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What Is This Indicator, and Why Is It Important?
This indicator describes the shape of patches of “natural”
lands in the farmland landscape, by reporting on the percentage
of patch area that is found in “compact” patches
(e.g., like a circle), “elongated” patches (e.g.,
like a long narrow rectangle), and an intermediate class of
patch shape. These classes are defined based on the ratio
of the perimeter, or edge, of each patch to its area; these
perimeter-to-area ratios will be divided by patch area for
the sake of comparison. “Natural” areas include
forest, grasslands and shrublands, wetlands, and lands enrolled
in the Conservation Reserve Program (CRP). These data would
be presented nationally and by region for the most current
year.
Natural lands within the farmland landscape control erosion,
facilitate groundwater recharge, provide critical habitat
for wildlife, and serve other important ecological functions.
The size and shape of these often small and isolated remnants,
along with restored conservation areas (e.g., CRP land), directly
influence the amount and type of ecosystem services provided.
Habitat fragmentation may create new kinds of habitats that
are colonized by generalist native species or exotic species.
For example, small patches and long narrow ones may have little
or no “interior” habitat. Since some species thrive
only in interior habitat—where there is a relatively
large and contiguous area of forest, grassland, or other natural
cover (see the forest fragmentation
indicator), small narrow areas may not provide habitat
for these species. On the other hand, narrow strips may function
quite well for erosion and sediment control.
Why Can't This Indicator Be Reported at This Time?
As is the case for the development
indicator, the land cover data necessary to report this
index are available, but have not been analyzed.
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