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| Ministry of Environment |
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| Conservation
Data Centre |
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Spatial Patterns of Different Community Types
Natural terrestrial communities may be categorized into four functional
groups on the basis of their current or historical patterns of occurrence,
as correlated with the distribution and extent of landscape features
and ecological processes. These groups are identified as matrix
communities, large patch communities, small
patch communities, and linear communities.
Matrix Communities
Communities that form extensive and often contiguous cover may be
categorized as matrix (or matrix-forming) community types. Matrix communities
occur on the most extensive landforms and typically have wide ecological
tolerances. Individual Element occurrences of the matrix type typically
range in size from 2000 to 405,000 hectares (approximately 5000 to 1,000,000
acres). In a typical ecoregion, the aggregate of all matrix communities
covers, or historically covered, as much as 75-80% of the natural vegetation
of the ecoregion. Any matrix occurrence is likely to have large patch
and small patch occurrences embedded within it. Matrix community types
are often influenced by large-scale processes (e.g., climate, fire),
and are important habitat for wide-ranging or large area-dependent fauna,
such as large herbivores or birds (e.g., bison, prairie chickens).
Large Patch Communities
Communities that form large areas of interrupted cover may be categorized
as large patch community types. Individual EOs of this community type
typically range in size from 20 to 2000 hectares (approximately 50 to
5000 acres). Large patch communities are associated with environmental
conditions that are more specific than those of matrix communities,
and that are less common or less extensive in the landscape. In a typical
ecoregion, the aggregate of all large patch communities covers, or historically
covered, as much as 20% of the natural vegetation of the ecoregion.
Like matrix communities, large patch community types are also influenced
by large-scale processes, but these tend to be modified by specific
site features that influence the community.
Small Patch Communities
Communities that form small, discrete areas of cover may be categorized
as small patch community types. Individual EOs of this community type
are typically 20 hectares (approximately 50 acres) or less. Small patch
communities occur in very specific ecological settings, such as on specialized
landform types or in unusual microhabitats. In a typical ecoregion,
the aggregate of all small patch communities covers, or historically
covered, only as much as 5% of the natural vegetation of the ecoregion.
Small patch community types are characterized by localized, small-scale
ecological processes that can be quite different from the large-scale
processes operating in the overall landscape. The specialized conditions
of small patch communities, however, are often dependent on the maintenance
of ecological processes in the surrounding matrix and large patch communities.
In many ecoregions, small patch communities contain a disproportionately
large percentage of the total flora, and also support a specific and
restricted set of associated fauna (e.g., invertebrates, herpetofauna)
dependent on specialized conditions.
Linear Communities
Communities that form as linear strips are often, but not always, ecotonal
between terrestrial and aquatic systems. Examples include coastal beach
strands, bedrock lakeshores, and narrow riparian communities. Similar
to small patch communities, linear communities occur in very specific
ecological settings, and the aggregate of all linear communities covers,
or historically covered, only a small percentage of the natural vegetation
of the ecoregion. They also tend to support a specific and restricted
set of associated flora and fauna. Linear communities differ from small
patch communities in that both local scale processes and large scale
processes, such as lake/ocean currents or riverine flow regimes, strongly
influence community structure and function. This characteristic often
leaves these communities highly vulnerable to alterations in the surrounding
land and waterscape.
Source: Draft
Element Occurrence Data Standard
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