Buffalograss (Bouteloua dactyloides): management plan 2023

Official title: Management Plan for the Buffalograss (Bouteloua dactyloides) in Canada

Species at Risk Act
Management Plan Series

2023

Preface

The federal, provincial, and territorial government signatories under the Accord for the Protection of Species at Risk (1996)^{Footnote 2} agreed to establish complementary legislation and programs that provide for effective protection of species at risk throughout Canada. Under the Species at Risk Act (S.C. 2002, c.29) (SARA), the federal competent ministers are responsible for the preparation of management plans for listed species of special concern and are required to report on progress five years after the publication of the final document on the SAR public registry .

The Minister of Environment and Climate Change is the competent ministers under SARA for the Buffalograss and has prepared this management plan as per section 65 of SARA. To the extent possible it has been prepared in cooperation with the province of Manitoba, and the province of Saskatchewan as per section 66(1) of SARA.

Success in the conservation of this species depends on the commitment and cooperation of many different constituencies that will be involved in implementing the directions set out in this plan and will not be achieved by Environment and Climate Change Canada, or any other jurisdiction alone. All Canadians are invited to join in supporting and implementing this plan for the benefit of the Buffalograss and Canadian society as a whole.

Implementation of this management plan is subject to appropriations, priorities, and budgetary constraints of the participating jurisdictions and organizations.

Acknowledgments

The management plan was prepared by Candace Neufeld (Environment and Climate Change Canada, Canadian Wildlife Service – Prairie Region) with contributions from Sarah Lee (Environment and Climate Change Canada – Canadian Wildlife Service, Prairie Region). Valuable reviews were provided by Yeen Ten Hwang and Medea Curteanu (Environment and Climate Change Canada – Canadian Wildlife Service, Prairie Region), Thomas Calteau (Environment Canada – National Capital Region), Manitoba Conservation and Saskatchewan Ministry of Environment. The Manitoba Conservation Data Centre and Saskatchewan Conservation Data Centre provided updated element occurrence information. Acknowledgement and thanks is given to all other parties that provided advice and input used to help inform the development of this management plan. The co-operation of all the landowners, lessees and land managers who granted access to their land to do surveys and who continue to provide habitat for species at risk is greatly appreciated.

Executive summary

Buffalograss (Bouteloua dactyoides) is a perennial grass. It reproduces asexually by aboveground stems that root at points along its length to form new plants (stolons), or by underground creeping stems (rhizomes), and sexually by male and female flowers which occur on separate plants. Seeds from the female plant are contained within protective, globular, hardened structures called burs.

In Canada, Buffalograss is restricted to two localized populations. One population is in southeast Saskatchewan and one population is in southwest Manitoba, both associated with the Souris River valley and tributaries.

Currently identified threats of low level impact or higher to Buffalograss are related to habitat loss and degradation from: invasive alien species; mining and quarrying; oil wells and related structures; natural system modifications due to a lack of grazing and/or fire suppression, urban or acreage development; cultivation; road construction and maintenance.

The management objective for Buffalograss is to ensure long-term persistence and natural expansion of all extant native populations in Canada, including any newly located or reconfirmed populations, within the natural range of variability. Broad strategies and conservation measures to address the threats are presented in the section on Broad Strategies and Conservation Measures.

1. COSEWIC* Species assessment information

Date of assessment: November 2011

Common name: Buffalograss

Scientific name: Bouteloua dactyloides

COSEWIC status: Special Concern

Reason for designation: This grass occurs in limited areas of remnant short-grass prairie in southern Saskatchewan and Manitoba. Threats to this species include coal strip mining, invasive alien plants and overgrowth by woody vegetation and high grass that were once controlled by bison grazing and fire. However, recent survey efforts have increased the known number of populations and it no longer qualifies as a threatened species.

Canadian occurrence: SK, MB

COSEWIC status history: Designated Special Concern in April 1998. Status re-examined and designated Threatened in November 2001. Status re-examined and designated Special Concern in November 2011.

* COSEWIC – Committee on the Status of Endangered Wildlife in Canada

2. Species status information

In Canada, Buffalograss (Bouteloua dactyloides) was listed as special concern under Schedule 1 of the Species at Risk Act (SARA) in 2017, having been downlisted from threatened status It is protected in Manitoba where it is listed as threatened under the provincial Endangered Species and Ecosystem Act. The conservation status of Buffalograss throughout its range in North America is described in Table 1. In the United States, detailed information is not available on the abundance of Buffalograss, but it is a co-dominant species in the core parts of its range and is considered abundant and widespread. Therefore, the percent of the species’ global distribution and abundance currently found in Canada is estimated to be less than 1%, based on its known range.

3. Species information

3.1. Species description

Buffalograss is a member of the grass family (Poaceae). Leaves are grayish-green and curly, about 2-10 cm long and 1-2 mm wide, with fine hairs on the upper and lower surfaces, including a fringe of hair where the leaf meets the stem. This perennial, warm‑season (C4) shortgrass is unusual because it can reproduce asexually (vegetatively) by above-ground stems that root at nodes to form new plants (stolons) and horizontal underground stems (rhizomes), as well as sexually by male and female flowers which almost always occur on separate plants (dioecious) (Mueller 1941, Quinn and Engel 1986, Huff and Wu 1992). Male plants have 2 or 3 flowering spikes, with each spike containing many spikelets. Spikelets are arranged in two rows on one side of the spike and each spikelet contains two pollen-bearing grass flowers. Pollen is wind dispersed, although dispersal distance is limited because the pollen is released close to the ground (Jones and Newell 1946, Beetle 1950, Quinn 1998). Male flowering spikes superficially resemble flowering spikes of Blue Grama (Bouteloua gracilis), and because both species occur in the same habitat, Buffalograss is often overlooked. Female plants have two or three female flowers hidden among the grass leaves, and enclosed in a bur-like structure on a short stalk. Upon maturing, these structures harden into globular, toothed burs containing 1-5 seeds (Looman and Best 1979, Boivin 1981, Quinn and Engel 1986, COSEWIC 2001). Flowering times vary among plants (Quinn 1991), but in Canada most flowering is complete by mid-July with ripened seed shattering by late July or early August (C. Neufeld, pers. obs.).

Buffalograss seeds, even within a single bur, have varying germination and dormancy periods, which may allow multiple chances to colonize a single microsite under varying climatic and competitive conditions (Quinn 1987). The burs protect seeds from fire or heat damage, desiccation, or animal digestion. Burs also aid in dispersal, anchor seedlings to the ground, enhance seed longevity and inhibit germination until sufficient moisture is available (Ahring and Todd 1977, Quinn 1987). Dispersal of the bur by wind is limited because of its weight and location lower down in the foliage; thus, seeds tend to end up clumped in the soil near parent plants (Coffin and Lauenroth 1989, Quinn 1998). Long distance dispersal of burs is achieved through ingestion and passage through the intestinal tract of grazers (e.g., cattle or bison), and to a lesser extent by attachment to animal fur, mud on animal hooves, or in runoff water after a storm (Quinn 1987, Quinn 1991, Quinn et al. 1994, Quinn 1998). At least 50% of burs contain seeds producing both male and female plants (Quinn and Engel 1986, Quinn 1987). Vegetative dispersal occurs mainly by stolons, which root at the nodes, resulting in clonal patches as large as 3 m or more in diameter. Under ideal conditions, stolons can grow as much as 5.72 cm per day whereas rhizomes only spread about 0.6 cm per year (Mueller 1941, Quinn 1991, COSEWIC 2001).

3.2. Species population and distribution

Global distribution

Buffalograss is native to North America, ranging from the southern Mexico, through the west interior basin, and south-central and west-central semi-arid prairies of the United States (U.S.), to the temperate semi-arid prairies of Canada (Figure 1). In Canada, Buffalograss is only known to occur in south-east Saskatchewan and south-west Manitoba.

Figure 1. Current distribution of Buffalograss in North America (Kartesz 2015, Villaseñor 2016, Manitoba Conservation Data Centre unpubl. data 2019, Saskatchewan Conservation Data Centre unpubl. data 2019, Pacific Northwest Herbarium unpubl. data 2020, Montana Natural Heritage Program unpubl. data 2020).

Canadian distribution

In Canada, Buffalograss is restricted to localized areas of Manitoba and Saskatchewan (Figure 2). In Manitoba, there is one extant^{Footnote 3} population^{Footnote 4} which occupies portions of 67 quarter sections in the Souris River Valley and its tributaries (Manitoba Conservation Data Centre, unpubl. data 2019; Appendix A). In Saskatchewan, there is also only one extant population along the Souris River Valley, southwest of Estevan, occupying portions of 27 quarter sections (Saskatchewan Conservation Data Centre, unpubl. data 2019; Appendix A). The full extent of occurrence^{Footnote 5} is not known yet for Saskatchewan but is more well documented in Manitoba. The extent of occurrence was reported in COSEWIC (2011) as 2,383 km²; however, as the intervening habitat between the Manitoba and Saskatchewan populations is almost all cultivated, the actual extent of occurrence is 138 km². The detailed area of occupancy^{Footnote 6} has not been recorded for a large portion of the Buffalograss populations in Manitoba or Saskatchewan; for many quarter sections, only the presence of Buffalograss has been documented. COSEWIC (2011) reported the area of occupancy of Buffalograss in Saskatchewan to be over 0.03 km² and in Manitoba to be over 4 km²; however, both these estimates are very coarse^{Footnote 7}. Future surveying and mapping efforts will increase the known area of occupancy, and additional populations may be discovered in native grasslands in the vicinity of Estevan or elsewhere in Saskatchewan along the U.S. border. Although it is very likely that Buffalograss sites have been lost due to threats like cultivation, strip mining, and urban development, there is insufficient historical and long-term data collected for this species to determine the extent. It is not possible to determine a population trend due to the lack of long-term data on abundance and distribution collected using standardized methods, however, the extent of occurrence has not decreased over time, and due to increased survey effort, it has increased (COSEWIC 2011).

Figure 2. Current distribution of Buffalograss in Canada (compiled from data provided by Manitoba Conservation Data Centre 2019 and Saskatchewan Conservation Data Centre 2019).

3.3. Needs of the Buffalograss

Habitat and biological needs

Buffalograss occurs in the Moist Mixed Prairie Ecoregion of Saskatchewan and in the Aspen Parkland Ecoregion of Manitoba, within the Prairie Ecozone (Wiken 1986, Marshall and Schut 1999). This area is dominated by a steppe climate (northern cool‑temperate zone) characterized as having occasional water deficits resulting from low precipitation, high evaporation, and rapid surface run-off (Fung et al. 1999).

Buffalograss is co-dominant with Blue Grama over much of the shortgrass and mixed‑grass prairie of the United States, and is also common there in numerous other ecosystems (e.g., semidesert grasslands, coastal prairie, tallgrass prairie, pinyon‑juniper, ponderosa pine woodland). In Canada, Buffalograss is at its northernmost extent and appears restricted to specific habitat along the Souris River valley and tributary coulees in Saskatchewan and Manitoba, including the Blind River valley in Manitoba, where it inhabits shale outcrops, dry, shallow coulee bottoms, lower coulee slopes (usually west or south facing), mid-slope benches which may be eroded, and adjacent upland, sometimes in slight depressions or adjacent to soil disturbances like cattle trails (COSEWIC 2001, Reimer et al. 2003, C. Neufeld, pers. obs.). It appears more prevalent on lower slope positions relative to upland summits (Richard and Redente 1995, Reimer et al. 2003, C. Neufeld, pers. obs.), although cattle foraging behavior may explain some of the distribution of Buffalograss in these areas (COSEWIC 2011). On a microsite level, Buffalograss occurs mostly on clay to loam soils with a relatively high moisture and phosphorus availability, and exhibits a high alkali-tolerance (Eilers et al. 1978, Schimel et al. 1985, Bai 1989, Richard and Redente 1995, Reimer et al. 2003, COSEWIC 2011). Soil parent materials include glacial fluvial meltwater channels with marine sedimentary rock exposures, as well as more recent eroded and colluvial slopes, alluvial fans and channels surrounded by glacial moraine and lacustrine deposits.

In Canada, Buffalograss occurs in grazed rangeland dominated by Blue Grama , Needle-and-thread Grass (Hesperostipa comata), June Grass (Koeleria macrantha) and Western Wheatgrass (Pascopyrum smithii) along with the non-native Kentucky Bluegrass (Poa pratensis) (for a more detailed species list, see COSEWIC 2001, Reimer et al. 2003, COSEWIC 2011). As Buffalograss typically forms dense circular clones which exclude most other species, it is often the dominant plant where it grows, comprising up to 80-90% of the ground cover (Reimer et al. 2003, C. Neufeld unpubl. data).

Ecological role

Buffalograss is an important forage grass for livestock grazing in the United States, due to its resilience to grazing, tolerance to semi-arid and drought conditions, and its palatability to cattle with high protein and nutrient content year-round (Dittberner and Olson 1983, Howard 1995). It is also important forage for a variety of wildlife, including Elk (Cervus elaphus), deer (Odocoileus spp.), and Pronghorn Antelope (Antilocapra americana). Buffalograss is increasingly becoming important in the United States as a turfgrass for golf courses and landscaping projects, including ditches, airport runways, athletic fields, and recreational areas because of its low maintenance, sod-forming nature, short stature, drought tolerance, trampling tolerance, and good competitive abilities (Pozarnsky 1983, Quinn 1998, Mintenko et al. 2002); cultivars have been developed which are easier to establish from seed rather than from plugs or sod (Mintenko et al. 2002). Buffalograss is also being used in revegetation projects to decrease erosion and rehabilitate surface-mined lands, bentonite/coal-mine spoil piles, and drilling fluid burial sites (Vogel 1981, Thornburg 1982, Sieg et al. 1983, McFarland et al. 1994). In the United States, studies have found Buffalograss to be an important recolonizer of cultivated fields and old roads 5-10 years after abandonment because of its ability to rapidly spread vegetatively (Judd 1974, Coffin et al. 1996). This recolonization reduces wind and water erosion, and returns these areas back to native species. These abandoned fields can become dominated by Buffalograss and Blue Grama 25-50 years after abandonment (Coffin et al. 1996).

Historically, Buffalograss served numerous functions. Buffalograss sod was used by settlers to build sod houses in the west-central Great Plains, and likely was used for grazing cattle and horses (Lowe 1940, COSEWIC 2001). Acoma and Laguna tribes in the southern United States crushed Buffalograss stolons with Soapweed (Yucca glauca) root or soaked it in water for use as a dermatological aid to make hair grow (Swank 1932). The Blackfoot tribe used Buffalograss as forage for horses during fall and winter (Johnston 1987).

Limiting factors

As a warm-season perennial grass at the extreme northern edge of its range, Buffalograss is probably limited primarily by growing season length and habitat differences. Warm-season perennial grasses transplanted further north often develop slower and fail to complete reprodu ction (Potvin 1986, Linhart and Grant 1996). Also, populations at the limits of a species’ range often are more fragmented and less dense, and they occupy poorer habitat than populations at the core of the species’ range (Channell and Lomolino 2000, Vucetich and Waite 2003). This may make them more susceptible to fragmentation effects, such as lower immigration rates and higher extinction rates.

4. Threats

4.1. Threat assessment

The threat assessment is based on the IUCN-CMP (World Conservation Union–Conservation Measures Partnership) unified threats classification system. Threats are defined as the proximate activities or processes that have caused, are causing, or may cause in the future the destruction, degradation, and/or impairment of the entity being assessed (population, species, community, or ecosystem) in the area of interest (global, national, or subnational). Limiting factors are not considered during this assessment process. Historical threats, indirect or cumulative effects of the threats, or any other relevant information that would help understand the nature of the threats are presented in the Description of Threats section.

4.2. Description of threats

Loss of habitat quantity and quality among the known populations of Buffalograss may adversely affect the species persistence in Canada. Future loss or degradation of habitat will be partially as a result of threats acting together, acting cumulatively, or acting on their own. Threats are discussed in more detail below in decreasing order based on the Level 1 threat impact. Appendix A (Table A1) identifies the threats associated with each population.

IUCN-CMP Threat 8 - Invasive and other problematic species and genes (medium)

8.1 Invasive non-native/alien species (medium)

Invasive non-native plants can pose a direct threat through competition because they are aggressive and can displace native species, can decrease species diversity or richness through their superior competitive ability, and/or result in overall negative effects on ecosystem functioning (Wilson 1989, Wilson and Belcher 1989, Reader et al. 1994, Christian and Wilson 1999, Bakker and Wilson 2001, Henderson 2005, Henderson and Naeth 2005, Jordan et al. 2008, Dillemuth et al. 2009, Koper et al. 2010). In the case of Buffalograss, invasive non-native species can also cause shading, and/or a build up of a litter layer with a moisture microclimate that would not be compatible with the dry, unshaded, and shorter vegetation associated with Buffalograss and its habitat (Wu and Harivandi 1995, COSEWIC 2001). Stoloniferous and less productive plants, like Buffalograss, tend not to persist in areas with more productive dense grass (Richard and Redente 1995). The most common invasive non-native plant species occurring in Buffalograss habitat in Saskatchewan and Manitoba (unless otherwise specified), are Leafy Spurge (Euphorbia esula), Kentucky Bluegrass (Poa pratensis), Crested Wheatgrass (Agropyron cristatum), Smooth Brome (Bromus inermis), Sweet Clover (Melilotus spp.), Canada Thistle (Cirsium arvense, SK only), Alfalfa (Medicago sp., SK only), Absinthe (Artemisia absinthium, SK only), Quack Grass (Agropyron repens, MB only) (COSEWIC 2001, Reimer et al. 2003, COSEWIC 2011, Saskatchewan Conservation Data Centre unpubl. data 2019, Manitoba Conservation Data Centre unpub. data 2019). Kentucky Bluegrass has become a dominant species within the Buffalograss Ecological Reserve in Saskatchewan, likely due to the lack of grazing management, but it is prevalent in all quarters containing Buffalograss, being more dense in some quarters than others. Leafy Spurge is thought to be a major threat to Buffalograss and has been rapidly expanding through the Souris and Blind River valleys in Manitoba and has recently appeared in the Saskatchewan population. Leafy Spurge can spread quickly, and with its extensive root systems, can form a dense monoculture stand and produce which reduces the distribution and abundance of other plant species occupying the habitat (Selleck et al. 1962, Belcher and Wilson 1989, Wilson and Belcher 1989, Butler and Cogan 2004). An added concern is that Leafy Spurge is extremely difficult to control by chemical and physical means and produces a milk substance that is an irritant to ungulates (Kronberg et al. 1993, Trammell and Butler 1995, Pachkowski 2003, Lesica and Hanna 2004, Crone et al. 2009, Rinella et al. 2009, Progar et al. 2011). Lastly, a few years of monitoring post flooding in areas occupied by Buffalograss found an initial plant community shift to more “weedy” and colonizer species; with an anticipated increase in flood events (threat 11.4) this may continue (Murray 2013, Murray 2014). Controlling the abundance and further spread of all invasive non-native species is critical for the survival of Buffalograss; however, care must be taken that Buffalograss is not harmed, or its habitat negatively altered, by indiscriminate use of any herbicides used to control invasive non-native species.

8.2 Problematic native species (negligible)

Shrubs can invade prairie to where it shades out or outcompetes grasses (Manske 2006). Studies have found fire suppression, certain grazing management practices, and areas in pastures with higher water availability can favour shrub growth (Pelton 1953, Anderson and Bailey 1980, Fitzgerald and Baily 1984, Fitzgerald et al. 1986, Kirby et al. 1988, Higgins et al. 1989b, Bailey et al. 1990, Kochy and Wilson 2004, Manske 2006). Encroachment or increasing abundance of snowberry (Symphoricarpos spp.), and to a lesser extent Wolfwillow (Elaeagnus commutata) and Chokecherry (Prunus virginiana), has been reported in quarters containing Buffalograss in both provinces.

IUCN-CMP Threat 3 - Energy production and mining (medium-low)

3.1 Oil and gas drilling (Low)

Active and inactive oil wells exist on quarters occupied by Buffalograss in Saskatchewan, mainly in the quarters that fall within the Winnipegosis oil pool (Saskatchewan Mining and Petroleum Geoatlas 2020). The intial impact of drilling the wells would be historical, although some impacts would be ongoing and cumulative (e.g. invasive species introduction on access roads and well pads, road maintenance, fire suppression); these will be considered under the respective threat categories. It is probable that in the future new oil wells will be put on the same quarters as existing wells, or abandoned wells reactivated, or new wells placed in adjacent quarters. The amount of new activity will likely be dependent on oil prices. The areas containing Buffalograss in both Manitoba and Saskachewan hold helium potential, and with the global helium shortage, development of helium wells may become prevalent, particularly due to recent successful test wells in south-western Saskatchewan and an increased interest in this resource in recent years (Yurkowski 2016, Nicolas 2018, Saskatchewan Mining and Petroleum GeoAtlas 2020).

3.2 Mining and quarrying (Medium-Low)

Lignite coal occurs in horizontal beds within the Ravenscrag Formation which extends over the Estevan area in Saskatchewan. Coal is surface mined from large open pits, created by draglines removing topsoil, subsoil, and overlying rock covering the coal seams (Saskatchewan Energy and Mines 1994). The Estevan mine covers over 20,000 ha and has four actively producing pits (Westmoreland Mining LLC 2020, Saskatchewan Mining and Petroleum GeoAtlas 2020). The mine is operating immediately adjacent to existing Buffalograss occurrences. Expansion of strip mining in the direction of existing sites would destroy large portions of the Saskatchewan population. There are also multiple past-producing coal mines in the Estevan area. It is unknown whether any portion of the Saskatchewan population has already been impacted by strip mining but given the large area that has been mined since the 1800s, some of which are adjacent to current Buffalograss occurrences, it is very likely. Fragmentation and destruction of potential habitat is evident in the area. Surveys of proposed mining areas are important to ensure occurrences are not impacted.

In addition to strip coal mining, other forms of mining or quarrying are potential future threats in Buffalograss habitat. Clay (kaolinite) pit mining historically occurred in the area, and at least two historical mines are in close proximity to existing Buffalograss sites (Saskatchewan Mining and Petroleum GeoAtlas 2020). Although these mines appear to be abandoned, it is probable that some Buffalograss was destroyed in the past by one of these mines, as evident by Buffalograss currently occurring adjacent to the pit. There is revised interest in mining clay in southern Saskatchewan as an additive in specialized concrete mixes so the mines may become active again. The area has also been explored for kimberlite, diamond, potash, clinker and leonardite but these had lower potential in the area (Saskatchwan Mining and Petroleum Geoatlas 2020). In Manitoba, a few Buffalograss sites are adjacent to old gravel extraction pits.

IUCN-CMP Threat 7 - Natural system modifications (low)

7.1 Fire and fire suppression (Negligible)

Prairie plants evolved with the ecological processes of fire and grazing which were important for maintaining ecosystem function. Post-European settlement reduced both the frequency and extent of prairie fires, and variability in grazing patterns, which has collectively changed the structure and composition of many plant communities (Higgins et al. 1989a, Frank et al. 1998, Brockway et al. 2002). Historically, Buffalograss adapted to fire and grazing by evolving structures, such as hardened burs, which protect the enclosed seeds from heat damage and aid in endozootic dispersal (Ahring and Todd 1977, Wright and Bailey 1982, Quinn et al. 1994, Ford 1999).

The impact of fire on Buffalograss appears largely dependent on precipitation, seasonality, and the time since the last fire (Higgins et al. 1989a, Ford 1999, Ford 2003). Because Buffalograss is a late-developing, warm season grass, a fire during the growing season kills actively growing leaves. Buffalograss cannot reallocate its energy reserves to produce more leaves before the end of the season, significantly reducing its cover for up to two years post-fire (Brockway et al. 2002, Ford 2003, Ford and Johnson 2006). Fire during the dormant season (e.g., fall, winter) has been found to have little effect on Buffalograss cover because aboveground tissues are already dead (Ford 1999, Ford 2003, Ford and Johnson 2006). Fires that occur during dry years also appear to elicit at least an initial negative response by Buffalograss as the plants may already be under physiological stress. It can take over three years for Buffalograss to recover after a dry-season fire (Brockway et al. 2002, Ford 2003). A review of studies on Buffalograss and fire found that, overall, Buffalograss shows a positive to neutral response to fire (Ford 1999). More long-term investigations are needed on the interactions of factors such as drought, season, and fire history, and the mechanisms driving responses. For example, Ford (2003) found greater Buffalograss cover in an area that had a growing-season fire than an unburned control area and an area with a dormant-season fire during a drought year five years after the experiment. Studies are also needed on long-term effects of fire on Buffalograss and its ecosystem in Canada. Although Buffalograss still dominates areas where fire or grazing have been excluded (Hulett et al. 1972, Howard 1995), a lack of these disturbances can increase litter levels and vegetation height (Hayes and Holl 2003), which can result in reduced growth of short growing and shade intolerant species like Buffalograss. Perhaps more importantly, removal of grazing and fire can also increase the susceptibility of rangeland to invasion by weedy species, or less fire-tolerant exotic invasive species (Higgins et al. 1989a, Milchunas et al. 1989, Milchunas et al. 1992). Prescribed burns are not a regular practice on any of the occupied sites and wildfires are typically suppressed.

7.2 Dams and water management/use (Unknown)

Changes to the moisture regime at a site could adversely affect Buffalograss growth and survival. Due to widespread cultivation of the upland prairie, most of the remaining Buffalograss sites occur on lower slopes of valley and coulee walls; any prolonged inundation of these areas from developments or disturbances that cause unnatural flooding, inhibit channel migration, or divert water could alter the disturbance regime beyond the range of natural variability, negatively impacting Buffalograss habitat. Historically, small catchment dams, impoundments and associated dugouts have been placed in the bottoms of coulees to retain runoff water. In the COSEWIC (2001) report, the author estimated that these have eliminated a 300 m extent of Buffalograss habitat in coulee bottoms. Also, the creation of the Rafferty and Boundary dams and reservoirs in Saskatchewan flooded a considerable area of habitat along the Souris River Valley where populations of Buffalograss likely occurred. Sites that currently exist adjacent to the Rafferty reservoir may be at risk in years when water levels rise. To date, no dams have been built in Manitoba on the Souris or Blind rivers that affect populations of Buffalograss, but a dam exists on the Souris River in North Dakota, upstream of Buffalograss sites in Manitoba, and may have been a seed source before that area was flooded (Reimer et al. 2003). In Manitoba, a river channel was artificially straightened affecting some of the Buffalograss plants that were in the area. Small water control structures, drainage projects and ditch deepening may increase in an attempt to control flooding and water levels as a result of increased flood events (threat 11.4).

7.3 Other ecosystem modifications (Low)

Over its North American range, Buffalograss appears in prairies that are in a state of succession or disclimax (a plant community kept from reaching the final "climax condition" due to natural disturbances of grazing and fire) (Clements 1934, Costello 1944, Osborn 1949, Andelt et al. 1987). At its northernmost range limit in southeastern Saskatchewan and southwestern Manitoba, it is limited to shaley-clayey soils, and unshaded habitat with little competition from taller species. Cattle grazing, which somewhat replicates historical bison grazing, is essential in maintaining suitable habitat for Buffalograss by reducing surrounding vegetation height, reducing litter levels (litter accumulation can suppress germination), and managing invasive plant species (Hart and Ashby 1998, Higgins et al. 1989a, Milchunas et al. 1989, Milchunas et al. 1992, Hayes and Holl 2003). Increased grazing intensity has been found to increase Buffalograss cover and/or frequency (Herbel and Anderson 1959, Anderson et al. 1970, Bonham and Lerwick 1976, Klatt and Hein 1978, Ring et al. 1985, Hart and Ashby 1998). Buffalograss appears tolerant of moderate to heavy grazing, and may have an advantage over other grasses by rapidly spreading vegetatively once grazing has reduced competitors. It has evolved deepset root crowns which seem resistant to trampling by ungulates, making Buffalograss quite hardy even during active growing periods (Young 1956). Grazing also aids in dispersal of seed-containing burs, either through attachment to fur or through the digestive tract, the latter of which also increases germination rates (Quinn et al. 1994, Ortmann et al. 1998). In the absence of these grazing animals to disperse seeds, there may be an accumulation of seeds under the parent plants leading to a lack of germination, seedling death or eventual inbreeding depression (Quinn 1987, Coffin and Lauenroth 1989, Quinn 1991, Quinn et al. 1994). With a lack of reproductive dispersal, vegetative growth by stolons would be the main method of increasing distribution. Grazing is absent in Sourisford Park in Manitoba (mowing occurs) and the Buffalograss Ecological Reserve in Saskatchewan. Both sites have problems with invasive species, and the ecological reserve is dominated by taller invasive species such as Kentucky Bluegrass and Crested Wheatgrass. Grazing on other properties with Buffalograss in Saskatchewan and Manitoba varies in frequency, intensity, and duration and some may not be at levels suitable to maintain ideal Buffalograss habitat, as indicated by observations on some quarters where grazing levels were not sufficient (Saskatchewan Conservation Data Centre, unpubl. data 2019).

IUCN-CMP Threat 1 – Residential and commercial development (low)

1.1 Housing and urban areas (Low)

In Saskatchewan, the entirety of the known population is within 10 km of city limits and locations of Buffalograss have been found within one kilometer of the city. Future growth of the city, or placement of acreages on the west and southwest sides of Estevan, may destroy existing Buffalograss sites, or further reduce or degrade remaining suitable habitat. Issues with a landowner stockpiling old farm materials from the yard onto adjacent prairie and Buffalograss plants was reported from one acreage. It is possible some Buffalograss was lost during the development of Estevan, but no historical records exist to document this.

1.3 Tourism and recreation areas (Negligible)

A small campground in Manitoba has maintenance and improvement practices that may threaten the Buffalograss that occurs on the quarter section. These include frequent mowing (reduces reproductive structures and can scalp the grass, but maintains habitat), tree planting (creates shade), and campground site maintenance/ upgrades/expansion, and road maintenance/upgrades/expansion.

IUCN-CMP Threat 2 - Agriculture and aquaculture (low)

2.1 Annual and perennial non-timber crops (Low)

The threat of cultivation is mostly historical. Cultivation has likely reduced overall habitat availability, population size, and genetic diversity of this species to the point where parts of its historical range may have been destroyed, and larger expansion of its current range is no longer possible.The majority of land surrounding the two Buffalograss populations is cultivated. While there still remains cultivatable land occupied by Buffalograss (COSEWIC 2011), a large portion of the remaining uncultivated prairie where Buffalograss occurs will likely not be cultivated due to topography and soil conditions. In Manitoba, Buffalograss grows on soils that have severe limitations for crops due to soil structure, low permeability and presence of soluble salts (Eilers et al. 1978). In Saskatchewan, soils with Buffalograss are more suited for grazing due to their shallow nature, bedrock exposures, and dissected terrain. A few Buffalograss sites have suitable agricultural soils, but they occur in irregular bands in valleys where tilliage is less feasible (Saskatchewan Soil Survey 1997). Additionally, the topography of sites located on valley walls or dissected coulee bottoms is not conducive to cultivation. The use of herbicides on adjacent cultivated areas has the potential to alter habitat on the native prairie, particularly where there is herbicide drift or run-off (e.g. change species composition, canopy cover, hydrology, and soil stability). Encroachment of invasive species or tame forage species from adjacent cultivated or tame fields is also a threat to habitat quality and persistence of Buffalograss plants (threat 8.1).

IUCN-CMP Threat 4 – Transportation and service corridors (low)

4.1 Roads and railroads (Low)

Road construction has likely impacted Buffalograss populations in the past. Highway 18 in Saskatchewan, heading west from Estevan, dissects Buffalograss occurrences which now exist adjacent to the highway ditches. These fragmented occurrences were likely joined prior to the construction of that highway (COSEWIC 2001). Similarly, highway 251 and an abandoned railbed dissect Buffalograss populations near Coulter, Manitoba. Buffalograss is occasionally found along, or adjacent to, vehicle track trails where it seems to take advantage of decreased competition. Upgrades to these roads could destroy the Buffalograss clones growing along them (COSEWIC 2011). In general, habitat and plants can be damaged or destroyed by road construction or maintenance activities such as road widening, grading, ditch deepening, trenching, drainage projects, and realigning or improving the road. In Manitoba, construction of a new road paralleling the Souris River valley, south of highway 251, could impact plants in 10 quarter sections. Road upgrades along highway 251 and highway 3 could also impact portions of the population in 10 quarter sections. In Saskatchewan, upgrades to, or construction along, highway 18, or any of the secondary or gravel roads adjacent to Buffalograss patches, could impact upwards of 20 quarter sections. Roads can also change the hydrology of habitat by modifying drainage patterns and water flow in an area. The linear disturbances created from roads also increase the potential for introduction and invasion by invasive non-native species which may compete with Buffalograss (threat 8.2).

4.2 Utility and service lines (Negligible)

Pipelines carrying crude oil, natural gas, and effluent are in 14 quarter sections in SK. Since these are already installed, they would be be considered historic, although there would be ongoing impacts like invasive species (8.1), and the potential for leaks or ruptures. Additional pipelines or pipeline upgrades might be installed in future if more oil drilling occurs in the area. Utility or other service lines may also be put in if acreage development continues.

IUCN-CMP Threat 11 - Climate change and severe weather (unknown)

11.4 Storms and flooding (Unknown)

A substantial increase of flooding in the Souris River Basin has occurred since the 1970s (Nustad et al. 2016). Taking into account past climate record and trends in how the Souris River Basin responds to various climatic conditions and extreme precipitation events, statistical models predict the flood risk will remain high as long as the wet climate period continues (Whittrock 2016, Nustad et al. 2016, Ryberg et al. 2016, Gregory 2020). One study led by the United States Geological Survey predicted a 30% chance of the Raferty Reservoir capacity being exceeded at least once in the next 10 years in the current wet climate state (Nustad et al. 2016). As there are still a lot of unknowns regarding impacts of climate change, research and modeling continues in order to gain a better understanding the probability of future flooding and drought scenarios under a new climate regime (Gregory 2020). Buffalograss survived being submerged under flood waters for at least five weeks during a seasonal flooding event in the United States (Parks 1993). Buffalograss also persisted in Manitoba when some of the area it occupies was flooded in 2009 and 2011 for part of the growing season; however, the flood left large amounts of debris and fibrous material and an initial change in species composition occurred (monitoring has not continued) (Murray 2013, Murray 2014). Based on flood mapping from 2009 and 2011 along the Souris River in Manitoba, about 50% of the quarter sections containing Buffalograss were affected by the flood waters. Extreme flood events appear to be increasing (threat 11.4), but the severity these events will have on Buffalograss populations are unknown (COSEWIC 2011).

5. Management objective

The management objective for Buffalograss is to ensure long-term persistence and natural expansion of all extant native^{Footnote 8} populations in Canada, including any newly located or reconfirmed^{Footnote 9} populations, within the natural range of variability.

Rationale: There has been an increase in knowledge about the distribution of Buffalograss over the last decade as survey effort has increased, to the result of Buffalograss being downlisted from threatened to special concern in 2011 (COSEWIC 2011). Substantial increases to number of populations or area of occupancy are less likely to be documented in the future given that: 1) the suitable habitat for the species is limited and highly fragmented; 2) the majority of suitable habitat has been surveyed; and 3) the Canadian populations exist at the northern limit of the species’ range. However, it is likely that some additional populations will be found with future survey effort. Based on the nature of the continuing threats, it is expected that habitat quality and quantity will continue to decline, and known populations may also decline as a result. Therefore, the management objective has been set in the context of reversing or preventing further declines in quality and quantity of habitat through beneficial management practices and stewardship arrangements in order to maintain, and if possible, increase existing populations over the long term.

6. Broad strategies and conservation measures

6.1. Actions already completed or currently underway

Inventory and monitoring

In Manitoba, Manitoba Conservation (Conservation Data Centre), along with other botanists, have conducted targeted or incidental surveys for Buffalograss since 1993 when first observed (Reimer and Hamel 2002, Foster and Hamel 2006, Foster and Reimer 2007, Foster 2008, Krause Danielson and Friesen 2009, Murray 2013, Murray 2014, Manitoba Conservation Data Centre unpubl. data 2019). It is likely these surveys and/or monitoring will continue at the Manitoba populations. The Nature Conservancy of Canada is doing habitat modelling to identify priority areas for future inventory work (R. Neufeld, pers. comm. 2020).

In Saskatchewan, Environment and Climate Change Canada, Nature Saskatchewan, Native Plant Society of Saskatchewan, Saskatchewan Research Council and various botanists have conducted targeted surveys for Buffalograss over the last 15 years (Saskatchewan Conservation Data Centre unpubl. data 2019, Environment and Climate Change Canada unpubl. data 2020).

Research as part of an adaptive management framework

Nature Conservancy of Canada is investigating the unknown impact of the anticipated increase in future extreme flood events on the Manitoba Buffalograss population. By using data from past flooding events in the Souris and Blind River Valleys, along with Buffalograss occurrence data and LiDAR imagery, they are trying to determine duration and extent of flooding events where Buffalograss occurs, and how this might impact persistence of Buffalograss in these areas (R. Neufeld, pers. comm. 2020).

Habitat assessment, management, and conservation

In Manitoba, Buffalograss is listed as threatened under Manitoba’s Endangered Species and Ecosystem Act. In Manitoba, habitat containing Buffalograss has been conserved or managed through 20 conservation agreements (easements) and five Species at Risk Partnership on Agricultural Lands (SARPAL) agreements through Manitoba Habitat Heritage Corporation. The Critical Wildlife Habitat Program implemented twice-over grazing management on a property containing Buffalograss in 2011-2013 and monitored results (Murray 2013, Murray 2014).

In Saskatchewan, stewardship agreements have been set up on some properties containing Buffalograss through Nature Saskatchewan. The Native Plant Society of Saskatchewan has created and implemented property-specific beneficial management plans (BMPs) for Buffalograss on properties of landowners with stewardship agreements, which includes adaptive monitoring (assessing the effect of the recommended management activities and making adjustments as needed).

6.2. Broad strategies

In order to achieve the management objective, conservation measures will be organized under four broad strategies:

• inventory and monitoring
• research as part of an adaptive management framework
• communication, collaboration and engagement
• habitat assessment, management and conservation

6.3. Conservation measures

7. Measuring progress

The performance indicators presented below provide a way to measure progress towards achieving the management objectives and monitoring the implementation of the management plan.

All extant native populations of Buffalograss in Canada, as well as any newly located or reconfirmed populations, are maintained or increased in the long-term.

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Appendix A: Summary of Buffalograss populations in Canada

Appendix B: Effects on the environment and other species

A strategic environmental assessment (SEA) is conducted on all SARA recovery planning documents, in accordance with the Cabinet Directive on the Environmental Assessment of Policy, Plan and Program Proposals^{Footnote 10}. The purpose of a SEA is to incorporate environmental considerations into the development of public policies, plans, and program proposals to support environmentally sound decision-making and to evaluate whether the outcomes of a recovery planning document could affect any component of the environment or any of the Federal Sustainable Development Strategy’s^{Footnote 11} (FSDS) goals and targets.

Recovery planning is intended to benefit species at risk and biodiversity in general. However, it is recognized that implementation of management plans may inadvertently lead to environmental effects beyond the intended benefits. The planning process based on national guidelines directly incorporates consideration of all environmental effects, with a particular focus on possible impacts upon non-target species or habitats. The results of the SEA are incorporated directly into the management plan itself, but are also summarized below in this statement.

The potential for the management plan to inadvertently lead to adverse effects on other federally listed species that may co-occur or exist in and around areas occupied by Buffalograss (Table B1) was considered. While all these species would benefit from conservation of native prairie, the beneficial management practices may differ amongst them. Management actions intended to maintain native prairie and suitable habitat for Buffalograss may include practices like prescribed burns, grazing, introduced invasive species control, or brush control of encroaching woody vegetation. Although these activities would be aimed at maintaining native grassland, they may have the potential to minimally harm some species, at least in the short term. For the most part, managing for healthy native ecosystems will benefit non-target species, natural communities, or ecological processes. Management actions, including disturbances such as fire and grazing, are natural components of prairie ecosystems. Negative impacts on other species should be minimized if the timing, intensity and frequency of these management actions mimic natural processes (Samson and Knopf 1994). As mentioned in section 4.2, 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. 1989a, Milchunas et al. 1989, Milchunas et al. 1992). However, conservation measures, management actions and beneficial management practices should strive to benefit as many species as possible and the ecological risks of any action must be considered before undertaking them in order to reduce possible negative effects on other species.