Ministry of Environment

Environmental Stewardship Division

SEI Update


A publication of the Sensitive Ecosystems Inventory Project
October 2002

Loss of Sensitive Ecosystems Continues

Development pressures continue to threaten the remaining sensitive ecosystems on east Vancouver Island and Gulf Islands. This is the finding of a recent audit of selected SEI polygons in urban and rural landscapes that was conducted by the Ministry of Water, Land and Air Protection.

Using 1999 ortho-photos and some field checking, the audit assessed 27% (1,994) of the sites identified in the original SEI, documenting changes to these ecosystems in urban and rural landscapes since the original mapping 6-8 years earlier. Sites were documented as to level of disturbance (undisturbed, disturbed, or severely disturbed/degraded) and land use (federal, greenspace, urban, rural, forestry, and Vancouver Island Highway Project).

One in nine of these audited sites (224 sites or 11.2%) were disturbed to some degree. Even in areas designated as greenspace, there were impacts to several sites from trails and tourist facilities. The greatest changes had occurred in urban landscapes, where almost 23% of the audited polygons showed some degree of disturbance. Of the seven sensitive ecosystem types, the greatest impact was to Older Forests (17.6%). The greatest level of disturbance overall was to Older Second Growth Forest polygons (24.9%).

The rate of modification averaged 1.6% per year, and appeared to be higher in the late 1990s than earlier in the decade. If the present rate of disturbance were to continue, all of the remaining natural sensitive ecosystems could be impacted within the next few decades.
These results are disturbing because even small disturbances within or adjacent to an SEI polygon can affect the ecological integrity of the remainder, especially as many SEI polygons are already small and fragmented. These ecosystems provide habitat for many rare or threatened species that cannot survive in modified environments.

“if the present rate of disturbance were to continue, all of the remaining natural sensitive ecosystems could be impacted within the next few decades”

A copy of the audit is available at the Ministry’s Vancouver Island Region website.

Always check for changes!

Changes to the landscape are continual (see articles on SEI Audit and SEI Upgrade). Although we do our best to keep the SEI database current, you may be looking at information that is out of date. For the most recent available information, check with the BC Conservation Data Centre (CDC), Jan.Kirkby@gems9.gov.bc.ca, phone (250) 387-0732.

More field checking of SEI polygons

In the original SEI, approximately 30% of the SEI polygons were field-checked to verify the air photo interpretation and evaluate the condition of the sites. An SEI Upgrade Project was recently conducted to increase the number of field-checked polygons, providing a higher level of information to support ecosystem-based land use planning decisions

During 2001-2002, field crews visited more than 250 SEI sites to gather information on their current condition, environmental characteristics, vegetation, disturbance factors and more. Most sites visited for the SEI Upgrade had not been fieldchecked as part of the original groundtruthing phase in 1994-1996; however, some polygons that had originally been fieldchecked were revisited to obtain current information.

The Conservation Data Centre is currently updating the SEI database with this new information, and a revised version of the database will be available in December 2002. In the meantime, contact the CDC (see above) for a list of polygons in your area that were field-checked as part of the SEI Upgrade.



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