Projects

MICROCLIM A micro-scale perspective on alpine floras under climate change

2020-2026, ERC Advanced Grant (P.I.: Stefan Dullinger)

The diversity of organisms, one of the most striking features of life on Earth, is under threat, and climate change may become a major driver of the biodiversity crisis in the decades to come. However, climate effects on species will vary across ecosystems and regions. The fate of the rich and peculiar alpine flora in a warming world is particularly contentious. While some researchers expect massive loss of cold-adapted plants because they have little options to escape the heat (‘mountaintop extinction’), others assume low sensitivity of high-mountain floras due to widespread microclimatic refugia in the topographically complex alpine terrain. MICROCLIM aims to assess the evidence for these contradictory expectations by linking so far separated research strands of monitoring and predictive modelling of alpine plant distribution. In particular first, MICROCLIM provides a comprehensive evaluation of standard modelling approaches by comparing their predictions with Europe-wide monitoring of mountain top floras and analyse the role of spatial scale for possible mismatches between models and observations of change. Second, it includes the development of a novel modelling framework that simulates the simultaneous range dynamics of many interacting species. The model is parameterised by means of experiments and observational data and evaluated against monitoring data on an exemplary mountain. It will be then applied to simulate the dynamics of the flora of this mountain over the 21st century at a very fine spatial resolution to evaluate the proposed rescue effect of microclimatic variation in alpine terrain. The results achieved will be generalized in these dynamic simulations to all summits included in the European mountaintop monitoring network. The results of MICROCLIM will help understanding how threatened the unique alpine flora of Europe actually improve our understanding of the future of European high mountain plants. Field Pictures

GLORIA GLobal Observation Research Initiative in Alpine environments

1994-Present, Austrian Academy of Sciences (IGF) & University of Natural Resources and Life Sciences Vienna (P.I: Harald pauli)

Global climate warming will affect all ecosystems on the planet. High mountain biota, however, are particularly sensitive to warming because they are determined by low-temperature conditions. Accelerating climate change can lead to a decline of cold-adapted species and thus to drastic biodiversity losses. GLORIA aims to establish and maintain a worldwide network of long-term observation sites in alpine environments. It will act as a warning system to detect and assess critical changes in the species composition and habitat stability. Monitoring data are a crucial requirement for making reliable predictions about future impacts on alpine ecosystems world-wide. Field Pictures

TRAPA Multitrophic functional integration of C sequestration in High Arctic Soils

2017-2019, Czech Science Foundation Fellow (P.I.: P. Macek, M. Devetter & F. de Bello)

Ongoing global changes challenge the carbon (C) sink status of Arctic soils and loops of positive feedback are seriously feared. A switch from C sink to source would cascade from the response of Arctic terrestrial ecosystems to global changes and warming in particular. To assess the sustainability and sensitivity of Arctic soils C sequestration service, TRAPA  investigates the links among plants, soil invertebrate and microbial communities, and the C biogeochemical cycle in high Arctic terrestrial habitats. The project combines samplings along environmental gradients to investigate the variability of functional relationships, field and lab experiments testing the contribution of the communities to soil organic matter (SOM) transformation, and a modelling approach to outline the multitrophic web of interactions underlying Arctic soil sequestration. In the field, the project illustrates the breakthrough in functional ecology where a multidisciplinary approach truly integrates the holistic aspect of the ecosystem. The correlations among functional divergences and variations of the communities associated to a change in the C cycle characterize the complexity of the network and the strength of the functional relationships. Manipulative experiments investigate threshold dynamics and keystone structure of the ecosystem. Eventually, the modeling approach will translate the conceptual framework of multidiversity to quantitative assessment of the ecosystem functional structure. Field pictures

DeVeSh Decadal time-scale vegetation shifts at high latitudes: causes and consequences

2012-2016, Academy of Finland fellow (P.I.: R. Virtanen)

High latitudes ecosystems are facing strong and rapid climate and land-use changes inducing contrasting responses in plant community composition and functioning. In such slow growing system, long-term approaches, both experimental and observational, are susceptible to improve our understanding of the causes and consequences of the ongoing vegetation dynamic. The present project combines analyses of long-term experiments in arctic tundra and regional resampling in northern Scandinavia to address at diverse spatial scales the relative modulating role of the main biotic and abiotic drivers of plant communities. In the surrounding of Kilpisjärvi, northern Finland, several experiments were set up since the end of the 80’s and maintained through the time until nowadays. They test the roles of browsing and grazing disturbances, nutrient and soil water content and environmental perturbation for the composition and dynamics of shrub and dwarf-shrub dominated tundra communities. The effects of decadal treatments are analyzed to produce new knowledge on the interdependence between biotic and abiotic factors in a long-term perspective. In parallel, old vegetation analyses (sampled from 20 to 100 years) from the northern Finland are collected, geographically positioned and resampled to quantify the shifts in vegetation at a larger scale. Vegetation changes will be compared to environmental, climate and land-use data to identify the main correlations. Finally, the project includes a meta-analyses approach to compare results from the project data sets to those from collaborators in the Scandinavian area.  My main involvement in the project concerns the analyses of data set from the long-term experiments.     Field pictures

 PHENOALP Toward a monitoring protocol of alpine plant phenology.

2009-2012, European Interreg project (P.I.: U. Morra di Cella, E. Cremonese & A. Delestrade)

PhenoAlp is a EU co-funded project aiming to get a better understanding of phenological changes in the Alps. Concerning plants, the main goal is to define the better phonological indicator in the field data set.After two growing seasons, my work consisted in the preliminary analyses of data and in the correction of the grassland protocol iregarding to the field difficulties met. As a result we wrote a simplified protocol for the field managers.   

VERTICAL ECOLOGY (ECOVER) Structuration of communities associated to cushion plants of high mountain.

2008-2011, LECA transversal fellow (P.I.: C. Albert, S. Ibanez, S. Lavergne & P. Saccone)

We developed a multi-approach project aiming to explore the structure of community associated to cushion plants of high mountain cliffs. Because they are strongly isolated at small scale such as natural mesocosms, and because they occupy the end of environmental constraints gradients these communities represent very interesting studies models. The first results of this study highlighted the variability of structuring role of cushion plant on fungal and bacterial communities. I was one of the initiators of this project and I participate to the sampling design, the field campaigns, the data analyses and the co-writing of the paper.        Field pictures, TV report (in French), and project’s page on the Parc National des Ecrins’ web site         

NEVE Snow, plant litter and soil micro-organisms relationships.

2008-2009, LECA, LGGE, LEM collaborative project (P.I.: J.C. Clement, F. Domine, S. Morin & P. Saccone)

In cold ecosystems, winter activities represent an important part of total ecosystem functioning and the effects of climate changes on snow cover brought up some questions. In subalpine meadows, also affected by agricultural practices, the functioning of the ecosystem during the wintertime, as the plant litter decomposition, remains poorly known. We set up a litter bag experiment to test the effect of snow depth and litter quality on the rates of litter decomposition. These rates of decomposition were primarily affected by the snow depth and more precisely by the stability and the maintaining of its buffering effect in regards of daily thermal amplitudes. In these subalpine systems, snow cover could vary around the threshold of depth and stability necessary to provide a thermal insulation. As co-initiator of the project I participated to the design of the experimentation and I managed the field works, analyzed the data and wrote the first paper.      Field pictures

VALIDATE Response of subalpine meadows to simulated climate and land-use changes.

2007-2010, ANR project (P.I.: J.F Soussana & S. Lavorel)

The aim of the project is to evaluate for France the vulnerability of grasslands and livestock to climate change and extreme events, combining ecosystem manipulation experiments and modeling at scales ranging from the plot, to the field and to the region. High resolution climatic model was used to predict future rainfall and temperature and the results of manipulation experiment will be used to improve socio-economical models. The simulation of climate changes included (1) eight roller blinds which intercept natural rainfall (precipitation treatment controlled by a watering system) and night time soil infra-red emission (simulating a global warming to +1°C) and (2) infra-red ceramics which heat plant canopy to + 6°C compared to control plots in order to punctually simulate an heatwave event. The complete design crosses to the climate treatment a land-use treatment composed by mown and unmown plots. Plant responses to treatments were measured by physiological and morphological traits. The first results highlighted the resistance of subalpine plant community to climate changes compared to the effect of land use change. In this project, my work consisted in the design and installation of the microclimate instrumentation, the management of the whole experimental design on the Lautaret pass site and the supervising of students. I also participated to the analyses of the data and to the writing of the papers.      Field pictures, and TV report (in french, from 19' 20")

BIOCATCH Alpine Biodiversity and Catchment value in a land use context

2007-2012, International volunteer collaboration (P.I.: J.C. Clément, C. Körner, S. Lavorel, E. Tasser & U. Tappeiner).

The project aims at documenting the significance of biodiversity and land-use for the hydrological catchment value. The experimental design is based on mesocosms ( Soil + Plant) from several agricultural practices transplanted in lysimeters allowing to collect deep seepage water for chemical analyses. Data from sites in the Western, Central and Eastern Alps will be complemented by data from the Southern Alps and the Central Caucasus through our associated partners. My contribution to this project consisted in the management of the French field site during one year and in the set-up of the rain simulator. I also participated to the analyses of the data and to the writing of the papers and supervised some students in the field.       Field pictures

GUISANE 2080 Experimental test of climate and biotic interactions effects on tree seedlings recruitment in alpine meadows.

2006-2009, (P.I.: W. Thuiller)

Current global warming induces changes in species distributions. Predictions of future distributions were mainly based on global climatic models and species average responses. In contrasted temperature and sun radiation meadows of the Guisane valley, we sowed seeds and transplanted one-year-old seedlings of Larix decidua and Pinus unicinata, with and without herbaceous neighbors. This designs allowed us to explore i) the variability of the specific response traits to environmental conditions ii) The local filter effect of biotic interactions for the specific response to global warming. We expect the results to improve predictive models relevance. I designed and set-up the field experimentation.           Field pictures

CONTRACER Acer negundo invasiveness vs. Middle Rhone floodplain communities’ resistance

2005-2007, Local council fellow -CG38 Biodiv- (P.I.: J.J. Brun & P. Saccone)

In the context of biological invasion, the management of floodplains communities represents a real and strong challenge. To help managers, we performed an observational study to evaluate the risk of spread of the invasive Acer negundo along the Rhone river riparian forests. This project was a part of my PhD. I wrote the proposal and the sampling design and I co-supervised the student in charge of the field work.

INVABIO Floodplain functional composition, disturbance regimes and Acer negundo invasion

2004-2007, French Environment Ministry (P.I.: R. Michalet, E. Tabbacchi, J.J. Brun & P. Saccone)

Acer negundo, a North-American maple introduced in Europe, has invaded the lower and middle parts of the Garonne and Rhone rivers. The invasive species occurs in the successional dynamic at the ecotone between pioneer willows and mature ash communities. The objective of our work was to assess to what extent the invasion of the lower parts of the rivers could be imputable to a particular functional composition of the recipient community in regards to the competitive effects or the disturbance tolerance of the invader. Results showed that the alien was restricted to the lower and middle parts of the rivers, and we did not observe an obvious actual colonization towards the upper part of the valleys. Overall community richness was not negatively affected by the alien. The success of the alien was due to both a strong morphological plasticity in full resource conditions and a high shade-tolerance. Its ability to tolerate both shade and disturbance allows the species to arrive in advance to ash species below the canopy of willows where it is facilitated. Later on, A. negundo outcompetes the willows and facilitates itself. The alien remains in the succession in the lower and middle parts of the rivers together with F. angustifolia which exhibited a similar competitive ability. This project was a part of my PhD. I participated to the selection of study sites and I designed and set-up the field experimentation. I managed the field work, collected the transplants at the end of the experiment, analyzed the data and wrote the papers.            Field pictures

 PhD in forest ecology Role of plant-plant interactions and place of exploitative competitor species in forest dynamics under global changes: a mountain and a riparian case

2002-2007 Cemagref Grenoble. Supervised by J.J. Brun and R. Michalet (Bordeaux I University)

Most of abiotic and biotic factors structuring plant communities had been identified, but their relative importance and their precise roles lead to strong debate among ecologists. The role of these factors in the response of plants to global changes questions scientists.

Our study focused on the role of plant-plant interactions and on plant strategies as structuring factors of temperate forest communities. Our study sites were a post-cultural mountain forest dominated by Acer pseudoplatanus et Fraxinus excelsior in the Northern French Alps and a riparian forested system in the Rhone River floodplain under Acer negundo invasive pressure. A first descriptive approach allowed us highlighting the importance of these mid-successional species within the studied forested landscapes. Through experimental designs, we have compared the seedling responses of these trees to that of other dominant or potentially dominant trees of these forested systems. Our results showed that these species have developed an exploitative competitor strategy associating strong competitive abilities to high resources acquisitions abilities. In the mountain system, A. pseudoplatanus and F. excelsior did not have better performances than late-successional species tested which reject the hypothesis of a succession locking. In the riparian system, the exploitative competitor strategy of A. negundo was an invasive advantage in the downstream section of the system while the biotic resistance occurring in the upstream section limits its propagation. Moreover, our results highlighted the major role of biotic interactions for the responses of plant communities to global changes. A. negundo performances were facilitated in the downstream section of riparian system by the direct or indirect effects of the tree canopy while they were reduced in the upstream section by the neighborhood of trees and herbs. In the mountain system, the trees canopy of the mesoxeric sites increased the negative impacts of 2003 European heatwave on A. pseudoplatanus and P. abies seedlings while the trees canopy of mesohygric sites have buffered these impacts on the survival of A. alba seedlings. Finally our results revealed the memory of targets individuals in their responses to biotic interactions. The PhD included the management of the Rhone River part of the INVABIO project and the CONTRACER project (see above). Field pictures from the mountain forest, and the short report for users.