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Overview
of Ecological Units Data
NatureServe
Explorer provides data for ecological units (communities
and systems) primarily in the contiguous United States
and Hawaii. Canadian data are provided in NatureServe
Explorer where available. Ecological systems data
will be provided in the future for Latin America and
the Caribbean on InfoNatura. The completeness
of ecological unit inventory and classification work
varies widely among states, provinces and regions,
and NatureServe Explorer reflects these variations.
Ecological units are defined by the International
Ecological Classification Standard, primarily composed
at present of the International Vegetation Classification
(IVC) and the NatureServe Ecological Systems Classification. For details on this system, see Classification of Standard Ecological Units.
The
Comprehensive Report for ecological units contains
available information in the following categories:
classification; related names; global conservation
status; distribution; environmental setting; vegetation
structure; dynamic processes; authors and contributors;
and references. This information is continually reviewed
and updated in the NatureServe Central Databases in
order to reflect ongoing inventory and classification
efforts, and new status assessments. NatureServe
Explorer is updated periodically from the NatureServe
Central Databases.
Because
of the wide variation in ecological units inventory
and classification throughout the United States, it
is not possible to make a definitive interpretation
of the differences in diversity of ecological units
among states or regions. Some states or regions focus
efforts on those US-NVC alliances and associations that are
considered imperiled (conservation ranks G1 or G2),
while others, like the western U.S. Forest Service
Districts, focus on more common units. Also,
while the classification system is intended to develop
units with consistent scale, associations are more
narrowly defined in some regions, resulting in a greater
number of associations per alliance than average.
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Ecological
Communities Records in NatureServe Explorer
|
| "*"
denotes groups for which detailed summary information
is provided for all native communities. |
Communities
with U.S. Distribution |
Communities
with Canadian Distribution |
Total
Communities |
| All Communities | 7,101 | 1,220 | 7,444 |
| Forest* | 2,078 | 360 | 2,149 |
| Woodland* | 1,197 | 150 | 1,235 |
| Shrubland* | 1,388 | 140 | 1,471 |
| Dwarf-shrubland* | 207 | 67 | 218 |
| Herbaceous Vegetation* | 1,984 | 396 | 2,090 |
| Nonvascular Vegetation* | 40 | 14 | 44 |
| Sparse Vegetation* | 207 | 93 | 237 |
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Ecological
System Records in NatureServe Explorer
|
|
Systems with
U.S. Distribution |
Systems
with Canadian Distribution |
Total
Systems |
| All Ecological Systems | 825 | 198 | 855 |
| Forest and Woodland | 180 | 53 | 193 |
| Shrubland | 90 | 14 | 93 |
| Steppe/Savanna | 48 | 10 | 48 |
| Herbaceous | 72 | 15 | 75 |
| Woody Wetland | 156 | 44 | 165 |
| Herbaceous Wetland | 128 | 25 | 130 |
| Mixed Upland and Wetland | 45 | 14 | 45 |
| Barren | 106 | 23 | 106 |
Ecological Associations by NatureServe Conservation Status |
| |
Potentially Extinct (GX, GH) |
At Risk (G1, G2, G3) |
Apparently Secure (G4, G5) |
Unrankable (GU) |
Not Yet Ranked(GNR) |
| Forest | 2 | 1,068 | 536 | 13 | 180 |
| Woodland | 0 | 666 | 217 | 11 | 155 |
| Shrubland | 1 | 499 | 322 | 20 | 208 |
| Dwarf-shrubland | 1 | 92 | 31 | 0 | 23 |
| Herbaceous Vegetation | 0 | 894 | 268 | 59 | 224 |
| Nonvascular Vegetation | 0 | 11 | 5 | 0 | 8 |
| Sparse Vegetation | 0 | 58 | 30 | 3 | 80 |
| Total | 4 | 3,288 | 1,409 | 106 | 878 |
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