Conn. Agencies Regs. § 22a-426-5 - Biological condition gradient model
(a) The Biological
Condition Gradient Model is a model that describes how ecological attributes
change in response to increasing levels of stressors. In accordance with the
Biological Condition Gradient Model, as the level of stress gets progressively
greater, the biological communities, which start out in a natural condition,
begin to change as they respond to the stress.
CONNECTICUT BIOLOGICAL CONDITION GRADIENT MODEL
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(b) The
ecological attribute changes are categorized into tiers, as follows:
(1) Tier 1 - Native condition is such that
the native structural, functional and taxonomic integrity is preserved;
ecosystem function is preserved within the range of natural
variability.
(2) Tier 2 - Minimal
changes in the structure of the biotic community and minimal changes in
ecosystem function are such that virtually all native taxa are maintained with
some changes in biomass or abundance; ecosystem functions are fully maintained
within the range of natural variability.
(3) Tier 3 - Evident changes in structure of
the biotic community and minimal changes in ecosystem function due to loss of
some sensitive-rare taxa; shifts in relative abundance of taxa but
sensitive-ubiquitous taxa are common and abundant; ecosystem functions are
fully maintained through redundant attributes of the system.
(4) Tier 4 - Moderate changes in structure of
the biotic community with minimal changes in ecosystem function due to
replacement of some sensitive-ubiquitous taxa by more tolerant taxa, but
reproducing populations of some sensitive taxa are maintained; overall balanced
distribution of all expected major groups; ecosystem functions largely
maintained through redundant attributes.
(5) Tier 5 - Major changes in structure of
the biotic community and moderate changes in ecosystem function are such that
the sensitive taxa are markedly diminished; conspicuously unbalanced
distribution of major groups from that expected; organism condition shows signs
of physiological stress; ecosystem function shows reduced complexity and
redundancy; increased build-up or export of unused materials.
(6) Tier 6 - Severe changes in structure of
the biotic community and major loss of ecosystem function are such that there
are extreme changes in structure; wholesale changes in taxonomic composition;
extreme alterations from normal densities and distributions; organism condition
is often poor; ecosystem functions are severely altered.
Notes
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