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|Título :||Monitoring tools to assess vegetation successional regression and predict catastrophic shifts and desertification in Mediterranean rangeland ecosystems|
|Autor :||Alados, Concepción L., El Aich, Ahmed, Papanastasis, Vasilios P., Ozbek, Huseyin, Freitas, Helena|
|Fecha de publicación :||2006|
|Citación :||Desertification in the Mediterranean Region. A Security Issue: 431-449 (2006)|
|Citación :||Nato Security Through Science Series|
|Resumen:||The relationship between grazing intensity and ecosystem performance is complex and can depend on the prevailing ecological conditions. Previous studies have revealed that,in traditional grazing ecosystems, grazing can reduce ecosystem diversity in poor soils, butincrease diversity and productivity in rich ecosystems subject to moderate grazing pressure. We are interested in detecting long-term structural changes or drift in an ecosystem before itis too late to prevent irreversible degradation. We analyzed vegetation spatial patterns andcomplexities of four Mediterranean communities: Tihmadit Region (Middle Atlas, Morocco),Camiyayla (Namrum) Region (Taurus Mountain, Turkey), Sykia Region (south of theSithonia Peninsula, Greece), and Cabo de Gata Nijar Natural Park, Spain. Grazingdisturbance was most intense near shelter and water points, which lead to gradients in soilsurface disruption, compaction, and changes in the composition and cover of perennialvegetation. Dense matorral was more resistant to species loss than were moderately denseand scattered matorral, and grassland. Information fractal dimension decreased as we movedfrom a dense matorral to a discontinuous matorral, and increased as we moved to a morescattered matorral and to a grassland, which resulted in two opposing processes (interactiondeclining with ecosystem development, and immigration increasing with degradation) in acommon pattern, i.e., small patches homogeneously distributed in the landscape. Characteristic species of the natural vegetation declined in frequency and organization inresponse to higher grazing disturbance, while species of disturbed areas exhibited theopposite trend. Overall, the spatial organization of the characteristic plants of each community decreased with increasing vegetation degradation, with the intensity of the trend being related to the species' sensitivity to grazing. Developmental instability analyses of key species were used to determine the sensitivity of dominant key species to grazing pressure. Palatable species, which are better adapted to being eaten, such as Periploca laevigata, Phillyrea latifolia and Genista pseudopilosa, were able to resist moderate grazing pressure, while species of disturbed, grazed sites did not change developmental instability in response to increasing grazing pressure, such as Thymus hyemalis, Teucrium lusitanicum and Cistus monspeliensis. The usefulness of these monitoring tools in preventing land degradation is discussed.|
|Descripción :||20 páginas, 6 figuras, 1 tabla.-- En el capítulo 5: "Soil and Vegetation Monitoring".-- Editores: William G. Kepner, Jose L. Rubio, David A. Mouat and Fausto Pedrazzini.|
|Versión del editor:||http://dx.doi.org/10.1007/1-4020-3760-0_20|
|Appears in Collections:||(IPE) Libros y partes de libros|
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