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Kapfer, Jutta ; Audorff, Volker ; Beierkuhnlein, Carl ; Hertel, Eduard:
Do bryophytes show a stronger response than vascular plants to interannual changes in spring water quality?
In: Freshwater Science.
Bd. 31
(2012)
Heft 2
.
- S. 625-635.
ISSN 2161-9565
DOI: https://doi.org/10.1899/11-037.1
Abstract
Springs are characterized by consistent thermal and hydrologic conditions, which enable use ofspring-inhabiting organisms as sensitive indicators of biogeochemical changes in their catchments. Wehypothesized that bryophytes would show a stronger response than vascular plants to changes in springwater quality because submerged bryophytes do not take up compounds from the soil. We analyzedspecies responses to interannual changes in spring water quality (discharge, water temperature, electricalconductivity, and pH) in 57 forest springs over 4 consecutive years. We calculated interannual turnover inspecies composition for bryophytes and vascular plants with the Bray–Curtis dissimilarity index. Weapplied regression analysis to test interannual changes in species composition of the taxonomic groupsover time, and we used 2-sided t-tests to compare year-to-year changes in species composition betweenbryophytes and vascular plants. We used boosted regression tree (BRT) models to quantify the relativeimportance of different physicochemical variables and Pearson linear correlation to quantify short-termchanges in vegetation relative to changes in spring-water pH. For both groups, interannual changes inspecies composition were significantly positively related to time scale. Bryophytes did not show asignificantly stronger response than vascular plants to interannual changes in the environment. Alterationsin pH and conductivity explained most of the observed interannual changes in species composition of bothgroups, whereas changes in water temperature and discharge were less important. However, responses ofsingle species to environmental change may be delayed, resulting in inertia at the community andecosystem scales. Hence, longer time periods need to be considered for a better understanding of responsetimes of the vegetation of European forest springs to changes in spring water quality.