El paisatge vegetal dels Monegros
The vegetation of the plains in the central depression of the Ebro valley is conditioned by some remarkable factors, besides scarce rainfall(300-350 mm yearl). First, the frequent thermal inversions modify the local climate in the sense of increasing its montane character, a fact reflected in the pr...
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| Tipo de documento: | artigo |
| Data de publicação: | 1986 |
| País: | España |
| Recursos: | Universitat Autònoma de Barcelona |
| Repositório: | Dipòsit Digital de Documents de la UAB |
| Idioma: | catalão |
| OAI Identifier: | oai:ddd.uab.cat:38925 |
| Acesso em linha: | https://ddd.uab.cat/record/38925 |
| Access Level: | Acceso aberto |
| Palavra-chave: | Catena Gypseous soils Juniperus thurifera Landscape ecology Mediterranean ecosystems Pinus halepensis Thermal inversion Semi-arid zones Vegetation-climate relationships |
| Resumo: | The vegetation of the plains in the central depression of the Ebro valley is conditioned by some remarkable factors, besides scarce rainfall(300-350 mm yearl). First, the frequent thermal inversions modify the local climate in the sense of increasing its montane character, a fact reflected in the presence of some species, specially Juniperus thurifera. When passing from the endorheic central plains to the peripheral areas of torrential relief connecting the plains to the Ebro river, thermal inversions become less important because of increased air turbulence. Second, relief features impose catenary systems in response to opposed gradients of soil water availability and soil salinity. Subdesertic grey soils are well represented and this does not support the hypothetical existence of a forested climax in the recent past. The landscape of the central plains, today profoundly transformed by man, is interpreted, in view of these factors and of floristic, chorological and phytosociological data from the literature as a soil-determined, pluriteselar complex linked to the pattems of relief. The Rharnno-Quercetum cocciferae macchia seems to have always had, at most, a partia1 dominance, and J. thurifera has been able to occupy only favourable parts of the mosaic. Pinus halepensis remains confined to hilltops and, together with most of the macchia species, to the inversion-free peripheral areas. Hence, we accept the hypothesis of a terminal vegetation of macchia with P. halepensis occupying these peripheral areas, while the central plains must have always been partially deforested since the end of the last glaciation and, indeed, most of the time since the late Miocene. The central plain and its characteristic vegetation is presently under regression because of erosion and climatic warming, but some species of steppic afinities have spread due to the anthropic degradation of the xerogamgue. |
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