Ecosystem Services Provided by Beavers:

• The Hydrogeochemical effects of beaver dam-building activity - by Angela Gurnell: The author synthesizes much of the available literature on both the North American and European beaver to describe beaver family habits and the effects dams and foraging have on the river and riparian ecosystems. (Progress in Physical Geography, 1998)
• The importance of beavers to duck populations in Wyoming - by Mark McKinstry: Beaver activities broadly influence many plants and other animals. They are especially important in the Western US where Riparian and wetland habitats comprise less than 2% of the landscape yet support 80% of wildlife species. (Birdscapes Research, Winter 2002)
• Central place foraging by beavers: A test of foraging predictions and the impact of selective feeding on the growth form of cottonwoods - by Mark McGinley: High rates of branch removal caused cottonwoods to develop a shrubby architecture. The importance of selective branch choice by beavers on patterns of cottonwood reproduction is discussed. (Oecologia, 1985)
• Beaver Influences on the long-term biogeochemical characteristics of boreal forest drainage networks - by Robert Naiman: Beaver ifluence the distribution, standing stocks, and availability of chemical elements by hydrologically induced alteration of biogeochemical pathways and by shifting element storage from forest vegetation to sediments and soils. One such alteration is the increase of plant-available forms of nitrogen in the organic horizons of soil by 295%. (Ecology, 1994)
• Ecological impact of beaver and their ability to modify ecosystems - by Frank Rosell, et al.: Another good overview of beaver ecosystem benefits.  The study concludes that beaver foraging has a considerable impact on the course of ecological succession, species composition and structure of plant communities. (Mammal Review, 2005)
• Dispersal, boundary processes, and trophic-level interactions in streams adjacent to beaver ponds - by Isaac Schlosser: Uses a 10 year study to assess the effect of the spatial proximity of beaver ponds and variation in stream discharge on fish populations. Beaver ponds act as reproductive "sources" for fish, indicate results. (Ecology, 1995)
• Modification of stream ecosystem structure and function by beaver in the Adirondack mountains of New York - by Michael Smith et al: Focuses on the chemical and invertebrate community changes within streams near beaver ponds. Results show that beaver dams modify stream ecosystems longitudinally and temporally and ameliorate stream acidity. (Thesis, Department of Civil and Environmental Engineering, 1989)
• An Ecosystem Engineer, the Beaver, increases species richness at the landscape scale - by Justin Wright
• Leaving it to Beaver - by Sally Duncan: The American attitude towards beaver needs to change from considering them a nuisance and competition for livestock and forestry to seeing them as a cost effective modifier of wetland and riparian areas (Environment, 1984).
  
• Beaver pond biogeochemical effects in the Maryland Coastal Plain - by David Correll: A study shows a decrease in the discharge of water, total-N, total-P, dissolved silicate, TOC, and TSS by beaver ponds (Correll et al. 2000). 
• Water Quality: Phosphorus and Nitrogen export from forested stream catchments in Central Ontario - by P.J. Dillon: In this study designed to predict long-term, average annual algal nutrient export from forested catchments in central Ontario, it was found that beaver ponds and other wetlands were probably major sources of the large amounts of total phosphorus and total organic nitrogen exported from those catchments in which export exceeded deposition rates (Journal of Environmental Quality, 1991).