Beaver impact on canals of land reclamation in two different landscapes

Abstract

We tested the assumption that beavers can differently impact land reclamation canals (open drains) in two types of landscapes – hilly moraine uplands (uplands) and clayey plains (plains). The two types of landscapes differ in physical peculiarities as well as in the level of agricultural use, which influence beaver impact and capabilities of this ecosystem engineer to renaturalize open drains. Generally, beavers had a greater impact on open drains in uplands. It was expressed in a higher proportion of beaver sites with beaver-made channels and beaver-formed wetlands and in wider beaver impoundments, compared with plains. Beaver sites in land reclamation canals in plains had longer impoundments; however, the mean number of beaver dams per site did not reliably differ between the two landscape types. We found beaver sites being more expressed in outskirt and forest canals than in field canals in both landscapes. The longevity of beaver sites (many of which persist for decades due to interchanging recolonization and temporal abandonment) is among the most important factors determining beaver impact on open drains. The longevity of beaver sites seems to be influenced by relief features, beaver population structure, canal type, and extent of beaver persecution by humans, which differs in two studied landscapes.

Keywords:

• beaver
• Castor fiber
• impact on environment
• canals of land reclamation
• landscape factor