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Experimental extensification of mountain grasslands restores plant species richness but not species composition in the mid-term

Cite this dataset

Humann-Guilleminot, Ségolène et al. (2022). Experimental extensification of mountain grasslands restores plant species richness but not species composition in the mid-term [Dataset]. Dryad. https://doi.org/10.5061/dryad.ksn02v787

Abstract

  1. The traditional grasslands that characterize the cultural landscapes of the palaeartic mountain massifs represent biodiversity hotspots. Yet, they are currently threatened by the intensification of farming practices, notably excesses in fertilization and irrigation.
  2. We experimentally investigated the passive restoration of montane and subalpine hay meadows after six years of management intensification, with different levels of fertilization and irrigation, followed by five years of release of intensive management, i.e. extensification. More specifically, relying on a full randomized block-design replicated at 11 Swiss study sites constituted of extensively-managed meadows, we exposed during six years (2010-2015) four 20 m diameter plots to three levels of intensification (low, medium and high inputs), while a fourth plot served as a control (no inputs). In the second phase of the experiment (2016-2020), all study meadows underwent farming extensification.
  3. We monitored total species richness and plant diversity (Simpson diversity), indicator plant species as well as the composition and variability of the plant communities based on Bray-Curtis dissimilarity distances.
  4. We found that total species richness decreased in the most intensified plots after six years of intensification, but all plots retrieved their baseline species richness after five years of re-extensification. Additionally, we found no difference between the years in plant diversity (Simpson diversity) among the treatments. Yet, intensification led to different plants communities’ compositions in all three levels of intensification in 2015 compared to the extensive plots, and this structural difference remained after five years of re-extensification.
  5. Synthesis and applications. Land-use intensification induces a rapid impoverishment of the flora of mountain meadows. Our results demonstrate the potential of mountain hay meadows to passively restore plant species richness after re-extensification, however plants communities did not fully recover. We recommend maintaining fertilization inputs as low as possible and operating active restoration on grasslands formerly intensified.

Methods

Within each meadow, four circular plots of 20 m diameter were delimited. In each circular treatment plot, a permanent subplot of 2 × 4 m was placed at a distance of 4 m from the plot centre, with the rectangle being oriented longitudinally parallel to the slope axis. Baseline vegetation relevés have been conducted with the help of a professional botanist prior to treatments, in 2010 and in the last year with experimental inputs, in 2015. In June 2020, we conducted new vegetation relevés with the help of a professional botanist, following the exact same procedure as in 2010 and 2015, at nine of the 11 study sites. Plant species richness was assessed from field vegetation relevés while the cover of each species within the plot was estimated visually before the first mowing in June-July. Plant species covering only < 0.1% were arbitrary attributed a percentage of 0.03.

Usage notes

File in .txt format

Funding

Swiss National Science Foundation, Award: 31003A_172953/1