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A) View of biological soil crusts dominating the spaces between plants in non-disturbed gypsum outcrops from central Spain, B) Close up view of the lichens forming the crust; the main species in this picture are Fulgensia subbracteata (yellow thalli) and Toninia sedifolia (grey and black thalli).
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Numerous theoretical and modeling studies have demonstrated the ecological significance of the spatial patterning of organisms on ecosystem functioning and dynamics. However, there is a paucity of empirical evidence that quantitatively shows how changes in the spatial patterns of the organisms forming biotic communities; are directly related to eco...
Contexts in source publication
Context 1
... strongly significant and positive relationship between the number of discrete plant patches ( S. tenacissima constitut- ed between the 38% and 94% of the total plant cover) – a simple indicator of the spatial patterning of vegetation – and both the number and diversity of perennial plant species in 30 m-long transects ( Fig. 3). This relationship, which was maintained even when controlling for plant cover – a key vegetation attribute that could confound it –, indicates that the spatial patterning of S. tenacissima tussocks is an important attribute for maintaining the structure of these ecosystems. Positive effects of S. tenacissima tussocks on the diversity and richness of vascular plants in semi-arid steppes may be related to facilitative processes mediated by their effects on microclimate and soil properties. Recent studies have thor- oughly described the effect of these tussocks on their own microenvironment through microclimatic amelioration (Maestre et al. 2001, 2003a), the improvement in the soil structure and depth (Bochet et al. 1999, Puigdefábregas et al. 1999), and the increase in soil moisture (Puigdefábregas and Sánchez 1996, Maestre et al. 2001), water infiltration (Cerdà 1997, Maestre et al. 2002a), and carbon storage and nitrogen (Martínez-Sánchez et al. 1994, Sánchez 1995, Bochet et al. 1999) in relation to adjacent areas devoid of vascular plants. Therefore, S. tenacissima creates the so-called “resource islands” (Reynolds et al. 1999), a phe- nomenon commonly described in shrub species from arid and semi-arid areas throughout the world (Whitford 2002). Through the creation of resource islands, S. tenacissima modifies the small-scale distribution and performance of a wide variety of taxa. In semi-arid steppes of SE Spain, Maestre (2003a, b) and Maestre et al. (2002a) have described how S. tenacissima tussocks modify the small-scale spatial patterning of soil lichens, cyanobacteria and mosses, with mosses dominating in the vicinity of the tussocks and cyanobacteria and lichens dominating the bare ground areas located between them. Interestingly, a significant negative relationship between the cover of cyanobacteria, which dominate bare-ground areas, and the infiltration rate was found (Maestre et al. 2002a), suggesting that the effect of S. tenacissima on these organisms could modify the source-sink process described above on its own ben- efit. Regarding vascular plants, it has been found that the vicinity of S. tenacissima tussocks holds more diversity and abundance of annual plants than the adjacent open ground areas (Sánchez 1995). Observational studies have reported positive spatial interactions between the spatial patterns of S. tenacissima and those of species such as An- thyllis cytisoides (Webster and Maestre 2004, Maestre et al. 2005b), as well as higher survival of seedlings and adults of woody species in the vicinity of S. tenacissima tussocks than in open ground areas (García-Fayos and Gasque 2002). The implications of plant-plant interactions involv- ing S. tenacissima for the restoration and management of these ecosystems will be discussed below. Biological soil crusts (BSC), composed of bacteria, cyanobacteria, algae, mosses, liverworts, fungi and lichens, are a major biotic component of arid and semi-arid ecosystems world-wide (West 1990, Belnap and Lange 2001). These crusts frequently cover soil surfaces (Fig. 4) and ex- ert a strong influence on critical ecosystem processes like infiltration, carbon sequestration and nutrient cycling (Beymer and Klopatek 1991, Evans and Ehleringer 1993). They also influence the distribution and abundance of plants and animals (Prasse and Bornkamm 2000, DeFalco et al. 2001, Shepherd et al. 2002). Despite important ad- vances in our knowledge of the structure, composition, physiology and biogeography of biological soil crusts (re- viewed by Belnap & Lange 2001), little is known on ...
Context 2
... soil crusts (BSC), composed of bacteria, cyanobacteria, algae, mosses, liverworts, fungi and lichens, are a major biotic component of arid and semi-arid ecosys- tems world-wide (West 1990, Belnap andLange 2001). These crusts frequently cover soil surfaces (Fig. 4) and ex- ert a strong influence on critical ecosystem processes like infiltration, carbon sequestration and nutrient cycling (Beymer andKlopatek 1991, Evans andEhleringer 1993). They also influence the distribution and abundance of plants and animals ( Prasse and Bornkamm 2000, DeFalco et al. 2001, Shepherd et al. 2002. Despite ...
Citations
... We observed interspecific plant spatial patterns ranging from dis-aggregation (i.e., spatial overdispersion) to aggregation depending on the site and plant species pair in our system. In nature, intra-and interspecific plant spatial patterns reflect many ecological and abiotic processes (Terborgh et al. 2002), such as plant-soil feedbacks (Schroeder et al. 2020), seed dispersal (Bagchi et al. 2018), or microhabitat characteristics such as topography, soil moisture, and light (García and Houle 2005), or soil compaction and type (Maestre 2006). It would be interesting to repeat studies like ours at a scale where we can compare behaviors among sites with different spatial patterns, or a range of spatial patterns. ...
Floral constancy of foraging bees influences plant reproduction. Constancy as observed in nature arises from at least four distinct mechanisms frequently confounded in the literature: context-independent preferences for particular plant species, preferential visitation to the same species as the previous plant visited (simple constancy), the spatial arrangement of plants, and the relative abundances of co-flowering species. To disentangle these mechanisms, we followed individual bee flight paths within patches where all flowering plants were mapped, and we used step selection models to estimate how each mechanism influences the probability of selecting any particular plant given the available plants in a multi-species community. We found that simple constancy was positive: bees preferred to visit the same species sequentially. In addition, bees preferred to travel short distances and maintain their direction of travel between plants. After accounting for distance, we found no significant effect of site-level plant relative abundances on bee foraging choices. To explore the importance of the spatial arrangement of plants for bee foraging choices, we compared our full model containing all parameters to one with spatial arrangement removed. Due to bees' tendency to select nearby plants, combined with strong intraspecific plant clumping, spatial arrangement was responsible for about 50% of the total observed constancy. Our results suggest that floral constancy may be overestimated in studies that do not account for the spatial arrangement of plants, especially in systems with intraspecific plant clumping. Plant spatial patterns at within-site scales are important for pollinator foraging behavior and pollination success.
... playing a fundamental role in maintaining the structure, functioning and dynamics of ecosystems (Maestre, 2006). Additionally, the spatial pattern of organisms can determine their population dynamics and the presence of spatial heterogeneity in the distribution of abiotic factors such as climate and soil type affects many biotic attributes, including the diversity and composition of animal, plant and microbial communities (Legendre & Fortin, 1989). ...
Human activities have doubled, or even tripled, the amount of nitrogen (N) fixed globally, which alters the functioning and reduces the biodiversity of terrestrial ecosystems.
In this study, we used a 10‐year N addition experiment in a semi‐arid Mediterranean shrubland in central Spain to evaluate the effects of increased N deposition on biocrust cover, soil microbial enzymatic activity and their spatial patterns. We collected highly replicated, spatially explicit data to carry out Moran's I correlograms at the plot level and used linear mixed models to evaluate the effects of N addition on cover, microbial activity and Moran's I values for each distance class of correlograms.
High N deposition (50 kg N ha⁻¹ year⁻¹) reduced the cover of the foliose lichen Cladonia foliacea, an important component of biocrusts, and generated significant alterations and losses of the spatial pattern of biocrusts and soil microbial enzymatic activity. Furthermore, we found indication that N addition altered the relationship between biocrust cover and microbial enzymatic activity, suggesting that the presence of well‐developed biocrust communities modulates the effects of high N deposition on soil microbial activity.
Synthesis. Overall, our study suggests that an increase in N deposition may have important consequences for the structure and functioning of Mediterranean ecosystems and that some of these consequences may be due to alterations in the way in which different soil communities (e.g. moss‐lichen biocrusts and soil microorganisms) interact with one another.
A free Plain Language Summary can be found within the Supporting Information of this article.
... Furthermore, a positive relationship between the spatial organization of vegetation patches and plant species richness has also been found (Maestre, 2006;Pueyo et al., 2013). Our results represent a step forward, as the network approach used here considers both positive and negative spatial associations of plant species, and shows a positive relationship between community organization in differentiated patches and plant diversity. ...
Despite commonly used to unveil the complex structure of interactions within ecological communities and their value to assess their resilience against external disturbances, network analyses have seldom been applied in plant communities. We evaluated how plant–plant spatial association networks vary in global drylands and assessed whether network structure was related to plant diversity in these ecosystems.
We surveyed 185 dryland ecosystems from all continents except Antarctica and built networks using the local spatial association between all the perennial plants species present in the communities studied. Then, for each network, we calculated four descriptors of network structure (link density, link weight mean and heterogeneity, and structural balance) and evaluated their significance with null models. Finally, we used structural equation models to evaluate how abiotic factors (including geography, topography, climate and soil conditions) and network descriptors influenced plant species richness and evenness.
Plant networks were highly variable world‐wide, but at most study sites (72%) presented common structures such as a higher link density than expected. We also find evidence of the presence of high structural balance in the networks studied. Moreover, all network descriptors considered had a positive and significant effect on plant diversity and on species richness in particular.
Synthesis . Our results constitute the first empirical evidence showing the existence of common network architectures structuring dryland plant communities at the global scale and suggest a relationship between the structure of spatial networks and plant diversity. They also highlight the importance of system‐level approaches to explain the diversity and structure of interactions in plant communities, two major drivers of terrestrial ecosystem functioning.
... Furthermore, a positive relationship between the spatial organization of vegetation patches and plant species richness has also been found (Maestre, 2006;Pueyo et al., 2013). Our results represent a step forward, as the network approach used here considers both positive and negative spatial associations of plant species, and shows a positive relationship between community organization in differentiated patches and plant diversity. ...
Aim
Despite their widespread use and value to unveil the complex structure of the interactions within ecological communities and their value to assess the resilience of communities, network analyses have seldom been applied in plant communities. We aim to evaluate how plant-plant interaction networks vary in global drylands, and to assess whether network structure is related to plant diversity in these ecosystems.
Location
185 dryland ecosystems from all continents except Antarctica.
Methods
We built networks using the local spatial association between all the perennial plant species present in the communities studied, and used structural equation models to evaluate the effect of abiotic factors (including geography, topography, climate and soil conditions) and network structure on plant diversity.
Results
The structure of plant networks found at most study sites (72%) was not random and presented properties representative of robust systems, such as high link density and structural balance. Moreover, network indices linked to system robustness had a positive and significant effect on plant diversity, sometimes higher that the effect of abiotic factors.
Main conclusions
Our results constitute the first empirical evidence showing the existence of a common network architecture structuring terrestrial plant communities at the global scale, and provide novel evidence of the importance of the network of interactions for the maintenance of biodiversity. Furthermore, they highlight the importance of system-level approaches to explain the diversity and structure of interactions in plant communities, two major drivers of terrestrial ecosystem functioning and resilience against the likely impacts derived from global change.
... Such patterns are often of critical ecological significance as they shed light on many interesting processes operating at community level and provide explanation of not only within-community patterns but also vegetation processes such as dynamics, stability, structuring and functioning of communities and species diversity (Monzeglio, 2007;Legendre and Fortin, 1989;Harte et al., 2005;Warrens, 2008). Regardless of their immense importance only a few investigations have directed their attention on these processes (Kareiva and Wennegren, 1995;Tilman and Kareiva, 1997;Bolker et al., 2003;Herben et al., 2006;Maestre, 2006;Schmitz, 2010). For the quantitative assessment of the spatial structures, several approaches have been proposed. ...
The investigation focuses on species composition, spatial heterogeneity, diversity and interspecific associations in an early successional plant community. A total of twenty species were recorded of which five were grasses while the rest were undershrubs or perennial herbs. Out of 11 species investigated for spatial pattern using variance/ mean ratio and Morisita’s index, ten exhibited aggregated distribution pattern which was presumably caused by topographic-edaphic heterogeneity or by limited seed dispersal. Test for species richness pattern within the community showed variability in species richness which can be attributed to environmental heterogeneity. Species diversity (H´) was moderate (H´ = 2.442), equitability was also moderate (J´= 0.815) while species richness (d) was 0.575. Dominance-diversity curve approached geometric distribution. Dominance (D) was low. Ten different species association coefficients (or similarity indices) were tested and compared of which three including those proposed by Jaccard, Soenesen & Dice and Ochiai provided consistent results in terms of disclosing the degree of interspecific association. These three measures are recommended for application in ecology.
... Such patterns are a central concern of ecology as they shed light on some interesting ecological processes operating at community level and provide explanation of not only within community patterns of plant populations but also community processes such as vegetation dynamics and stability, functioning and structuring of communities and species diversity (Monzeglio, 2007;Legendre & Fortin, 1989;Harte et al., 2005;Warren et al., 2009). However, despite their recognized significance, only a few ecological studies have focused attention on these processes (Tilman & Kareiva, 1997;Bolker et al., 2003;Herben et al., 2006;Maestre, 2006). The present study analyses the spatial patterns of 14 important perennial species that occurred in 10 or more stands and attempts to explain their within community dispersion patterns, their causes and ecological consequences. ...
... This would explain the aggregated as well as random patterns exhibited by the physiographic climax tree Acacia senegal which presumably changes its pattern with the passage of time (in ecological time scale) because of differential mortality and different phases of competition (cf. Kenkel et al., 1997;Maestre, 2006). Furthermore, the community composition and structure could be influenced by individual species tolerances to abiotic conditions and the competitive or facilitative interactions that individuals exert over their neighbors (Miriti, 2007). ...
... This mechanism elegantly explains why the aggregated and random patterns are observed for some of the shrub species equally often. Various stands sampled are not in the same stage of succession (see below) and because of facilitative/competitive processes operating in the community and owing to temporal changes in abiotic conditions and soil heterogeneity the spatial patterns change over time (Skarpe, 1991;Miriti et al., 1998;Miriti, 2007;Callaway, 1995;Callaway et al., 2002;Tirado &Pugnaire, 2003 andMaestre, 2006). In particular, moisture regime in arid regions changes frequently and often drastically (Evans & Ehleringer, 1994) also accumulation of leaf litter and consequently nutrients (Tirado & Pugnaire, 2003). ...
A study of vegetation structure, composition and diversity of Hub-dam catchment area was conducted. A total of 106 species were recorded of which 57 were annuals while 49 were perennials. The vegetation was dominated by small trees and shrubs. Spatial patterns within-community of plant populations using variance/mean ratio and Morisita's index was also investigated. Of the 14 perennial species investigated seven (Barleria acanthoides, Grewia tenax, Indigofera oblongifolia, Aerva persica, Rhazya stricta, Iphiona grantioides and Cymbopogon jwarancusa) predominately exhibited aggregated pattern. Four species (Acacia senegal, Prosopis juliflora, Salvadora oleoides and Calotropis procera) usually exhibited random distribution but infrequently aggregated pattern. Three species (Senna holosericea, Zizyphus nummularia and Vernonia cinerescens) showed aggregated pattern or random distribution more or less equally often. The distribution pattern of vegetation composition and the underlying environmental gradients, correspondence analysis (CA) ordination and canonical correspondence analysis (CCA) were employed. Group structure inherent in the vegetation was disclosed using Ward's agglomerative cluster analysis. Species diversity was measured and diversity was averaged for each group. Diversity of group I (Acacia senegal and Prosopis juliflora community type) was highest because this community included a number of mid-succession species, while diversity was lowest for group 4 (Prosopis juliflora and Capparis decidua community type) as this community was highly disturbed. In the climax community (group 3), the diversity level slightly decreased, suggesting the monopolization of resources by this community. Four major community types were recognized by Ward's cluster analysis, each of which was associated with particular topographic-edaphic factors, while one was mainly governed by anthropogenic disturbance. Biological spectrum constructed for the flora showed dominance of therophytes and chamaephytes.
... At the micro-site scale, the overland flow of water and sediments is retained in the uphill part (or terrace) of the S. tenacissima tussock. This soil under the tussock has more infiltration (Cerdà 1997), abundance and stability of organo-mineral of aggregates (Puigdefábregas et al. 1999;Bochet el al. 1999), soil moisture (Puigdefábregas and Sánchez 1996), and organic matter content (Sánchez 1995;Bochet et al. 1999;Maestre et al. 2001) than bare soil areas, which helps create "resource islands" in this ecosystems (sensu Reynolds et al. 1999) that facilitate the establishment of other vascular plants (Maestre et al. 2001;Maestre 2006). In turn, the intensity of the accumulation of soil sediments influences the mortality of stems and the branching rate, which ultimately has a negative effect on the space occupation of the tussock (Sánchez and Puigdefábregas 1994). ...
Bare soil forms an important part of the surface cover in Mediterranean arid and semiarid areas dominated by Stipa tenacissima L. tussock grass. Some studies have stressed the relevance of the spatial arrangement of this species in the improvement of sediment dynamic and soil characteristics close to the tussock. Reciprocally, bare soil condition has been considered as a key factor in the physiological performance of S. tenacissima stands. On the other side, other studies have neglected the capacity of the root system of this species to explore and consume resources from bare soil surrounding the tussock. In the present work we show some evidences that suggest the importance of bare soil near to the tussock in the water status of this species, especially in the high water stress season. We have found that water gains in bare soil from water vapour adsorption were highly coincident with the S. tenacissima stand transpiration. Furthermore, S. tenacissima sub-populations living in rock outcrops with lower connectivity with the surrounded bare soil showed higher signs of physiological water stress than those stands in areas with more soil availability. We believe that an interaction of water dynamics between bare soil and S. tenacissima tussocks would have to be reconsidered to fully understand ecophysiology of this species.
... Spatial heterogeneity in soil resources and vegetation is a hallmark of dryland ecosystems worldwide (Maestre, 2006). Mound building termites, which are common in some of the arid and semiarid ecosystems of the world, play a significant role in recycling nutrients and creating heterogeneity in soil and vegetation (Coventry et al., 1988;Grohmann, 2010;Petts, 2009;Sileshi et al., 2010). ...
... If resource conservation and management is to be improved in areas where mound-building termites are common, a predictive understanding of the patterns they generate is needed. This is because pattern has strong influence on ecosystem structure and functions such as productivity in dryland ecosystems (Maestre, 2006;Pringle et al., 2010). ...
Although termites have been widely reported to induce heterogeneity in soil resources, vegetation and patch use by herbivores, little effort has been made to examine spatial patterns around mounds. In this mini review we re-examine published studies on the variation in soil properties, herbage biomass and herbivore foraging with distance from termite mounds with reference to distance–decay models. The analyses revealed a significant decline in soil clay and silt, soil nutrients, herbage biomass, grazing and browsing with distance from termite mounds consistently with distance–decay models. This has both theoretical and practical significance to our understanding of processes and resource degradation in dryland ecosystems where termite mounds are common. From a sampling perspective, our analyses imply that measured variables around termite mounds are spatially structured. Therefore, we advocate geostatistical model-based sampling as a framework in future studies on termite mounds.
... The availability of major resources including light, water and nutrients for plants can change within a few metres (Gallardo 2003; Gómez et al. 2004; Quero et al. 2011). Also, these environmental factors exhibit complex mutual relationships (Sack and Grubb 2002; Gallardo 2003) and can vary widely in space and time, affecting ecosystem structure and composition (Terradas 2001; Maestre 2006). Thus, open forest areas possess a light availability that influences not only abiotic resources, such as nutrients or soil moisture (Pérez-Ramos et al. 2010), but also the structure and composition of the herbaceous layer (Milton 1995). ...
... Plot 2 exhibited some zones where a decrease in moisture during July was associated with a low establishment success. However, other factors such as topography, soil stoniness or nutrient distribution (Maestre et al. 2006) could determine the presence of zones of a low or high establishment success. Water is known to be a major limiting factor in Mediterranean ecosystems, especially during the summer droughts (Herrera et al. 1994). ...
Introduction
The great spatial and temporal heterogeneity of Mediterranean ecosystems can influence establishment success in woody species, whose natural regeneration occurs to a very small extent. In this work, the effect of the spatial pattern of environmental variables (light availability, soil moisture and herbaceous production) on seedling emergence, growth, survival and establishment success was examined by using a spatially explicit approach.
Methods
Seeds of four Quercus species differing in leaf longevity (Quercus ilex, Quercus suber, Quercus faginea and Quercus pyrenaica) were sown in two plots located in a holm oak forest (southern Spain). The spatial pattern of the studied variables was examined by Spatial Analysis by Distance Indices.
Results
All environmental variables exhibited an aggregated spatial pattern. There was no clear spatial association between the environmental variables and emergence and survival. Only soil moisture during the dry season was spatially associated with the establishment success of all the species. Species also differed in survival and establishment success, with evergreens having higher percentages than deciduous. No aggregated spatial pattern for growth and morphological traits was apparent, these being more dependent on seed mass than on environmental factors. Identifying which microsites facilitate regeneration may provide useful hints with a view in focusing restoration endeavours on microenvironments with high survival percentage.
... L'hétérogénéité spatiale de ces contraintes physiques explique ainsi une part non négligeable de l'organisation spatiale des plantes à diverses échelles (e.g. Grime, 1979;Maestre, 2006;Maestre and Reynolds, 2007). Aux larges échelles, on parle de 'filtrage environnemental' (Weiher and Keddy, 1995 ;Diaz et al., 1998). ...
L'hétérogénéité spatiale est aujourd'hui reconnue comme un facteur primordial pour la diversité et le fonctionnement des écosystèmes prairiaux pâturés, mais reste souvent négligée dans l'analyse des impacts de différents modes d'utilisation pastorale. Les communautés prairiales subalpines sont des milieux hautement diversifiés, au coeur d'enjeux écologiques, socio-économiques et culturels. Elles sont soumises actuellement à des changements d'usage, notamment l'extensification, qui peut parfois aller jusqu'à l'abandon. Comprendre la réponse spatiale de ces communautés à ces changements d'utilisation des terres peut constituer unenjeu important pour mieux prédire les conséquences en termes de valeurs écologiques et agronomiques.L'objectif général de ce travail est d'identifier les mécanismes de réponse de l'organisation spatiale des composantes spécifiques et fonctionnelles de trois communautés prairiales subalpines en réponse à des situations contrastées d'usage : pâturage traditionnel et abandon sur le moyen terme (20 ans). Les conséquences potentielles de modifications d'organisation spatiale du couvert sur les valeurs d'usage de ces milieux sont ensuite explorées. Ce travail révèle que l'arrêt du pâturage conduit à de profondes modifications de l'organisation spatiale à la fois des espèces et de traits fonctionnels aériens. La variabilité spatiale de ces composantes est augmentée dès des échelles très fines (100 cm²) en situation d'abandon et ce jusque des échelles plus larges ce qui révèle un grain plus grossier de l'hétérogénéité spatiale des communautés. Ceci est relié à une action positive du pâturage sur la coexistence des espèces et des valeurs de traits dès les échelles fines, limitant la convergence fonctionnelle observée dans ces communautés et ainsi favorisant un grain très fin d'hétérogénéité. D'autre part, nous observons que les patrons spatiaux des espèces peuvent être renforcés en situation d'abandon, suggérant une plus grande extension spatiale des espèces, mais cette réponse est faible, ce qui indique l'absence d'une action structurante forte du pâturage qui agit donc surtout sur la variabilité. Une expérimentation in situ a permis de montrer que seuls des patrons spatiaux de défoliation assez marqués et entrainant la création de contrastes abiotiques forts entre zones perturbées et non perturbées pouvaient entrainer une modification des patrons spatiaux des espèces. La formation de patrons spatiaux marqués semble donc limitée dans ces prairies relativement peu productives. Ces résultats suggèrent ainsi l'expression d'un pâturage peu sélectif exprimé par les troupeaux ovins, et la prépondérance du filtre abiotique dans les assemblages, sur ces milieux faiblement productifs. La formation de patchs très contrastés et très structurés spatialement est plus probable dans des milieux très productifs où la compétition est plus intense et dans lesquels le pâturage pourrait cette fois conduire à plus d'hétérogénéité. Les différents modèles d'organisation spatiale que nous avons observés sont susceptibles d'influencer l'expression dans l'espace des composantes de la valeur d'usage fourragère de ces prairies. Notamment, en situation pâturée, les assemblages plus diversifiés dès des échelles fines permettent de capter très rapidement la valeur d'usage fourragère moyenne de la prairie. La prise en compte de la variabilité autour de la réponse moyenne des communautés se révèle donc un élément essentiel pour analyser l'évolution des prairies subalpines en réponse au changement d'usages pastoraux. Une des perspectives fortes suite à ce travail est l'analyse de la synergie entre la réponse de l'hétérogénéité spatiale du couvert et celle du compartiment souterrain (traits racinaires, mycorhization, diversité microbienne).
