (CWM) of functional traits. Data were analysed in a linear mixed effect model for vascular plants and bryophytes jointly and for vascular plants separately. The results of the restoration treatments were compared to data from a reference-site.

Results: Among vascular plants, tree cutting caused a decrease in SLA as shade sensitive species increased. In accordance with the change in SLA, FDis increased. In the joint analysis, tree cutting lead to increased FDis, FDiv and FRic. The increase in FDis, FRic and FDiv indicates reduced filtering caused by the removal of shading canopy, which allowed shade sensitive species to establish. The comparison to the reference-site shows that even after eight years the restoration treatments have higher trait diversity than the reference-site, indicating that the restoration-sites have a too relaxed trait filter compared to the conditions of an undisturbed fen. Our interpretation is that this is primarily caused by insufficient rewetting (and increased nutrient availability) that allow species of both natural and degraded fen conditions to coexist, and which has failed to suppress the regrowth of trees.

Conclusions: The analysis of functional diversity improves our understanding of the ecological mechanisms affecting the restoration results, and allows for comparison among regions and communities with different species composition.

Keywords

Bryophyte; Ditch blocking; Environmental filter; Functional diversity; Peatland; Specific leaf area; Tree cutting; Vascular plant

Published in

Applied Vegetation Science
2013, Volume: 16, number: 4, pages: 658-666
Publisher: WILEY-BLACKWELL

SLU Authors

• Sundberg, Sebastian

  • SLU Swedish Species Information Centre, Swedish University of Agricultural Sciences
    

Associated SLU-program

Biodiversity
Cross-programme


UKÄ Subject classification

Ecology
Botany
Other Biological Topics


Publication identifier

DOI: https://doi.org/10.1111/avsc.12042

Permanent link to this page (URI)

https://res.slu.se/id/publ/52590