Estudi fitocenològic de les pastures de la Plana de Vic. I: comunitats vivacies (Mesobromion i Aphyllanthion)

Abstract

In this work, the authors describe the perennial pastures and grasslands occuring in the Plana de Vic country, a sub-Mediterranean area which lies between the eastern Pyrenees and the Mediterranean areas of north-eastern Iberian peninsula. It is a depressed basin with an intense farming activity, and over such flat landscape, there are some hills bearing diverse litology (marls, sandstones and conglomerates) and topography. The communities studied are distributed on the slopes and top of the hills, according to he geomorphological diversity mentioned, and also depending on microclimate. The study deals with the species composition, ecology, distribution and syntaxonomy of the communities. Among them, Euphrasio-Plantaginetum is a mesophilous pasture, common in and around the Pyrenees and related to centroeuropean biogeographical region. It inhabits the north-facing, low slopes, with deep soil. Plantagini-Aphyllanthetum is a bit more Mediterranean community, and is very common on intermediate slopes, also with well developed soils. The most diversified community is a more Mediterranean one, Brachypodio-Aphyllanthetum. It contains three subassociations: a) typicum, a Brachypodium phoenicoides grassland very common on south-facing aspects with deep soil; b) stipetosum, nova, which settles on warm, rocky, dry slopes, and is differentiated by the dominance of Stipa iberica; and c) sideritido-brachypodietosum retusi, dominated by Brachypodim retusum, and extended on steep, eroded, south-facing slopes. From the first to the last of all these communities, hemicryptophytes decrease while chamaephytes and therophytes become more abundant and dominant. Another community, Thymo-Globularietum cordifoliae, is a chamaephytic, permanent one, and settles on stony surfaces of the slopes or at the summit of the hills.