Distribution of some vulnerable epiphytic bryophytes in the north of the province of Groningen, The Netherlands

Abstract

Several Dutch bryophyte species, formerly more or less common, are becoming rare due mainly to the destruction of natural habitats and to air pollution. Some of these species survive in coastal areas (where the air quality is relatively good), for instance in the north of the province of Groningen, on the bark of old elms. Examples are Leucodon sciuroides, Orthotrichum lyellii, Tortula laevipila, T. papillosa, Ulota phyllantha and Frullania dilatata. However, the number of bryologically valuable elms ( Ulmus spp.) is decreasing rapidly, partly because of Dutch elm disease. Tortula papillosa and T. laevipila are less endangered than the other species because they also grow, although rarely, on other broadleaved trees, and the latter also on cement roof tiles in rural areas. These cement tiles are nowadays often replaced by more modern types of roofing which are unsuitable for these mosses. Because of the decrease of suitable habitats all the species mentioned are vulnerable or endangered in the north of the province of Groningen.