Plant β-diversity i in human-altered forest ecosystems: the importance of the structural, spatial, and topographical characteristics of stands in patterning plant species assemblages

An understanding of spatial patterns of plant species diversity and the factors that drive those patterns is critical for the development of appropriate biodiversity management in forest ecosystems. We studied the spatial organization of plants species in human- modified and managed oak forests (primarily, Quercus faginea) in the Central Pre- Pyrenees, Spain. To test whether plant community assemblages varied non-randomly across the spatial scales, we used multiplicative diversity partitioning based on a nested hierarchical design of three increasingly coarser spatial scales (transect, stand, region). To quantify the importance of the structural, spatial, and topographical characteristics of stands in patterning plant species assemblages and identify the determinants of plant diversity patterns, we used canonical ordination. We observed a high contribution of ˟-diversity to total -diversity and found ˟-diversity to be higher and ˞-diversity to be lower than expected by random distributions of individuals at different spatial scales. Results, however, partly depended on the weighting of rare and abundant species. Variables expressing the historical management intensities of the stand such as mean stand age, the abundance of the dominant tree species (Q. faginea), age structure of the stand, and stand size were the main factors that explained the compositional variation in plant communities. The results indicate that (1) the structural, spatial, and topographical characteristics of the forest stands have the greatest effect on diversity patterns, (2) forests in landscapes that have different land use histories are environmentally heterogeneous and, therefore, can experience high levels of compositional differentiation, even at local scales (e.g., within the same stand). Maintaining habitat heterogeneity at multiple spatial scales should be considered in the development of management plans for enhancing plant diversity and related functions in human-altered forest

Effects of Previous Land-Use on Plant Species Composition and Diversity in Mediterranean Forests

At some point in their history, most forests in the Mediterranean Basin have been subjected to intensive management or converted to agriculture land. Knowing how forest plant communities recovered after the abandonment of forest-management or agricultural practices (including livestock grazing) provides a basis for investigating how previous land management have affected plant species diversity and composition in forest ecosystems. Our study investigated the consequences of historical “land management” practices on present-day Mediterranean forests by comparing species assemblages and the diversity of (i) all plant species and (ii) each ecological group defined by species’ habitat preferences and successional status (i.e., early-, mid-, and late-successional species). We compared forest stands that differed both in land-use history and in successional stage. In addition, we evaluated the value of those stands for biodiversity conservation. The study revealed significant compositional differentiation among stands that was due to among-stand variations in the diversity (namely, species richness and evenness) of early-, intermediate-, and late-successional species. Historical land management has led to an increase in compositional divergences among forest stands and the loss of late-successional forest species

Effets des modifications de l'utilisation des terres sur la conservation des pâturages subalpins du Parc National de Ordesa Mont-Perdu

Les écosystèmes montagnards, tels que nous les connaissons aujourd'hui, résultent de l'interaction entre l'action de l'homme et les facteurs biogéophysiques qui a conduit à la création d'espaces particuliers possédant une grande biodiversité végétale. Ce travail vise a étudier, la dynamique de la végétation dans les pâturages subalpins du Parc National de Ordesa-Mont Perdu (Pyrénées espagnoles), confrontés à une réduction du pâturage. Le pâturage peut avoir un effet positif ou négatif sur la biodiversité végétale en fonction de l'échelle d'étude considérée : à l'échelle de la communauté végétale le pâturage entraine une perturbation de l'organisation spatiale alors qu'à grande échelle, l'effet du pâturage est positif car il favorise l'hétérogénéité des espèces végétales. La superficie de Echinospartum horridum a été multipliee par deux (268 ha vs. 530 ha) au cours des 46 dernières années, avec une vitesse de colonisation atteignant 2 mètres.année-1. La distribution spatiale de E. horridum est surtout dépendante des facteurs biogéophysiques (altitude, pente, radiation solaire). Les plantes situées en bordure des patches présentent des caractères démographiques de plantes invasives et ont une grande capacité de colonisation. Les simulations de colonisation de la plante suggèrent une combinaison entre brûlage et pâturage pour freiner son expansion. Comme le montre la colonisation de E. horridum, le maintien du pâturage est nécessaire pour contenir l'expansion des espèces ligneuses. L'effet du pâturage est différent selon l'échelle d'étude considérée, en conséquence un choix se pose quant à la conduite à tenir pour la conservation de la biodiversité des pâturages du PNOMP.Many mountain ecosystems are significantly influenced by the interactions between human activities and biogeophysical factors, which can lead to the development of areas that have high biodiversity. This study examined the vegetation dynamics in the subalpine grasslands of the Ordesa Monte Perdido-National Park (Spanish Pyrenees) vis-à-vis a reduction in grazing pressure by livestock. The effects of grazing on the vegetation of the subalpine grasslands of OMPNP differed depending on the scale of the analysis. At the scale of the community, grazing disturbed the spatial distributions of plants in the community while at the landscape scale, grazing increased heterogeneity in the distribution of plant species. In the last 46 years, the area in the park occupied by Echinospartum horridum doubled (from 268 ha to 530 ha) with an expansion rate of about 2 m.years-1. The spatial distribution of E. horridum was mainly a function of biogeophysical factors (elevation, slope, solar radiation) where simulation of the expansion demonstrated the necessity of prescribed burning and grazing to limit the colonization. The populations of E. horridum exhibited the characteristics of invasive plants and had a highest capacity for colonization. The demographics of the colonization of subalpine grasslands by E. horridum suggests that, to impede the expansion of woody species, livestock grazing pressure will have to be maintained. The effects of differs among plant communities and the pastoral unit; consequently land managers are face with a dilemma, but the maintenance of past agropastoral practices is necessary in the conservation of biodiversity in the grasslands of OMPNP.CHAMBERY -BU Bourget (730512101) / SudocSudocFranceF

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

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

Fig. S1 A) Location of study sites in the central Pyrenees (NE Spain). B) Schematic representation of the experimental design. In each site, three plots were randomly selected for the rainfall reduction treatment (striped pattern). In each plot, one subplot was randomly selected for the snow removal treatment (dark filling). C, control subplots with neither snow removal nor rainfall reduction; S, subplots with snow cover removal; R, subplots with rainfall reduction; and S + R, subplots with the combination of snow removal and rainfall reduction. C) Pictures showing examples of plots with rain-out shelters at each study site.-- Fig. S2 Mean monthly temperature (light red, mean of maximum temperatures; dark red, mean of minimum temperatures), precipitation, snow cover and number of days with snow cover presence over the study period (2016-2019) at the nearest weather station from Torla (approx. 750 m). Data was provided by the State Meteorological Agency (Spanish Ministry for Ecological Transition and Demographic Challenge).-- Fig. S3 Mean monthly temperature (light red, mean of maximum temperatures; dark red, mean of minimum temperatures), precipitation, relative air humidity, snow cover and number of days with snow cover presence over the study period (2016-2019) at the nearest weather station from Pineta (approx. 2000 m). Data was provided by the State Meteorological Agency (Spanish Ministry for Ecological Transition and Demographic Challenge).-- Fig. S4 A) Relationship (linear regression) between minimum soil temperature in February and year per treatment, B) relationship (linear regression) between leguminous forbs aboveground dry biomass and year per treatment and C) plant diversity (effective number of species, mean ± SE) per treatment and study site. Different letters indicate significant differences among treatments. Symbol shape indicates study site (circle and square for Torla and Pineta, respectively), symbol/line color indicates snow removal treatment (gray and black for no snow removal and snow removal, respectively) and symbol/line pattern indicates reduced precipitation treatment (solid and dashed for no reduced precipitation and reduced precipitation, respectively). C, control, gray solid line; S, snow removal, black solid line; R, reduced precipitation, gray dashed line; S + R, snow removal plus reduced precipitation, black dashed line.-- Fig. S5 A) February’s soil freeze/thaw cycles (mean ± SE) per study site, treatment and year. Horizontal lines indicate mean values per treatment and year. Symbol shape indicates study site (circle and square for Torla and Pineta, respectively), symbol/line color indicates snow removal treatment (gray and black for no snow removal and snow removal, respectively) and symbol/line pattern indicates reduced precipitation treatment (solid and dashed for no reduced precipitation and reduced precipitation, respectively). C, control, gray solid line; S, snow removal, black solid line; R, reduced precipitation, gray dashed line; S + R, snow removal plus reduced precipitation, black dashed line. B) Relationship (linear regression) between minimum soil temperatures in February and soil freeze/thaw cycles per study site.-- Table S1 Mean plant cover (%) at the subplot level for each species found per study site and treatment. Color intensity highlights dominant plant species.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

Comparing Direct Abiotic Amelioration and Facilitation as Tools for Restoration of Semiarid Grasslands

International audienc

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

Resilience, Self-Organization, Complexity and Pattern Formation

International audienceClarity of definitions is fundamental to the successful completion of any interdisciplinary project. In this chapter, we focus on defining a number of key terms that recur throughout the volume, and thus it acts as both a foundation and glossary for understanding the material covered. Ideas of resilience, self-organization and complexity are widely used across in constituent disciplines discussed in Chap. 1, but their use varies and we attempt to define this variation and thus the context of use in the book. There is also a strong emphasis on pattern, so we provide here an initial definition, to be followed up in more detail in Chaps. 7 and 8. We then move onto the specific nature of drylands and the need to understand land degradation within them and through them. How the mode of study affects our understanding is the next theme, in particular how case studies based in different places can be generalized, given the variations in landscape and vegetation type within them. Following an initial summary of the preceding material to evaluate why self-organization and complexity are useful frameworks for understanding patterns and processes in drylands, the chapter concludes with an overview of the deterministic and stochastic frameworks for understanding patter

Resilience in sensitive mountain forest ecosystems under environmental change

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