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About UNEP
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United Nations Environment Programme
Division of Technology, Industry and Economics
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Newsletter and Technical Publications
Freshwater Management Series No. 5

Guidelines for the Integrated Management of the Watershed
- Phytotechnology and Ecohydrology -


E. Examples of the use of phytotechnology and ecohydrology in temperate and tropical catchments

In the developed countries of Europe and North America commonly referred to as the G-7 countries, phytotechnologies and ecohydrological approaches are gaining currency as measures to be utilised in catchment management. Numerous examples of the use of such measures can be found in the technical literature published since the pioneering work of the International Joint Commission’s Pollution from Land Use Activities Reference Group (PLUARG) during the 1970s. The PLUARG studies, summarised in Thornton et al. (1999), established not only the fact that human activities on and within the landscape have both a direct and an indirect affect on water resources, but also the fact that land management measures can influence the degree and extent of these impacts. As a result of these studies, and those of the OECD that followed, concepts such as conservation tillage, grassed waterways, and vegetative buffer strips began to be more widely accepted and implemented. Initial actions focused on rural, agricultural areas, as these areas were focal points for the application of significant volumes of fertilisers and other (artificial) agrochemicals. Next to point sources such as sewage treatment plant discharges and industrial discharges, agriculture was the single largest potential source of nutrients to the Laurentian Great Lakes system. While these agrotechnologies are not phytotechnologies, they do form the logical stepping off place for the subsequent development of phytotechnologies. Recognition that vegetation can be effective in reducing soil loss, maintaining the hydrological integrity of waterways, and providing habitat for both terrestrial and aquatic life was to follow.

Key advances in the integration of hydrology into landscape planning and management included the principles embodied in McHarg’s (1969) "design with nature" approach to urban and regional planning. This approach recognised that the attempt of humans to impose structural measures upon the environment, especially in the years following the Second World War, had been less than effective in minimising risks from "natural disasters," such as flooding. To the contrary, by managing development so that structures were not placed within floodplains or on steeply sloping and highly erodible lands, communities would benefit from fewer economic losses while maintaining the aesthetic appeal of these open spaces. During the 1980s, the Australians took this approach further by merging this land use management strategy with the concept of wildlife corridors to create networks of open lands within urban and urbanising areas to retain and maintain the underlying ecological base. The integration of these land use planning and management tools with the hydrological imperatives, as described herein, is the next natural step forward in providing mechanisms whereby humans can achieve their economic purposes with minimal risk from "natural disasters."

North America and Europe

One of the most important tasks undertaken by the Southeastern Wisconsin Regional Planning Commission as part of its regional planning efforts in the metropolitan Milwaukee (Wisconsin, United States of America) area was the identification and delineation of those areas within the region having high concentrations of natural, recreational, historic, aesthetic, and scenic resources (Rubin and Emmerich 1981). These areas were considered to be of such importance as to be preserved and protected in order to maintain the overall quality of the environment. Such areas normally included one or more of the following seven elements of the natural resource base which are essential to the maintenance of both the ecological balance and the natural beauty of the region:

  • lakes, rivers, streams, and their associated undeveloped shorelands and floodlands;
  • wetlands;
  • woodlands;
  • prairies and undeveloped grasslands (= savannah areas);
  • wildlife habitat areas;
  • wet, poorly drained areas with organic soils; and
  • rugged terrain with high-relief, steeply-sloped topography.

In addition to these seven elements which were considered to constitute integral parts of the natural resource base underlying the metropolitan region, there were five additional elements that, although not a part of the natural resource base per se, were closely related to, or centred on, the natural resource base. These additional elements, therefore, also are important elements to be considered in identifying and delineating areas with scenic, recreational, and educational value. These additional elements are:

  • existing outdoor recreational sites;
  • potential outdoor recreational and related open space sites;
  • historic, archaeological, and other cultural sites;
  • significant scenic areas and vistas; and
  • natural areas and scientific areas.

The Southeastern Wisconsin Regional Planning Commission determined that the delineation of these 12 natural resource and natural resource-related elements on a map resulted in an essentially linear pattern of relatively narrow, elongated areas which were termed "environmental corridors" by the Commission. Those areas designated as primary environmental corridors included a wide variety of important resource and resource-related elements. These areas were at least 400 acres in area, two miles in length, and 200 feet in width.

Many interlocking and interacting relationships were determined to exist within these corridors between the living organisms and their environment. The destruction or deterioration of one element of this environment could lead to a chain reaction of deterioration and destruction. For example, the drainage of wetlands may have far-reaching effects on other elements of the environment. The drainage of wetlands can destroy fish spawning grounds, wildlife habitat, groundwater recharge areas, and natural filtration and floodwater storage areas for their interconnecting lake and stream systems. The resulting deterioration of surface water quality may, in turn, lead to the deterioration of the quality of the groundwater. Groundwater, in turn, serves as a source of domestic, municipal, and industrial water supply and provides a basis for low flows in rivers and streams. Similarly, the destruction of woodland cover, which may have taken a century or more to develop, may result in soil erosion and stream siltation and in more rapid runoff and increased flooding, as well as destruction of wildlife habitat. Although the effects of any one of these environmental changes may not, in and of itself, be overwhelming, the combined effects of these sequential changes may lead eventually to the deterioration of the underlying and supporting natural resource base and overall quality of the environment for life.

The primary environmental corridors in Southeastern Wisconsin generally lie along major stream valleys and around major lakes, and contain almost all of the remaining high-value woodlands, wetlands, and wildlife habitat areas, and all of the major bodies of surface water and related undeveloped floodlands and shorelands within the region. Primary corridors may be subject to urban encroachment because of their desirable natural resource amenities. Unplanned or poorly planned intrusion of the urban development into these corridors not only tends to destroy the very resources and related amenities sought by the development, but it tends to create severe environmental and development problems as well.

In addition to the primary corridors, the Commission identified and delineated secondary environmental corridors. These areas were located generally along intermittent streams or in areas that served as links between segments of primary environmental corridors. These secondary environmental corridors contained a variety of resource elements, often comprised as remnants of primary environmental corridors that have been developed for intensive agricultural purposes or urban land uses. Such secondary environmental corridors facilitate surface water drainage, maintain "pockets" of natural resource features, and provide for the movement of wildlife, as well as for the movement and dispersal of seeds for a variety of plant species. Such corridors, while not as important as the primary environmental corridors, also were determined to be preserved in essentially open, natural uses as urban development proceeds. These areas, within catchments, can be incorporated within urban stormwater detention areas, associated drainageways, and neighborhood parks.

Finally, in addition to the primary and secondary environmental corridors, other, smaller concentrations of the natural resource base elements exist that are isolated from the environmental corridors by urban development or agricultural uses. Even though these areas are separated from the environmental corridor network, they can have important natural values. Isolated natural areas can provide the only available wildlife habitat in a specific area, good locations for local parks and nature study areas, and areas with outstanding aesthetic character or natural diversity within an area. Important isolated natural features within southeastern Wisconsin included geographically well-distributed, isolated wetlands, woodlands, and wildlife habitats.

Riverbanks and lakeshores located within environmental corridors were determined to be ideal candidates for protection through proper land use zoning and/or through public acquisition and ownership. In addition, isolated natural features, determined to be worthy of protection and preservation in a natural state were also recommended for protection and preservation whenever possible, but especially when such areas were five or more acres in area.

Recently, building upon this concept and implementing the principles of phytotechnology and ecohydrology, the Minnesota Department of Natural Resources - and more recently the Wisconsin Department of Natural Resources and University of Wisconsin-Extension - have promoted the concept of "lakescaping" as a means of maintaining and enhancing shoreland vegetation. As the development of the lakeshore areas of the north central United States has progressed following the Second World War, the shoreland vegetation, grasses, brush, and tree canopy have been progressively removed and replaced with lawns and dwelling units. This has had repercussions on the songbirds, amphibians, and other shoreland wildlife, which populations have diminished, being replaced by more urban species or invasive species that can utilise these disturbed shoreland areas. In addition, the removal of shoreland structure has limited the presence of large woody debris, comprised of treefalls, in nearshore waters, reducing breeding habitat for fishes, amphibians, and shore-dwelling reptiles. To counteract these trends, programs have been developed to encourage riparian property owners to maintain or restore native plants within a zone extending from about 35 feet landward of the shoreline and 30 feet or more lakeward of the shoreline. The extent to which native plants and vegetation is disturbed is proposed to be limited to only those areas necessary to accommodate a pier and swimming area, if desired, while the balance of the shoreland is recommended to be maintained in a natural state.

As a consequence of this major shift in management approach, there has been a significant amount of public debate surrounding this concept. Because of the resistance encountered among the public, efforts have been made by the agencies to promote the concept of lakescaping as one wherein the homeowner can maintain a manicured, landscaped appearance while simultaneously achieving enhanced water quality and habitat benefit. In keeping with this approach, efforts to encourage the use of native, rather than exotic, grasses within the lawns, and the planting of native (prairie) plants - especially flowering perennials - have been widely undertaken with some success.

 

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