DOI: 10.5061/dryad.ksn02v787
title: Experimental extensification of mountain grasslands restores plant species richness but not species composition in the mid-term

description: 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. 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. 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. 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. 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.
description: 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
 &lt; 0.1% were arbitrary attributed a percentage of 0.03.
description: File in .txt format