KNOWLEDGE BASE

By damming, beavers impact the habitats available in an Alaskan river. This influenced other aspects of the ecosystem, including the amount and distribution of juvenile salmon. Such young salmon could still access most of the small streams and young ponds, but were blocked from accessing some of the older ponds. Times of flood helped the salmon to get around the dams.

Aspen trees have struggled to grow in part of Yellowstone, USA, due to elk grazing and lack of disturbance. Beaver reintroduction in 1991 helped by 'disturbing' the ecosystem by removing mature trees and stimulating aspen regrowth. However, elk browsing held back the recovery. Since wolves return, the lower number of elk has allowed aspen communities to regenerate. Please note, this resource is not open-access.

This study seeks to understand how the willow tree food web works in Yellowstone, USA. They find that the fate of the willow doesn't only rely on the population density of elk who graze on them, but also relates to beaver populations, landscape features, the age of willow plants, and the climate.

This study examines fish populations in beaver ponds found in dry areas. It found that these ponds, compared to stretches of river without beaver activity, had more non-native fish species. Native fish were the minority in all stretches, but were still less common in beaver ponds. This suggests that beaver ponds could be sources of non-native fish which might harm native fish populations.

This paper explored the genetics of ancient and modern beavers. By the late 19th century, human hunting had wiped out Eurasian beavers across much of their original range; this study found that this hunting has led to a decline in beavers' genetic diversity. There are three distinct genetic groups of beavers now existing and, even though populations are recovering, the genetic diversity of beavers is not as broad as it was before the low-point of beaver population. Please note, this resource is not open-access.