Habitat Supply Modelling: a subset of Environmental Risk Assessment.A presentation for the Habitat Modelling workshop. March 9, 2000 Mike FengerHabitat Branch Ministry of Environment Lands and Parksprepared with Greg UtzigKutenai Nature Investigations
Environmental Risk Assessment Evaluation of the likelihood of an adverse outcomedue to changes in environmental conditions resulting from human activities
Example Risk Classes Very Low: Most populations are likely to remain stable, or possibly increase where habitat restoration is successful. There is likely to be sufficient redundancy in habitats to withstand changes due to all but the most catastrophic natural stand-replacing events. Where local extirpations occur, connectivity is likely to allow for re-establishment of replacement populations. Very High: Major reductions or extirpations are likely in populations dependent on mature and/or old forest cover. Extensive areas of early seral and/or mid seral forests will create imbalances in habitat supply through time (e.g. “boom and bust” feeding areas for grizzly bears). There is significant potential for contributing to permanent and/or regional extirpations or extinctions if risk level is long-lasting and/or area covers a significant portion of a given species’ range.
Impact Analysis Risk Classes Percentages are relative to the FPC predictions of “natural” for the NDT under consideration.
Risk Assessment Steps 1 Establish context 2 Characterize environmental pressures 3 Select values and indicators 4 Characterize trends and relationships for indicators; define risk classes 5 Evaluate changes to indicators and risk for management options 6 Report results and develop risk reduction strategies
Risk Reduction Strategies • Identify “most limiting” habitat elements or non-habitat stresses • Identify management practices/ strategies linked to limiting factors • Recommend changes to management regimes to minimize risk
Administrative Application Levels • Operational • Site specific • Forest Development Plans • Strategic Planning • Landscape Units • Management Units (TSA, TFL) • Regional and Provincial
Biophysical Application Levels • Single species - habitat quality, minimum viable population • Habitat niches/species guilds - CWD, old growth • Watershed - stream channel stability, water quality, aquatic habitats • Landscape/regional levels - ecosystem processes, seral stage distribution
“Back-of-an-envelope” Analysis Values: fish/aquatic habitat Indicators: channel stability, ECA, road density Historic Conditions: 10% ECA (0-50?); NO roads Cumulative Impacts: over fishing, past mining disturbance, harvesting (25% ECA), roads = channel erosion and increased bar activity Risk Classes: ECA >30%+high road density = High Proposed Development: 35% ECA+more roads Results: High to Very High Risk Risk Reduction: Road rehab, partial cut, green-up
Risk Classes for Watersheds Based on Road Density and Equivalent Clearcut Area (ECA)
Habitat modelling normally means modelling for a single species Environmental Risk Assessment is more inclusive of ecosystem indicators such as, seral stages, riparian condition, coarse woody debris.
Kootenay/Boundary Region Long Term (250+ years) Low Risk High Risk