1. An Introduction to Ecosystem Ecology Print Version
The term ecosystem was first used in 1935 by A.G. Tansley to describe a biological community and its physical and chemical environment (Tansley 1935; pp. 8-9, Golley 1993). Ecosystems perform numerous functions essential to life, including the recycling of nutrients and energy flow. Nutrients cycle through an ecosystem and energy flows through it via trophic, or feeding relationships.
Initially, ecosystem ecologists concentrated their research on this transfer of nutrients and energy with little attention paid to the various biological components that comprised each trophic level. Meanwhile, population ecologists were focusing on interactions within trophic levels or between two adjacent levels, but were not considering the entire biological community or the physical/chemical environment. A synthesis of these two disciplines began in the 1980's with the concept trophic cascade.
The trophic cascade hypothesis states that nutrient and energy inputs determine the potential productivity of an ecosystem, but interactions between and within the trophic levels are responsible for deviations from that potential. This set into motion a series of experimental studies that examined whether such a cascade existed.
For example Research Connection 3 examines the effects of trophic level interactions on ecosystem structure using a comparison of terrestrial and pelagic ecosystems (in this case, open waters of a lake). In Research Connection 4, the cascading effect of introduced, invasive earthworms on northern forest ecosystems is documented.
However, we begin the study of ecosystem ecology more broadly with an examination of the world's major terrestrial biomes. Biomes classify ecosystems based on their predominant vegetation. Research Connection 1 demonstrates the link between the physical/chemical environment and biological communities by accurately predicting biome distribution based on only two abiotic factors: temperature and precipitation.
Although the concept of biomes is useful on a large scale, applied ecological work often requires an understanding of the distribution of vegetation on a finer scale. For example, Environmental Impact Assessments (EIA's) of development in Alberta's Oil Sands region are based primarily on the distribution of vegetation. If this were done at a Biome level, much of the area would simply be classified as "Boreal Forest" and provide little information to provincial biologists trying to mitigate the negative effects on those wildlife species with more specific habitat requirements.
Thus, it is also important to understand the underlying causes of plant distribution on a small scale. That is exactly what the authors of Research Connection 2 set out to do in their study of small-scale plant distribution in the boreal forest of Prince Albert National Park.
6. RESEARCH LITERATURE CONNECTION Print Version
Bohlen, P.J., S. Scheu, C.M. Hale, M.A. McLean, S. Migge, P.M. Groffman, and D. Parkinson. 2004. Non-native invasive earthworms as agents of change in northern temperate forests. Frontiers in Ecology and the Environment 2(8): 427-435..
Bridge, S.R.J. and E.A. Johnson. 2000. Geomorphic principles of terrain organization and vegetation gradients. Journal of Vegetation Science 11: 57-70.
Clements, F.E. 1936. Nature and structure of the climax. The Journal of Ecology 24: 252-284; Reprinted as Paper 3, pp. 59-97 In Real, L.A. and Brown, J.H. (Ed.) 1991. Foundations of Ecology: Classic Papers with Commentaries. The University of Chicago Press: Chicago, IL.
Gleason, H.A. 1926. The individualistic concept of the plant association. Bulletin of the Torrey Botanical Club 53: 7-26; Reprinted as Paper 4, pp. 98-117 In Real, L.A. and Brown, J.H. (Ed.) 1991. Foundations of Ecology: Classic Papers with Commentaries. The University of Chicago Press: Chicago, IL.
Golley, F.B. 1993. A History of the Ecosystem Concept in Ecology: More than the Sum of the Parts. Yale University Press: New Haven, CT.
Hairston, N. G. Jr. and N. G. Hairston, Sr. 1993. Cause-effect relationships in energy flow, trophic structure, and interspecific interactions. American Naturalist 142 (3): 379-411.
Küchler, A.W. 1964. The potential natural vegetation of the conterminous United States. American Geographical Society Special Publication Number 36.
Neilson, R.P. 1995. A model for predicting continental-scale vegetation distribution and water balance. Ecological Applications 5: 362-385.
Neilson, R.P. et al. 2005. Forecasting regional to global plant migration in response to climate change. BioScience 55(9): 749-759.
Pickett, S.T.A. and White, P.S. (Ed.) 1985. The Ecology of Natural Disturbance and Patch Dynamics. Academic Press, Inc.: Orlando, FL.
Power, M.E. 1990. Effects of fish in river food webs. Science 250: 811-814.
Tansley, A.G. 1935. The use and abuse of vegetational concepts and terms. Ecology 16: 284-307; Reprinted as Paper 15, pp. 318-341 In Real, L.A. and Brown, J.H. (Ed.) 1991. Foundations of Ecology: Classic Papers with Commentaries. The University of Chicago Press: Chicago, IL.
