Habitat modelling for Pacific water shrew SOBE capability ratings Vancouver watersheds W N E High Moderate Low Very Low / Nil >650m elevation Water S Photo credit: C. Schmidt
Prepared for: South Coast Conservation Program Species at Risk Training for Professionals Workshop 2: Pacific water shrew habitat management March 11, 2008 By: Vanessa Craig, Ph.D., R.P.Bio. EcoLogic Research 406 Hemlock Ave., Gabriola Island, BC V0R 1X1 Tel: (250) 247-7435 Email: Vanessa.Craig@EcoLogicResearch.ca www.ecologicresearch.ca
Habitat modelling Is a widely used technique for mapping and describing habitat values Defines the relative importance of various ecological units Allows extrapolation of information over a large area A repeatable technique easily updated to incorporate more information Allows the prediction of the spatial distribution of a species
Habitat models Can be used to prioritize areas for research stratify research effort Conduct landscape level planning (such as corridors), and identify habitat essential for the survival of the species
Two types of mapping data TEM Terrestrial Ecosystem Mapping Requires direct photo interpretation of ecosystem attributes by a mapper and rigorous field verification Typically used at larger scales where require detailed info Assigns an ecological site series classification to an area based on site indicators such as soil moisture, soil nutrient status, and plant communities Available at a few sites in the lower mainland (Vancouver watersheds, Mount Seymour, Chilliwack River Valley) The provincial standard for habitat capability/suitability modelling
Two types of mapping data PEM Predictive Ecosystem Mapping A modelling approach Typically used at smaller scales where less info Existing knowledge of ecosystem attributes and relationships are used to predict ecosystem representation in the landscape Cheaper to obtain Not available for lower mainland
Habitat modelling The mapping data are combined with species- or guild-specific habitat ratings to develop a spatiallybased map of habitat
Habitat ratings There are two main categories of habitat ratings: A capability rating is defined as the ability of the habitat, under the optimal natural conditions, to provide suitable habitat for a species, irrespective of its current condition A suitability rating is defined as the ability of the habitat in its current condition to provide suitable habitat for a species
Habitat Photo credit: V. Craig, EcoLogic Research
Habitat Photo credit: V. Craig, EcoLogic Research
Habitat Photo credit: D, Nagorsen
Habitat modelling During modelling, the habitat capability or suitability of habitat types is rated based on known habitat associations of the species Ratings are typically in a series of 4 or 6, depending on the level of information available about the species Ratings may also vary by season (e.g. breeding habitat, wintering habitat), while other ratings are for year-round habitat Ratings are relative to a benchmark habitat There are RISC standards which prescribe how a model is to be created and documented
Habitat model A habitat model has been created for Pacific water shrew TEM-based model Ratings are on a 4-series scale for year-round habitat use High (1), Moderate (2), Low (3), Nil (4) Nil (4) ratings increase to Low (3) within 100 m of water Ratings available in the document Species Account and Preliminary Habitat Ratings for Pacific Water Shrew (Sorex bendirii) using TEM Data v. 2 Ratings for habitat capability and suitability are available Only habitat capability ratings are used during environmental assessments
Habitat model Benchmark habitat Highest ratings were assigned to site series with indicators of very wet habitat (e.g. skunk cabbage, Labrador tea), and riparian habitat with diverse understorey communities Both moderate and high rated habitat is considered very suitable for Pacific water shrew
Habitat model How was this model created? Reviewed plant communities and description of each site series known to occur in the range of Pacific water shrew
Habitat model Example CWHms1 07 Ss Salmonberry 08 Act Red-osier dogwood 09 Act -- Willow
Habitat model Example CWHms1 PWS ratings 4 4 4 3 4 2 2 1 2 1 1 07 08 09
Habitat model Can easily be revised to incorporate new information Include additional information submitted to MoE by consultants and researchers Information on habitat in areas where PWS is present and in areas where they are absent
Example Habitat model applied to (non-standard) TEM from the Vancouver watersheds
Example About 10 km long Stretch of high capability habitat
Example Presence of high capability habitat Recommend protection of high capability habitat associated with stream with 100 m sections of protective habitat If possible, protect 1.5 linear km more likely to protect a population of Pacific water shrews
Example No high or moderate capability habitat Conduct livetrapping session in low quality habitat If capture PWS, recommend habitat protection If no capture of PWS, no habitat protection required Report all habitat and trapping data to MoE
Example High capability habitat in discrete sections Recommend 100 m protective area around high capability habitat + connecting habitat Approx 1.6 km of linear stream habitat
Potential drawbacks to TEM model The emphasis is on the terrestrial habitat, and does not incorporate information about watercourses Habitat could be rated capable that is not close to water Addressed in guidelines by only requiring an EA when project is to occur within 100 m of water, and will alter the habitat Habitat could be rated not capable when it is close to water, and has potential to serve as corridor habitat Addressed in guidelines by increasing habitat ratings from Nil to Low within 100 m of water (and thus requiring trapping)
Potential drawbacks to TEM model The TEM model works in conjunction with TRIM (Terrain Resource Information Mapping) data to identify the presence of water However, TRIM does not identify many smaller or nonpermanent watercourses or small wetlands Thus the model will not always correctly assign habitat suitability/capability ratings This is potentially an issue for on-the-ground assessments as well, for example if the assessment is conducted in the summer when some intermittent streams/non-permanent ponds may dry up
Potential drawbacks to TEM model The TEM model is only appropriate for assessing habitat capability/suitability of natural forested sites Not useful for assessing anthropogenic (modified) areas such as agricultural areas, ditches, or right-of-ways Areas such as these may appear blank in TEM data (not an issue for on-the-ground assessments) Addressed by adding in section to model that assigns a moderate ranking to all non-classified wetlands, and a low rating to anthropogenic sites such as ditches
Habitat modelling TEM modelling has the potential to assist in the identification of important areas of habitat across the range of PWS Assist in landscape planning (corridors), prioritize areas for protection or assessment Feedback from consultants on habitat assessments is important to ensure the accuracy of the model The model is a living document that will be modified as new information becomes available