Consequences of the activities of Eurasian beaver on local plants and vegetation cover – an overview. (original) (raw)
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BEAVER ACTIVITY AND ENVIRONMENTAL AND HYDROLOGICAL CHANGES IN FOREST AREAS
Acta Sci. Pol. Silv. Colendar. Ratio Ind. Lignar., 2020
The purpose of the study was to present researchers' knowledge of the impact of beavers on hydrological conditions in forests. A historical outline, reasons for the drastic decline in the beaver population in Poland and Europe, as well as positive examples of the restoration of the Eurasian beaver population are presented. The paper provides information given by authors from countries with beaver populations on the impact of these rodents on the natural environment, the way in which it transformed it, as well as threats, losses and benefits of beaver activity brought to man.
Roczniki Naukowe Polskiego Towarzystwa Zootechnicznego
Research on the impact of the European beaver population on the species composition of forest stands was conducted in Wigry National Park, situated in north-eastern Poland. The study was conducted in forest stands on a dystrophic lake of the ‘suchar’ type,� i.e. a dystrophic lake with high acidity and low species diversity of vegetation on its shores, on the banks of a river and a drainage ditch, and in a field environment. A ThermoPro TP8 thermal imaging camera with an uncooled microbolometer matrix of 384x288 pixels was used to confirm that the designated observation areas were inhabited by beavers. In each research area five transects four metres in width were established, where measurements were taken of five classes of trunk damage and two classes of trunk diameter. We examined the seasonal preferences of beavers in gnawing particular species of woody plants. An analysis was performed for each environment. The results indicate that after an average 15-year presence of beavers i...
Medium vs. short-term effects of herbivory by Eurasian beaver on aquatic vegetation
Aquatic Botany, 2014
It is important to disentangle the effects of physical ecosystem modifications from plant-herbivore interactions to understand how keystone species, such as beavers, influence aquatic ecosystems, especially when populations are reintroduced or non-native. Through dam building beavers have the potential to influence macrophytes indirectly by altering the hydrological regime, but macrophytes also comprise a major component of beaver diet. In water bodies uninfluenced by dams, direct grazing will therefore be the primary basis of beaver-induced effects on macrophytes. Temporal change in macrophyte height, abundance and composition from three habitats within a pond system in Scotland were measured over a nine year period following beaver introduction. From 2003 to 2012, persistent, selective grazing by beaver led to three-fold increases in macrophyte richness and significant turnover in composition, reflecting overall reductions in abundance of the preferred dominant species (e.g. Iris pseudacorus). Within-season herbivory effects were quantified in 2011-2012 using exclosures and by conducting cafeteria-style choice experiments. Significant volumes of macrophyte biomass (mostly rhizomes of Menyanthes trifoliata) were removed at constant rates throughout the growing season. Feeding was highly selective whilst effects on diversity were negligible in the short term. In the medium term, selective foraging by beavers significantly increased alpha and beta diversity of macrophytes. Macrophytes in temperate and boreal regions are potentially widely influenced by beaver grazing, although the positive effects we observed are not necessarily universal and are unlikely to persist within individual sites indefinitely.
Characteristics of trees and shrubs felled by a Eurasian beaver
The Eurasian beaver Castor fiber is on the verge of a return to Luxembourg. Between 2000 and 2002, beaver activity was recorded on the river Clerve in the North of the country. For 234 trees and shrubs felled during this time, species respectively genus as well as diameter and distance from the water were recorded. 78% of the felled trees and shrubs that could be found were willows Salix spp. European alder Alnus glutinosa was hardly taken, and Norway spruce Picea abies was not felled at all. 80% of cut trees and shrubs had a diameter of less than 10 cm, and 97% were felled at a distance of less than 10 m from the water. These results are consistent with findings from other countries and highlight the importance of riparian vegetation bands along water courses for beaver conservation and management.
Mammal Review, 2005
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 communities, 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 managers determine the likely outcome of beaver activity.
Beaver: Nature's ecosystem engineers
WIREs Water, 2020
Beavers have the ability to modify ecosystems profoundly to meet their ecological needs, with significant associated hydrological, geomorphological, ecological, and societal impacts. To bring together understanding of the role that beavers may play in the management of water resources, freshwater, and terrestrial ecosystems, this article reviews the state‐of‐the‐art scientific understanding of the beaver as the quintessential ecosystem engineer. This review has a European focus but examines key research considering both Castor fiber—the Eurasian beaver and Castor canadensis—its North American counterpart. In recent decades species reintroductions across Europe, concurrent with natural expansion of refugia populations has led to the return of C. fiber to much of its European range with recent reviews estimating that the C. fiber population in Europe numbers over 1.5 million individuals. As such, there is an increasing need for understanding of the impacts of beaver in intensively pop...
Biological Invasions
Habitat requirements largely determine the distribution and abundance of a species. An invasive species can therefore threaten the survival of a native species, if the two species are similar in niche use. In Finland, the distribution of the invasive North American beaver (Castor canadensis) is approaching the range of the native Eurasian beaver (Castor fiber) possibly creating a threat for the latter. We compared the habitat use of the native and invasive beaver species in Finland in the main distribution of the species and within a smaller area where the species live in sympatry. We compared the used habitats (volume of birch and other deciduous trees and distance to agricultural and urban areas) at beaver lodges and at random locations in the available riparian habitat with (conditional) logistic regression models. Results indicated that the native beaver lodges were located closer to agriculture than those of the invasive beaver. The volume of birch was also slightly greater near the lodges of the native beaver than those of the invasive beaver. However, habitat use of both of the species seemed quite flexible, because the habitat near lodges did not differ much from the available habitat. We conclude that the probability that the North American beaver will invade the distribution area of the Eurasian beaver in Finland depends, at least partly, on the ability of the former to live in proximity to agricultural areas. However, methods other than those related to managing habitat quality may be the best approach to controlling the invasive species.
Beaver in the drainage basin: an ecosystem engineer restores wetlands in boreal landscape
Dissertationes Forestales, 2016
Wetland and deadwood loss have had a profound effect on boreal aquatic and terrestrial ecosystems and their biodiversity. Deadwood-dependent species are one of the most endangered organism groups in the world, while amphibians on the other hand excellently represent the ecological state of wetlands. The boreal region contains a large proportion of the world's wetlands, which have undergone two major alterations during the last 500 years: first the extirpation of beavers and secondly draining during the 20th century. Beavers are well-known ecosystem engineers of the Northern Hemisphere. They modify their surroundings by damming water systems. Damming raises flood waters into the surrounding riparian forest and changes environmental conditions both on land and in water. Ecosystem processes are altered when beavers turn a lotic water system into a lentic one, but the alteration is also evident when beavers modify initially lentic water systems. Organic matter and nutrients are transferred into a wetland from beaver-felled trees and vegetation killed by flooding. The amount of dissolved organic carbon increases during the first three impoundment years, which enhances the growth of aquatic vegetation and the abundance of phyto-and zooplankton, thereby also increasing invertebrate abundances. Luxuriant vegetation and ample plankton and invertebrate populations facilitate frogs, which become abundant in beaver wetlands. The moor frog in particular favours beaver-created wetlands. Flooding and beavers kill trees, producing high amounts of deadwood. The riparian forests of beaver wetlands include much higher deadwood levels than wetlands without beavers. Increased deadwood creates substrate resources for deadwood-dependent species. Snags are a typical deadwood type in beaver wetlands. Calicioids are deadwood-dependent species particularly specialised in inhabiting standing deadwood. The comeback of beavers has aided the restoration of wetlands and deadwood. Beaver wetlands can be seen as carbon and biodiversity hot spots that increase the heterogeneity and hydraulic connectivity of the boreal landscape.
Beaver (Castor canadensis) Impacts on Herbaceous and Woody Vegetation in Southeastern Georgia
The American Midland Naturalist, 2009
North American beavers are considered ecosystem engineers. Their activities can quickly and drastically alter habitat properties and perhaps permit highly aggressive colonizing plants, notably non-native species, to invade and potentially dominate. This study examined if beavers in southeastern Georgia have an effect on the terrestrial plant community. Sampling areas included beaver modified (N=9) and nearby but relatively non-impacted riparian habitat (N=9) in a matched pairs design. Vegetation surveys were performed in spring and summer. Species richness was calculated for herbs, vines, woody seedlings, and woody vegetation. Richness of herbaceous vegetation was higher at distances closer to shore while richness of large woody vegetation increased with distance from shore. Woody vegetation also was more abundant in beaver sites. Composition was not different between the two site types. The presence of exotic species was rare and did not differ by site type. This study provides evidence that beavers may play an important role in determining the vegetative structure of their community.
Forest damage caused by the Canadian beaver (Castor canadensis) in South Savo, Finland
Silva Fennica, 1999
Härkönen Forest Damage Caused by the Canadian Beaver (Castor canadensis) in South Savo, Finland 247 Forest damage caused by the Canadian beaver (Castor canadensis) in South Savo, Finland Sauli Härkönen Härkönen, S. 1999. Forest damage caused by the Canadian beaver (Castor canadensis) in South Savo, Finland. Silva Fennica 33(4): 247-259.