Guide to Significant Wildlife Habitat - Door County Web Map

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An ecosystem is a dynamic complex of plant, animal, fungal and
microorganism communities and their associated nonliving environment
interacting as an ecological unit.
An appreciation of the complexity of ecosystems is at the very root of ecology. It is not
uncommon for ecologists who have devoted their lives to researching a particular species or natural
process to insist that they have only scratched the surface of understanding. Ecologists hold to this
position in part because natural systems are ever changing, and in part because our ability to get the right
answers is limited by our ability to ask the right questions.
Yet the fact that our study of the natural world will always be a work in progress does not mean
that we cannot make decisions based upon what knowledge we have already acquired. Just as the equally
inexact science of medicine is routinely used to guide the decisions we make about our health care, we
must actively use the understandings gained by ecological research to guide our land use decisions. What
has the study of ecology taught us? A few generally accepted concepts include:
Having a diversity of native species - many different kinds of naturally occurring plants and
animals - tends to make an ecosystem more stable and better able to handle stress, and may be
used as one of the indicators of health. It is therefore desirable to maintain the biological
diversity that is naturally characteristic of a site, with the understanding that some areas are
naturally lower in diversity, as well as some are naturally higher, as in a rain forest.
Plants and animals do not occur randomly over the landscape; they occur in identifiable and
recurring groupings of species known as "natural communities." Populations that comprise a
community may live in proximity because of interdependent relationships (predator/prey), or
similar habitat requirements and physical tolerances, such as fish species that share a need for
high oxygen waters or insects that require high humidity environments, or plants that can thrive in
dry climates. [Note: For a listing of Door County’s natural communities see Appendix “A” and
for a description of these areas see Appendix “C”].
Energy moves through natural systems in complex ways, so that each organism plays a role in
determining the conditions for other organisms. For a system to be sustained, nutrients must be
transferred from one species to another, and dead and decaying materials must be allowed to
break down or decompose and reenter the system to support the development of new life.
There are limits to the adaptability of species and ecosystems. Change is inherent in natural
systems and occurs when species expand their range into new territories, or when populations
fluctuate in response to food availability and climate changes, or when one plant community is
gradually supplanted by another through the process of succession. Accelerated rates of change
can produce conditions that cause populations of species and even entire natural systems to
collapse. Declines are not always gradual; species may decline to critical threshold level and then
crash. Worldwide, 99% of modern-day, post-1600 species extinctions are considered attributable
to human activity. (Primack 1995)
Chapter 1– A Short Course in Ecology