The hydrogeomorphological effects of beaver dam-building activity
In order to review the hydrogeomorphological effects of beaver dam-building activity, this article places a context on the likely distribution and magnitude of beaver activity by considering the spatial and temporal variability of distributions
of beaver and the habitat characteristics which might favour the establishment of substantial beaver populations. A description is then given of the nature and potential dimensions of instream structures built by beaver and the environmental conditions under
Natural and historical variability in fluvial processes, beaver activity, and climate in the Greater Yellowstone Ecosystem
Beaver ; C 14 dating ; Climatic variability ; Ecosystem ; Holocene ; Human impact ; Montana ; Palaeo-ecology ; Palaeo-environment ; Stream ; United States of America
The AA. used beaver-pond deposits as proxy records of beaver occupation to compare historical beaver activity to that throughout the Holocene. Carbon-14 (14C) ages on beaver-pond deposits from Grand Teton National Park indicate that beaver activity
was episodic. These gaps in the sequence of dated deposits coincide with episodes of severe, prolonged drought, e.g. within the Medieval Climatic Anomaly. In contrast, many beaver-pond deposits date correspond to the colder, effectively wetter Little Ice Age
. Abundant historical beaver activity in the early 1900s is coincident with a climate cooler and wetter than present. Reduced beaver populations after the 1920s, particularly in the northern Yellowstone winter range, are in part a response to elk overbrowsing
of willow and aspen that later stemmed from wolf extirpation. Beaver populations on small streams were also impacted by low streamflows during severe droughts in the 1930s and late 1980s to present. Thus, both abundant beaver in the 1920s and reduced beaver
The beaver meadow complex revisited – the role of beavers in post-glacial floodplain development
Beaver ; C 14 dating ; Channel geometry ; Colorado ; Ecosystem ; Floodplain ; Geo-ecology ; Geochronology ; Holocene ; Postglacial ; Quaternary ; Rocky Mountains ; Sedimentation ; United States of America
The AA. focus on 2 low-gradient broad valleys, Beaver Meadows and Moraine Park, in Rocky Mountain National Park (Colorado, USA). Both valleys experienced a dramatic decrease in beaver population in the past century. They examine the geomorphic
significance of beaver-pond sediment by determining the rates and types of sedimentation since the middle Holocene and the role of beaver in driving floodplain evolution through increased channel complexity and fine sediment deposition. Channel complexity
increases directly downstream of beaver dams. The increased complexity forms a positive feedback for beaver-induced sedimentation; the multi-thread channel increases potential channel length for further damming, which increases the potential area occupied
by beaver ponds and the volume of fine sediment trapped. Channel complexity decreased significantly as surveyed beaver population decreased. These findings underscore the importance of understanding the historical range of variability of valley bottom
Patterns of landscape use by beaver on the lower Roanoke River floodplain, North Carolina
Satellite imagery was used to map dramatic increases in area impounded by beaver activity between 1984 and 1993 in the Roanoke River floodplain of eastern North Carolina. The results were analyzed within a geographic information system to examine
patterns of landscape use by, and landscapes changes resulting from, beaver activity. Localized beaver activity may result in decreased forest regeneration owing to the extended flooding caused by beaver impoundments and the growth of shrub-herbaceous
beaver meadows along the saturated fringes of beaver impoundments.
The geomorphic influences of beaver dams and failures of beaver dams
The AA. examine the zoogeomorphological influences of the construction of beaver dams. They restrict their discussion to North America and the species C. canadensis. Removal of beavers by overtrapping in the 16th-19th centuries severely reduced
their number and the number of ponds and dams. Partial recovery of beaver populations in the 20 th century has allowed reoccupation of the entirety of the pre-contact range, but at densities of only one-tenth the numbers. During the past 20 years, numerous
Characteristics of beaver ponds on deltas in a mountain environment
Beaver ; Dam ; Delta ; Glacial lake ; Montana ; Mountain ; Rocky Mountains ; United States of America ; Zoogeomorphology
This paper describes floodplain beaver ponds on low-gradient deltas in glacial finger lakes in Glacier National Park, Montana. These ponds are distinctly larger, probably fed by hyporheic flow, and stable and long-lived. Ponds examined were
, with one exception, 44 years old. Glacial discharge is present in each valley where beaver ponds occupy low-gradient deltas, and this discharge likely sustains pond water level over the course of the summer. As glaciers recede and disappear, deltaic beaver
Geomorphic changes upstream of beaver dams in Bridge Creek, an incised stream channel in the interior Columbia River basin, eastern Oregon
The AA. examined the extent of localized aggradation behind beaver dams on an incised stream in the interior Columbia River basin to assess the potential for using beaver, Castor canadensis, dams to restore such channels, and the effect
of the aggradation on riparian habitat. They compared the area surrounding reaches upstream of beaver dams that were within 0.5 m elevation of the stream channel with adjacent reaches where no dams existed. The results suggest that restoration strategies
that encourage the recolonization of streams by beaver can rapidly expand riparian habitat along incised streams.
Beavers as agents of biogeomorphic change : a review and suggestions for teaching exercises
The beaver (Castor canadensis) has been responsible for widespread landscape transformation in North America. The effects of these animals in cutting vegetation and rearranging the hydrography become a plausible field trip objective. - (DWG)
The impact of beaver dams on the morphology of a river in the eastern United States with implications for river restoration
Bank erosion ; Beaver ; Biogeography ; Channel geometry ; Dam ; Ecological restoration ; Stream ; United States of America ; Virginia
A channel on the Atlantic Coastal Plain was analyzed before, during, and after beaver dams were constructed to evaluate the lasting impact of the beaver on channel morphology. The channel was actively evolving in a former reservoir area upstream
of a dam break. Colonization by the beaver focused the flow into the channel, allowed for deposition along the channel banks, and reduced the channel width such that when the beaver dams were destroyed in a flood, there was no channel migration and net
sediment storage in the reach had increased. The study indicated that where channels are unstable laterally and bank erosion is a concern, the introduction of beavers can be a useful restoration tool. However, because of the likelihood of increased channel
bed erosion in a reach with multiple beaver dams, they may not be the best solution where aggradation of an incised channel bed is the desired result.
Hydrogeomorphic effects of beaver dams in Glacier National Park, Montana
This study provides additional data on sedimentation and stream flow in order to better understand the efficacy of beaver dams to trap sediment and alter the flow regime of streams, respectively. Data are collected on sedimentation depth (thickness
) and volume, as well as stream velocity and discharge above and below beaver dams in eastern Glacier National Park (GNP), Montana. In addition, measurements of dam and pond morphology are examined in relation to sedimentation and flow alteration patterns.
The aims of this study were to quantify geomorphic alterations caused by beavers inhabiting ditches in an anthropogenically transformed landscape of the Middle Lithuanian Lowland, in the Nevėžis basin, and to predict the shifts in the magnitude
of alterations as the beaver population fluctuates. Two methods, aerial photographs and global positioning system, were used to map all ditches in selected sites and all available beaver-created visible structures therein. On the drainage ditch network scale
, the quantitative geomorphic effect of beaver activities resulting from construction of dams, burrowing into the ditch slopes, and digging of lateral canals, as well as the development of scours was estimated. On the catchment scale of the whole hydrographical
network, an increase in either the length of dammed drainage ditches, or the density of beaver-sites, resulted in the potential growth of the total geomorphic effect.
The geomorphic influences of burrowing beavers on streambanks, Bolin Creek, North Carolina
Bank erosion ; Beaver ; Biogenic process ; Biogeography ; Burrowing animal ; Erosion budget ; Geomorphometry ; Habitat ; Mass movement ; North Carolina ; Stream ; United States of America
Sedimentation rates and patterns in beaver ponds in a mountain environment
The AA. examine the rates and volume of sedimentation occuring in recently constructed beaver ponds of known age in the northern Rocky Mountains of Glacier National Park, Montana, USA. They describe how these factors vary by pond-site type
Beaver-pond sequence morphology and sedimentation in northwestern Montana
Two adjacent beaver-pond sequences of seven ponds each were examined along the eastern boundary of Glacier National Park, Montana, to determine spatial patterns and amounts of sedimentation, both within individual ponds and along pond sequences
A survey of Beaver sites based on winter food caches was conducted in Gatineau Park during the fall of 1973. A total of 472Beaver sites were surveyed| 125of those sites were actually occupied while 198others had been inhabited by Beavers in the few
years preceeding 1973. The 127colonies counted during the survey showed a density of 0.36colony per km and approximately 650individuals. Each site was also classified according to its quality: 90of the 271 very high quality sites were occupied by Beavers
during the fall of 1973| the remaining 181sites were still available for settling future colonies. Beavers were particularly abundant in the area of the Eardley Plateau which offers the best possibilities for settling new colonies or resettling existing
Interaction of Laurentide and Cordilleran ice in the Beaver Mines area, southwestern Alberta
La cartographie des dépôts superficiels dans la région de Beaver Mines, la répartition des blocs erratiques du bouclier canadien, la stratigraphie des sédiments du Quaternaire, et leur corrélation avec la géochronologie du sud-ouest de l'Alberta
Du ski de fond avec Leonhard Euler à Beaver Creek (Colorado, Etats-Unis)
mathématiques appliquées à propos de la station de Beaver Creek (27 sommets, 44 arcs et 18 faces). Parcours topologiquement correct. Deux essais pour trouver un circuit esthétique. Solution permettant de multiples circuits esthétiques.