Contribution to the Macrophytic Typology of Belgian Reference Watercourses

Abstract

The objective of the study is to create a typology of macrophytes for the reference watercourses of the Meuse River catchment basin in Wallonia as a step towards the implementation of the European Water Framework Directive. The 50 sites studied are the object of a physicochemical and environmental characterization followed by a floristic survey (phanerogams, mosses, liverworts, and macroalgae). Six clusters of watercourses with their characteristic species are highlighted by two-way clustering and indicator species. The abundance of phanerogams in some watercourses of the Arden region is not only linked to light intensity but also depends on the degree of slope and the nature of the geological substrate.

Factors Affecting the Presence and the Diversity of Bryophytes in the Petrifying Sources Habitat (7220) in Wallonia and the Brussels-Capital Region, Belgium

“…These studies may address a wider range of conditions than in the present study and suggest that this relationship is scaledependent. The majority of the richest sites were characterized by PO 4 concentration < 0.1 mg⋅L −1 which is very close to the 0.05 mg⋅L −1 threshold determined by Galoux et al [41] for the reference conditions of Walloon watercourses. Brusa and Cerabolini [11] in Italy using multivariate analysis found that the 3 major factors explaining their species assemblages were the permanency/nonpermanency of the water flow, the slope, and the canopy cover.…”

“…This suggests that other variables not measured here could explain better the observed species assemblages. Following other authors [41,42], we suggest that factors such as the substrate itself (sand, loam, and rock), the micro topography [11,16,18,33,43], the water turbulence [2,8,44], the distance from the spring [8,13], the presence and characteristics of travertine-productive microorganisms like cyanobacteria [8,16,45], and the local relative humidity could…”

“…This species is not recognized in Wallonia as a characteristic species of the 7220 habitat as it is widely distributed [19], occupying calcareous meadows, calcareous springs, and wet rocks, as well as forest tracks where dolomite gravels have been added to harden the soil. In the Walloon watercourses Cratoneuron filicinum has been identified as one of the few indicative species of more or less calcareous streams [41]. In our sites the species has a relatively wide ecological amplitude as regards canopy cover and light to moderate eutrophication.…”

“…It occurs along water courses and in marshes, though it is less linked to calcareous waters. In Wallonia it has been demonstrated that it has very wide ecological amplitude that is common in every natural region independent of the substrate [41]. It has also wide ecological amplitude occurring in a range of trophic levels and tolerating shade but preferring open sites [50].…”

Trend Analysis in Ecological Status and Macrophytic Characterization of Watercourses: Case of the Semois-Chiers Basin, Belgium Wallonia

“…Between 2007 and 2013, this network undertook several macrophytic surveys of waterbodies [27]. The reference macrophytic communities were waterbodies classified by the Walloon Government as being areas showing little or no human impact [28].…”