Evolution of the Riparian Forest Corridor in a Large Mediterranean River System

Abstract The central reach of the Ebro River, one of the largest rivers in the Mediterranean region, is characterised by a meandering channel that develops into a wide floodplain. In the present study, we analysed the evolution of the landscape structure and function of riparian forests in the Middle Ebro River (~ 250 km long) in 1927, 1957 and 2003 in order to evaluate the forest dynamics in this river corridor. In the 20th century, the Ebro floodplain suffered a dramatic hydromorphological transformation as a result of urban and agricultural encroachment on the river territory and modifications to its flow regime. This study assesses the overall morphology and connectivity of riparian forest patches in the study area using a wide range of parameters. The influence of the hydromorphological changes of the river system on the general status of the riparian forests was then determined. The analysis revealed a profound trend toward the homogenisation and isolation of forest patches. Habitat loss and landscape fragmentation were the dominant processes in the study area and were especially intense in some river segments, where large forest patches and high connectivity once prevailed. Landscape modification and overall homogenisation intensified during the second half of the last century. The results for the entire set of parameters can be used to identify guidelines for the effective attenuation of these trends and for the progressive rehabilitation of the dynamics of the Middle Ebro landscape.