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In subalpine grasslands of the central French Alps, cessation of traditional mowing promotes dominance of Patzkea paniculata (L.) G.H.Loos (Poaceae) tussocks, with high biomass but low fodder quality. Mowing limits P. paniculata abundance through the depletion of its water‐soluble carbohydrate (WSC) reserves, which sustain early spring growth initiation. However, the effectiveness of mowing effects is modulated by grassland functional composition, fertilization and climate change, as WSC compounds, and notably fructans, support plant physiological responses to climate stresses such as drought or frost.To characterize the mechanisms underpinning the control of P. paniculata under global change, we tested the effects of climate manipulation (combined snow removal and drought) and management (cutting and fertilization) alone or in combination on P. paniculata WSC storage in assembled grassland communities of varying functional composition.Management and climate treatments individually decreased seasonal fructan storage, with neither additive nor synergic effects between them, primarily due to the dominance of management over climate effects. Fructan amounts were higher in individuals growing in unmanaged exploitative communities compared to unmanaged conservative communities, regardless of climate treatments, but management overrode these differences.Our findings suggest that reduction by combined snow removal and drought of P. paniculata carbon allocation to WSC storage may similarly limit its dominance to that in current mowing practices. [ABSTRACT FROM AUTHOR]

Mountain social‐ecological systems (MtSES) are vital to humanity, providing ecosystem services to over half the planet's human population. Despite their importance, there has been no global assessment of threats to MtSES, even as they face unprecedented challenges to their sustainability. With survey data from 57 MtSES sites worldwide, we test a conceptual model of the types and scales of stressors and ecosystem services in MtSES and explore their distinct configurations according to their primary economic orientation and land use. We find that MtSES worldwide are experiencing both gradual and abrupt climatic, economic, and governance changes, with policies made by outsiders as the most ubiquitous challenge. Mountains that support primarily subsistence‐oriented livelihoods, especially agropastoral systems, deliver abundant services but are also most at risk. Moreover, transitions from subsistence‐ to market‐oriented economies are often accompanied by increased physical connectedness, reduced diversity of cross‐scale ecosystem services, lowered importance of local knowledge, and shifting vulnerabilities to threats. Addressing the complex challenges facing MtSES and catalyzing transformations to MtSES sustainability will require cross‐scale partnerships among researchers, stakeholders, and decision makers to jointly identify desired futures and adaptation pathways, assess trade‐offs in prioritizing ecosystem services, and share best practices for sustainability. These transdisciplinary approaches will allow local stakeholders, researchers, and practitioners to jointly address MtSES knowledge gaps while simultaneously focusing on critical issues of poverty and food security. Plain Language Summary: Mountain ecosystems and the human communities that inhabit them deliver critical resources—such as fresh water and timber—to over half the planet's human population. Despite their importance, there has been no global assessment of threats to mountain systems, even as they face unprecedented challenges to their sustainability. With survey data from 57 mountain sites worldwide, we test our understanding of the types of stresses that are threatening mountain systems as well as the resources and benefits that come from mountains. We find that mountain systems worldwide are experiencing both gradual and abrupt climatic, economic, and governance changes. One of the most ubiquitous challenges facing mountain systems is that policies directly affecting mountain systems are being made by those living outside of the mountains themselves. Mountains that support primarily subsistence‐oriented livelihoods in the developing world, especially mixed agriculture and animal husbandry systems, deliver abundant services but are also most at risk. Addressing the complex challenges facing mountain systems will require partnerships among researchers, stakeholders, and decision makers to jointly identify the types of futures they desire and the actions to achieve these. This approach will address knowledge gaps in mountains while simultaneously focusing on critical issues of poverty and food security. Key Points: Mountain social‐ecological systems (MtSES) worldwide face climatic, economic, and governance threats; policies made by outsiders are a critical challengeMountains that support subsistence‐oriented livelihoods deliver abundant cross‐scale ecosystems services, but these MtSES are also most threatenedAddressing threats to MtSES requires the united effort of policymakers, land users, scientists, and practitioners at local to global scales [ABSTRACT FROM AUTHOR]

Mountain regions are key for humanity's water supply, and their water yield depends on climatic, soil and vegetation effects. Here we explore the effects of vegetation composition and structure on the water balance of high elevation grasslands with different climatic conditions across the Alps. Using a total of 220 deep seepage collectors with intact soil-vegetation monoliths in different types of mountain grasslands in the Austrian, French and Swiss Alps, we solved the water balance equation for evapotranspiration (ET) and related the results to biomass, the abundance of certain plant functional types and structural and functional vegetation properties. While daily mean ET during the growing season was similar at all sites, ET to precipitation ratios were significantly higher and ET to potential ET ratios significantly lower at the drier French sites than at the more humid Swiss and Austrian site. Large variability of ET, seepage and soil moisture within all sites pointed at a high influence of vegetation on the water balance. While ET increased significantly with biomass at all sites, the influence of other vegetation properties was site specific. At the more humid, subalpine Austrian site the effects of vegetation on ET were stronger and more diverse than at the higher elevation Swiss site and the drier French sites, where climatic drivers dominated ET. The potential to influence ET and water yield of mountain areas by manipulating the plant canopy with systematic land management is therefore higher in regions with good growing conditions than in areas with harsh climate. Copyright © 2014 John Wiley & Sons, Ltd. [ABSTRACT FROM AUTHOR]

Question To what extent do historical and present-day management regimes and landscape characteristics affect the functional structure of semi-natural grassland communities? Location Semi-natural grasslands, the Baltic island of Öland, Sweden. Methods We assessed community functional structure within 475 (50 cm × 50 cm) semi-natural grassland vegetation plots using two indices: community-weighted mean trait values ( CWM) and functional divergence ( FD), calculated using the Rao quadratic entropy index. Spatially explicit regressions were used to assess the extent to which the CWM and FD for different plant traits are explained by past and present levels of local grazing management, and the present and historical characteristics of the surrounding landscape. Results Across traits, the CWM and FD of individual grasslands were strongly associated with current grazing intensity, but also with local management history and past landscape structure. Conclusions Our results indicate that grassland functional structure in the fragmented present-day landscape reflects not only present conditions, but also the historical context of the grassland fragments - where the presence of extensive grassland habitat in the surroundings provided a diverse pool of grazing-tolerant species. The study also suggests that information on landscape history, and its effects on the local species pool, may improve predictions of future plant community structure. [ABSTRACT FROM AUTHOR]

Cessation of traditional management threatens semi-natural grassland diversity through the colonisation or increase of competitive species adapted to nutrient-poor conditions. Regular mowing is one practice that controls their abundance. This study evaluated the ecophysiological mechanisms limiting short- and long-term recovery after mowing for Festuca paniculata, a competitive grass that takes over subalpine grasslands in the Alps following cessation of mowing. We quantified temporal variations in carbon (C) and nitrogen (N) content, starch, fructan and total soluble sugars in leaves, stem bases and roots of F. paniculata during one growth cycle in mown and unmown fields and related them to the dynamics of soil mineral N concentration and soil moisture. Short-term results suggest that the regrowth of F. paniculata following mowing might be N-limited, first because of N dilution by C increments in the plant tissue, and second, due to low soil mineral N and soil moisture at this time of year. However, despite short-term effects of mowing on plant growth, C and N content and concentration at the beginning of the following growing season were not affected. Nevertheless, total biomass accumulation at peak standing biomass was largely reduced compared to unmown fields. Moreover, lower C storage capacity at the end of the growing season impacted C allocation to vegetative reproduction during winter, thereby dramatically limiting the horizontal growth of F. paniculata tussocks in the long term. We conclude that mowing reduces the growth of F. paniculata tussocks through both C and N limitation. Such results will help understanding how plant responses to defoliation regulate competitive interactions within plant communities. [ABSTRACT FROM AUTHOR]

• In subalpine grasslands, changes in abiotic conditions with decreased management intensity alter the functional composition of plant communities, leading to modifications of ecosystem properties. Here, it is hypothesized that the nature of plant feedbacks on soil moisture is determined by the values of key traits at the community level. • As community functional parameters of grasslands change along a gradient of land uses, those traits that respond most to differences in abiotic conditions produced by land use changes were identified. A vegetation removal experiment was then conducted to determine how each plant community affected soil moisture. • Soil moisture was negatively correlated with community root length and positively correlated with canopy height, whereas average leaf area was associated with productivity. These traits were successfully used to predict the effects on soil moisture of each plant community in the removal experiment. This result was validated using data from an additional set of fields. • These findings demonstrate that the modification of soil moisture following land use change in subalpine grasslands can be mediated through those plant functional traits that respond to water availability. [ABSTRACT FROM AUTHOR]

1. Increasing functional diversity often leads to an increase in ecosystem productivity in the form of overyielding. While the mechanisms (i.e. complementarity or facilitation) that underlie overyielding provide strong insights into species coexistence and community assembly, they are rarely tested. In subalpine grasslands, traditional management through manuring and hay-making results in intermediate productivity that is associated with high functional diversity. This functional diversity results from the coexistence between conservative plant species (with slow growth rates, low specific leaf area) and exploitative species (with fast growth rates, high specific leaf area). 2. We hypothesized that overyielding occurs among these two functional groups and tested whether complementarity or facilitation can explain overyielding. Using three perennial grass species per functional group, we compared single and mixed functional group mesocosms at low and intermediate levels of fertilization to test the occurrence of overyielding. Additionally, we measured the outcomes of biotic interactions among these two functional groups by manipulating plant density. 3. After two growing seasons, we found evidence of overyielding under intermediate levels of fertility. Overyielding was associated with a reduction of competition intensity when both functional groups were grown together. These results suggest that complementarity, as evidenced by a decrease in competition intensity, rather than facilitation, explains the observed overyielding. Indeed, we found evidence for complementarity for light and modification of nutrient use as possible mechanisms for the overyielding. 4. Synthesis. Complementarity between functional groups might be an important mechanism enhancing functional diversity, particularly in harsh environments at intermediate rather than low fertility. [ABSTRACT FROM AUTHOR]

Humans are altering the composition of biological communities through a variety of activities that increase rates of species invasions and species extinctions, at all scales, from local to global. These changes in components of the Earth's biodiversity cause concern for ethical and aesthetic reasons, but they also have a strong potential to alter ecosystem properties and the goods and services they provide to humanity. Ecological experiments, observations, and theoretical developments show that ecosystem properties depend greatly on biodiversity in terms of the functional characteristics of organisms present in the ecosystem and the distribution and abundance of those organisms over space and time. Species effects act in concert with the effects of climate, resource availability, and disturbance regimes in influencing ecosystem properties. Human activities can modify all of the above factors; here we focus on modification of these biotic controls. The scientific community has come to a broad consensus on many aspects of the relationship between biodiversity and ecosystem functioning, including many points relevant to management of ecosystems. Further progress will require integration of knowledge about biotic and abiotic controls on ecosystem properties, how ecological communities are structured, and the forces driving species extinctions and invasions. To strengthen links to policy and management, we also need to integrate our ecological knowledge with understanding of the social and economic constraints of potential management practices. Understanding this complexity, while taking strong steps to minimize current losses of species, is necessary for responsible management of Earth's ecosystems and the diverse biota they contain. [ABSTRACT FROM AUTHOR]

We examined the relationship between plant species diversity, productivity and the development of the soil community during early secondary succession on former arable land across Europe. We tested the hypothesis that increasing the initial plant species diversity enhances the biomass production and consequently stimulates soil microbial biomass and abundance of soil invertebrates. We performed five identical field experiments on abandoned arable land in five European countries (CZ, NL, SE, SP and UK) which allowed us to test our hypothesis in a range of climate, soil and other environmental factors that varied between the experimental sites. The initial plant diversity was altered by sowing seed mixtures of mid-successional grassland species with two or five grass species, one or five legumes and one or five forbs. The results of low and high sown diversity treatments were compared with plots that were naturally colonized by species present in the seed bank. In three out of the five field sites, there was no correlation between plant species number and plant biomass production, one site had a positive and the other a negative relation. Treatments with a high diversity seed mixture had a higher biomass than the naturally colonized plots. However, there was no significant difference between high and low sown diversity plots at four out of five sites. The three-year study did not give any evidence of a general bottom-up effect from increased plant biomass on biomass of bacteria, saprophytic fungi or abundance of microarthropods. The biomass of arbuscular mycorrhizal was negatively related to plant biomass. The abundance of nematodes increased after abandonment and was related to plant biomass at four sites. Our results support the hypothesis that plant species diversity may have idiosyncratic effects on soil communities, even though studies on a longer term could reveal time lags in the response to changes in composition and biomass production of plant communities. [ABSTRACT FROM AUTHOR]

Summary 1 Anthropogenic changes in the global climate are shifting the potential ranges of many plant species. 2 Changing climates will allow some species the opportunity to expand their range, others may experience a contraction in their potential range, while the current and future ranges of some species may not overlap. Our capacity to generalize about the threat these range shifts pose to plant diversity is limited by many sources of uncertainty. 3 In this paper we summarize sources of uncertainty for migration forecasts and suggest a research protocol for making forecasts in the context of uncertainty. [ABSTRACT FROM AUTHOR]

Summary 1. The concept of plant functional type proposes that species can be grouped according to common responses to the environment and/or common effects on ecosystem processes. However, the knowledge of relationships between traits associated with the response of plants to environmental factors such as resources and disturbances (response traits), and traits that determine effects of plants on ecosystem functions (effect traits), such as biogeochemical cycling or propensity to disturbance, remains rudimentary. 2. We present a framework using concepts and results from community ecology, ecosystem ecology and evolutionary biology to provide this linkage. Ecosystem functioning is the end result of the operation of multiple environmental filters in a hierarchy of scales which, by selecting individuals with appropriate responses, result in assemblages with varying trait composition. Functional linkages and trade-offs among traits, each of which relates to one or several processes, determine whether or not filtering by different factors gives a match, and whether ecosystem effects can be easily deduced from the knowledge of the filters. 3. To illustrate this framework we analyse a set of key environmental factors and ecosystem processes. While traits associated with response to nutrient gradients strongly overlapped with those determining net primary production, little direct overlap was found between response to fire and flammability. 4. We hypothesize that these patterns reflect general trends. Responses to resource availability would be determined by traits that are also involved in biogeochemical cycling, because both these responses and effects are driven by the trade-off between acquisition and conservation. On the other hand, regeneration and demographic traits associated with response to disturbance, which are known to have little connection with adult traits involved in plant ecophysiology, would be of little relevance to ecosystem processes. 5. This... [ABSTRACT FROM AUTHOR]

A series of communities were established in situ to differentiate the effects of species richness, functional richness and functional group identity on invasibility of Mediterranean annual old fields. We monitored the demographic and vegetative parameters of two exotic annuals introduced as seedlings, Conyza bonariensis and C. canadensis. Community species richness and functional composition determined resistance to invasion by Conyza. Conyza bonariensis biomass decreased with increasing species richness. Legumes increased the biomass and consequently the net fecundity of both Conyza, while survival was favoured by Asteraceae. Communities with fewer Asteraceae and grasses increased the reproductive effort of C. bonariensis. A separate glasshouse experiment using the same species mixes revealed that establishment of Conyza decreased with increasing species richness or when grasses were present. Patterns of Conyza performance are interpreted in the light of measurements of ecosystem functional parameters, making it possible to formulate hypotheses about mechanisms limiting community invasibility. [ABSTRACT FROM AUTHOR]

Experimental disturbance and fertilisation in two Mediterranean old fields, three and nine years old, respectively, were used to identifyfunctional groups for response to disturbance. Five morphological traits (canopy structure, height, lateral spread, habit and plasticity)and five regeneration traits (life cycle, seed mass, fecundity, dispersal mode and germination seasonality) were used for species classification. Correlation patterns of species composition and species attributes with disturbance treatments were analysed in order to characterise groups of response to disturbance. The classification based on morphological traits was repeatable across fields and reflected natural correlation patterns among attributes. Erect rosettes with low morphological plasticity and moderate lateral spread, mostly grasses, were intolerant of disturbance. Partial rosettes with low morphological plasticity and wide lateral spread, e.g. Asteraceae species, colonised disturbed locations. Flat proto-rosettes with a plastic architecture were indifferent to disturbance in the young plot but required disturbance to establish in the older plot. The classification based on regeneration traits repeatedly identified germination period to be correlated with disturbance response. Species with early germination were intolerant of disturbance while late-germinating species colonised disturbances. These groups were clearly distinct from groups based onnatural attribute correlation patterns which related primarily to seed mass, and secondarily to dispersal mode and fecundity. Effects of fertilisation were detected only within disturbed quadrats of the oldplot. Fertilisation favoured the colonisation of disturbances by species with a partial rosette and low plasticity and by species with late germination and high fecundity. These results, complemented by direct analyses on individual traits, are mostly consistent with previous descriptions of the ruderal strategy. This study shows that additional [ABSTRACT FROM AUTHOR]

Research on the function of biodiversity has stimulated a renewed interest in the mechanisms underlying the invisibility of plant communities. Conflicting results provide evidence that observational correlative studies are a dead end if isolated from manipulative experiments. Using two studies in France, Portugal and Australia we illustrate how invasion research can move from pattern observation to the investigation of processes. Artificial annual communities representing a factorial combination of one to three functional groups and one to six species per group were sown in Montpellier. Natural invisibility of the plots from the seed bank showed no strong relationship with functional or species richness. The survival of individuals of two congeneric exotic species (Conyza canadensis and C. bonariensis) introduced as seedlings did not relate to these simple diversity indices. On the other hand, their adult biomass did with a decrease in vegetative performance with increasing species richness but a decrease with increasing number of functional groups. Survival and biomass of invaders were strongly influenced by the identity of the resident functional groups. In a study of the mechanisms underlying the demographic success of the pasture weed Echium plantagineum in Australia, germinations in mixtures with varying numbers, densities, and identities of co-germinants showed no evidence that increasing diversity increased the competitive effect. Rather, significant reduction of recruitment resulted from increased densities. These examples suggest that patterns and mechanisms of community invisibility are likely to be far more subtle than people have acknowledged so far. Controlled experiments coupled with theoretical work are required to advance our understanding. [ABSTRACT FROM AUTHOR]

Studies the effects of environmental factors and exogenous disturbances on species composition. Survey of understorey trees in a temperate grassland in Australia; Difference in species present in soil disturbed and in water enriched sites; Use of life-form classification scheme in monitoring the effect of disturbance.

Editorial. Comments on the effect of global climatic changes on landscape and regional patterns of plant diversity. Researches on regional distributions of plant species from climatic and terrain factors; Relevance of programs such as the International Geosphere Biosphere Program; Differences between fundamental and realized niche.

Data referring to changes in vegetation composition resulting from cattle exclosure and ploughing in a Portuguese pasture dominated by annuals were used to test hypotheses regarding the biology of species favoured or eliminated by disturbance in semi-natural herbaceous communities. These hypotheses were tested in two ways. First we compared the distribution of six a priori groups - grasses, small rosettes, large rosettes, small species with leafy stems, large species with leafystems, legumes - across grazed, ploughed and undisturbed plots. In asecond set of analyses we examined changes in the frequencies of individual biological attributes in response to grazing and ploughing. These analyses were carried out separately for grasses and dicot forbs. Overall, the species composition showed little response to either grazing or ploughing, though species dominance changed. This lack of responsiveness of species composition was attributed to the long history of intensive land use which has resulted in the loss of disturbance-intolerant species over entire landscapes. When considering a priori groups, small rosettes were indifferent to disturbance. grazing andploughing showed that dominated. Large rosettes, large species with leafy stems and legumes were generally intolerant to both grazing andploughing, though individual species may increase in response to disturbance. Small species with leafy stems were the only group favouredby grazing whereas ploughing favoured grasses. As to individual traits, grazing excluded large grass species with heavy seeds and promoted a flat rosette canopy structure and a small size, along with a moderate dormancy and protected inforescences. In forbs, grazing favouredsmall species, as expected, while it excluded tall species, and, in contrast to earlier results, a rosette canopy. These attributes were consistent with responses of the a priori groups, though it would nothave been possible to reconstruct groups directly from the attributelist. P [ABSTRACT FROM AUTHOR]

Plant functional traits and types are useful concepts in relation todisturbance responses of natural and managed ecosystems. To explore their applicability in greater depth, a set of 12 papers presents a broad range of issues from methodologies to the results of particular trait studies in the field, and modelling approaches. So far, empirical studies have only allowed us to identify a few functional traits that are consistently associated with disturbance. To determine the trait variations associated with climate, disturbance history and current disturbance regime as well as the interactions between these factors, global-scale comparisons of numerous individual studies are required. Significant advances toward this ambitious goal are presented tothese papers, and include: ( I ) the articulation of experimental and analytical methodologies for individual studies that could usefullycontribute to a global comparison; (2) the identification of core traits that can be used in the further search for disturbance-related traits common to a range of environments: (3) further information on vegetation response to disturbance in terms of trait representation, and the identification of attribute syndromes; (4) the identification of issues for modelling disturbance dynamics using functional types. [ABSTRACT FROM AUTHOR]

We analysed attributes of the understorey flora in different plant communities along two grazing gradients in arid Australian rangelands.We aimed to determine if there were patterns among species in response to grazing, and easily recognizable 'indicator response types' formonitoring grazing-induced change in community composition. Measurements were stratified by vegetation patch type, in woody groves and open patches. Trait selection and analyses followed a hierarchical approach which searched for patterns within major plant life forms. Patchtype exerted a dominant influence on both life forms and species attributes, but interacted with grazing. Grazing was associated with loss in differentiation of species composition between patch types, rather than loss in numbers of species overall. Heavy grazing was variously associated with small size, prostrate habit, low meristems, small leaves, coated leaves, high regrowth potential, plasticity in response to grazing, and high fecundity; and light grazing with opposing attributes. Many attributes tended to vary independently of each other and grazing-related attribute syndromes were recognisable only among grasses. This could be because the environmental filters acting on thecommunities have given rise to many different species with differentnatural attribute combinations, few of which are closely associated with grazing resistance. For grassy communities 'large, erect tussocks branching above-ground' and 'small, sprawling basal tussocks' may have potential as response types indicative of light and heavy grazingrespectively, but no response types could be identified for herbaceous communities. [ABSTRACT FROM AUTHOR]

Previous work on trait correlation patterns has contributed to the identification of broad patterns of plant distribution along environmental gradients in vegetation. However, these general trends may conceal subtle mechanisms of response that are specific to particular types of disturbance. To address this, we propose a generic methodology for the analysis of traits, using herb-dominated vegetation as a model. Hypothetical biological traits are identified for testing against disturbance gradients. The traits were selected for their perceived relevance to disturbance response generally, but also include a specific focus on domestic livestock grazing. The analysis is structured hierarchically to enable attributes to be analysed within major life forms. A different selection of traits is identified as being relevant to each major life form. Flexible adaptation in the use of the trait set is suggested as a way of comparing functional response to disturbance over a series of locations. For example, assemblages will vary intheir representation of the major life forms, and it may be relevantto analyse traits within a subset of these life-form groups. Becauseindividual studies encompass a limited range of environmental variation, and local floras may be constrained by their evolutionary context, similar approaches need to be tested over a range of vegetation types and geographic situations. A significant advance in functional trait analysis could be achieved if individual studies provide explicitdescriptions of their evolutionary and ecological context from a global perspective. [ABSTRACT FROM AUTHOR]