| Popis: |
During River Habitat Surveys on the physical structure of the watercourses in the U.K., channel vegetation types were recorded as present or extensive in 10 m wide belt transects at 50 m intervals over 500 m reaches for some 2435 stratified random sites in 1995–96. Data on attached, submerged, emergent and free-floating aquatic vegetation were grouped into nine broad morphological groups such as submerged broad-, linear- and fine-leaved, free-floating, emergent, etc. Vegetation data are supported by assessments of physical parameters at each site including dimension, flow types, channel substrate and the slope of the channel. The general habitat requirements for each group are shown to agree with assumed requirements but with a broader distribution of habitats. Eight percent of channels had excessive growths of vegetation and would normally be considered for weed control; this was a minimum estimate. |
