A methodological approach for monitoring of riparian forests in protected areas on Danube islands.
In the last decades, invasive plant species have rapidly settled on the islands in the Danube River. This process is closely related to anthropogenic activities, such as felling and cultivation of soil for afforestation of Euro-American poplar trees throughout the Danube River basin. In this regard, it is important to: (i) determine the speed and scope of invasive vegetation establishment and (ii) determine more precisely the ongoing successional dynamics. Monitoring in permanent plots is needed to track the changes and assist in decision-making processes for the management of protected areas on the islands in the Danube River. The aim of the study is to describe and justify an innovative approach to analyse the dynamic of the invasion species occurrence and development as related to site conditions and management across the islands in the Danube River. The following methodological approach was considered: (1) selection of islands with well-preserved and sufficient in area covered by natural forest vegetation; (2) differentiation of strata by forest type, age and canopy cover; (3) setting up permanent sample plots for long-term monitoring in natural riparian forests.