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Monitoring Invasive Ludwigia grandiflora in the Vilaine Basin using multispectral remote sensing

Abstract : Ludwigia grandiflora (Water primrose) is an aquatic invasive species in the Vilaine Basin (North-West of France). It invades rivers, lakes and marshes and it can develop a terrestrial form in floodplains. Its dense mats cause changes in ecosystem functioning and undermine both human fishing activities and navigation. It is spreading through vegetative growth from cuttings and flooding allows dispersion far away. To control it, management must be realised at catchment river scale. Maps of a large area and for inaccessible sites can be produced from remote sensing images. Remote sensing data are SPOT 5 data have been acquired during summer, when water primrose forms large and dense mats and is flowering, for the years 2003 and 2005. For these years, maps of L. grandiflora distribution are available. In order to use a supervised classification, nine classes have been identified with visual interpretation. Pixels are selected on a site where stands of L. grandiflora are large and dense. The defined classes are: water primrose, aquatic vegetation (few dense and with a lower spectral response in the near infrared than water primrose), 4 classes for crops, 2 classes for forest, and water. Firstly, no class for amphibious vegetation is defined, because it forms heterogeneous stands, with spatial variability in species and density. The classification based on these pixels is applied on two other sites, distant from 15 km: a marsh where mats of L. grandiflora are in mixture with water and other amphibious vegetation and a site with lakes and a network of channels. This extension is realised to assess if it is possible to map L. grandiflora on a large region, with data from a localised site. Results are compared with historical maps and experts knowledge about colonisation by water primrose of aimed sites. The distinction/confusion between water primrose and the other classes, and with amphibious vegetation is studied in order to define precisely the accurate of obtained maps. These results show that remote sensing is useful to map large stands of water primrose and is a base to monitor evolution of colonisation by this species. Complementary researches are needed to determine minimal size of mats that can be detected with this type of sensor and to define confusion sources, which appear during classifications.
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Submitted on : Friday, September 7, 2012 - 4:06:59 PM
Last modification on : Friday, August 26, 2022 - 11:11:38 AM


  • HAL Id : hal-00730026, version 1


A. Sourisseau, Jacques J. Haury, B. Bottner, Rim Amri, Hervé Nicolas. Monitoring Invasive Ludwigia grandiflora in the Vilaine Basin using multispectral remote sensing. 12th EWRS Int. Symp. on Aquatic Weeds, Aug 2009, Jyväskylä (FI), Finland. ⟨hal-00730026⟩



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