The Tour du Valat (TdV) is a private research centre located on a 2 600 ha estate (of which 1 800 ha are classified in natural reserve) in the Camargue (Rhône delta), south of France. Created in 1954 and legally recognised as a non-profit-making association, it has set itself the mission to halt and reverse the destruction and degradation of Mediterranean wetlands and their natural resources, and promote their wise use.
Pioneer in producing management plans for protected natural areas, its activities are today largely oriented towards multidisciplinary research, co-constructed with or transferred to stakeholders and aimed at preserving the biodiversity, functions and services provided by ecosystems in a context of global changes. Disciplines such as hydrology, remote sensing, plant and animal ecology are combined into three main ecosystem approaches corresponding to modeling, restoration and management. A large part of these research activities are carried out in the Camargue which benefit from various protection status at different scale.
The Camargue Biosphere Reserve
The Camargue Biosphere Reserve covers 193 000 ha, including 50% of natural and semi-natural habitats dominated by lagoons, brackish/freshwater open and reed marshes, halophilous steppes, rangelands and fallow lands. Resilience of these ecosystems to anthropogenic influences is variable and can translate into alpha, beta and gamma biodiversity loss through ecosystem fragmentation and transition (eg, from halophilous steppes to reed marsh following freshwater input), and modification of ecosystem health state with feedbacks on ecosystem services, especially in terms of human uses (waterfowl hunting, bull grazing, reed harvesting, nature conservation). These natural ecosystems are intermingled with agro-systems of which the evolution from family to speculative farming is likely to affect biodiversity. The delta is almost completely polderized, and each year about 400 000 000 m3 of water is pumped from the Rhône to permit rice cultivation (and incidentally water management of marshes and pastures), of which 55% is pumped back to the Rhône, the rest being evacuated (when possible!) to the sea through the Vaccarès lagoon. Sea level rise, climatic variability, modification of agricultural policy (affecting rice farming areas), freshwater availability (increased penetration of the saltwater wedge from the Rhône) and underground salinisation will differently affect these ecosystems of which the dependency upon the hydro-system, primarily developed for rice production, is variable. Considering the high degree of 'artificialisation' of the delta, research and transfer activities at Tour du Valat are mostly targeting human behaviors, since we consider that management actions have currently more impact than evolution of abiotic conditions on ecosystems. Our mail goal is to foster adaptation of users, managers and decision makers to global changes.
The Camargue hosts 34 habitats of EU interest (Annex I of Habitats Directive), including 7 priority ones. Actually, most of the surface area of natural habitats is either occupied by habitats of EU interest or by habitats of priority species according to the Bird Directive. Although the Camargue represents only 0,3% of the country area, it hosts 400 (289 regularly) of the 570 French bird species, 50% of dragonflies and freshwater fishes, 30-40% of reptiles, amphibians, terrestrial mammals and nearly 25% of the flora (1200 species) for a total of 489 species of conservation interest. The Camargue also plays an important role for bird migration routes with nearly one million individuals from over 350 species transiting each year though the delta (site of international relevance according to Ramsar for 31 species). The only breeding colony of flamingos (flagship species) in France is also located in the Camargue. Tour du Valat is involved in several long-term population surveys, mostly on birds.
Research activities are mainly focused on provisioning services associated with the main socio-economic activities of the delta (reed harvesting, waterfowl hunting, rice farming, cattle raising, fishing, ecotourism), including supporting service such as biodiversity. Indicators used to monitor these services are often related to plant community (state of conservation, richness, vegetation structure). Wetland vegetation also contributes to improving water quality in coastal lagoons and marshes.
Tour du Valat is involved in two restoration projects within the Camargue biosphere reserve:
- Cassaïre estate: 70 ha of former ricefields are converted into natural meadows and temporary marshes through topographic modifications and soil inoculation to improve biodiversity and provide a demonstrative case of sustainable hunting management scheme (respectful of the Mediterranean specificity of marsh ecosystems).
- Former Salworks: 5 500 ha of pre-concentration basins for salt exploitation formely polderized and receiving pumped seawater are being restored into lagoon and coastal ecosystems (dunes, salt steppes, temporary marshes) having a more natural functioning through reconnection with the neighboring hydrosystems (Vaccarès), part of the catchment area and the sea (following the multiplication of breeches in seafront dykes). This is currently the biggest project on which Tour du Valat is working (initial state on species/ecosystem diversity, prospective modeling on water-salt-flora-fauna interactions to orient engineering works and management actions).
Current modeling activities
Mainly focused on hydrology and salinity as driving factors of ecosystems health in interaction with management related to human activities, each associated with different water regime and resulting in conflicts among users:
Hydrosystems of the Vaccarès lagoon: 2D and 3D hydrodynamic modeling (lagoon) and conceptual model of water and salt mass balance model. Components: Rainfall-runoff model for the catchment, GIS for land use, empirical relationships derived from hydrodynamic simulations or field data analyses.
Hydrological modeling of the former saltworks based on a detailed DTM (Digital Terrain Model) and including wind effects.
Hydrological functioning of marshes: hydrological and salinity model developed from long-term empirical data to simulate the impact of climatic scenarios on marsh hydrology and salinity (and to calculate the water volume needed to reach different management goals).
Wetland vegetation: mechanistic models on the relationship between temporal variation in hydrology & salinity on reed density and height, floristic diversity and mediterranean specificity of submerged macrophytes, presence of proliferating exogenous plants (eg: Ludwigia).
Wetland birds: mechanistic models on ecological requirements of herons, ducks and passerines associated with management of reed marshes and open marshes, as well as for Flamingo (food requirements and avaibility) in relation to management of salinas and coastal lagoons.
Agricultural landscapes: mechanistic models on the effect of landscape compositional and spatial heterogeneity on biodiversity and ecosystem services in cultivated crops (mostly rice and wheat).
Global change implications for the future of iconic parks: identifying values allocated by local, management, policy and interest communities through a GIS participatory platform with modeling of hydrology and flamingo populations.
Land cover/use available since 1984, renewed every 5 years (PRNC) and derived from ortho photographs (resolution 0,5-1 m).
Satellite imagery: seasonal time series of SPOT-5 scenes in 2005-2006 and 2011-2012 used to estimate area of reed beds, of submerged macrophytes and of open water through data mining using decision trees (Remote Sensing of Environment 114: 552-562, 138:165-171), as well as state assessment of reed beds (RSE 114:1602-1609).
Considering the relatively fast coastal erosion/accreation observed along the littoral coast of the Camargue reserve, the monitoring of changes in beach profile suggested by ISPRA_Italy (Andrea Taramelli, Emiliana Valentini) would be most relevant for our site.
A list of metadata is available under request. The Camargue is not benefitting from national standardized surveys (unlike the Netherlands, for instance). Many of these data are thus irregularly collected in time or/and space.
Transfer to stakeholders
In addition to traditional vulgarization documents, various simulation tools have been developed to increase awareness about wetland sustainable use and to foster adaptation to global changes: agent-based model on the reedbed socio-ecosystem (interactions between hydrology, vegetation, biodiversity, and economic activities), various role playing games (on territorial planning within the whole Camargue biosphere reserve, on sustainable hunting activity, on reedbed management, etc); simulation of the water management of the Vaccarès hydrosystems, interactive web interface on marsh hydrology and its consequences on vegetation development and bird abundance.
Expectations from Eco-potential H2020 project
Tour du Valat is obviously keen in pursuing/sharing its current approach within this project if deemed useful/relevant by project partners. Among our priority activities are 'connecting' the Vaccarès-marsh-ricefield hydro-systems in order to carry out prospective modeling analyses on how changes in agricultural practices, climate and sea level are likely to affect the functioning of the whole delta integrating the feedback loop on ecosystem services. Another line of research activities that we wish to develop is to better quantify the ecological, social and economical changes occurring following the reconversion of the former saltworks into 'natural' ecosystems open for ecotourism as well as several human activities. Ecosystem restoration (and territorial mutation) is a fast growing field that would certainly benefit from experience sharing.
At the same time, we consider this project as a great opportunity to adhere to a larger, standardized monitoring scheme. I look forward to improving our data management/collection to favor their wider and more efficient exploitation. In particular, analyzing these data (available or to be collected) under a different perspective by capitalizing on the complementarities from our in-house expertise with that found among the project partners is most challenging and stimulating.