Vegetation responses to snow cover removal and rainfall reduction in subalpine grasslands: Insights from a 4-year field experiment in the Spanish Pyrenees

© 2024 The Author(s). Published with license by Taylor & Francis Group, LLC. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0/), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited. The terms on which this article has been published allow the posting of the Accepted Manuscript in a repository by the author(s) or with their consent.Reduced precipitation as well as warming may result in less snow accumulation in seasonally snow-covered areas, leading to lower minimum soil temperatures and more frequent and severe soil frosts. Therefore, plant stress is increased not only by drought in warmer months, but also by increased exposure to frost in cooler periods. We conducted a 4-year field experiment to evaluate the effects of diminished snowpack accumulation (through snow removal) and rainfall reduction (through rain-out shelters) on aboveground plant productivity, diversity and species composition of two subalpine grassland plant communities from the central region of the Spanish Pyrenees. We found that the snow removal treatment decreased minimum soil temperature by 0.5°C. Plant diversity decreased by 16 percent, although this effect was only observed in one of the grasslands studied. Aboveground primary productivity seemed to be unaffected. In contrast, we found that the rainfall reduction treatment negatively affected aboveground productivity of leguminous forb species, yet no effect on plant diversity was observed. Both treatments were important drivers of changes in plant species composition. Overall, our results suggest that the resilience of subalpine grasslands to snow cover removal and rainfall reduction treatments may depend on the specific community composition and dominant plant groups.This work was supported by the Consejo Superior de Investigaciones Científicas [PIE, no. 202230E013]; Ministerio de Ciencia, Innovación y Universidades [FPU16/05508; FPU Program 2016].Peer reviewe

Effectiveness of two mechanical shrub removal treatments for restoring sub-alpine grasslands colonized by re-sprouting woody vegetation

13 Pags.- 7 Figs.- 3 Tabls. © 2023 The Authors. Published by Elsevier Ltd. This is an open access article under the CCBY-NC-ND license.The extent of European sub-alpine grasslands and their associated ecosystem services are decreasing due to woody plant encroachment. Commonly used methods of woody vegetation suppression like prescribed burning or clearcutting usually cause little damage to belowground bud-banks, offering poor results against re-sprouting shrubs. In this study, we assessed the effects on vegetation and soil properties of two mechanical shrub removal methods for restoring sub-alpine grasslands colonized by the re-sprouting shrub Rosa sp. in the Central Spanish Pyrenees: a commonly used method based on clearcutting (Clearcutting); and a non-previously assessed method based on pulling shrubs off the soil to remove both the aerial and belowground bud-banks (Uprooting). We set a parallel experiment to test whether or not clustering Rosa sp. debris generated in Uprooting (which held many mature fruits) at certain grassland locations may promote colonization of new grassland spots by Rosa sp. seedlings. By the end of the study period, vegetation composition and structure was more similar to the reference grassland in Uprooting than in Clearcutting. Indeed, woody vegetation cover was 71 % smaller in Uprooting than in Clearcutting three years after shrub removal. Nevertheless, by the end of the study period, chemical and microbiological soil properties were slightly more similar to the reference grassland in Clearcutting than in Uprooting. Additionally, the results of our study showed that clustering unusually high number of mature fruits of Rosa sp. at certain grassland locations increased shrub seedling colonization in comparison with other areas of the reference grassland, indicating that operational planning needs to take into account shrub phenology. In conclusion, our work showed that Uprooting may be a useful tool for land managers aiming to restore sub-alpine grasslands colonized by re-sprouting shrubs, though it is advisable using it for scatter shrub patches to prevent significant medium to long-term soil disturbance at landscape scale.This work was funded by FEADER, European Union, and Gobierno de Aragón (project name: Proyecto de cooperación para el seguimiento y control de zonas de pastos en la Reserva de la Biosfera Ordesa Viñamala); and by Ministerio de Ciencia, Innovación y Universidades del Gobierno de España (PhD scholarship FPU16/05,508, 2016 and project CGL2016-80783-R).Peer reviewe

Changes in plant vegetation structure and diversity with distance from herder shelters in the Middle Atlas Mountains

Livestock grazing intensity gradients associated with sheep holder shelters influenced the longevity of rangelands vegetation. This study aimed to examine the effects of livestock grazing pressure on vegetation structure and diversity with distance from herder shelters. Six shelters were sampled. From each herder shelter, a grazing gradient was set aligned to the contour lines. Along each grazing gradient, we surveyed seven 100-m transects between 10 and 800 m from the herder shelter. The standing crop biomass (dry matter = DM) along the gradient from the shelters, bare soil, cover of vegetation functional groups and plant species diversity were determined using the point intercept method along each transect. Bare soil cover increased as we approached herder shelter. The total standing crop biomass (DM) (in g DM m−2) increased with the distance from the shelter. Shrub biomass decreased when approaching shelters, as so did the percentage of shrub cover. Cover of perennial forbs and grass also increased with distance from shelter, whereas annual cover increased as we approached the shelter. Species richness and diversity increased when moving away from the shelter. Changes in vegetation structure were not linear. Strong changes were detectable within the first 200 m, whereas little responses were found behind this threshold. The 200 m threshold should be used to monitor the main keystone species that preserved these rangelands