Ecología de leguminosas pratenses en relación con algunos factores ambientales en la cuenca baja del Narcea (Asturias)

Abstract

The influence of altitude, slope, aspea (orientation) and distance from the sea on the distribution of grassland leguminosae species has been studied, covering a 250 km.2 área at the lower tract of River Narcea (Asturias, Spain). Floristic composition of 76 samples, representative of the 8 types of geological formations present in the área has been determined. Being 45 the number of leguminosae species detected. The frequency of each species, as percentage of samples in which the species is present respect to the total number of observed samples, has been estimated. The more frequent species are (in decreasing order) TrifoUum pratense, T. repens, Lotus corniculatus and Vicia sativa (> 75 % of the total number of samples). Among the species of lower frequency it can be remarked the presence of TrifoUum ligusticum Balbis ex Loisel, unknown in Asturias and in all the Spanish Cantabric área (only one data in Galicia, MERINO, 1905). The influence of each studied ambiental faaor on each species has been tested by an statistical approach of signification of deviation of the mean of valúes of the samples where the considered species is present and the mean valué of all the samples. Also, frequency histograms and diagrams have been made. TABLE 2 shows a summary of results. The species of higher frequency are indiferent for the studied ambiental faaors. The more remarkable results have been obtained in Anthyttis vulneraria, TrifoUum campestre and species of Melilotus, Ornithopus, Hippocrepis and Scorpiurus.