KNOWLEDGE BASE

Researchers describe how populations of three species (among them the North American beaver) have changed over almost 150 years in a Canadian park. Beaver populations started very low but increased and remained high until the 1970s when there was a sharp decline. This decline is attributed to the maturation of the broader forest ecosystem in the park. The authors say that the beavers' decline may represent a stress on local wolf populations who eat them.

Researchers found that areas with beaver dams created ideal conditions for an invasive plant species (Phalaris arundinacea) in Oregon, USA. This invasive plant outcompeted native plants and led to a reduction of biodiversity. Since there are a lot of beaver wetlands in the area, the researchers warned that this plant presents a threat to local ecosystem health. Please note, this resource is not open-access.

This study tracked 32 young beavers in southern Illinois to understand their movements as they disperse from their home sites. They present a wide variety of results, including: how far the beavers travel, when in the year the beavers left and when they settled, how many left the home site and how many survived the process. They also explore the impact of geography, sex, and age on each these findings; for example, male beavers moved more frequently and for further distances than females, but ended up settling a similar distance away. Please note, this resource is not open-access.

Researchers studied how plants help each other grow in four beaver wetlands in the USA. This is relatively well understood for saltwater wetlands, but less so for freshwater wetlands. The researchers looked at a type of rush plant called Juncus effusus and found that when its stems are upright, it crowds out other plants. However, after the stems collapse, it creates a nice spot for other plants to grow on top, potentially by providing a stable place to grow or by increasing oxygen in the soil with its roots. Please note, this resource is not open-access.

Effective management of riparian areas is important to protecting water quality. This paper summarised how best to create buffer zones with grasses and woody vegetation. The advice covered soil management, plant species management, and animal species management. The text recognised long-term beneficial impacts of beavers, but also warned that beaver browsing can "devastate" efforts to re-establish riparian buffer zones, and so require strict management. Please note, this resource is not open-access.