Cécile H. Albert

A global meta‐analysis of the relative extent of intraspecific trait variation in plant communities

Recent studies have shown that accounting for intraspecific trait variation (ITV) may better address major questions in community ecology. However, a general picture of the relative extent of ITV compared to interspecific trait variation in plant communities is still missing. Here, we conducted a meta-analysis of the relative extent of ITV within and among plant communities worldwide, using a data set encompassing 629 communities (plots) and 36 functional traits. Overall, ITV accounted for 25% of the total trait variation within communities and 32% of the total trait variation among communities on average. The relative extent of ITV tended to be greater for whole-plant (e.g. plant height) vs. organ-level traits and for leaf chemical (e.g. leaf N and P concentration) vs. leaf morphological (e.g. leaf area and thickness) traits. The relative amount of ITV decreased with increasing species richness and spatial extent, but did not vary with plant growth form or climate. These results highlight global patterns in the relative importance of ITV in plant communities, providing practical guidelines for when researchers should include ITV in trait-based community and ecosystem studies.

Intraspecific trait variability mediates the response of subalpine grassland communities to extreme drought events

Climate change is expected to increase the magnitude and the frequency of extreme climatic events such as droughts. Better understanding how plant communities will respond to these droughts is a major challenge. We expect the response to be a shift in functional trait values resulting from both species turnover and intraspecific trait variability, but little research has addressed the relative contribution of both components. We analysed the short-term functional response of subalpine grassland communities to a simulated drought by focusing on four leaf traits (LDMC: leaf dry matter content, SLA: specific leaf area, LNC: leaf nitrogen concentration and LCC: leaf carbon concentration). After evaluating species turnover and intraspecific variability separately, we determined their relative contribution in the community functional response to drought, reflected by changes in community-weighted mean traits. We found significant species turnover and intraspecific variability, as well as significant changes in community-weighted mean for most of the traits. The relative contribution of intraspecific variability to the changes in community mean traits was more important (42-99%) than the relative contribution of species turnover (1-58%). Intraspecific variability either amplified (for LDMC, SLA and LCC) or dampened (for LNC) the community functional response mediated by species turnover. We demonstrated that the small contribution of species turnover to the changes in community mean LDMC and LCC was explained by a lack of covariation between species turnover and interspecific trait differences.Synthesis. These results highlight the need for a better consideration of intraspecific variability to understand and predict the effect of climate change on plant communities. While both species turnover and intraspecific variability can be expected following an extreme drought, we report new evidence that intraspecific variability can be a more important driver of the short-term functional response of plant communities.

The Monteregie Connection: linking landscapes, biodiversity, and ecosystem services to improve decision making

To maximize specific ecosystem services (ES) such as food production, people alter landscape structure, i.e., the types of ecosystems present, their relative proportions, and their spatial arrangement across landscapes. This can have significant, and sometimes unexpected, effects on biodiversity and ES. Communities need information about how land/use activities and changes to landscape structure are likely to affect biodiversity and ES, but current scientific understanding of these effects is incomplete. The Monteregie Connection (MC) project has used the rapidly suburbanizing agricultural Monteregien landscape just east of Montreal, Quebec, Canada, to investigate how current and historic landscape structure influences ES provision. Our results highlight the importance of forest connectivity and functional diversity on ES provision, and show that ES provision can vary significantly even within single land-use types in response to changes in landscape structure. Our historical analysis reveals that levels of ES provision, as well as relationships among individual ES, can change dramatically through time. We are using these results to build quantitative ES-landscape structure models to assess four future landscape scenarios for the region: Periurban Development, Demand for Energy, Whole-System Crisis, and Green Development. These scenarios integrate empirical and historical data on ES provision with local stakeholder input about global and local social and ecological drivers to explore how land-use decisions could affect ES provision and human well-being across the region to the year 2045. By integrating empirical data, quantitative models, and scenarios we have achieved the central goals of the MC project: (1) increasing understanding of the effects of landscape structure on biodiversity and ES provision, (2) effectively linking this knowledge to decision making to better manage for biodiversity and ES, and (3) creating a vision for a more sustainable social-ecological system in the region.

Evaluating conceptual models of landscape change

&NA; A variety of landscape models are used to conceptualize and interpret human impacts on ecosystems and their biodiversity. The simplest, a ‘patch‐matrix’ model, is rooted in island biogeography theory and assumes a dichotomy between generic, easily‐defined habitat patches and a surrounding matrix that is completely inhospitable. This dichotomy between patch and matrix habitats has been recently relaxed, with the ‘continuum’ model taking this relaxation to its extreme and logical endpoint – a species‐based model with no a priori definition of habitat or matrix, but rather focusing on ecological gradients. Yet, because few empirical comparisons of these bookending models exist, we lack understanding of their relative utility or the merits of hybrid approaches that combine attributes of patch‐matrix and continuum models. To guide such considerations, we first develop a decision‐making framework for the application of patch‐matrix, continuum, and hybrid models. The framework takes into account study objectives, attributes of the landscape, and species traits. We then evaluate this framework by empirically comparing how continuum, patch‐matrix, and hybrid models explain beetle distributions across two contrasting fragmented landscapes, for species differing in trophic level and habitat specificity. Within the Hope River Forest Fragmentation Project, a system with strong landscape contrast and distinct (‘hard’) structural edges between forest fragments and grassland, we find broad support for hybrid models, particularly those incorporating surrounding landscape structure. Conversely, within the Wog Wog Habitat Fragmentation Experiment, a system with weak landscape contrast and ‘soft’ structural edges between natural and plantation forest, we find co‐support for continuum and hybrid models. We find no support in either system for patch‐matrix, relative to continuum and hybrid models. We conclude by considering key questions and areas of research for advancing the application of models to understand species responses and biodiversity patterns associated with land‐use change.

Sampling in Landscape Genomics

Landscape genomics, based on the sampling of individuals genotyped for a large number of markers, may lead to the identification of regions of the genome correlated to selection pressures caused by the environment. In this chapter, we discuss sampling strategies to be used in a landscape genomics approach. We suggest that designs based on model-based stratification using the climatic and/or biological spaces are in general more efficient than designs based on the geographic space. More work is needed to identify designs that allow disentangling environmental selection pressures versus other processes such as range expansions or hierarchical population structure.

Structural uncertainty in models projecting the consequences of habitat loss and fragmentation on biodiversity

&NA; Ecological theory is essential to predict the effects of global changes such as habitat loss and fragmentation on biodiversity. Species–area relationships (SAR), metapopulation models (MEP) and species distribution models (SDM) are commonly used tools incorporating different ecological processes to explain biodiversity distribution and dynamics. Yet few studies have compared the outcomes of these disparate models and investigated their complementarity. Here we show that the processes underlying SAR (patch area), MEP (patch isolation) and SDM (environmental conditions) models can be compared with a common statistical framework. Our approach allows for species and community‐level predictions under current and future landscape scenarios, facilitates multi‐model comparison and provides the machinery for integrating multiple mechanisms into one model. We apply this framework to the distribution of eight focal vertebrate species in current and future projected landscapes where 10% of the landscape is lost to land‐use change in southwestern, Quebec, Canada. Based on a model selection approach, we found that a model including patch area was the top ranked model for four of our focal species and models including patch isolation and environmental conditions were the top ranked models for two focal species each. Community‐level predictions of models based on patch area, patch isolation and environmental conditions for both current and future landscapes showed high spatial overlap, however, patch area models always predicted a reduction of species richness per patch whereas both the patch isolation and environmental conditions models predicted an increase or decrease in species richness per patch following habitat loss and fragmentation. Our comparative tool will allow ecologists and conservation practitioners to relate structural uncertainty to key mechanisms underlying each model. Ultimately, this approach is one step in the direction of deriving robust predictions for the change and loss of biodiversity under global change, which is key for informing conservation plans.

Prioritizing conservation areas for coastal plant diversity under increasing urbanization

Coastal urban expansion will continue to drive further biodiversity losses, if conservation targets for coastal ecosystems are not defined and met. Prioritizing areas for future protected area networks is thus an urgent task in such urbanization-threatened ecosystems. Our aim is to quantify past and future losses of coastal vegetation priority areas due to urbanization and assess the effectiveness of the existing protected area network for conservation. We conduct a prioritization analysis, based on 82 coastal plants, including common and IUCN red list species, in a highly-urbanized but biotically diverse region, in South-Eastern France. We evaluate the role of protected areas, by taking into account both strict and multi-use areas. We assess the impact of past and future urbanization on high priority areas, by combining prioritization analyses and urbanization models. We show that half of the highly diverse areas have already been lost due to urbanization. Remaining top priority areas are also among the most exposed to future urban expansion. The effectiveness of the existing protected area (PA) network is only partial. While strict PAs coincide well with top priority areas, they only represent less than one third of priority areas. The effectiveness of multi-use PAs, such as the Natura 2000 network, also remains limited. Our approach highlights the impact of urbanization on plant conservation targets. By modelling urbanization, we manage to identify those areas where protection could be more efficient to limit further losses. We suggest to use our approach in the future to expand the PA network in order to achieve the 2020 Aichi biodiversity targets.

Islands, mainland, and terrestrial fragments: How isolation shapes plant diversity

Abstract The fragmentation of natural habitats is a major threat for biodiversity. However, the impact and spatial scale of natural isolation mechanisms leading to species loss, compared to anthropogenic fragmentation, are not clear, mainly due to differences between fragments and islands, such as matrix permeability. We studied a 500 km2 Mediterranean region in France, including urban habitat fragments, continuous habitat, and continental‐shelf islands. On the basis of 295 floristic relevés, we built species–area relationships to compare isolation in fragments after urbanization, with continuous habitat and continental‐shelf islands. We assumed either no dispersal, infinite dispersal, or estimated intermediate levels of habitat reachability through graph theory. Isolation mechanisms occurred in fragments but with a lower strength than in near‐shore islands, and most importantly affected perennial plants. Annual plants were less affected, probably due to their smaller size and shorter life cycle. Isolation occurred at landscape level in fragments and at patch level in islands. The amount of reachable habitat (accounting for spatial configuration) explained local species richness in both systems, but the amount of habitat (no consideration of spatial configuration) was already a good predictor. These results suggest an important role of habitat amount around fragments in mitigating the isolation effects observed in near‐shore islands, and the importance of carefully considering different functional groups.

Towards an applied metaecology

The complexity of ecological systems is a major challenge for practitioners and decision-makers who work to avoid, mitigate and manage environmental change. Here, we illustrate how metaecology - the study of spatial interdependencies among ecological systems through fluxes of organisms, energy, and matter - can enhance understanding and improve managing environmental change at multiple spatial scales. We present several case studies illustrating how the framework has leveraged decision-making in conservation, restoration and risk management. Nevertheless, an explicit incorporation of metaecology is still uncommon in the applied ecology literature, and in action guidelines addressing environmental change. This is unfortunate because the many facets of environmental change can be framed as modifying spatial context, connectedness and dominant regulating processes - the defining features of metaecological systems. Narrowing the gap between theory and practice will require incorporating system-specific realism in otherwise predominantly conceptual studies, as well as deliberately studying scenarios of environmental change.

Complementary crops and landscape features sustain wild bee communities

Wild bees, which are important for commercial pollination, depend on floral and nesting resources both at farms and in the surrounding landscape. Mass-flowering crops are only in bloom for a few weeks and unable to support bee populations that persist throughout the year. Farm fields and orchards that flower in succession potentially can extend the availability of floral resources for pollinators. However, it is unclear whether the same bee species or genera will forage from one crop to the next, which bees specialize on particular crops, and to what degree inter-crop visitation patterns will be mediated by landscape context. We therefore studied local- and landscape-level drivers of bee diversity and species turnover in apple orchards, blueberry fields, and raspberry fields that bloom sequentially in southern Quebec, Canada. Despite the presence of high bee species turnover, orchards and small fruit fields complemented each other phenologically by supporting two bee genera essential to their pollination: mining bees (Andrena spp.) and bumble bees (Bombus spp.). A number of bee species specialized on apple, blueberry, or raspberry blossoms, suggesting that all three crops could be used to promote regional bee diversity. Bee diversity (rarefied richness, wild bee abundance) was highest across crops in landscapes containing hedgerows, meadows, and suburban areas that provide ancillary nesting and floral resources throughout the spring and summer. Promoting phenological complementarity in floral resources at the farmstead and landscape scales is essential to sustaining diverse wild bee populations.