Assessing Vulnerability

How vulnerable is a natural community to elimination? Ecologists assign each natural community a conservation status rank that incorporates information about the natural community’s extent, rarity, and resilience, as well as threats to that community. These ranks help natural resource managers focus their conservation efforts where the needs and benefits are greatest.

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Defining Conservation Status Ranks

There are five conservation status ranks, ranging from Critically Imperiled (1) to Secure (5).

Definitions for the ranks are below. A rank may be given for different reasons for different natural communities. For example, one community may be ranked Critically Imperiled because there are very few occurrences, while another may be ranked Critically Imperiled because of very severe threats.

1: Critically Imperiled: At very high risk of extinction or elimination due to very restricted range, very few populations or occurrences, very steep declines, very severe threats, or other factors.

2: Imperiled: At high risk of extinction or elimination due to restricted range, few populations or occurrences, steep declines, severe threats, or other factors.

3: Vulnerable: At moderate risk of extinction or elimination due to a fairly restricted range, relatively few populations or occurrences, recent and widespread declines, threats, or other factors.

4: Apparently Secure: At fairly low risk of extinction or elimination due to an extensive range and/or many populations or occurrences, but with possible cause for some concern as a result of local recent declines, threats, or other factors.

5: Secure: At very low risk of extinction or elimination due to a very extensive range, abundant populations or occurrences, and little to no concern from declines or threats.

A letter preceding the number indicates the geographic scale of the assessment (G=global, N=national, S=state/subnational). Example: G1=Globally Critically Imperiled.

A question mark in the conservation status rank indicates imprecision (example: Apparently Secure?), whereas a range indicates that the assessment found nearly equal support for each of two ranks (example: Apparently Secure to Secure).

These same five ranks are also used for individual species of plants and animals. Whether assessing species or ecosystems, ecologists follow a detailed and rigorous set of established rules when assigning a conservation status rank.

More information is available through NatureServe Explorer.

On this website, a natural community's conservation status rank is reported on each natural community's Conservation Status and Classification page.


Global Conservation Status: G4 – Apparently Secure

Subnational Conservation Status: D.C.: SNR – Not yet assessed

Next steps

Review the differences between natural communities, semi-natural communities, not-so-natural communities, and ecological systems in Seeing the Patterns.

Review how (and why) ecologists identify and map natural communities in Naming and Mapping the Paterns.

Start exploring natural communities in a park! Go to Parks & Places, and pick a featured park.

Or, learn more about ecology in Ecology Basics.