Macroinvertebrate distributions and the conservation value of aquatic Coleoptera, Mollusca and Odonata in the ditches of traditionally managed and grazing fen at Wicken Fen, UK

biodiversidad biodiversity bovin cattle coleoptera conservation de la nature drainage drainage systems drenaje fens ganado bovino grasslands grazing herbage invertebrados invertebrates land mollusca multivariate analysis nature conservation nature reserves odonata pastoreo praderas red de drenaje reino unido reservas naturales species diversity statistical methods terre terre humide tierras united kingdom vegetation wetlands