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

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.

[1]  R. Naiman.  Characteristics of Sediment and Organic Carbon Export from Pristine Boreal Forest Watersheds , 1982 .

[2]  D. J. Neff.  ECOLOGICAL EFFECTS OF BEAVER HABITAT ABANDONMENT IN THE COLORADO ROCKIES1 , 1957 .

[3]  R. Baxter.  Environmental Effects of Dams and Impoundments , 1977 .

[4]  R. Naiman,et al.  Characterization of Particulate Organic Matter Transported by Some Cascade Mountain Streams , 1979 .

[5]  J. Skriver,et al.  Inputs and transformation of allochthonous particulate organic matter in a headwater stream , 1982 .

[6]  J. Aber,et al.  Factors controlling mass loss and nitrogen dynamics of plant litter decaying in northern streams , 1984 .

[7]  J. Downing,et al.  A Manual on Methods for the Assessment of Secondary Productivity in Fresh Waters , 1984 .

[8]  R. Paine,et al.  The Pisaster-Tegula Interaction: Prey Patches, Predator Food Preference, and Intertidal Community Structure , 1969 .

[9]  Gene E. Likens,et al.  Energy Flow in Bear Brook, New Hampshire: An Integrative Approach to Stream Ecosystem Metabolism , 1973 .

[10]  THE HAGUE-THE NETHERLANDS , 2022 .

[11]  M. Aleksiuk.  Scent-Mound Communication, Territoriality, and Population Regulation in Beaver (Castor canadensis Kuhl) , 1968 .

[12]  Jackson R. Webster,et al.  Nutrient recycling and the stability of ecosystems , 1975 .

[13]  J. B. Wallace,et al.  Quantification of Wood Habitat in Subtropical Coastal Plain Streams , 1984 .

[14]  R. Ruedemann,et al.  BEAVER-DAMS AS GEOLOGIC AGENTS. , 1938, Science.

[15]  M. E. Conners,et al.  Particulate Allochthonous Inputs: Relationships with Stream Size in an Undisturbed Watershed , 1984 .

[16]  Cathy M. Tate,et al.  The Effects of Watershed Disturbance on Dissolved Organic Carbon Dynamics of a Stream , 1983 .

[17]  Donald R. Johnson,et al.  Presettlement overharvest of upper Columbia River beaver populations , 1974 .

[18]  R. O'Neill,et al.  Organic carbon spiralling in stream ecosystems , 1982 .

[19]  R. Billington,et al.  The eyes of discovery , 1950 .

[20]  G. B. Kolenosky,et al.  Changes in Summer Foods of Wolves in Central Ontario , 1976 .

[21]  G. Minshall,et al.  INTERBIOME COMPARISON OF STREAM ECOSYSTEM DYNAMICS , 1983 .

[22]  W. Lawrence.  Michigan Beaver Populations as Influenced by Fire and Logging , 1954 .

[23]  A. T. Bergerud,et al.  Population dynamics of Newfoundland beaver , 1977 .

[24]  C. Lorenzen,et al.  DETERMINATION OF CHLOROPHYLL AND PHEO‐PIGMENTS: SPECTROPHOTOMETRIC EQUATIONS1 , 1967 .

[25]  G. Minshall,et al.  The River Continuum Concept , 1980 .

[26]  R. O'Neill,et al.  Principles of energy and material exchange in ecosystems , 1975 .

[27]  James R. Sedell,et al.  Nitrogen Budget for a Small Coniferous Forest Stream , 1984 .

[28]  T. Paine.  Experimental Studies on the Relationship between a Dominant Competitor and Its Principal Predator , 1974 .