Northern spotted owl
1
A pairwise function was used for the main map to illustrate the most suitable habitats. Maps for point allocation and ratio estimation were produced for the sensitivity analysis. Ratio estimation showed more unsuitable areas in regards to point allocation. In comparison to the pairwise function, both weighting schemes showed identical locations of suitable and unsuitable habitats but with minor changes in weighting. This shows that the results are typical and not largely sensitive to changes in weighting. Habitat Suitability for the Northern Spotted Owl in British Columbia Christina Borowiec, Nicolette Francis, Kristin Clements BACKGROUND INFORMATION AND PURPOSE STUDY AREA FINDINGS AND RECOMMENDATIONS MODEL IMPROVEMENTS REFERENCES/DATA SOURCES HABITAT SUITABILITY Northern Spotted Owls are an endangered species known to live in southwestern British Columbia. They are found within old growth forests, with a preference for coniferous trees. Much of the species habitat has been disturbed and destroyed due to ongoing logging operations in the area. Scientists estimate that fewer than a dozen breeding pairs remain in the wild in Canada. Historic population figures state that about 500 pairs of owls were present in B.C. prior to European settlement. 1 Thus, recovery and protection of this species is of the upmost importance. The purpose of this project is to determine the areas that are most suitable for the habitat of the Northern Spotted Owl in B.C. The study area is located in southwestern British Columbia. The area is bounded in the south by the American and Canadian border, north by Elaho River, Pemberton and Carpenter Lake, west by the coastline, and east by Fraser Canyon, Coquihalla and Manning Park. 2 To produce the habitat suitability map for the Northern Spotted Owl throughout B.C., constraints, factors, and a weighted overlay based on Pairwise Comparison weighting was applied. The map depicts that the most suitable habitat for the Northern Spotted Owl in B.C. is primarily along the west coast, Vancouver Island, and a few areas in the middle of the province. Moderate levels of suitability are coloured yellow, and located to the middle and northeast. The least suitable areas are shown in red and are found near the northeastern corner of the province. A suitable habitat for the species must have an elevation below 1370 meters. Areas with elevations above this are beige on the map and are deemed unsuitable. Within the study area, most of the area is green, and therefore has the highest level of habitat suitability for the species. To begin, the model does not include a logging layer because it was difficult to find. Had this layer been added to the map, more accurate habitat suitability locations could have been shown. Also, the old growth forest layer was somewhat exclusive. Only trees with ages over 300 years were selected. Had a younger age been chosen (i.e. 200 years) then more suitable habitat locations for the Northern Spotted Owl would exist. 1. Canada. Canadian Wildlife Service. Species at Risk Public Registry. Species Profile: Spotted Owl (caurina subspecies). Government of Canada, 2013. Accessed October 14, 2013, from http://www.sararegistry.gc.ca/species/speciesDetails_e.cfm?sid=33. 2. Dupuis, L. Wildlife in British Columbia at Risk: Northern Spotted Owl. Government of British Columbia, 1998. Accessed October 14, 2013, from http://www.env.gov.bc.ca/wld/documents/spottedowl.pdf. BCStats. (2009). Provincial Electrical Districts [shp]. Retrieved from http://www.bcstats.gov.bc.ca/StatisticsBySubject/Geography/TranslationsDataSets.aspx. DataBC. (2013). VRI-Forest Vegetation Composite Polygons and Rank 1 Layer [shp] Retrieved from https://apps.gov.bc.ca/pub/geometadata/metadataDetail.do?recordUID=47574&recordSet=ISO19115. Commision for Environmental Cooperation. (2013). Rivers and Lake [shp]. Retrieved from http://www.cec.org/Page.asp?PageID=122&ContentID=2336. Commision for Environmental Cooperation. (2013). Major Roads [shp]. Retrieved from http://www.cec.org/Page.asp?PageID=122&ContentID=2336. U.S. Geological Survey’s Center for Earth Resources Observation and Science (EROS). (2010). 30 arc-second DEM of North America [raster grid] Retrieved from http://databasin.org/datasets/d2198be9d2264de19cb93fe6a380b69c. DECISION CRITERIA Criteria Factor Constraints Methods Pairwise Comparison (weights) Point Allocation (weights) Ratio Estimation (weights) Old Growth Closer the better Must be within old growth forest Euclidean distance 0.57 0.50 0.43 Elevation Lower the elevation the better Must be below 1370 meters Reclassified DEM 0.24 0.25 0.32 Rivers Closer the better Euclidean distance 0.04 0.05 0.06 Lakes Closer the better Euclidean distance 0.04 0.05 0.06 Roads Further away the better Euclidean distance 0.11 0.15 0.13 SENSITIVITY ANALYSIS STUDY AREA CONCLUSIONS The utilization of constraints, factors, and pairwise weighting to determine the habitat suitability for the Northern Spotted Owl in B.C. was successful. However, a few model improvements could be implemented to improve the results. Nevertheless, the output supports previous research of the owls habitat in the study area. METHODS AND ASSUMPTIONS The following assumptions were made when determining the most suitable habitat for the species: the species is not affected by factors outside the study area, but is affected by all factors within the “Decision Criteria” . In regards to methods, the Euclidean distance and Reclassify tools were used. Habitats for the Northern Spotted Owl are better when “closer” to old growth forests, rives, and lakes, “further” from roads, and in areas of “lower” elevation. These methods are displayed in the cartographic model.
-
Upload
mcmaster-school-of-geography-earth-sciences -
Category
Documents
-
view
213 -
download
0
description
Habitat Suitability model from GEOG 3GI3, Fall, 2013
Transcript of Northern spotted owl
A pairwise function was used for the main map to illustrate the most suitable habitats. Maps for point allocation and ratio estimation were produced for the sensitivity analysis. Ratio estimation showed more unsuitable areas in regards to point allocation. In comparison to the pairwise function, both weighting schemes showed identical locations of suitable and unsuitable habitats but with minor changes in weighting. This shows that the results are typical and not largely sensitive to changes in weighting.
Habitat Suitability for the Northern Spotted Owl in British Columbia Christina Borowiec, Nicolette Francis, Kristin Clements
BACKGROUND INFORMATION
AND PURPOSE
STUDY AREA
FINDINGS AND RECOMMENDATIONS
MODEL IMPROVEMENTS
REFERENCES/DATA SOURCES
HABITAT SUITABILITY
Northern Spotted Owls are an endangered species known to live in southwestern British Columbia. They are found within old growth forests, with a preference for coniferous trees. Much of the species habitat has been disturbed and destroyed due to ongoing logging operations in the area. Scientists estimate that fewer than a dozen breeding pairs remain in the wild in Canada. Historic population figures state that about 500 pairs of owls were present in B.C. prior to European settlement.1 Thus, recovery and protection of this species is of the upmost importance. The purpose of this project is to determine the areas that are most suitable for the habitat of the Northern Spotted Owl in B.C.
The study area is located in southwestern British Columbia. The area is bounded in the south by the American and Canadian border, north by Elaho River, Pemberton and Carpenter Lake, west by the coastline, and east by Fraser Canyon, Coquihalla and Manning Park.2
To produce the habitat suitability map for the Northern Spotted Owl throughout B.C., constraints, factors, and a weighted overlay based on Pairwise Comparison weighting was applied. The map depicts that the most suitable habitat for the Northern Spotted Owl in B.C. is primarily along the west coast, Vancouver Island, and a few areas in the middle of the province. Moderate levels of suitability are coloured yellow, and located to the middle and northeast. The least suitable areas are shown in red and are found near the northeastern corner of the province. A suitable habitat for the species must have an elevation below 1370 meters. Areas with elevations above this are beige on the map and are deemed unsuitable. Within the study area, most of the area is green, and therefore has the highest level of habitat suitability for the species.
To begin, the model does not include a logging layer because it was difficult to find. Had this layer been added to the map, more accurate habitat suitability locations could have been shown. Also, the old growth forest layer was somewhat exclusive. Only trees with ages over 300 years were selected. Had a younger age been chosen (i.e. 200 years) then more suitable habitat locations for the Northern Spotted Owl would exist.
1. Canada. Canadian Wildlife Service. Species at Risk Public Registry. Species Profile: Spotted Owl (caurina subspecies). Government of Canada, 2013. Accessed October 14, 2013, from http://www.sararegistry.gc.ca/species/speciesDetails_e.cfm?sid=33.
2. Dupuis, L. Wildlife in British Columbia at Risk: Northern Spotted Owl. Government of British Columbia, 1998. Accessed October 14, 2013, from http://www.env.gov.bc.ca/wld/documents/spottedowl.pdf.
BCStats. (2009). Provincial Electrical Districts [shp]. Retrieved from http://www.bcstats.gov.bc.ca/StatisticsBySubject/Geography/TranslationsDataSets.aspx. DataBC. (2013). VRI-Forest Vegetation Composite Polygons and Rank 1 Layer [shp] Retrieved from https://apps.gov.bc.ca/pub/geometadata/metadataDetail.do?recordUID=47574&recordSet=ISO19115. Commision for Environmental Cooperation. (2013). Rivers and Lake [shp]. Retrieved from http://www.cec.org/Page.asp?PageID=122&ContentID=2336. Commision for Environmental Cooperation. (2013). Major Roads [shp]. Retrieved from http://www.cec.org/Page.asp?PageID=122&ContentID=2336. U.S. Geological Survey’s Center for Earth Resources Observation and Science (EROS). (2010). 30 arc-second DEM of North America [raster grid] Retrieved from http://databasin.org/datasets/d2198be9d2264de19cb93fe6a380b69c.
DECISION CRITERIA
Criteria
Factor
Constraints
Methods
Pairwise
Comparison
(weights)
Point
Allocation
(weights)
Ratio
Estimation
(weights)
Old Growth
Closer the
better
Must be
within old
growth
forest
Euclidean
distance
0.57
0.50
0.43
Elevation Lower the
elevation the
better
Must be
below 1370
meters
Reclassified
DEM
0.24
0.25
0.32
Rivers Closer the
better
Euclidean
distance
0.04
0.05
0.06
Lakes Closer the
better
Euclidean
distance
0.04
0.05
0.06
Roads Further away
the better
Euclidean
distance
0.11
0.15
0.13
SENSITIVITY ANALYSIS
STUDY AREA
CONCLUSIONS The utilization of constraints, factors, and pairwise weighting to determine the habitat suitability for the Northern Spotted Owl in B.C. was successful. However, a few model improvements could be implemented to improve the results. Nevertheless, the output supports previous research of the owls habitat in the study area.
METHODS AND ASSUMPTIONS The following assumptions were made when determining the most suitable habitat for the species: the species is not affected by factors outside the study area, but is affected by all factors within the “Decision Criteria”. In regards to methods, the Euclidean distance and Reclassify tools were used. Habitats for the Northern Spotted Owl are better when “closer” to old growth forests, rives, and lakes, “further” from roads, and in areas of “lower” elevation. These methods are displayed in the cartographic model.
