Résumé
Background : In Mediterranean cultivated lands, exogenous variables controlling spatial distributionof non-cropped plant species at the landscape scale are habitat variables, seed-sources proximity,and lastly human practices. In order to manage ecosystem services provided by head catchmentsdrainage networks (ditch networks), we need to predict spatial distribution of plant species living inthem. Geomorphological variables have shown to be important habitat variables in otherecosystems (riverine, wetlands,...), but whether such variables can be used to predict plantdistribution in ditch drainage networks is unknown. An arising question is then : which is theimportance of geomorphological landforms in driving plant species distribution at the ditch networkscale ?Methodology : We collected presence and absence data for 10 plant species (herbaceous) on a 35-km drainage ditches network in a Mediterranean agricultural landscape. We simulated their spatialdistribution using geomorphological and land-use derivative variables (representative of seed-sources proximity) with Maxent and GLM model. Each plant species was considered separately andeach model was validated using k-fold cross-validation (k=4). We compared mean AUC (AreaUnder the Curve) values obtained for each model and relative importance of explanatory variables.We analysed compiled false positive and false negative residual maps.Results : Mean AUC values for Maxent model ranged from 0.92 for Mentha aquatica to 0.67 forRubus fruticosus. Mean AUC values for GLM ranged from ranged from 0.86 for Lythrum salicariato 0.61 for Rubus fruticosus and Sorghum halepense. Both geomorphological and land-usederivative variables were important to explain Asparagus Acutifolius, Equisetum arvense, Menthaaquatica, Mentha suaveolens, Rumex crispus, Scirpus holoschoenus distribution and onlygeomorphological variables well explained Lythrum salicaria distribution. The models failed toexplain accurately Sorghum halepense, Rubus fruticosus and Elytrigia juncea distribution.Compiled residual maps showed a false positive predictions pattern at the South of the catchment.Conclusion : We highlighted the importance of considering geomorphological variables to explainspatial distribution of plant species in Mediterranean head catchments drainage ditches. Resultssuggested that part of the remaining non-explained variability for some species was induced byhuman practices. Agro-ecological measures aiming at managing ecosystem services provided byditch networks have to consider plant specific predictors at the local and landscape scale in order tobe successful. They further have to investigate human practices effects on ditch plant distribution.