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The riparian vegetation of the Mediterranean rivers and its quality: The use of the riparian vegetation quality index

Abstract:

An index of riparian quality (QBR) was applied to 157 sampling sites in streams of twelve Mediterranean basins. Our results show that approximately 34% of the total number of sampling sites had riparian habitat in natural conditions and of good quality (QBR >75), while 45% had experienced strong alteration of natural conditions, and quality of the riparian was poor (QBR < 50). The good quality QBR sites were found in sampling areas located in upstream areas of calcareous basins and in karst zones. The stream type called "ramblas" and the "temporary streams" included many sampling sites with riparian of very bad quality. For these types of stream, no sampling site with riparian habitat in "natural condition" was found. Riparian high quality sites were scarcer in sites located to the south of the Iberian Peninsula. This may be explained by the increasing aridity gradient towards the South. In the catchments located in the south of the Iberian Peninsula, the riparian vegetation typical of the areas was usually absent. Moreover, we have identified a strong degradation of the riparian from the head to the mouth of all streams studied. Therefore, both aridity and human induced degradation explain the present quality status of riparian vegetation in the catchments studied. Finally, we discuss the scope of use and limitations of the QBR index in streams experiencing extreme hydrological and environmental stress. © Asociación Española de Limnología.