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Assessing the Efficacy of Beaver Dam Analogues in Willow Restoration
Apr 24, 2023 07:27 ET

Assessing the Efficacy of Beaver Dam Analogues in Willow Restoration


Willow establishment is a necessary objective of stream restoration due to their role in bank stabilization, stream shading, and enhancement of biodiversity across the riparian zone. However, anecdotal observation indicated that establishment on restored streams may be lacking. For example, we observed no natural willow recruitment at a beaver dam analogs (BDAs) restoration project in Lolo National Forest (Montana). BDA’s mimic the pooling effects of natural beaver structures and are intended to help recreate historic conditions that existed before beaver extirpation. When working as intended, ecosystem function is restored, and a major aspect of this is willow presence. Because of these observations, as well as limited information specifically on willow recruitment following restoration, we ask the following questions. First, after BDA restoration, what is the rate of willow recruitment? And, what is the abundance of willows in these restored sites? Finally, to what extent do the environmental factors of water access, soil compaction, and abundance of competitor species impact the recruitment of willow? To answer this, we measured the density of willow and collected environmental data across 6 sites. We found willow density to be lower than expected with densities ranging from 1.6 stems/m2 to less than 0.1 stems/m2. Root sprout presence was almost non-existent, aside from two study sites that had additional restoration treatments. Although the two sites with root sprouts cannot paint a full picture of the correlation between our measurements and density, it is clear that willow regeneration is limited, if not nonexistent, without further interference. These findings contribute insight into the factors influencing willow recruitment and highlight a need to develop practices to improve willow establishment after restoration.

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