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Publication type: Article in scientific journal
Type of review: Peer review (publication)
Title: Optimal site conditions for dry grasslands of high conservation value in the canton of Zurich, Switzerland
Authors: Büchler, Marc-Olivier
Billeter, Regula
Dengler, Jürgen
et. al: No
DOI: 10.14471/2020.40.021
Published in: Tuexenia
Volume(Issue): 40
Pages: 527
Pages to: 546
Issue Date: Nov-2020
Publisher / Ed. Institution: Floristisch-Soziologische Arbeitsgemeinschaft
ISSN: 0722-494X
Language: English
Subject (DDC): 333.7: Land, natural recreational areas
Abstract: Semi-dry semi-natural grasslands such as those of the alliance Mesobromion (Festuco-Brometea) are one of the most-diverse habitat types in Europe with regard to many taxonomic groups, but these remnants of traditional extensive agriculture are currently threatened throughout the continent. It is important to know how and where such valuable vegetation types could be best maintained (or re-established) under current environmental conditions. To address this question, we selected 27 dry grassland sites in the canton of Zurich, Switzerland, half of which had been classified as of “good” and half as of “poor” quality one decade ago. We sampled vegetation, soil and topographical data in three 1-m² plots in each of these sites. We then compared the current environmental conditions and plant species composition of the two original quality levels. Furthermore, we related four metrics of current conservation value (vascular plant species richness, evenness, forb/graminoid ratio and an ad hoc developed conservation score) to measured environmental predictors and mean ecological indicator values. We found that the “good” and “poor” sites differed in only few environmental predictors, such as good sites having higher pH, lower soil nitrogen and steeper slopes, while they had higher numbers and covers of typical semi-dry grassland species and a higher conservation value. The metrics of con-servation value behaved inconsistently when relating them to various environmental predictors. Inter-estingly, species richness decreased with slope inclination, but was also marginally negatively related to soil phosphorus. Conservation score, in contrast, increased with inclination, but also with increasing litter cover and soil nitrogen. While evenness largely showed similar response as conservation score, those of the forb-graminoid ratio were reversed for several environmental predictors. Overall, our results indicate that the conservation value of semi-dry grasslands cannot simply be attributed to one or two main factors. As different metrics of conservation value behaved differently, taking just one as a proxy would not be sufficient. Despite some variation, generally lower nutrient status, higher pH and steeper slopes seem to favour the maintenance of dry grasslands of higher quality. Some of our counter-intuitive results such as the higher litter cover in the plots of higher conservation value may indicate that current conservation management of these grasslands is too extensive to maintain their quality, par-ticularly given the high atmospheric nitrogen input in the region. We thus propose an experiment to test whether earlier and/or more frequent mowing helps in maintaining the quality of semi-dry grasslands.
Fulltext version: Published version
License (according to publishing contract): Licence according to publishing contract
Departement: Life Sciences and Facility Management
Organisational Unit: Institute of Natural Resource Sciences (IUNR)
Appears in collections:Publikationen Life Sciences und Facility Management

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