A method for assessing the ecological quality of riparian forests in subtropical Andean streams: QBRy index

A modified QBR index adapted to examine the riparian quality of streams included in the Yungas biome is presented. The index, named QBRy, included modifications of the original index in three of the four sections in order to be useful for the studied region. The assessment of QBRy included trials in three subtropical sub-basins of Tucumán province (Argentina). Thirty-seven sampling sites were assessed. The composition of riparian forest varied in relation to a geographical pattern, and this was related with the climatic differences existing within the same ecoregion. The quality of riparian vegetation was poor near population centers and in sites impacted by livestock, while good quality conditions were related with areas adjacent to a protected region and in physiographical inaccessible zones. The introduction of exotic species represents a real problem to the integrity of Yungas riparian vegetation. The protection of the few well preserved zones and the necessity of restoration of highly altered ones becomes an essential priority for biodiversity conservation.