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BC Conservation Data Centre: Conservation Status Report

Purshia tridentata / Pseudoroegneria spicata
antelope-brush / bluebunch wheatgrass

 
Scientific Name: Purshia tridentata / Pseudoroegneria spicata
English Name: antelope-brush / bluebunch wheatgrass
   
Provincial Status Summary
Status: S2
Date Status Assigned: June 15, 2000
Date Last Reviewed: January 18, 2018
Reasons: This small patch community is distributed over a very small range. It has been seriously impacted by overgrazing, invasion of alien plant species, and forest encroachment associated with fire exclusion.
 
Range
Range Extent: D = 1,000-5,000 square km
Range Extent Estimate (km2): 3496
Biogeoclimatic Unit: IDFdm2/02
PPdh2/00
Range Extent Comments: The range of this ecological community is estimated with BEC map version 9 (B.C. Ministry of Forests, Lands and Natural Resource Operations, Biogeoclimatic Ecosystem Classification Map Version 9, 2014). It occurs in the lower elevations of the Rocky Mountain Trench.
Area of Occupancy (km2): G = 20-100 km²
Area of Occupancy Comments: The Grasslands Conservation Council of B.C. mapped 331 km2 of grasslands within the range of this ecological community in 2004 (Hectares BC, Open Grasslands Theme, accessed 19/01/2018). These grasslands belong to several different grassland associations, so the total area of this particular ecological community is likely less than 100 km2. Terrestrial ecosystem mapping (TEM) covers 23% of the range of this ecological community (TEM 1998o, 1999n, 2000e, 2001e, 2003i). Within the area covered by TEM, 6.24 km2 or 0.77% is identified as this ecological community. If these values are extrapolated to the range of this community, this ecological community is estimated to occupy 27 km2 (0.77% of 3496 km2) of its range.
Spatial Pattern: Small patch
 
Occurrences
Number of Occurrences: Rank Factor not assessed
Number of Occurrences with Good Viability / Ecological Integrity: Rank Factor not assessed
Percent Area with Good Viability / Ecological Integrity: B = Very small (<5%)
Comments: Very little of this ecological community is in good to excellent condition. It is difficult to find examples of late seral vegetation when field sampling grassland ecosystems (pers. obs. K. Iverson 2013-14; pers. comm. G. Berg and L. Columbo 2014).
 
Threats (to population, occurrences, or area affected)
Degree of Threat: B = High
Comments: Threats that directly and indirectly affect this ecological community include forest encroachment, domestic and wildlife grazing, ongoing  urban and commercial development, invasive alien plants, and climate change impacts.
 
Trend (in population, range, area occupied, and/or condition of occurrences)
Short-Term Trend: F = Decline of 10-30%
Comments: Grasslands are being lost to forest encroachment at a rate of approximately 1-2% per year (Ross 1998) or 30 km2 per year. Additional losses to human developments and invasive alien plants affect this community.
Long-Term Trend: D = Decline of 50-70%
Comments: Ross (1998) estimated a 50% loss of grasslands to encroachment from 1958 to 1994. Baseline Thematic Mapping indicates that 10% of the range of this ecosystem has been converted to urban or agricultural land cover (B.C. Ministry of Forests, Lands and Natural Resource Operations, Baseline Thematic Mapping, 19/01/2018). Invasive alien plants have been mapped in 20% of the range of this ecological community, though it is not known what proportion of that area has a high enough cover of invasive alien plants that it may not recover (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Invasive Alien Plant Site, accessed 19/01/2018).
 
Other Factors
Intrinsic Vulnerability: B=Moderately vulnerable
Comments: Soils on steep slopes are vulnerable to erosion with disturbance.
Environmental Specificity: C=Moderate. Generalist or community with some key requirements scarce.
Comments: This ecological community occurs on dry crests and upper slopes with shallow soils.
Other Rank Considerations:
 
Information Gaps
Research Needs:
Inventory Needs:
 
Stewardship
Protection:
Management: Requires active restoration efforts to maintain plant community.
 
Version
Author: Iverson, K. E.
Date: January 18, 2018
 
References
B. C. Forest Practices Board. 2007. The Effect of Range Practices on Grasslands: a test case for upper grasslands in the sourth central interior of British Columbia. Special Investigation FPB/SIR/19, July, 2007.
B.C. Ministry of Environment. Terrestrial Ecosystem Information System database (a). WHSE_TERRESTRIAL_ECOLOGY.STE_TEM_PROJECT_BOUNDARIES_SVW [ESRI ArcSDE format]. Ministry of Environment, Knowledge Management Branch. Victoria, B.C. Updated Regularly.
B.C. Ministry of Environment. Terrestrial Ecosystem Information System database (b). WHSE_TERRESTRIAL_ECOLOGY.STE_TEM_ATTRIBUTE_POLYS_SVW [ESRI ArcSDE format]. Ministry of Environment, Knowledge Management Branch. Victoria, B.C. Updated Regularly.
B.C. Ministry of Forests, Lands, and Natural Resource Operations. Biogeoclimatic Ecosystem Classification (BEC) Map, WHSE_FOREST_VEGETATION.BEC_BIOGEOCLIMATIC_POLY [ESRI ArcSDE format]. Version 9. Ministry of Forests, Lands, and Natural Resource Operations, Forest Analysis and Inventory Branch, Victoria, B.C. Updated Regularly.
B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development. Baseline Thematic Mapping Present Land Use Version 1 Spatial Layer, WHSE_BASEMAPPING.BTM_PRESENT_LAND_USE_V1_SVW. GeoBC, Ministry of Forests, Lands, and Natural Resource Operations and Rural Development. Victoria, B.C. Updated Regularly.
B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development. Digital Road Atlas (DRA) - Master Partially-Attributed Roads, WHSE_BASEMAPPING.DRA_DGTL_ROAD_ATLAS_MPAR_SP [ESRI ArcSDE format]. Ministry of Forests, Lands, and Natural Resource Operations, GeoBC. Victoria, B.C. Updated Regularly.
B.C. Ministry of Forests, Lands, and Natural Resources Operations. CBM - Integrated Cadastral Fabric (Public View), WHSE_CADASTRE.CBM_CADASTRAL_FABRIC_PUB_SVW [ESRI ArcSDE format]. Ministry of Forests, Lands, and Natural Resource Operations, GeoBC, Victoria, B.C. Updated Regularly.
B.C. Ministry of Forests, Lands, and Natural Resources Operations. Range Tenures, WHSE_FOREST_TENURE.FTEN_RANGE_POLY_SVW [ESRI ArcSDE format]. Ministry of Forests, Lands, and Natural Resource Operations, Provincial Range Operations, Victoria, B.C. Updated Regularly.
Biodiversity Guidebook. 1995. Forest Practices Code of British Columbia. B.C. Minist. For. and B.C. Minist. Environ., Victoria B.C. ix + 99p.
Boundary Invasive Species Society. 2014. Strategic Plan for Invasive Species Management in the Boundary. Rock Creek, BC.
Braumandl, T.F., and M.P. Curran. 1992. A field guide for site identification and interpretation for the Nelson Forest Region. B.C. Minist. For., Res. Branch, Victoria, Land Manage. Handb. No. 20.
British Columbia Government. Hectares BC. Victoria, BC. Open Grasslands Theme, data from Grasslands Conservation Council of B.C . Available: http://hectaresbc.ca/app/habc/HaBC.html
British Columbia Government. Hectares BC. Victoria, BC. Vegetation Resources Inventory theme. Available: http://hectaresbc.ca/app/habc/HaBC.html
Crowley, S. and M. Gall. 2011. East Kootenay Grassland Ecosystem Restoration: Project Synthesis: 2005-2010. Habitat Conservation Trust Fund Project 4-299. B.C. Ministry of Environment.
Dorey, J. 1979. A fire history investigation and effects of fire exclusion in a ponderosa pine forest in southeastern British Columbia. BSF thesis. Faculty of Forestry, University of British Columbia, Vancouver, B.C.
East Kootenay Invasive Species Council. 2013. 2013-2018 Regional Strategic Plan. East Kootenay, BC.
Flynn, Samantha. 2000. Plant Association Status Ranking 1999-2000. Access Digital Database. BC Ministry of Environment, Conservation Data Centre. Victoria, BC.
Forest Practices Board. 2015. Follow-up Report on Wildlife and Cattle Grazing in the East Kootenay. July 2015. FPB/SR/51.
Forest Practices Board. 2016. Restoring and Maintaining Rangelands in the East Kootenay. November 2016. FPB/SR/53.
Gayton, D. 1998. Calculation of forest ingrowth and resulting forage impact in BC's Rocky Mountain Trench. Ecosystem Management Specialist
Forest Research Extension Partnership, Nelson BC.
Gayton, D. 2004. Native and non-native plant species in grazed grasslands of British Columbia?s southern interior. BC Journal of Ecosystems and Management 5(1):51?59.
Grasslands Conservation Council of British Columbia. 2004. BC grasslands mapping project: A conservation risk assessment. Final report. 116 pp.
Hamann, A., and T. Wang. 2006. Potential effects of climate change on ecosystem and tree species distribution in British Columbia. Ecology 87 (11) Pp 27732786.
Nitschke, C.R. and J. Innes. 2008. Climatic change and fire potential in south-central British Columbia, Canada. Global Change Biology 14 (4):841-855.
Pacific Climate Impacts Consortium (PCIC). 2012. Plan2Adapt Online Tool. Pacific Climate Impacts Consortium, University of Victoria, Victoria, B.C. 
Pike, R., K. Bennett, T. Redding, A. Werner, D. Spittlehouse, R.D. Moore, T. Murdock, J. Beckers, B. Smerdon, K. Bladon, V. Foord, D. Campbell, & P. Tschaplinski. 2010. Climate change effects on watershed processes in British Columbia. In: R.G. Pike, T.E. Redding, R.D. Moore, R.D. Winkler, & K.D. Bladon (editors). Compendium of Forest Hydrology and Geomorphology in British Columbia. Land Management Handbook 66. BC Ministry of Forests and Range, Victoria, BC. pp. 699-747.
Rodenhuis, D.R., K.E. Bennett, A.T. Werner, T.Q. Murdock, & D. Bronaugh. 2009. Climate Overview 2007: Hydro-Climatology and Future Climate Impacts in British Columbia. Pacific Climate Impacts Consortium, University of Victoria, Victoria, B.C. http://pacificclimate.org/sites/default/files/publications/Rodenhuis.ClimateOverview.Mar2009.pdf
Ross, T. J. 1998. Forest ingrowth and encroachment between 1958 and 1994 on the Grasmere Range Unit. B.C. Ministry of Agriculture and Food, Kootenay/ Boundary Grazing Enhancement Fund, and Grasmere Grazing Association. 24pp. + appendices
Spittlehouse, D.L. 2008. Climate Change, impacts and adaptation scenarios: climate change and forest and range management in British Columbia. B.C. Min. For. Range, Res. Br., Victoria, B.C. Tech. Rep. 045. http://www.for.gov.bc.ca/hfd/pubs/Docs/Tr/Tr045.htm.
Terrestrial Ecosystem Mapping (TEM) and Wildlife Interpretations for the East Columbia Lake Study Area. 1998o. Prepared for Columbia Basin Fish and Wildlife Compensation Program, Invermere, B.C. by JMJ Holdings Inc. Nelson, B.C. 1:20 000 spatial data.
Terrestrial Ecosystem Mapping (TEM) of Premier Lake Study Area. 2001e. Prepared by G. Kernaghan and T. Robertson of JMJ Holdings Ltd., Nelson, B.C. 1:10 000 spatial data.
Terrestrial Ecosystem Mapping (TEM) of the Brewer Creek Study Area. 2003i. Prepared for Ministry of Environment, Lands and Parks. Invermere, B.C. by JMJ Holdings Inc., Nelson, B.C. 1:20 000 spatial data.
Terrestrial Ecosystem Mapping [TEM] and Bioterrain Mapping of the Galton Range. 1999m. Prepared for BC Ministry of Environment, Lands and Parks, Cranbrook BC by Wildlands Ecological Consulting Ltd. Red Deer, Alberta. 1:20,000 spatial data.
Terrestrial Ecosystem Mapping [TEM] of the Dunkley Lumber Ltd Tree Farm License 53. 1999n. Prepared by OIKOS Ecological Services, Ltd, Smithers, B.C. for Dunkley Lumber Ltd, Prince George, B.C. 1:20 000 spatial data.
Wang, T., E.M. Campbell, G.A. O'Neill, and S.N. Aitken. 2012. Projecting future distributions of ecosystem climate niches: Uncertainties and management applications. Forest Ecology and Management 279: 128-140.
Wikeem, B and S. Wikeem. 2004. Grasslands of British Columbia. Grasslands Conservation Council, Kamloops, B.C. 497pp. http://www.bcgrasslands.org/our-publications
 

Please visit the website Conservation Status Ranks for information on how the CDC determines conservation status ranks. For global conservation status reports and ranks, please visit the NatureServe website http://www.natureserve.org/.

Suggested Citation:

B.C. Conservation Data Centre. 2018. Conservation Status Report: Purshia tridentata / Pseudoroegneria spicata. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 16, 2026).