Ecosystem engineering at the regional scale—Beaver impact on floodplain pondscapes

Abstract

Currently, global climate change has led to alterations in river discharge. In Eastern and Southern Europe, decreasing spring flood levels are observed, leading to drying and overgrowth of floodplain water bodies, especially in semiarid regions. Under such conditions, the scale of influence of the ecosystem engineer, the Eurasian beaver, which is often considered one of the tools for wetland restoration, is of interest. The aim of this study was to analyze beaver digging activity on a regional scale by estimating beaver abundance and occurrence patterns in floodplain pondscapes of the upper Khoper River and by quantifying changes in the morphometric parameters of water bodies due to the impact of this species. During the field survey and remote GIS analysis, 80 water bodies were surveyed. The results of the field study revealed that 67 % of the water bodies were inhabited by beavers, 21 % of which were inhabited by large families. Only 5.6 % of the water bodies had no traces of beaver activity. Approximately 30 % of all the water bodies under study were significantly altered, and 10–13 % were almost completely excavated by beavers. The remote sensing analyses revealed that beavers digging increased the area of the water bodies by an average of 40 %, the perimeter of the water bodies by an average of 60 %, and the shoreline development (complexity) by 60 %. In total, beaver-created structures occupied 0.05 km² in the floodplain of the upper reaches of the river, and their total length reached 30.5 km. The main factor influencing beaver digging activity was the drying of water bodies; the values of morphometric parameters altered or created by beavers increased significantly at large differences in the maximum and minimum water levels. Our results highlight the importance of ecosystem engineering activities at the regional scale in the face of climate change and provide insight into the possibility of considering beaver digging activities as an inspiration for the development of nature-based strategies.