Experiment‐based recommendations for biodiversity‐friendly management of mountain hay meadows

Abstract

Question: The biodiversity of mountain hay meadows has historically been maintained through traditional, low-intensity farming practices. In recent decades, however, agricultural intensification for hay production has led to dramatic declines in their biodiversity. This study asks: which management practices can contribute to maintaining the biodiversity value of mountain hay meadows without jeopardizing agricultural revenue?Location: Eleven semi-natural meadows, canton of Valais, inner Alps, southwest Switzerland.Methods: We experimentally measured the effects of various intensities of fertilization (slurry) and aerial irrigation (sprinklers) on the taxonomic, phylogenetic and functional diversity of plants. The experiment consisted of six different treatments, each randomly applied to one of six plots within a meadow. A plot therefore was (1) not irrigated and only fertilized with slurry, (2) not fertilized and only irrigated with a sprinkler, (3-5) receiving low, medium or high amounts of both fertilizer and water, respectively, or (6) receiving no input of irrigation or fertilizer (control plots).Results: After 4 yr, all biodiversity metrics were negatively impacted under the highest management intensity (irrigation combined with fertilization at concentrations corresponding to the input necessary to achieve maximum local hay yield, i.e. three-thirds of inputs). In contrast, at low-and mid-intensity management levels (irrigation combined with fertilization at one-third and two-thirds of the maximum concentration, respectively) most diversity metrics did not differ from the controls, except for forb species richness, which was already reduced under mid-intensity management compared to low-intensity and control plots. Neither irrigation nor fertilization alone had a negative impact on plant biodiversity.Conclusions: Low to moderate agricultural intensification of hay production does not appear to be detrimental to plant biodiversity among mountain meadows. These results suggest that sustainable management would be obtained via irrigation and fertilization corresponding to one-third to two-thirds of the quantity necessary to achieve maximum local hay yield.

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

“…Intensification induces a rapid impoverishment of the flora of montane and subalpine meadows in the short term (Andrey et al, 2014) and mid-term (Boch et al, 2021;Lessard-Therrien et al, 2017), as demonstrated by our earlier work within the same experimental set up and corroborated in this study. In addition, effects of intensification are more pronounced in species-rich grasslands (e.g.…”

“…The treatment plots received low, medium or high inputs, corresponding to a combination of aerial irrigation (sprinklers) and fertilization (slurry) that mimicked a gradient of intensification, with, respectively, 1/3 (low intensity; I + F 1/3), 2/3 (mid intensity; I + F 2/3) and 3/3 (high intensity; I + F 3/3) of the quantity of inputs that would be necessary to achieve the maximum local hay yield in a given meadow according to its agronomic properties. The exact amount of slurry applied per plot are presented in Table S2, and in Andrey et al (2014, 2016) and Lessard‐Therrien et al (2017). Mowing regimes had to be adapted to phytomass production to simulate local farming practice: C‐ and I + F 1/3 plots were mown once a year, the other plots twice a year (see Andrey et al, 2014, 2016; Lessard‐Therrien et al, 2017 for details).…”

Plant Responses to Changing Water Supply and Availability in High Elevation Ecosystems: A Quantitative Systematic Review and Meta-Analysis

“…Alternatively, the outcomes of plant responses to water supply increase may reflect experimental design. All studies focussing on precipitation increases were conducted in situ where increased precipitation was typically applied to experimental plots using sprinklers [51,52] or by diverting rainfall from passive rainout shelters [53]. Studies rarely reported soil moisture at varying depths, yet these methods of water application potentially only recharge the surface soil layers.…”

Direct and indirect effects of land use on bryophytes in grasslands

“…The first dataset (called the observational dataset, henceforth) contains observational data on bryophyte species richness along a land-use intensity gradient in German grasslands (the German Biodiversity Exploratories; Fischer et al, 2010). The second dataset (called the experimental dataset, henceforth) contains experimental data on bryophyte species richness from a replicated field experiment that tested the effects of modern fertilization and irrigation upon plant and invertebrate communities of Swiss mountain hay meadows, with the objective to define optimal trade-offs for sustainable grassland management (e.g., Andrey et al, 2016;Lessard-Therrien et al, 2017). Combining these two datasets therefore allowed us to generalize findings across a range of different grassland types and to assess i) how intensification of land-use components affects bryophyte species richness and ii) how important direct intensification effects on bryophyte species richness are, compared to plant biomass-mediated indirect ones (see details below).…”