Evaluation of the biodiversity in Bryophytes and Pteridophytes in Nueva’s river basin (Llanes, Asturias, North Iberian Peninsula): scientific grounds for its protection and conservation

Nueva’s River Valley lies close to the Cantabrico sea, facing towards the east. The upper and middle part of its basin, with a surface of 5.5 Km2, shows a high
diversity of bryophytes, as we have identified 145 taxa (85 mosses, 59 liverworts and 1 hornworts), which represent 23% of the Asturias bryophytic flora. The use as sampling unit UTM squares of 0.5 Km side, shows also the richness in bryophytes of this place, as we have found up to 70 different taxa in each square unit. From the catalogue made, Dicranodontium asperulum turns out to be new for the Iberian Peninsula, as in the same way for Principado de Asturias are the mosses Dicranum
scottianum and Plagiothecium platyphyllum, and the liverworts Bazzania trilobata var. depauperata, Cephalozia crassifolia, Cephalozia loitlesbergeri, Kurzia sylvatica, Lepidozia cupressina, Nowellia curvifolia and Jungermannia paroica. Most of these
taxa have very reduced distribution area. At the regional level, our data represent to enlarge the area of some other rare or threatened species (15 liverworts and 5 mosses), included in the «Red List of Bryophytes of the Iberian Peninsula» (Sérgio & al. 1994). A phytosociologic study of the bryo-pteridophytic communities has been made, especially on those dominated by ferns bearing «subtropical» character: Woodwardia
radicans, Hymenophyllum tunbrigense, Culcita macrocarpa, Stegnogramma pozoi, Vandenboschia speciosa, etc. Most of these communities belong to the alliance Hymenophyllion tunbrigensis (Order Anomodonto-Polypodietalia, Class Anomodonto-
Polypodietea). This alliance gathers phytocoenoses mainly made by bryophytes and pteridophytes, that inhabit sides of large rocks, walls and compact earth slopes, rootin in a thin layer of soil (exocomophytes), and developed in a really wet
environment, under the canopy of forest formations. Through calculation of the «Rare specific index», coefficient of diversity phytocenotics and of botanic quality, among others, we have evaluated the zone with the aim to lay the scientific grounds for its protection and conservation.