Climate variability and human disturbances as drivers of vegetation health in the riparian zone of the Danube
Abstract
Forests along rivers are among the most valuable ecosystems, buffering climate extremes and sustaining biodiversity and ecosystem services at the land–water interface. However, many of these riparian forests have a long history of human intervention, leaving many of them in a degraded state. Restoration projects aim to slow down or reverse these negative human impacts, while drought and rising temperatures add additional pressure.
Yet long-term monitoring and robust evaluation of their success is rare. Here, we focus on the Slovak Danube, where decades of flow regulation, plantation-based forestry, and artificial channelization have degraded riparian forests. Analyzing four decades of satellite-based vegetation health index (VHI), an integrated measure of canopy photosynthetic performance and thermal stress, revealed that riparian vegetation was generally in good physiological condition, with some restored reaches showing trends of improvement. Specifically, we measured the causal effect of hydrological reconnection on forest health using a marginal structural model within a potential outcome framework, estimating the average treatment effect on the treated across three restored reaches. A significant, yet modest ≈7.7% recovery (+0.05 VHI units) relative to the pre-restoration baseline emerged six to ten years post-intervention. We interpret this as evidence that decades of hydrological disconnection have reduced riparian forest resilience, necessitating sustained, long-term restoration actions to reverse the legacy of human disturbances. Our research demonstrates how satellite-based monitoring can guide such restoration strategies by measuring the effects of hydrological reconnection of floodplain forests on vegetation health.
Hamid Afzali
Visiting Scientist Alumni
Tobias Kuemmerle
Professor & Head of the Conservation Biogeography Lab
