Site Analysis - Project Planning and Management for Ecological Restoration - page 57

has documented significant improvements in water quality. Government organizations are now
reestablishing fish populations previously unable to survive.
Landscape Ecology Considerations. In the past few decades, attention has been drawn to
landscape ecology, the evaluation of how landscape pattern influences species within various eco-
systems and communities. One aspect of landscape ecology receiving attention is biological cor-
ridors, core areas, and refuges (Adams and Dove 1989). Numerous habitat conservation planning
efforts are addressing these issues (Smith and Hellmund 2006). Corridors are not always nice
linear belts of vegetation or habitat leading to large core areas. Depending on the species and
communities, the width and quality of a corridor can be highly variable. Just how wide a corridor
needs to be is elusive. What is required for butterfly populations to successfully find breeding and
foraging habitat, for example, may be unacceptable for small mammals or even some bird species.
Understanding habitat requirements of different species and establishing your goals will direct the
project design. Commonly, it is possible to provide the habitat requirements for numerous species
at the same time.
Another important landscape ecology factor to consider is edge. The term edge refers to the
change in habitat or structure within a vegetation community. Most often, edge is the linear
border where two different vegetation communities meet. However, edge is also present where
different age classes meet or where a physical element breaks up the vegetation or creates a change
in the vegetation.
Numerous edge patterns are possible, from a very straight, smooth contact edge between a
forest and a meadow to an extremely sinuous or meandering contact line between a river and
the adjacent riparian habitat. Sometimes an edge is less controlled and may vary depending on
the season or cycle of rainfall. While meeting some aesthetic or specific species needs, a longer
edge may be more harmful to one or more of the vegetation communities by providing increased
avenues for invasion by undesirable species. Research has identified specific tolerances for some
species in their ability to invade various plant communities. Observation can show that many
exotic or undesirable species may reside in what appears to be a native community. Upon closer
examination, however, one can observe several exotic species occupying those small edges or
pockets of openings where the competition for space or nutrients is less. Typically, bare or open
areas exist in natural vegetation communities, however small. These small openings may become
invaded by undesirable species.
This condition will be important when establishing a restored project site. It may not be pos-
sible to have a corridor to each core or population center. Your restoration project may be rather
small and not connected physically to adjacent natural lands. This should be considered when
establishing goals. Detached pockets of habitat will most likely mean that some animals and even
some plants may not be able to use the site to its fullest (Morrison 2009). There is nothing wrong
with that situation, as long as it is acknowledged and understood that not all possible species will
become permanent residents of the project site.
Despite the debate over isolated habitat refuges, it is our opinion that all these sites have value.
A series of refuges may be the only means of connecting two core areas that permits exchange of
plant and animal genes. The basic question relating to the size of a site is whether it can serve the