N2000-Alien plants along river banks

Study Extent

The study took place along river banks included in the N2000 network of the Walloon Region (Southern Belgium), between May and September 2013.

Sampling

A stratified sampling was performed across the N2000 network in the Walloon Region, using bioclimatic subregions (Ardenne, Lorraine, Famenne, Condroz and Hesbaye) and water basin size (> or < 100 km²) as strata. A sampling unit consisted in a 150 long x 10m wide strip of river bank. In a total of 187 sampling units (corresponding to ca. 0.4% of the 6800 km of rivers in the Wallon Natura 2000 network), vegetation surveys were realized between May and September 2013.

Method steps

1. A map of the N2000 network was crossed with the hydrographic network map of Wallonia.
2. Using this map, 10 strata were defined based on bioclimatic subregions (Ardenne, Lorraine, Famenne, Condroz and Hesbaye) and water basin size (> or < 100 km²) and the number of potential sampling units in each stratum was calculated.
3. A constant proportion of sampling units were randomly selected in each stratum.
4. Each sampling unit was visited and vegetation relevés were realized.

Wallonia, southern Belgium.