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Old 12-11-2008, 02:31 PM
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bluebird2
Nontypical Buck
 
Join Date: Apr 2008
Posts: 3,879
Default Ecological Carrying Capacity Verses the Nutritional Carrying Capacityal Carrying Capacity

A lot of guys have been complaining about the excessive herd reduction and here is the reason the PGC is reducing the herd. Instead of managing the herd based on the nutritional carrying capacity of the habitat , the herd is being managed on the ecological carrying capacity ,which is a lot lower than the nutritional carrying capacity.

Carrying capacity
Much confusion about deer management stems from the fact that more
than one definition of “carrying capacity” is used, even among scientists
and wildlife managers. The different meanings reflect very different
philosophical and practical approaches to deer management.
• Ecological carrying capacity
Ecological carrying capacity focuses on the interaction between a
population of herbivores (plant-eaters, such as white-tailed deer) and the
plants that they eat. It is defined as “the maximum density of animals that
can be sustained in the absence of harvesting without inducing trends in
vegetation.”9 At ecological carrying capacity, the rate of browsing is
roughly equal to the rate of food-plant regrowth. The definition also
implies that there are no major changes in plant species composition
resulting from an increase in the density of an animal population to its
carrying capacity.
• Nutritional carrying capacity
In contrast, some highly simplified, deterministic models used in
managing deer, elk, and moose throughout the United States focus
instead on maximum sustained harvest yields (M.S.Y.). These models
are used to estimate, from hunter harvest numbers and sometimes the
physical condition of deer, where a population lies on the yield curve,
which shows the hump-shaped relationship between deer population
density and sustainable annual harvest (see Figure 9, page 160). Many
managers who use these models believe that deer should be managed
to stay near the peak (the nutritional carrying capacity) of the yield Part V concludes , both overharvest and underharvest (so-
called management “errors”) theoretically are automatically compensated
by population responses of deer. The concept of nutritional carrying
capacity disregards plant species composition and considers only the
total availability of essential nutrients. From this perspective, the ideal
deer habitat is fields of corn and other crops side by side with old fields
or clearcuts overgrown with shrubs and tree seedlings. In fact, deer
persist in high numbers partly because of the inadvertent input of
resources as byproducts of human activity. Artificially high disturbance
rates (logging), agricultural fields, and suburban gardens generate high-
quality deer food in greater abundance or more consistently, or both,
than processes that are not supported by humans, including those that
perpetuate forests. The deterministic, single-species approach
characterized by M.S.Y. has fallen out of favor with most scientists and
many managers.10
• Cultural carrying capacity
The maximum number of deer a habitat is physically equipped to
support can be much higher than the number that will allow other forest
management goals to be achieved. Management goals take more than
the number of huntable wildlife into account. Forest management
elements that are adversely affected by high deer densities include tree
regeneration, conservation of rare plant species, and maintenance of
habitat for watchable wildlife, rare animal species, and game other than
deer. Cultural carrying capacity is a values choice, which takes into
consideration the needs and concerns of a range of stakeholders.[/quote]
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