Fabien Quétier

PLANT TRAITS IN A STATE AND TRANSITION FRAMEWORK AS MARKERS OF ECOSYSTEM RESPONSE TO LAND-USE CHANGE

Understanding and forecasting changes in plant communities, ecosystem properties, and their associated services requires a mechanistic link between community shifts and modifications in ecosystem properties. In this study, we test the hypothesis that plant traits can provide such a link. Using subalpine grasslands in the central French Alps as a case study, we investigate the response of plant traits to changes in soil resource availability and disturbance regimes associated with changing grassland management as well as the effects of changes in plant traits on measured ecosystem properties. We found that fertilization leads to greater specific leaf area and leaf nitrogen content which leads to greater productivity and faster litter decomposition, and that grazing leads to higher leaf toughness and leaf dry matter content which leads to lower productivity and slower decomposition compared to mowing. A state and transition model was used as a flexible conceptual tool for integrating data on community composition, plant traits, and ecosystem properties in the context of management-mediated successional dynamics in subalpine grasslands. Focusing on the biology driving the transition between grassland states, we incorporated plant traits into the formulation of a state and transition model and demonstrated how they could be used to provide a mechanistic link between community shifts and ecosystem properties under complex management regimes with strong land-use legacies.

Leaf traits capture the effects of land use changes and climate on litter decomposability of grasslands across Europe

Land use and climate changes induce shifts in plant functional diversity and community structure, thereby modifying ecosystem processes. This is particularly true for litter decomposition, an essential process in the biogeochemical cycles of carbon and nutrients. In this study, we asked whether changes in functional traits of living leaves in response to changes in land use and climate were related to rates of litter potential decomposition, hereafter denoted litter decomposability, across a range of 10 contrasting sites. To disentangle the different control factors on litter decomposition, we conducted a microcosm experiment to determine the decomposability under standard conditions of litters collected in herbaceous communities from Europe and Israel. We tested how environmental factors (disturbance and climate) affected functional traits of living leaves and how these traits then modified litter quality and subsequent litter decomposability. Litter decomposability appeared proximately linked to initial litter quality, with particularly clear negative correlations with lignin-dependent indices (litter lignin concentr tion, lignin:nitrogen ratio, and fiber component). Litter quality was directly related to community-weighted mean traits. Lignin-dependent indices of litter quality were positively correlated with community-weighted mean leaf dry matter content (LDMC), and negatively correlated with community-weighted mean leaf nitrogen concentration (LNC). Consequently, litter decomposability was correlated negatively with community-weighted mean LDMC, and positively with community-weighted mean LNC. Environmental factors (disturbance and climate) influenced community-weighted mean traits. Plant communities experiencing less frequent or less intense disturbance exhibited higher community-weighted mean LDMC, and therefore higher litter lignin content and slower litter decomposability. LDMC therefore appears as a powerful marker of both changes in land use and of the pace of nutrient cycling across 10 contrasting sites.

Linking functional diversity and social actor strategies in a framework for interdisciplinary analysis of nature's benefits to society

The crucial role of biodiversity in the links between ecosystems and societies has been repeatedly highlighted both as source of wellbeing and as a target of human actions, but not all aspects of biodiversity are equally important to different ecosystem services. Similarly, different social actors have different perceptions of and access to ecosystem services, and therefore, they have different wants and capacities to select directly or indirectly for particular biodiversity and ecosystem characteristics. Their choices feed back onto the ecosystem services provided to all parties involved and in turn, affect future decisions. Despite this recognition, the research communities addressing biodiversity, ecosystem services, and human outcomes have yet to develop frameworks that adequately treat the multiple dimensions and interactions in the relationship. Here, we present an interdisciplinary framework for the analysis of relationships between functional diversity, ecosystem services, and human actions that is applicable to specific social environmental systems at local scales. We connect the mechanistic understanding of the ecological role of diversity with its social relevance: ecosystem services. The framework permits connections between functional diversity components and priorities of social actors using land use decisions and ecosystem services as the main links between these ecological and social components. We propose a matrix-based method that provides a transparent and flexible platform for quantifying and integrating social and ecological information and negotiating potentially conflicting land uses among multiple social actors. We illustrate the applicability of our framework by way of land use examples from temperate to subtropical South America, an area of rapid social and ecological change.

The diversity of the ecosystem services concept and its implications for their assessment and management

The ecosystem services concept is used in different scientific disciplines and is spreading into policy and business circles to draw attention to the benefits that people receive from biodiversity and ecosystems. However, the concept remains multiform and is used interchangeably with a range of other terms such as ecological, landscape or environmental services. We argue that lexical differences, in fact, result from different understandings of the concept, which could slow its use in nature conservation or sustainable resource use. An application to semi-natural grasslands shows that such differences could lead to very different assessments, of quality, quantity and location of ecosystem services. We argue that a compromise must be found between a broad and simple definition, which is useful for communicating the concept and large-scale policies, and a more refined definition for research and implementation goals such as environmental management and national and international assessments and accounting.

PLANT‐TRAIT‐BASED MODELING ASSESSMENT OF ECOSYSTEM‐SERVICE SENSITIVITY TO LAND‐USE CHANGE

Evidence is accumulating that the continued provision of essential ecosystem services is vulnerable to land-use change. Yet, we lack a strong scientific basis for this vulnerability as the processes that drive ecosystem-service delivery often remain unclear. In this paper, we use plant traits to assess ecosystem-service sensitivity to land-use change in subalpine grasslands. We use a trait-based plant classification (plant functional types, PFTs) in a landscape modeling platform to model community dynamics under contrasting but internally consistent land-use change scenarios. We then use predictive models of relevant ecosystem attributes, based on quantitative plant traits, to make projections of ecosystem-service delivery. We show that plant traits and PFTs are effective predictors of relevant ecosystem attributes for a range of ecosystem services including provisioning (fodder), cultural (land stewardship), regulating (landslide and avalanche risk), and supporting services (plant diversity). By analyzing the relative effects of the physical environment and land use on relevant ecosystem attributes, we also show that these ecosystem services are most sensitive to changes in grassland management, supporting current agri-environmental policies aimed at maintaining mowing of subalpine grasslands in Europe.

Plant trait-based models identify direct and indirect effects of climate change on bundles of grassland ecosystem services

Significance The sustainable management of the supply of ecosystem services (ESs) in a context of global change is of major importance to sustain human livelihoods. Doing sustainable management requires us to understand and to quantify the effects and mechanisms of changes in driving variables on multiple ESs. However, few studies to date have analyzed ES scenarios, and even fewer have adopted a mechanistic approach. This study presents a unique approach to examine not only the direct effects of climate on multiple ESs, but also its indirect effects through its consequences for land management and for plant functional traits. The framework was tested in an alpine grassland system using ES models based on land use, plant functional traits, and soil data. Land use and climate change are primary causes of changes in the supply of ecosystem services (ESs). Although the consequences of climate change on ecosystem properties and associated services are well documented, the cascading impacts of climate change on ESs through changes in land use are largely overlooked. We present a trait-based framework based on an empirical model to elucidate how climate change affects tradeoffs among ESs. Using alternative scenarios for mountain grasslands, we predicted how direct effects of climate change on ecosystems and indirect effects through farmers’ adaptations are likely to affect ES bundles through changes in plant functional properties. ES supply was overall more sensitive to climate than to induced management change, and ES bundles remained stable across scenarios. These responses largely reflected the restricted extent of management change in this constrained system, which was incorporated when scaling up plot level climate and management effects on ecosystem properties to the entire landscape. The trait-based approach revealed how the combination of common driving traits and common responses to changed fertility determined interactions and tradeoffs among ESs.

The social value of biodiversity and ecosystem services from the perspectives of different social actors

Fil: Caceres, Daniel Mario. Universidad Nacional de Cordoba. Facultad de Cs.agropecuarias. Departamento de Desarrollo Rural; Argentina. Consejo Nacional de Investigaciones Cientificas y Tecnicas; Argentina

Response of herbaceous vegetation functional diversity to land use change across five sites in Europe and Israel

Only a few studies have examined responses of grassland functional diversity to management and major environmental gradients, in order to address the question of whether grassland use can promote functional divergence. For five grassland sites in Israel, Portugal, the Czech Republic, Mediterranean France, and the French Alps, where traditional grassland management is being abandoned, we quantified community-weighted means (CWM) and functional divergence (FDvg) for the three Leaf-Height-Seed (LHS) traits, individually and in combination. Responses of CWM and FDvg to land use were analyzed by mixed linear models with aridity, phosphorus, fertility, and the fractions of grasses and annuals as covariates. Responses of community-weighted traits to land use were consistent with current knowledge. More intense management favored plants with more rapid resource acquisition (high Specific Leaf Area, or SLA), whereas abandonment or less intense grassland management increased the dominance by tall plants with more c...

Assessing ecological and social uncertainty in the evaluation of land-use impacts on ecosystem services

Ecosystem services provided by semi-natural agro-ecosystems in Europe are vulnerable to land-use change. Typically, vulnerability assessments include uncertainty around the future political and economic context of land-use systems through the use of scenarios. Here, we use a novel indicator sequence to assess the acceptability of scenario impacts on ecosystem properties to social representations of ecosystem services in a case study area. The sequence can incorporate multiple sources of uncertainty, and we highlight the key role of plant dispersal in driving ecosystem service provision by comparing outcomes from different methods for projecting scenario impact on ecosystem properties. By varying which properties underly valued ecosystem services and by comparing how people could adapt their future demand for ecosystem services we also incorporate social uncertainty. We find that social representations most negatively affected by litter accumulation are the most vulnerable.

The many meanings of no net loss in environmental policy

Abstract‘No net loss’ is a buzz phrase in environmental policy. Applied to a multitude of environmental targets such as biodiversity, wetlands and land productive capacity, no net loss (NNL) and related goals have been adopted by multiple countries and organizations, but these goals often lack clear reference scenarios: no net loss compared to what? Here, we examine policies with NNL and related goals, and identify three main forms of reference scenario. We categorize NNL policies as relating either to overarching policy goals, or to responses to specific impacts. We explore how to resolve conflicts between overarching and impact-specific NNL policies, and improve transparency about what NNL-type policies are actually designed to achieve.For natural capital like wetlands, biodiversity and land productive capacity, ‘no net loss’ is becoming a policy goal. This study highlights that the intended outcomes of no net loss policies can be very different depending on the reference scenario.