BC Conservation Data Centre: Conservation Status Report
Physocarpus malvaceus - Holodiscus discolor - Pseudoroegneria spicata
mallow ninebark - oceanspray - bluebunch wheatgrass
| Scientific Name: | Physocarpus malvaceus - Holodiscus discolor - Pseudoroegneria spicata |
|---|---|
| English Name: | mallow ninebark - oceanspray - bluebunch wheatgrass |
| Provincial Status Summary | |
| Status: | S2? |
| Date Status Assigned: | April 21, 2023 |
| Date Last Reviewed: | April 21, 2023 |
| Reasons: | |
| Range | |
| Range Extent: | E = 5,000-20,000 square km |
| Range Extent Estimate (km2): | 18869 |
| Biogeoclimatic Unit: |
ESSFwh3/Gb03
ICHdm/Gb03 ICHdw1/Gb03 ICHmk1/Gb03 ICHmw2/Gb03 ICHmw4/Gb03 ICHmw5/Gb03 ICHxw/Gb03 ICHxwa/Gb03 IDFdm1/Gb03 IDFdm2/Gb03 MSdw/Gb03 PPxh1/Gb03 |
| Range Extent Comments: | The range extent estimate of this ecological community is based on Version 12 of the Biogeclimatic Ecosystem Classification (BEC) map (B.C. Ministry of Forests, Lands and Natural Resource Operations, Biogeoclimatic Ecosystem Classification Map Version 12). This ecological community is present in various BEC subzone variants, though occurrences are infrequent in the ESSFwh3 where the community will typically occur at the transition between the ICH and ESSF. |
| Area of Occupancy (km2): | DE = 10-100 kmē |
| Area of Occupancy Estimate (km2): | 32.9 |
| Area of Occupancy Comments: | Targeted ecosystem mapping and field verification has been undertaken across the entire range of this ecological community (Teck Metals 2021). The community is uncommon across its range and is estimated to occur across 32.9 km2 (0.17%) of its range. Due to variability in mapping scales, 32.9 km2 may overestimate area occupied by this community. |
| Spatial Pattern: | Large patch |
| Occurrences | |
| Number of Occurrences: | Rank Factor not assessed |
| Comments: | There are approximately 144 occurrences of this ecological community mapped within its range, but this estimate does not account for fragmentation. |
| Number of Occurrences with Good Viability / Ecological Integrity: | Rank Factor not assessed |
| Percent Area with Good Viability / Ecological Integrity: | DE = Moderate to good (11-40%) |
| Comments: | Approximately 40.5 km2 (48%) of occurrences mapped with the target ecological community do not have roads, trails, or utility lines through them (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Digital Road Atlas, accessed March 2023). Persistent impacts from cattle grazing include establishment of invasive alien plant species like cheatgrass and knapweed. Even though cattle grazing may not presently occur at some locations of this ecological community, wildlife may be a vector for weedy species. Occurrences near Wanita have been heavily grazed in the past and are presently degraded, but have been fenced in the last 5 years. Historical grazing impacts have been documented at occurrences at the Gilpin, near the confluence of the Ponderey and Columbia rivers, in Creston valley and at nearby wildlife management areas and presently remain weedy. |
| Threats (to population, occurrences, or area affected) | |
| Degree of Threat: | B = High |
| Comments: |
A number of direct and indirect threats to this ecological community warrant a high overall threat rating. Cattle grazing is a medium impact threat. Range tenures cover 5.4 km2 (6%) of occurrences (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Range Tenures, accessed March 2023), though trespass grazing occurs in the Ponderey despite no official grazing tenures there. Creston, Waneta, and Gilpin are also presently heavily grazed, which may impact adjacent areas and limit ecological community recovery. Invasive alien plant species are a medium threat and are pervasive across mapped occurrences of this ecological community. Invasive alien plant species establish in areas with disturbed soil, including recreational trails, roads, utility corridors, intense fires, and areas used by livestock. Invasive alien plant and problematic native species include black locust, bracken, cheatgrass, knapweed, hairy vetch, St. Johns wort, sulphur cinquefoil, dalmatian toadflax, etc. Roads and utility lines are a low threat. Ongoing maintenance of right-of-ways promotes bracken growth that outcompetes shrub growth and establishment (Ehman and Machmer, Pers. Comm.). Approximately 6.5% of polygon area containing this ecological community are impacted by power lines (B.C. Ministry of Forests, Lands and Natural Resource Operations, Baseline Thematic Mapping, accessed March 2023), and 2.3% of polygon area containing this ecological community have been converted to roads (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Digital Road Atlas, accessed March 2023). Additional construction of spur trails is expected off the roads, and would result in further losses, fragmentation of this ecological community, alteration of environmental factors, impact vegetation assemblages, and allow for the spread of invasive plant species and recreational use of the brushlands. Pollution is a low threat. Approximately 18.8 km2 (23%) of this ecological community occurs within an area polluted by metals (lead, zinc, cadmium, arsenic, etc.) (LCEMP 2022). SO2 can raise soil pH and increases the risk of metals becoming unbound in soils. Effects on vegetation include chlorotic foliage and impacted growth. Fires and fire suppression are low threats. Fires that burn through surface organic material expose mineral soil for invasive alien plant infestation and is of particular concern in areas that are already weedy, like the lower Arrow. Near Waneta, areas that have experienced hot fires due to fire suppression have been shown to recover slowly. Hot fires may also volatize pollutants when soil is burned. Climate change is anticipated to be a low threat at this time. By the 2050s in the Kootenay-Boundary region of British Columbia, there is a predicted 3.2 degree Celsius annual temperature increase and a decrease of 5.2% in annual precipitation (Pacific Climate Impacts Consortium Plan2Adapt 2012; accessed March 2023). Prolonged end of summer dry season could result in increased vegetation mortality towards the end of August. Prolonged drought may impact these ecological communities because soils are dry and have limited water storage capacity. Changes to adjacent forested areas may impact hydrological balances of these areas. This combination of cl |
| Trend (in population, range, area occupied, and/or condition of occurrences) | |
| Short-Term Trend: | E = Decline of 30-50% |
| Comments: |
There are approximately 93.4 km of roads within polygons mapped with this community (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Digital Road Atlas, accessed March 2023). Road density within this ecological community is 1.12 km/km2. When a 10-meter buffer is applied to roads, 1.9 km2 (2.3%) of this ecological community is directly impacted by roads and trails. Roads and trails contribute to direct area loss and are also a vector for invasive alien plant species. There are 28 km of transmission lines within polygons mapped with this ecological community (B.C. Ministry of Forests, Lands and Natural Resource Operations, Baseline Thematic Mapping, accessed March 2023). Transmission line density within this ecological community is 0.34 km/km2. When a 100-meter buffer is applied to transmission lines, 5.4 km2 (6.5%) of this ecological community is directly impacted by transmission lines. Maintenance of transmission lines is ongoing and includes brushing and use of machinery and contributes to direct loss of area, soil disturbance, and is a vector for invasive alien plant species. Fires during 2007-8, 2016-18, and 2021 have affected 4.2 km2 of the area mapped with this ecological community (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Historical Fire Mapping, accessed March 2023). The next earliest fires occurred in 1984, suggesting some degree of active fire suppression. Since fire records started at the turn of the century, repeat fires burned 84.73 km2 of this ecological community. The expected fire return interval for surface fires is 10-20 years in the IDF, 5-15 years in the PP (Parminter et al 1992). Additionally, the ICHwx is NDT4. These fire return intervals suggest that the brushland sites should have a shorter fire return interval than observed in the past century. Approximately 18.8 km2 (23%) of polygons mapped with this ecological community occur within an area polluted by SO2, lead, zinc, cadmium, arsenic, etc. (LCEMP 2022). SO2 can impact soil pH. Soils within the impacted area were documented to have a pH of 4 where a pH of 6.5-7 was expected. Impacts of pollution include chlorotic foliage and decreased vegetation growth and vigor. Range tenures cover 5.4 km2 (6%) of polygons mapped with this ecological community (B.C. Ministry of Forests, Lands, and Natural Resources Operations and Rural Development, Range Tenures, accessed March 2023), but there are additional areas that are trespass grazed. Desirable forage for cattle is largely bluebunch wheatgrass. Recovery of heavily grazed area may occur very slowly if at all once grazing pressures are removed. Invasive alien plant species are pervasive through almost all polygons mapped with this ecological community. Dispersal of weeds largely occurs via cattle, horses, wildlife, heavy machinery, vehicles, and rogue trail builders. Impacts from weeds are persistent and require intensive management. Manual pulling has limited success as it creates additional soil disturbance. Moisture is required to maintain and establish shrubs that shade out weeds and may be limited during dry summers or when adjacent forested land cover is harvested. |
| Long-Term Trend: | E = Decline of 30-50% |
| Comments: | SO2 pollution in the 1920-30's impacted at least 23% of the ecological community, reducing resilience of these ecological communities and killing most vegetation within impacted areas. Cultural burning was also restricted during the past century. |
| Other Factors | |
| Intrinsic Vulnerability: | A=Highly vulnerable |
| Comments: | Shallow soils are highly susceptible to erosion, compaction and disturbance, especially on steep sites. Prolonged dry periods preclude shrub establishment. |
| Environmental Specificity: | C=Moderate. Generalist or community with some key requirements scarce. |
| Comments: | Warm aspect sites with coarse textured shallow soils are requirements of this ecological community. |
| Other Rank Considerations: | |
| Information Gaps | |
| Research Needs: | |
| Inventory Needs: | |
| Stewardship | |
| Protection: | |
| Management: | At these sites, water management during restoration becomes difficult due to slope position, lack of water storage in soils, and prolonged summer dry periods and may limit restoration success. |
| Version | |
| Author: | A. Ehman, M. Machmer, E. Cameron |
| Date: | April 21, 2023 |
| References | |
| No references available | |
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. 2023. Conservation Status Report: Physocarpus malvaceus - Holodiscus discolor - Pseudoroegneria spicata. B.C. Minist. of Environment. Available: https://a100.gov.bc.ca/pub/eswp/ (accessed Jun 5, 2026).