Ecology Terms

Succession

In ecology, the orderly progression of changes in community composition that occurs during the development of vegetation in any area, from initial colonization to the attainment of the climax plant and animal community typical of a particular geographic area. Primary/early successional plants are usually weedy, they grow quickly and do well with abundant resources, particularly light. As succession continues shrub or tree seeds may be brought to a site by animals. As these grow they often shade out the early successional plants such that you end up with a secondary/mid successional system. Different ecosystems can have different numbers of successional stages, and they may not have clearly defined stages. This is a simplified model. It is believed by most ecologists that a system does not have a single end point or climax state. An ecosystem may exist in a similar state for a long period of time but that the composition and structure of a plant/animal community continues to change over time, especially on the scale of hundreds or thousands of years.

Competition

Interaction between members of the same population or of two or more populations to obtain a resource that both require and which is available in limited supply. I.e.. In many restoration projects weedy (generally non-native) grasses are very good competitors for light and nutrients and can prevent native plants and trees from growing even if an animal disperser brings the seeds to the site. In this case a system may be stuck in an early successional stage. Restoration is important to help a system like this move to a later successional stage which may have greater ecosystem function or provide better habitat for target organisms.

The struggle between plants to obtain sunlight, nutrients, water, and growing space. Every part of a plant - from the roots to the crown/apex - competes for space and food.

Nutrient Cycling

Nutrients, such as carbon, nitrogen, phosphorus and potassium, as well as micronutrients, move through cycles. They may exist in the air (CO2) and be uptaken by plants and converted to carbohydrates (C6H12O6...), get decomposed and broken down in the soil, get washed into rivers and feed micro and macro fauna in streams, river, estuaries, etc, etc. The cycle continues.

These cycles are important for plants to get the nutrients they need (but not in excess) for growth, but equally plants are important regulators of these cycles. In restoration we want and reestablish ecosystem functions. One function is the fixation of carbon by all plants. They take Carbon out of the atmosphere and lock it up (for a period of time) in living and dead vegetation. Important soil bacteria are able to fix atmospheric nitrogen into ammonium which plants need for survival.

Productivity

A system is generally considered 'productive' if plants are putting on biomass every season, the system is 'growing'. Part of this biomass is dying, decaying and contributing to nutrient cycling. If a system is going to be managed for timber or pasture grass it is desirable to have high productivity.

Micro-Climate

(1) The local climate of a site or habitat varying in size from a tiny crevice to a large land area, but being usually characterized by considerable uniformity of climate over the site involved and relatively local as compared to its enveloping macroclimate from which it differs because of local climatic factors (such as elevation and exposure). (2) A local climatic condition near the ground resulting from modification of relief, exposure, or cover. (3) The fine climatic structure of air space which extends from the very surface of the Earth to a height where the effects of the immediate character of underlying surface no longer can be distinguished from the general local climate (i.e., mesoclimate or microclimate). The microclimate varies with and in turn is superimposed upon the larger-scale conditions. While some rigid limits have been placed on the thickness of the layer concerned, it is realistic to consider variable thicknesses, e.g., the microclimate of a putting-green versus that of a redwood forest. Generally, four times the height of surface growth or structures defines the level where microclimatic overtones disappear. The word has been used to describe the climate of a cave, a plant, and an insect inside of a log.

Stress

The conditions resulting from any environmental change that disturbs the normal functioning of a plant or animal to such an extent that its chances for survival are reduced.

Landscape Ecology Terms

Island Biogeography

This is somewhat involved concept in ecology. It has to do with the number of species that will arrive to an island from a large land mass and how many species an island of a given size can handle. In the model we talk about islands surrounded by water, but this can equally apply to a patch of native prairie surrounded by a "sea" of agricultural land. If new insects, birds, seeds, etc., are going to arrive on the native grass "island" they need to come from far away. If you are restoring a site that is far from potential seed sources or pollinators, it is likely that you will need to play a large role helping introduce different plant and animal species. On the other hand, if adjacent to your restoration site you have a large natural ecosystem of a similar type you can simply let the seeds and natural organism do the work.

On this website is a fairly understandable definition if island biogeography:
http://www.stanfordalumni.org/birdsite/text/essays/Island_Biogeography.html

Patch

Patches are defined as regions that are more-or-less homogeneous with respect to a measured variable. When you look at the land from a place you see similar parts of the land. these maybe similar due to color, texture, or some characteristic your eye can distinguish. All of the areas that look the same, such as dark green forest, are considered different patches of the same type.

Corridor

(1) A linear strip of land connecting two similar ecosystem types. (2) A thin strip of vegetation used by wildlife and potentially allowing movement of biotic factors between two areas.

Matrix

The area between the patches of a landscape. If you look out the window a plane and see patches such as distinct clumps of forest as well as some rocky outcrops, these are two different patch types, and all the connected area between them is the 'matrix'.

Edge/Interior

The transition between two different types or ages of vegetation. This is the transition between two ecosystems and where two systems affect each other. The edge gets more disturbance/influence from the neighboring ecosystem than the interior of an ecosystem. The typical example use is in the Pacific Northwest is a clear cut in a conifer forest. Where tall forest meets the open space of a clear cut seeds, wind, light, heat and other variables penetrate into that forest, up to around 200 feet. In a restoration project you should be aware that the edges of your site may grow differently than the interior due to neighboring conditions

Landscape permeability

Landscape permeability is the ease with which animals, seeds, or substances can flow through the landscape. Forests are not very permeable if you are a wind-carried seed, but grasslands are.

Disturbance response

'Disturbance Processes' are actions, functions, or events that influence or maintain the structure, composition, or function of the terrestrial or aquatic components of ecosystems. Natural disturbances include, among others, drought, floods, -wind, fires, insects, and pathogens. Human-caused disturbances include actions such as recreational use, livestock grazing, mining, road construction, timber harvest, land-use development, and the introduction of exotic species.
In response to a disturbance a healthy ecosystem will begin the successional steps to rebuild the plant structure, the soil and habitat. However, the disturbed state can be habitat for some plants and animals. Unhealthy or human disturbed ecosystems can become stuck in an early successional stage and do not progress without restoration efforts to suppress invasive weeds or remove toxic chemicals from the soil.

Fragmentation/isolation

Fragmentation occurs when a continuous ecosystem, such as a Midwest prairie, gets cut into smaller pieces, such as when parts of the prairie get converted to agriculture. These smaller isolated patches of the native ecosystem will generally change and become less biodiverse or serve less ecosystem function as less seed dispersers reach the fragment, as less pollinators exchange new genetic material with the island, and as less natural processes affect the patch.