Riparian forests: a temporal analysis of their ecological status in urban river systems of the Andean Patagonia, Chubut, Argentina

Abstract

Streams and rivers are ecosystems strongly impacted by changes associated with urbanization, which cause ecological degradation of their banks and the deterioration in water quality. Assessing the ecological state of riverbanks and proposing measures to mitigate their degradation are priorities. This study aimed to evaluate the quality of riparian forests in three urban river systems with different population densities and to analyze changes over a temporal scale. The pre-urban, urban and post-urban sections of the rivers were analyzed. The Quality Index of Riparian Forests for Andean Patagonian rivers (QBRp) was used. This index assesses four riverbank attributes: vegetation cover, vegetation structure, cover quality and degree of naturalness of the river channel. In all cases, preurban sections showed the highest QBRp values, indicating good quality riverbanks. The application of the index at different times allowed the identification of temporal changes in the ecological quality of the riverbanks, both in general and regarding individual components. A general trend of stability or improvement in the ecological quality of the riverbanks was recorded in peri-urban sections; meanwhile, urban and one post-urban sections displayed a decrease in quality, a condition related to modifications in the structure and quality of vegetation and the loss of the river channel naturalness. Urban areas with medium-high population density were associated with poor quality riverbanks. The QBRp index enables the assessment of how urbanization affects diverseaspects of riparian quality over time and supports the development of concrete actions for the effective management of these riparian environments.