Riparian forests are as rich in biodiversity as equatorial jungles. Home to hundreds of plant and animal species, they are extremely important for the prevention of floods and landslides, and for naturally purifying the water in the river. These forests slow down the destructive speed of water during torrential rain and high water floods. This project has focused on one of several riparian forest habitat types - type 91E0* - Alluvial forests with Alnus glutinosa and Fraxinus excelsior (Alno-Padion, Alnion incanae, Salicion albae) which is one of the most vulnerable and rare habitats. Due to their accessibility the riparian forests have always been subject to long-term adverse human impact which has led to a continuous reduction in their surface area, as well as habitat degradation and other negative changes. Although occurring all over the country, type 91E0* occupies only 0,5% of the area of the Bulgarian forest territories. Reforestation activities were carried out in two Natura 2000 SCIs:Marten – Ryahovo SCI. The Lower Danube is one of the most valuable freshwater ecoregions in the world with unique vegetation and a rich biological diversity. The Danube islands are among the most representative sites in Bulgaria for alluvial forests. The forests were cut in the larger part of Aleko Island in Marten –Ryahovo SCI and 60% of it was afforested with hybrid poplars. The aim of including the site in the Natura 2000 network is to ensure the protection of remaining natural forests and to increase their coverage. The Reka Maritsa SCI is an important bio-corridor in Southern Bulgaria. It is of high ornithological interest, and is especially significant as a non-coastal wintering bird site. It is the biggest wintering site of the Pygmy Cormorant in Southern Bulgaria. Forest areas in the site are very scarce, composed mainly of artificial poplar stands.