Beaver dam

About: Beaver dam is a research topic. Over the lifetime, 176 publications have been published within this topic receiving 6781 citations.

Alteration of North American streams by beaver

Abstract: organic matter in the channel, create and maintain wetlands, modify nutrient cycling and decomposition dynamics, modify the structure and dynamics of the riparian zone, influence the character of water and materials transported downstream, and ultimately influence plant and animal community composition and diversity (Naiman and Melillo 1984, Naiman et al. 1986). In addition to their importance at the ecosystem level, these effects have a significant impact on the landscape and must be interpreted over broad spatial and temporal scales as beaver population dynamics shift in response to disturbance, food supply, disease, and predation. Although once more prevalent than they are today, beaver-induced alterations to drainage networks are not localized or unusual. Where beaver

Ecosystem Alteation of Boreal Forest Streams by Beaver (Castor Canadensis)

Abstract: Beaver (Castor canadensis) alter the structure and dynamics of aquatic ecosystems with a minimum of direct energy or nutrient transfer. Through dam building and feeding activities, beaver act as a keystone species to alter hydrology, channel geomorphology, biogeochemical pathways, and community productivity. Here we consider the effects of beaver activity on several major ecosystem components and processes in boreal forest drainage networks in Quebec, Canada. The density of dams on the small streams (≤4th order) we studied average 10.6 dams/km; the streams retain up to 6500 m3 of sediment per dam, and the wetted surface area of the channel is increased up to several hundred—fold. Beaver are also active in large order streams (≥5th order), but their effects are most noticeable along riverbanks and in floodplains. Comparative carbon budgets per unit area for a riffle on 2nd order Beaver Creek and a beaver pond downstream show the pond receives only 42% of the carbon acquired by the riffle annually. However, because the pond has a surface area seven times greater than the riffle, it receives nearly twice as much carbon as the riffle per unit of channel length. Carbon in the pond has an estimated turnover time of °161 yr compared to ° 24yr for the riffle. Beaver ponds are important sites for organic matter processing; the stream metabolism index (SMI), a measure of ecosystem efficiency for the utilization or storage of organic inputs, is 1.63 for the pond compared to 0.30 for the riffle; the turnover length (S) for particulate carbon is 1.2 km for the pond compared to 8.0 km for the riffle. Beaver—induced alterations to the structure and function of streams suggest removal of beaver prior to 1900 AD had substantial effects on the dynamics of lotic ecosystems. Our results suggest that current concepts of the organization and diversity of unaltered stream ecosystems in North America should recognize the keystone role of beaver, as drainage networks with beaver are substantially different in their biogeochemical economies than those without beaver.

Ecological impact of beavers Castor fiber and Castor canadensis and their ability to modify ecosystems

Abstract: The genus Castor comprises two species: the Eurasian beaver Castor fibre , and the North American beaver Castor canadensis . Both species suffered from overexploitation, but have seen a revival since the 1920s due to increased protection and reintroduction programmes. Increases in the populations and distributions of species that are able to modify ecosystems have generated much scientific interest. Here we review the available literature concerning the possible ecological impact of beaver species in the Old and New World. 2. Beavers, being ecosystem engineers, are among the few species besides humans that can significantly change the geomorphology, and consequently the hydrological characteristics and biotic properties of the landscape. In so doing, beavers increase heterogeneity, and habitat and species diversity at the landscape scale. Beaver foraging also has a considerable impact on the course of ecological succession, species composition and structure of plant commu- nities, making them a good example of ecologically dominant species (e.g. keystone species). 3. Nevertheless, the strength of beavers' impact varies from site to site, depending on the geographical location, relief and the impounded habitat type. Consequently, they may not be significant controlling agents of the ecosystem in all parts of their distribution, but have strong interactions only under certain circumstances. We suggest that beavers can create important management opportunities in the Holarctic, and this review will help land man- agers determine the likely outcome of beaver activity.

The hydrogeomorphological e•ects of beaver dam-building activity

Abstract: A characteristic of beaver ecology is their ability to build dams and, thus, to modify the landscape to increase its suitability for their occupation. This ability gives beaver great significance a...

The general ecology of beavers (Castor spp.), as related to their influence on stream ecosystems and riparian habitats, and the subsequent effects on fish – a review

Abstract: The Eurasian and North American beavers aresimilar in their ecological requirements, andrequire water deep enough to cover the entranceto their lodge or burrow. A food cache isoften built next to the lodge or burrow, exceptin some southern areas. On small streams (upto fourth order) dams are frequently built tocreate an impoundment, generally on lowgradient streams, although at high populationdensities dams may be built on steeper gradientstreams. On large rivers or in lakes, simply alodge with its food cache may be built. Thebeaver is a keystone riparian species in thatthe landscape can be considerably altered byits activities and a new ecosystem created. The stream above a dam changes from lotic tolentic conditions. There are hydrological,temperature and chemical changes, depending ontypes of dams and locations. Although theinvertebrates may be fewer per unit area, totalnumber of organisms increases, and diversityincreases as the pond ages. In cool, smallorder streams, the impoundments provide betterhabitat for large trout, possibly creatingangling opportunities. However, at sites wherewater temperatures rise above their optimumpreferenda, salmonids may be replaced by otherspecies, such as cyprinids, catostomids,percids or centrarchids. As the habitat isaltered, interactions amongst co-habiting species may change. For example, brown troutor brook trout (charr) may become dominant overAtlantic salmon. In warm water streams theremay be a shift from faster water dwellers topond dwellers. Larger bodied fish, such ascentrarchids and esocids may displace smallerbodied fish such as cyprinids, providing betterangling. Refugia from high or low water flows,low oxygen or high temperatures, may beprovided in adverse conditions in winter orsummer. However, in some cases dams areobstructions to upstream migration, andsediment may be deposited in former spawningareas. The practicality and benefits ofintroducing or restoring beaver populationswill vary according to location, and should beconsidered in conjunction with a managementplan to control their densities.