Environmental Engineering Reference
In-Depth Information
Remnant Patch
In some cases, the land to be restored may have a few existing islands of undisturbed natural vege-
tation that can serve as points of reference. As with the extant reference site approach, one method
of overcoming this situation is to collect data and material from a wide range of sites of varying
sizes throughout the vicinity (Packard and Mutel 1997). Using this technique will help develop a
composite picture of the species possible at your restoration project site. These patches can be cre-
ated by, for example, the proximity of two or more railroad tracks, older cemeteries in rural areas
with little to no maintenance, or isolated strips along roads and other rights-of-way where grazing
and human disturbance were prevented. In Asia, isolated shrine and temple grounds have protect-
ed vegetation remnants; a similar situation also exists in some villages of India, where sacred forests
can provide sources of material.
The presence of a plant species depends on several environmental factors, including the soil
type and its condition, elevation, slope, and even when it was last physically disturbed. Most plant
species require pollinators to produce viable seed. The ecological requirements of those pollina-
tors need to be met to be present on the remnant. Depending on the time of isolation, there may
have been several species that no longer are present. If a remnant was part of a larger community
that requires fire periodically, the isolation and cessation of fire may have negatively affected those
species needing fire for seed germination. Understanding how the ecosystem responds to an envi-
ronmental regime will assist in your determination of the appropriate species to include in your
reference model.
One of the most dramatic examples of using patch remnants is the prairie restoration effort of
the Great Plains of North America, with such projects as at the Fermi National Accelerator Labo-
ratory in Illinois and the Curtis Prairie in Madison, Wisconsin, being notable examples. At the Fer-
mi Lab outside of Chicago, a volunteer group began in 1975 that was to lead to a five-hundred-acre
prairie on former farmland inside the accelerator (Nelson 1987). The approach was to visit several
small patches of prairie remaining in the general vicinity. Tabulating species and collecting seed
from these sites formed the initial plantings of the prairie, which now comprises several hundred
acres. Comparison with these remnant patches also indicated the absence of some species at the
prairie project. Some species were less common, and seed had not been collected. Using these
various data sets, the group set about to collect and propagate those more uncommon species or
species with unique habitat requirements and introduce them onto the project site. Approximately
forty years earlier (in the 1930s), this same technique had been used on the Curtis Prairie (fig. 5-4),
established also on abandoned farmland, this time at the University of Wisconsin Arboretum. The
project was a vision of Aldo Leopold and was executed by Theodore Sperry and a team of Civilian
Conservation Corps workers. The approach was the same as described for the Fermi Lab.
Fabrication
A very common practice today, and one largely attributed to the “no net loss of wetland” policy, is
the establishment of an ecosystem on land that previously did not have this ecosystem—thus, it is
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