Buffalograss (Buchloë dactyloides) recovery strategy: chapter 3
- 2.1 Recovery Feasibility
- 2.2 Recovery Goal
- 2.3 Population and Distribution Objective(s)
- 2.4 Recovery Objectives
- 2.5 Approaches Recommended to Meet Recovery Objectives
- 2.6 Critical Habitat
- 2.7 Effects on Other Species
- 2.8 Statement on Action Plans
2.1 Recovery Feasibility
The recovery of buffalograss in Canada is considered feasible because 1) individuals capable of reproduction are available; 2) sufficient suitable habitat is available or could be made available through habitat management; 3) some of the significant threats to the species can be mitigated through stewardship agreements and beneficial management practices; and 4) the techniques for effective recovery appear achievable.
2.2 Recovery Goal
The recovery goal for buffalograss is to maintain the persistence of all naturally occurring4 populations in Canada.
The status of this species is not likely to be down-listed from threatened based on COSEWICassessment criteria for populations having a very restricted area of occupancy or number of locations which put it at risk of being impacted by human activities or stochastic events (COSEWIC2006). Nevertheless, it should be feasible to maintain this species under the normal range of environmental conditions with successful management of threats, implementation of stewardship agreements and beneficial management practices. Therefore, in the absence of information documenting the full area of occupancy and monitoring data to demonstrate a trend, the maintenance of populations and their habitat will define the recovery of buffalograss.
2.3 Population and Distribution Objective(s)
A numeric population objective cannot be described for this species. Buffalograss is a clonal species which forms patches containing hundreds or thousands of individuals which would not be feasible to count. The clonal patches often merge with other patches because of the stoloniferous nature, resulting in large, dense mats. This makes it impossible to distinguish and count individual clones. Further complications arise because burs often drop below the female plant, and new individuals can then grow very close to the parent plant, and soon thereafter form their own clone. Therefore, only distribution objectives will be set for this species.
The distribution objectives for this species will be set at two scales. At a finer scale, the distribution objectives will be based on buffalograss patch sizes, or the area of occupancy. At a coarser scale, the distribution objectives will be based on the number of quarter-sections in which buffalograss has been confirmed5, to represent a biologically relevant unit where soil, vegetation and management practices overlap and contribute to the occurrence of this species.
The area of occupancy of known buffalograss occurrences has not been determined for all of the quarter-sections in which it occurs. Also, new sites in additional quarter-sections are likely to be found with future survey effort. Nevertheless, we have established minimum area objectives. These should be viewed as short-term objectives (5 years) until more detailed mapping, surveying, and monitoring, allow refinement to more accurately represent the area of occupancy.
- Saskatchewan - Estevan population. Maintain at least 1.27 hectares in at least 17 quarter-sections.
- Manitoba - Souris River population. Maintain at least 402 hectares in approximately 43 quarter-sections.
- Manitoba - Sourisford Park population. Maintain at least 0.01 hectares (136 m²) in at least 1 quarter-section.
- Manitoba - Blind River Valley North (Element occurrence number 6). Maintain at least 4.2 hectares in at least 2 quarter-sections.
- Manitoba - Blind River Valley South (Element Occurrence Number 5). Maintain at least 0.79 hectares (7974 m²) in at least 1-2 quarter-sections.
- Manitoba - Blind River Valley East (Element Occurrence Number 11). Maintain at least 0.01 hectares (137 m²) in at least 1 quarter-section.
2.4 Recovery Objectives
Objective 1: Develop and promote beneficial management practices and stewardship agreements to land owners, land managers, stakeholders and industry to reduce threats to buffalograss and its habitat by 2012 (Priority – Urgent).
Objective 2: Complete critical habitat identification by 2011 (Priority – Urgent).
Objective 3: Identify extent of occurrence and area of occupancy of buffalograss populations, to the extent possible, by 2012 (Priority - Necessary).
The rationale for objective 3 is based on the limited area of habitat remaining to be surveyed for buffalograss and the relative ease with which this perennial species can detected in the field. Our underlying aim is to proceed with adaptive sampling until we achieve an asymptote where few or no new populations are located as the area searched increases and area remaining to be searched decreases.
Objective 4: Monitor trends in area of occupancy for existing populations through 2017 (Priority - Beneficial).
2.5 Approaches Recommended to Meet Recovery Objectives
The intent of this recovery strategy is to provide a general description of the research and management activities recommended to meet the objectives and address the threats (Table 2). The recovery strategy will be reviewed in five years to evaluate the progress on meeting its objectives and to identify additional approaches and changes that may be required. Performance measures that can be used to evaluate progress in meeting the recovery objectives are included in Table 2. The action plan(s) will contain more detailed information on the actions and the implementation schedule.
|Threats addressed||Priority||Broad strategy||Recommended approaches to meet recovery objectives||Performance Measures|
|Objective 1: Develop and promote beneficial management practices and stewardship agreements to land owners, land managers, stakeholders and industry to reduce threats to buffalograss and its habitat by 2012.|
|All threats||Urgent||Stewardship, Outreach, Habitat and Species Protection, Research, Management||
|Objective 2: Complete critical habitat identification by 2011.|
|All threats||Urgent||Research, Habitat Protection||
|Objective 3. Identify extent of occurrence and area of occupancy of buffalograss populations, to the extent possible, by 2012.|
|All threats||Necessary||Population inventory||
|Objective 4: Monitor trends in area of occupancy for existing populations through 2017.|
|All threats||Beneficial||Population monitoring||
2.6 Critical Habitat
2.6.1 Identification of the species' critical habitat
Critical habitat is defined in the Species at Risk Act (Subsection 2(1)) as “the habitat that is necessary for the survival or recovery of a listed wildlife species and that is identified as the species' critical habitat in the recovery strategy or in an action plan for the species”.
The majority of the information available on buffalograss in Canada has only been recently collected and lacks the coverage, quantitative detail, spatial and temporal scale necessary to identify scientifically-defensible and comprehensive critical habitat. The identification of critical habitat will occur following additional survey effort and will be done in one or more action plans. Consultations on critical habitat within the action plans will be required with landowners and lessees, as all known populations of buffalograss occur on private or municipal land in Manitoba and private or provincial crown land in Saskatchewan.
A schedule of studies has been outlined to aid in critical habitat identification and addressing knowledge gaps (see section 2.6.2 Schedule of studies to identify critical habitat). Identification of complete critical habitat will be based on the best scientific information available and expert opinion concerning the species' present and historical range, habitat, biology, and threats. Information reviewed will include known locations, the reason for listing the species, recent biological surveys and reports, peer-reviewed literature, local people and First Nations knowledge, the recovery strategy, and discussions and recommendations from plant experts. Specific locations and land descriptions of critical habitat may be withheld from the Public Registry to protect the species, as well as landowner privacy. Complete critical habitat will be identified with guidance from this recovery strategy as well as guidance from the Recovery Team and will be completed by or before December 2011 as part of the action plan(s).
2.6.2 Schedule of studies to identify critical habitat
Table 2 outlines recommended research and management activities to effect recovery and support the identification of critical habitat. This section outlines specific recommended studies and actions necessary in the identification of complete critical habitat:
- Collect information on habitat characteristics from known populations, as well as unoccupied sites, using standardized methods suitable for the species, that will be used in developing habitat suitability models. This information may be analyzed using multivariate analysis to identify key factors explaining the occurrence and abundance of buffalograss. Analysis will assist in determining locations and conditions under which critical habitat will be identified (to be completed by 2010).
- Identify additional suitable habitat, based on geospatial data, expert opinion, and habitat suitability modelling. Survey this habitat for new occurrences using standardized methods suitable for buffalograss (to be completed by 2010).
- Monitor existing populations to determine trends in area of occupancy, using standardized methods suitable for buffalograss. At least three intervals of monitoring are required for an accurate estimate of trends (to be completed by 2012-2017). Results will be used in population viability analysis (see step 5).
- Initiate genetic research among populations to determine genetic similarity and magnitude of isolation effects (to be completed by 2011). Results will be used in population viability analysis (see step 5).
- Perform population viability analyses (PVAs). The PVA will assist in determining which populations are viable and thereby assist in prioritizing critical habitat designation. However, reliable PVAs typically require long-term data sets. Because of dormancy in plants, short-term studies have been found to inflate mortality estimates when used in PVAs (Menges 2000), and long-term experiments are often needed to quantify seed bank dynamics (Reed et al. 2002). Therefore, it is unlikely a reliable PVA can be completed in less than 5 years for which there are limited data by the time critical habitat is designated in the action plan(s) by 2011. If this is the case, results from studies completed to date and the precautionary principle will be used to designate critical habitat for the action plan(s). Once enough information has been collected for a PVA, the areas initially designated for critical habitat will be reassessed.
2.7 Effects on Other Species
A few federally listed species at risk may be found in the same general area as buffalograss in Manitoba and Saskatchewan, including the Dakota skipper (Hesperia dacotae), Sprague's Pipit (Anthus spragueii), Burrowing Owl (Athene cunicularia) and the monarch butterfly (Danausplexippus). In addition, many provincially rare species also occur in these areas including the Baird's Sparrow (Ammodramus bairdii), whorled milkweed (Asclepias verticillata), whorled milkwort (Polygala verticillata var. isocycla), prairie bird's-foot trefoil (Lotus purshianus), purple coneflower (Echinacea angustifolia), and side-oats grama (Bouteloua curtipendula), among others (see Harms in press). These species would all benefit from conservation of native prairie, although beneficial management practices differ amongst them.
Management practices, including disturbances such as fire and grazing which would benefit buffalograss, are natural components of prairie ecosystems and may not negatively impact other native species particularly if the timing, intensity and frequency mimic natural processes (Samson and Knopf 1994). As mentioned in section 1.6.2, fire and grazing practices tend to reduce invasive exotic species and some competitively dominant native species, which is usually beneficial to an ecosystem (Higgins et al. 1989, Milchunas et al. 1989, Milchunas et al. 1992). However, in any management plan decisions should be made that benefit all target species and minimize negative effects to non-target native species. Any actions proposed for buffalograss should consider the impact on other species, and should include communication with other recovery teams working in the same area for the most efficient use of resources and to avoid duplication or conflicts with research. The creation of a multiple-species action plan may be beneficial for species inhabiting this ecosystem and should be considered.
2.8 Statement on Action Plans
The action plans for buffalograss will be completed by or before December 2011. Action plans will be completed by jurisdictions with guidance from this recovery strategy and the Recovery Team. There is the potential for a multispecies or an ecosystem-based action plan that could benefit multiple species at risk inhabiting this ecosystem. Steps to achieve recovery as listed in the recovery objectives will be ongoing in the interim.
4 Naturally occurring population refers to any population within the native range on naturally occurring habitat. It excludes horticultural populations or those that are dispersed by humans and establish themselves outside the native range or on unnatural habitats.
5 In Manitoba, the quarter-sections identified are based on polygons that have differing degrees of locational uncertainty as defined by NatureServe standards; therefore, it is possible that some quarter-sections listed may not actually contain buffalograss (C. Foster, pers. comm.).
6 Adaptive sampling, and other designs like adaptive cluster sampling or stratified adaptive cluster sampling, involve sampling at predetermined locations, and increasing or decreasing sampling effort in surrounding areas depending on the success of encountering the species (Thompson 1990, 1991, Smith et al. 2004). Adaptive monitoring continually uses existing monitoring data and applied management and monitoring actions to determine the intensity levels of future monitoring, and where it needs to occur (Ringold et al. 1996, Smit 2003).
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