The project of Zone Atelier Pyrenees-Garonne (ZA PYGAR)

South-Western France, going from the Pyrenees mountains to the plains of the Garonne river basin. PYGAR tries to answer three main scientific questions: 1/ What are the respective contributions of climate change and local anthropogenic disturbances to ecosystem changes (biodiversity, bio-physical characteristics)? 2/ How human practices drive ecosystem services? 3/ What are the relationships between resources availability and their accessibility, and the historic and prehistoric human population structure? The main transversal question of PYGAR is the adaption and response time of the different SES to global changes. The SES are studied at different time scales from the last glacial maximum to the present-day. PYGAR clusters 17 Labs (40 full-time permanent staffs: 23 researchers/professors & 17 engineers/technicians) from Toulouse and Bordeaux, supported by the University of Toulouse and several French research organisms (CNRS, INRA, IRSTEA, IRD, CNES, BRGM, Météo France). Socioeconomic partners (companies, farmer’s associations…) and public services (Occitania Region, Water Agency…) are strongly interested in the project. PYGAR includes 4 territories (sites ateliers): the central Pyrenees mountain range, the Garonne River, the agricultural hills and valleys of the Gascogne region and the Viaur-Aveyron river basin. The theory of SES provides a valuable tool to set up an interdisciplinary approach to deal with the co-evolution and resilience of the social and ecological templates of the studied systems facing global changes (climate change and land cover)

Éléments semi-naturels des paysages agricoles et boisés et connectivités pour les pollinisateurs sauvages

Les espaces agricoles couvrent plus de la moitié du territoire français. Ils ont donc un rôle essentiel dans la préservation de la biodiversité et des continuités écologiques. Ce rôle dépend fortement des pratiques agricoles. Parmi celles-ci, l’agro-écologie est une façon de concevoir des systèmes de production qui visent à diminuer les pressions sur l’environnement et sur les ressources naturelles et à préserver, voire amplifier, la fonctionnalité écologique des exploitations. Favoriser les infrastructures agro-écologiques est susceptible de contribuer à la circulation de nombreuses espèces et à favoriser la connexion écologique des espaces naturels ou semi-naturels.Cette biodiversité est par ailleurs utile à l’agriculture en raison des nombreux services qu’elle apporte (pollinisation, auxiliaires des cultures…).A une échelle plus vaste, la transition agro-écologique des territoires, peut conduire à la mise en place de projets favorables à la biodiversité tout en structurant des filières répondant aux besoins des consommateurs locaux.L’Agence française pour la biodiversité organise une journée d’échanges techniques dans le cadre du Centre de ressources Trame verte et bleue et en partenariat avec le ministère de la Transition écologique et solidaire et le ministère de l’Agriculture et de l’Alimentation.Cet événement cherchera à répondre aux questions suivantes : Quelles synergies peut-on développer entre agro-écologie et Trame verte et bleue ? Quels services réciproques peuvent se rendre les pratiques agro-écologiques et une biodiversité fonctionnelle ? Comment accompagner les acteurs de terrain dans cette approche ? L’objectif de cette journée est de favoriser le développement de l’agro-écologie dans les projets de Trame verte et bleue en réunissant les acteurs de la biodiversité et du monde agricole. Elle visera à présenter des retours d’expériences réussies illustrant les bénéfices mutuels entre production agricole et biodiversité

Spatial uncertainty effects on a species-landscape relationship model in ecology

In this study, we explore the effects of geometrical uncertainty in an existing species-landscape relationship model in the hoverfly communities. We also investigate how geometrical uncertainties affect a more complex model including both current forest patch features and past forest features. Because of a possible time-lag in biological responses to forest changes such as fragmentation, the historical dimension is added to the first model. The proposed approach relies on three spatial sources enabling to get forest fragments at different times: historical map (~1850), aerial black and white photographs (1954) and orthorectified photographs (2010). Firstly, we analyze the effect of the spatial data production method (manual versus automatic) on models using current forest patches only. Then, we build a more complex model including past changes in forest size. As previously, the effect of production-based uncertainty was assessed by comparing the models based on forests extracted manually and automatically. We address finally the impact of positional accuracy on the historical map by using a Monte Carlo simulation approach. Global results show that responses of the statistical models are strongly affected by spatial uncertainty in inputs

Spectro-temporal heterogeneity measures from dense high spatial resolution satellite image time series: application to grassland species diversity estimation

Grasslands represent a significant source of biodiversity that is important to monitor over large extents. The Spectral Variation Hypothesis (SVH) assumes that the Spectral Heterogeneity(SH) measured from remote sensing data can be used as a proxy for species diversity. Here, we argue the hypothesis that the grassland’s species differ in their phenology and, hence, that the temporal variations can be used in addition to the spectral variations. The purpose of this study is to attempt verifying the SVH in grasslands using the temporal information provided by dense Satellite Image Time Series (SITS) with a high spatial resolution. Our method to assess the spectro-temporal heterogeneity is based on a clustering of grasslands using a robust technique for high dimensional data. We propose new SH measures derived from this clustering and computed at the grassland level. We compare them to the Mean Distance to Centroid (MDC). The method is experimented on 192 grasslands from southwest France using an intra-annual multispectral SPOT5 SITS comprising 18 images and using single images from this SITS. The combination of two of the proposed SH measures—the within-class variability and the entropy—in a multivariate linear model explained the variance of the grasslands’ Shannon index more than the MDC. However, there were no significant differences between the predicted values issued from the best models using multitemporal and monotemporal imagery. We conclude that multitemporal data at a spatial resolution of 10 m do not contribute to estimating the species diversity. The temporal variations may be more related to the effect of management practices

Discriminating small wooded elements in rural landscape from aerial photography: a hybrid pixel/object-based analysis approach

While small, fragmented wooded elements do not represent a large surface area in agricultural landscape, their role in the sustainability of ecological processes is recognized widely. Unfortunately, landscape ecology studies suffer from the lack of methods for automatic detection of these elements. We propose a hybrid approach using both aerial photographs and ancillary data of coarser resolution to automatically discriminate small wooded elements. First, a spectral and textural analysis is performed to identify all the planted-tree areas in the digital photograph. Secondly, an object-orientated spatial analysis using the two data sources and including a multi-resolution segmentation is applied to distinguish between large and small woods, copses, hedgerows and scattered trees. The results show the usefulness of the hybrid approach and the prospects for future ecological applications

Les lisières forestières : quand l’agroécologie passe par les bois

Dans les paysages ruraux tempérés, les parcelles agricoles sont souvent en contact avec des bois. Ces lisières sont des milieux où se déroulent des processus écologiques particuliers. Certains d’entre eux peuvent être utiles à l’agriculture et leur gestion peut contribuer à une démarche agroécologique. Nous montrerons à travers différentes études portant sur les carabes, comment les lisières influencent la biodiversité et modulent ainsi des services dont peut bénéficier l'agriculture

Odonata communities in an agricultural lowland in the South of France

Odonata communities were studied in an agricultural landscape where semi-natural habitat patches (pastures and woods, with a dense network of deep ditches) are embedded in a crop mosaic (cereals, irrigated maize). We compared species richness and diversity of aquatic plants and odonata in ditches surrounded by pastures or by crops. Ours results showed that this surrounding (pastures vs crops) has no effect on aquatic plant and odonata species richness and diversity. However, in cultivated areas water supply through irrigation and deep ditches with plant-covered borders could promote odonata species. High level of vegetation cover (particularly with Typha sp.) limited odonata richness and diversity. A rare species in Europe, protected and sensible to pollution, Coenagrion mercuriale, occurred in many ditches including those surrounded by crops, particularly those with an intermediate semi-aquatic vegetation cover. The regular maintenance of ditches, by limiting shrubs and trees height, keep them open and facilitate the dispersal of this little mobile species. Although irrigated crops seem to support a high level of odonata diversity, a new intensification of agricultural practices in this area by increasing the pollutant input and/or by converting pastures to crops could be detrimental to odonata communities and particularly to some species like Coenagrion mercurialeLes peuplements d'odonates ont été étudiés dans une plaine où se pratique une agriculture intensive (maïs irrigué notamment) mais où subsistent encore quelques éléments semi-naturels (prairies, bois et fossés). Nous avons comparé des fossés bordés de cultures avec ceux bordés de prairies en termes de diversité et de richesse spécifiques en plantes semi-aquatiques et en odonates. Il apparaît que l'environnement immédiat des fossés (prairies versus cultures) n'a pas d'influence sur la diversité et la richesse spécifique en plantes semi-aquatiques et en odonates. Toutefois en zone de cultures, l'apport d'eau par l'irrigation et des fossés profonds bordés de végétation, pourrait favoriser ces espèces d'odonates. Les odonates préfèrent nettement les fossés plutôt peu recouverts par de la végétation aquatique (notamment par Typha sp.). Une espèce considérée comme rare, protégée et sensible à la pollution, Coenagrion mercuriale, est présente y compris en zone de cultures. Elle affectionne surtout les fossés moyennement recouverts par la végétation semi-aquatique. L'entretien régulier par élagage des fossés, se traduisant par une faible hauteur des ligneux, limite la constitution de barrières à la dispersion de cette espèce peu mobile. Bien que les cultures irriguées semblent promouvoir la diversité en odonates, une nouvelle intensification des pratiques agricoles, notamment en accentuant les problèmes de pollution et /ou en supprimant des zones prairiales, pourrait affecter les conditions de vie des libellules comme Coenagrion mercuriale

Biodiversité et services rendus à l’agriculture. Principaux enseignements de différents dispositifs de recherche récents et actuels en Midi-Pyrénées

Dans le canton d’Aurignac, des chercheurs de l’Institut national de la recherche agronomique et de l’Institut national polytechnique de Toulouse travaillent depuis une trentaine d’années sur l’agriculture, les paysages et la biodiversité. Les paysages agricoles étudiés sont caractérisés par une agriculture de polyculture élevage et la présence de petits bois. Ces paysages agri-forestiers constituent un site d’étude à long terme qui est reconnu au niveau national et européen

Potential of Sentinel-2 and SPOT5 (Take5) time series for the estimation of grasslands biodiversity indices

MultiTemp is a series of workshop (established in 2001) that provides a forum of discussion of scientific, methodological, and application issues related to multitemporal data analysis. The workshop aims to push novel solutions for technical problems related to the analysis of image time series and promotes the use of the multitemporal data in an ever increasing number of strategic and challenging applications, strengthening the connection between the scientfiic community, the industry and the end-users. (https://www.aconf.org/conf_111314.html

ATLAS: A tool to model spatial-temporal dynamics of processes influencing ecosystem services

Biodiversity provides various benefits to humankind throughout what is defined as ecosystem services. Within a specific ecosystem, a wide range of ecosystem services can be identified. During the past decades, human intervention has aimed to increase some services such as food production through agricultural intensification, at the expense of other services such as water regulation. Mapping, evaluating and quantifying each of these ecosystem services provided by biodiversity to crop production could help to increase the multi-functionality of agricultural landscapes. In this context, we developed a spatially-explicit model called ATLAS (AgriculTural LandscApe Simulator). ATLAS aims in simulating realistic spatio-temporal dynamics of agricultural landscapes, through crop rotations and phenology at the landscape scale. The robustness of the model was evaluated using two criteria: an accurate composition (crop area) and configuration (crop clustering) of crops. Here, we show the potential of such a tool to map and evaluate ecosystem services through the simulation of underlying ecological processes. We applied this model to two case studies: control of pests and crop pollination. First, we studied how the dynamics of a cereal aphid, Rhopalosiphum padi, respond to spatial-temporal crop availability. Second, we developed an extension to model spatialtemporal dynamics of flower resources in relation to wild pollinators and pollination. With a low amount of inputs and calibration needed in ATLAS, the impact of agricultural practices on ecosystem services can thus be explored to allow better comprehension and management