Undeveloped Streamsides: Corridors of Life

Reproduced below is Dr. Elizabeth Gutchess'  model of a draft research paper for English 101 students, "Undeveloped Streamsides: Corridors of Life." Dr E collected the arguments for streamside preservation under headings: protection of wildlife corridors, promotion of species diversity, cleansing of pollutants, and human greenspace.

Dr G has added boldface labels in brackets to reveal the essay structure.
Yellow highlighting
is added to show the "identification of the problem."
Gray highlighting is used to show the sources in the "body" or "discussion of the data."
Blue highlighting has been added to show transitional words between the parts.

 Undeveloped Streamsides: Corridors of Life

[BACKGROUND OR STATEMENT OF PROBLEM]    All too often, suburban developers ignore topography and build over creeks and streams that wind through areas undergoing suburban expansion. They resort to storm drains and culverts in order to divert natural waterways and convert watersheds into commercial and residential properties (McHugh). Not only does this practice result in flooded basements and roads. The inevitable elimination of the valuable sides of small streams robs the environment of a rich natural resource. The green borders of natural waterways--from the smallest streams to wide rivers--deserve the very apt metaphor Tim Palmer bestows on America's rivers: "corridors of life."  

[INTRODUCTION] Of course, throughout human history, these were important corridors for human life: for transportation, for instance, and milling, and irrigation for farms. And, granted, there still are serious reasons to develop the sides of some streams--for the prevention of destructive flooding, for example, and for mosquito (and disease) control, and to meet agricultural needs for access to water.  Furthermore, there are studies which show that stream side corridors can actually harm the larger ecosystems through which they run--by facilitating the advance of aggressive alien species or by transmitting pests and diseases (Perault and Lomolino). [THESIS STATEMENT] But in spite of these hypothetical dangers, and whenever human needs can be met in less intrusive ways than by destroying natural corridors, the preservation of streamsides should be a priority, for at least four reasons, for every community.

[BODY 1: CORRIDORS FOR WILDLIFE]     For one thing, undeveloped streamsides provide important corridors for wildlife. The pre-colonial forest of the eastern United States was made up of large, continuous tracts, unbroken by farm fields or towns. Native American villages and agricultural clearings were not extensive enough to create significant fragmentation of the forest ecosystem. But now, at the beginning of the twenty-first century, this forest is extensively fragmented, broken into discontinuous patches by cities, suburbs, and farms. Since so much of the forest survives in isolated tracts (islands in fact), corridors of woods and vegetation between these large forest patches have become important to the survival of wildlife (Yahner 108). Wooded corridors beside streams provide cover, food, and water for seasonal migrations as well as regular ranging activity (Yahner 110). They also provide protection from the inevitable inbreeding and the gradual extinction that would result from populations living in isolated habitats (Yahner 109), and they increase "the likelihood of recolonization" if a local extermination has already occurred (Henry et al).  

 [BODY 1: CORRIDORS FOR WILDLIFE]  Researchers at the University of Tennessee, in fact, have recorded how corridors can help large mammals survive in a landscape that is now fragmented. These wildlife biologists studied the movements of the Louisiana black bear between forest patches surrounded and isolated by farm fields (of soybeans, corn, and cotton) but also linked by wooded corridors of varying widths. Their findings include the following:

         Sub-adult bears used the corridors to disperse from their natal home range.

         Bears preferred corridors to agricultural fields when outside a forested tract. 

         Corridors allowed bears to move farther away from forested tracts.  

         Bear movement between wooded patches connected by corridors was more frequent than between patches that were not connected.  

         All female bear movement between wooded patches was between patches connected by corridors. (Henry et al.)

 [BODY 2: CORRIDORS FOR BIODIVERSITY] This movement of wildlife is related to another benefit provided by stream side habitat and another good reason for communities to preserve it--the remarkable level of biological diversity supported by this ecosystem. Streamside habitats have levels of bio-diversity which are among the highest in the world (Nilsson, Jansson and Zinko). Even in the Arctic, riparian areas are considered 'hot spots' of species richness in an ecosystem relatively poor in biological diversity  (Gould). There are several reasons for this diversity beside streams. The clearest is simply the gradient. Gradients, steep or gradual, along stream banks, can bring together vastly differing habitats. Cattails, for instance, emergents rooted in the water itself might grow a couple of meters away from a species like cinquefoil, which can tolerate almost desert-like dryness and grow in parched, even destitute soils on the tops of stream banks (Sanders 97). But the diversity of plant life on stream banks is caused not only by the proximity of extreme habitats but also by the variety produced by transitions between them. Obviously, transitions (ecotones) would occur between the hydric soils of a streamís marshy edges and the possibly xeric soils along dry ridges on top of its banks. "Transitions between two different ecosystem (or vegetation) types contain compositional and structural characteristics of both adjacent habitats as well as distinctive microhabitats found only in the intermediate ecotonal area" (Risser).  In short, plants abound beside streams and rivers.

[BODY 2: CORRIDORS FOR BIODIVERSITY]  Even the flooding which occurs intermittently along stream banks promotes diversity. It does this by "slowing competitive exclusion" (Pollock, Naiman, and Hanley):


The presence of water on a land surface dramatically changes the physical and chemical environment of soils. These changes have a tremendous influence on the competitive abilities of plants. The presence of water can create severe physiological stress on plants that are highly competitive under drier conditions, thereby lowering competitive abilities. Conversely, plants adapted to wetter conditions may be at a competitive advantage during a flood, but less competitive when water levels drop. Therefore, a flood can slow down rates of competitive exclusion without directly destroying vegetation (Pollock, Naiman, and Hanley).

Of course, sites that are continuously or severely flooded would promote the competitive exclusion of certain species and consequently be species-poor.

[BODY 2: CORRIDORS FOR BIODIVERSITY]  Streamside diversity can also be increased when streams act as "pathways for the invasion of exotic plants" (Risser). The stream corridor opens a range of habitats for new species to enter an entire region.2 Flooding plays its role here, too, because a flood will create the condition of habitat disturbance "necessary for colonizing" (Risser).

[BODY 3: CORRIDORS FOR CLEANSING POLLUTION] A third good reason to preserve streamsides is that their vegetation provides a cleansing system for undesirable amounts of agricultural run-off into streams.  Run-off from farmland contains fertilizer components--nitrogen and phosphorous--which are detrimental to the balance of life in streams, rivers, and lakes. When streamside plants absorb these nutrients, however, the quality of water downstream is protected (Nieriing 33).   A 1984 study of a streamside forest has shown the capture of nitrogen and phosphorous

as these chemicals moved from agricultural fields across the landscape and into the streams. The strips of riparian forest released relatively small amounts of the annual input of nitrogen and phosphorous. 60-75% of all the nutrients captured occurred in the first approximately 20m of the riparian forest ecotone" (Risser).

[BODY 4: CORRIDORS FOR GREEN SPACE] There's another reason to keep streamsides green: as they wind their way through neighborhoods, yards, towns, and villages, they can answer a basic human need for "small wildernesses" in everyday life. As Wendell Berry says,

I would argue that we do not need just the great public wildernesses, but millions of small private or semiprivate ones.  Every farm should have one; wildernesses can occupy corners of factory grounds and city lots--places where nature is given a free hand, where no human work is done, where people go only as guests, . . . . places we respect and leave alone, not because we understand well what goes on there, but because we do not (689).

[BODY 5: THE EXAMPLE OF DRYDEN LAKE CREEK] There are communities fortunate or wise enough to have preserved their watershed areas--their creeks and wetlands--in a relatively undeveloped state. In 1990, for instance, residents of the Town of Dryden, New York, agreed with members of their countyís Environmental Management Council that "the principal value" of a particular site in their town (Dryden Lake and its outlet, Dryden Lake Creek) lay in "its high quality as a natural area" (Tompkins) and opted for its preservation. Stretches of Dryden Lake Creek, protected from development by the councilís resolution, exhibit many of the features of a biologically diverse, species-rich ecosystem. Streambanks and marshes have acted as corridors for wildlife, as havens for the areaís surviving native plant species, as ribbons of natural history, and as pathways for the natural world to enter the environs of neighborhood and village.

[BODY 5: THE EXAMPLE OF DRYDEN LAKE CREEK] My web site "Dryden Lake Trail: Twelve Field Trips" shows some of this diverse habitat. As early as March, skunk cabbage flowers start rising out of half frozen water (actually melting it), and not long afterwards marsh marigolds are growing in the stream itself, trillium in the higher woods, and blue flag (wild iris) are growing on small silty islands in the fast current, iris colonies that might have been cultivated by local Cayugas, since Native Americans raised wild iris for its aromatic and medicinal roots. Creepy looking hellebore with its long, tongue-like, poisonous leaves, and starry-headed meadow rue, with its crowns of exuberant white stamens, are also there. So are swamp roses and swamp milkweed, new and old cattails, bedstraws, duckweed, and cress. A whole different assortment of plants grow on the tops of the streambanks, alongside the railroad tracks. These are species of dry and impoverished soil, and most of them are also be alien, or introduced, species, opportunistic weeds which traveled along the sides of roads, behind the pioneers who had built them: wild carrots and daisies, the thistles, teasels, and hawkweeds, butter-and-eggs, and St. Johnswort, mallows, burdocks, wild parsnips, and clovers, yarrow and bouncing bet. At the very top, growing out of the cinders themselves,  is a wild rose--cinquefoil--a true weed in its ability to flourish even in soils poisoned by industry. As the summer advances, back down at creekside, another raft of native plants hold their own in their original habitats and special niches: jewelweed, Joe-Pye-weed, boneset, and blue vervain, all growing on the same bank; here and there a dash of the most brilliant red--a cardinal flower; whorled loosestrife, turtlehead and great lobelia growing in the damp shade; bur marigolds with their feet right in the water; and wild cucumber vines and virginís bower draped over everything else. Then, as summer winds down slowly, asters and goldenrod grow all over.

[CONCLUSION] In short, this is a corridor of so much life, that most people would have to agree that streamsides should rarely, if ever, be developed.

Works Cited

Berry, Wendell. "Getting Along With Nature." A Forest of Voices:
      Reading and Writing the Environment
. Ed. Chris Anderson and Lex
      Runciman. Mountain View, California: Mayfield Publishing Company,
      1995.  681-91.

Gould, William A. "Biodiversity of an Arctic Riparian Ecosystem."
      William Gould Home Page. 8 July 1998
      <http://www.muskox.com/PhD.shtml >.

Gutchess, Elizabeth. Dryden Lake Trail: Twelve Field Trips. April 24,
      2002 <http://www.englishare.net/drydenlake/index.html>.

McHugh, Paul.  "The Secret Lives of Creeks." San Francisco Chronicle
      12 Sept. 1997: 1+.

Henry, A.C., D.A. Hosack, C.W. Johnson, D. Rol, and G. Bentrup.
     "Conservation Corridors in the United States: Benefits and
     Planning Guidelines." Journal of Soil and Water Conservation 54.4
     (1999): 645+.

Niering, William A. Wetlands. New York: Alfred A. Knopf, 1985.

Nilsson, Christer, Roland Jansson, and Ursula Zinko. "Long-term
     Responses of River-Margin Vegetation to Water-Level Regulation."
     Science 276.5313: (May 1997): 798-800.

Palmer, Tim. America by Rivers. Washington, D.C.: Island Press, 1996.

Perault, David R., and Mark V. Lomolino. "Corridors and Mammal
     Community Structure Across a Fragmented, Old-Growth Forest
     Landscape." Ecological Monographs 70.3 (August 2000): 401-22.

Pollock, Michael M., Robert J. Naiman, and Thomas A. Hanley. "Plant
     Species Richness in Riparian Wetlands: A Test of Biodiversity
     Theory." Ecology 79.1 (1998): 95-105.

Risser, Paul G. "The Status of the Science Examining Ecotones."
     Bioscience 45.5 (1995): 318+.

Sanders, Jack. Hedgemaids and Fairy Candles:  The Lives and Lore of
     North American Wildflowers. Camden, Maine: Ragged Mountain Press,

Tompkins County Environmental Management Council. "Resolution 7-90. 
     Proposed Dryden Lake Town Park.

Yahner, Richard H.  Eastern Deciduous Forest: Ecology and Wildlife
     Conservation.  Minneapolis: University of Minnesota Press, 1995.


         gutchess@englishare.net                    Academic writing home page                    Gary Gutchess © 2003