Guide to Significant Wildlife Habitat - Door County Web Map

A (very) Short Course in Ecology &
Related Land Use Philosophy
Chapter 1
Used with permission
of the Minnesota Department of
Natural Resources & Laurie Allman (1997)
At the root of every discussion and decision related to natural area protection are qualitative
judgements.
• What qualities are desirable in a natural area?
• What level and type of impacts resulting from a development, new home or
management practice will be considered acceptable?
• What exactly is one is trying to protect?
In any genuine initiative aiming to sustain the health of local natural areas, the answers to
questions such as these must be grounded in the basic principles of ecology.
Ecology is about relationships—relationships among living things, and between living things and
their non-living environment. As a scientific discipline, ecology pays attention to how things interact.
This discipline assumes that it is both impractical and misguided to look at individual living things in
isolation, because living things depend for their survival on the set of elements that surround them and the
processes that sustain their population over time. It considers natural areas to be intricate and interacting
systems that operate at many scales. Ecologists assess the condition of natural areas by looking at three
primary elements: composition, structure, and function.
Composition is a measure of the plant and animal species present, their relative
abundance, and the differing characteristics of individuals that make up populations,
such as age, ability to reproduce, and relative vigor.
Structure refers to the physical organization of natural elements across a landscape -
that is, awareness of patterns evident in the distribution of living things and how those
patterns change naturally over time. Elements of structure include the varying heights
of vegetation, the degree to which a community is open or unshaded, and the mosaic of
natural community types across a defined area, as well as the presence of nonliving
elements such as waterways, rocks, logs and woody debris on the forest floor.
Function refers to the processes and relationships that sustain a system. Such as the
flow of nutrients moving through an ecosystem, the natural disturbance regimes that
determine site conditions, such as wind events, fire, seasonal water level changes, and
the movement of animals to find food and appropriate sites for breeding and
reproduction. There are many ways that the needs of plants and animals are met
through interactions with each other and with their physical non-living surroundings,
and many roles that each individual or population plays in the operation of the system
as a whole.
A site with ecological integrity contains populations of native species in naturally occurring
patterns as determined by the unique physical characteristics, climate, and history of the site. Natural
processes will drive changes and fluctuations in structure and composition over time.
Chapter 1– A Short Course in Ecology 15