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Chapter 4 Ecoregions with Grasslands in , the , and Southern Ontario

Joseph D. Shorthouse Department of Biology, Laurentian University Sudbury, Ontario, P3E 2C6

Abstract. The second largest grasslands of Canada are found in south-central British Columbia in valleys between ranges and on arid mountain-side steppes or benchlands. The province contains five ecozones, with most of the grassland habitat in the Ecozone. This ecozone consists of a series of plateaux and low mountain ranges and comprises 17 ecoregions, 7 of which contain grasslands. Dominant grasses here are bunchgrasses. A few scattered grasslands are found in the Yukon in the Ecozone within three ecoregions. Grasslands in southwestern Ontario consist of about 100 small remnants of what was once much more abundant tallgrass prairie. These grasslands grow in association with widely spaced deciduous trees and are remnants of a past prairie peninsula. Grasslands called alvars are also found on flat limestone bedrock in southern Ontario. This chapter briefly describes the physiography, climate, soils, and prominent flora of each ecoregion for the benefit of future biologists wishing to study the biota of these unique grasslands.

Résumé. Les prairies du centre-sud de la Colombie-Britannique sont les deuxièmes plus vastes au Canada. Elles se trouvent dans les vallées séparant les chaînes de montagnes, et sur les steppes ou replats arides à flanc de montagne. La province renferme cinq écozones, et l’habitat de prairies se trouve principalement dans l’écozone de la cordillère alpestre. Cette écozone est constituée d’une série de plateaux et de chaînes de montagnes basses et se divise en 17 écorégions, dont 7 renferment des prairies. Les graminées dominantes sont des graminées cespiteuses. On trouve également quelques prairies isolées au Yukon, dans trois écorégions de l’écozone de la cordillère boréale. Les prairies du sud-ouest de l’Ontario, au nombre d’une centaine, sont de petits vestiges de ce qui formait autrefois une prairie haute beaucoup plus vaste. Ces prairies sont aujourd’hui associées à des arbres décidus très clairsemés et représentent ce qui reste de l’ancienne « péninsule de prairie ». On trouve également des prairies appelées alvars sur les plaines calcaires du sud de l’Ontario. Ce chapitre décrit brièvement la physiographie, le climat, les sols et les principales espèces végétales de chacune des écorégions à l’intention des biologistes qui souhaiteront dans le futur étudier les biotes de ces prairies uniques en leur genre.

Introduction Mention the word “grasslands” to most Canadians, and the prairies of , Saskatchewan, and Manitoba first come to mind. However, Canada’s second largest assemblage of grasslands is in British Columbia (Gayton 2003). The BC grasslands have many characteristics in common with prairie grasslands, but a few unique features as well. Grasslands comprising tallgrass species were once also found in southern Ontario from Toronto to Windsor. They have all but disappeared, with only scattered remnants remaining, one of the largest being the Ojibway Prairie near Windsor (see Chapter 9). Remnant grasslands also exist in northwestern Ontario, with additional scattered grasslands in the Yukon. The grasslands in each of these interesting ecoregions and their characteristics are presented here.

Shorthouse, J. D. 2010. Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario. In Arthropods of Canadian Grasslands (Volume 1): Ecology and Interactions in Grassland Habitats. Edited by J. D. Shorthouse and K. D. Floate. Biological Survey of Canada. pp. 83-103. © 2010 Biological Survey of Canada. ISBN 978-0-9689321-4-8 doi:10.3752/9780968932148.ch4 84 J. D. Shorthouse

Grasslands of British Columbia British Columbia is the most biodiverse province in Canada when one includes the marine environment (Cannings and Cannings 1996). British Columbia contains about 2,850 species of vascular plants of a total of about 4,150 in Canada and an estimated 35,000 species of insects of an estimated 55,000 in all of Canada (Harding and McCullum 1994). Much of this diversity is due to the province’s complex topography of mountain ranges with large intervening valleys and plateaux that run in a north–south direction. Eastward-flowing winds from the Pacific Ocean pick up vast amounts of precipitation and as the air masses rise over the mountain ranges, they drop most of their moisture on the west side where abundant forests grow. The eastern sides of the receive much less rainfall and are relatively dry. In these dry rain-shadow areas, the sparse spring and summer rains evaporate before they can penetrate the soil such that plant growth depends mostly on winter precipitation (Brayshaw 1965). Thus, most grasses start growing early in the season and finish their life cycles before the hottest and driest part of the year. Trees are unable to survive in these harsh conditions and are found only in areas where there is sufficient soil moisture. Most of the grassland communities are found in the south-central part of the province (Fig. 1) (Meidinger and Pojar 1991). Unfortunately, as is the case with the prairie grasslands to the east and the tallgrass grasslands in southern Manitoba (Chapter 3) and southwestern Ontario (see the “Grasslands in Southern Ontario” section), most of the grasslands of British Columbia have been disturbed or destroyed and there is urgent need to protect the few natural tracts that remain (Gayton 2003). Various systems have been used to classify the natural regions of British Columbia, including that of Meidinger and Pojar (1991), which describes zones based on climate, physiography, or vegetation. Pojar and Meidinger (1991) give a good overview of the ecosystems of British Columbia and describe the location of zones containing grasslands. Following their classification, three zones where grasses are dominant are the bunchgrass zone (Nicholson et al. 1991), the ponderosa pine zone (Hope, Lloyd et al. 1991), and the interior Douglas-fir zone (Hope, Mitchell et al. 1991). Scudder (see Chapter 6) used this system in his analysis of biodiversity hotspots in British Columbia. However, for reasons of consistency, the system used by the Ecological Stratification Working Group (1995) is used here as it is elsewhere in this volume. The five ecozones in British Columbia identified by the Ecological Stratification Working Group (1995) include the Boreal Cordillera to the north, the Montane Cordillera in the centre of the province, the Boreal Plains in the Peace River area, the Taiga Plains north of the Boreal Plains in the northeast, and the Pacific Marine along the entire western coastline. Most of the major grasslands of British Columbia are found in the Montane Cordillera Ecozone (Fig. 2). Within Canada, the Montane Cordillera Ecozone extends from the eastern Rocky Mountains in Alberta to the western slope of the Cascades in British Columbia and from the latitude of the Skeena Mountains in northern British Columbia to the USA border (Fig. 2). This ecozone is Canada’s sixth largest, covering more than 49 million ha, and is probably our most complex, with landscapes ranging from alpine tundra to dense coniferous forests, grasslands, riparian woodlands, and dry sagebrush. About 90% of the area of this ecozone in Canada is in the province of British Columbia and the remaining 10% is in western Alberta (Fig. 2). This interior region comprises a series of plateaux and low mountain ranges. A large from near the centre of the province extends to the border with Washington State. This plateau has been further subdivided into a series of smaller Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 85

Fig. 1. Map showing locations of grasslands of British Columbia.

plateaux and highlands. The interior plateau is a region of relatively low relief that includes large portions of the Fraser and Thompson- plateaux, undulating only 100 m or less over wide areas. Many of the region’s rivers have cut into the plateau, leaving deep, rugged canyons. The Okanagan Valley and the Creston Valley are two major agricultural areas in this ecozone. There are some large deep lakes and major river systems, including the and the headwaters. 86 J. D. Shorthouse

Fig. 2. Map of British Columbia and western Alberta showing the ecoregions in the Montane Cordillera Ecozone.

Of the 17 ecoregions in this ecozone, 7 (Fig. 2) contain significant grasslands. The most prominent grasslands are in the Okanagan Valley from the border with Washington State to Summerland, the Similkameen River Valley near Keremeos, the Valley from Spences Bridge to , the Nicola River Valley, and the middle Fraser and lower Chilcotin River valleys from the Farwell Canyon area to Big Bar (Meidinger and Pojar 1991). Outside of this ecozone, small grasslands occur in association with the Garry Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 87

oak meadows of southern Vancouver Island, the parklands of the Peace River country (see Chapter 3), and the cold mountain grasslands of the northern Rockies. Grasslands are also scattered throughout northern British Columbia, especially on south-facing slopes. The majority of British Columbia’s grasslands represent the northern limit of the Great Basin shrub-steppe grasslands found south of the border with Washington State and extending south to Mexico (Franklin and Dyrness 1973; O’Connor and Wieda 2001). Daubenmire (1992) referred to the part of the Great Basin from central Oregon northward across the states of Washington, Idaho, and western Montana to southern British Columbia as Palouse prairie, but this term is not used in Canada’s ecosystem classification. The most southern grasslands in the Okanagan Valley near Osoyoos have been referred to as “Canada’s Pocket Desert,” but some biologists argue that they are not deserts because they are not dry enough and are too cold (Cannings and Cannings 1996). The soils of the interior plateaux of British Columbia reflect a combination of many factors, including vegetation, slope, parent material, and climate, all of which are complicated by changes in elevation. Vast areas of the province are at such high elevations that they have almost no soil and are bare rock or ice fields. Grasslands in the southern Okanagan Valley where the climate is dry have light brown soils. Aridity in the valleys of interior British Columbia is a consequence of a climate typified by hot, dry summers and cold winters with relatively little snowfall. Low precipitation and high evapotranspiration results in some areas of British Columbia being more prone to drought than those of southern Saskatchewan. Long summer droughts effectively prevent tree seedlings from establishing in some areas. Fires that once occurred every 7–10 years, to the benefit of grasses, temporarily eliminated shrubs and small trees but did not affect ponderosa pine (Pinus ponderosa C. Lawson) or Douglas fir (Pseudotsuga menziesii (Mirb. Franco)) (Meidinger and Pojar 1991). Ponderosa pine occupies nearly 800,000 ha at an elevation of between 335 and 900 m, whereas Douglas fir is found in over 4.8 million ha (Pitt and Hooper 1994). Both tree species support grassland communities because the open nature of their canopy allows light to reach the forest floor where grasses and a variety of other plants flourish. Rocky talus and rock outcrop areas, gullies, ponds, and lakes occur throughout the forests, adding to the variety of habitats. The best and most extensive examples of BC grasslands are found in the valleys between mountain ranges and on arid mountain-side steppes or benchlands of the Fraser and Columbia watersheds below dry montane forests. Dominant grasses here are known as “bunchgrasses” and, depending on the elevation, are commonly associated with ponderosa pine and Douglas fir (Pitt and Hooper 1994). The abundance of bunchgrasses in these valleys has resulted in the area being commonly referred to as the “bunchgrass zone” or “bunchgrass ecosystems.” Bluebunch wheat grass (Pseudoroegneria spicata (Pursh) A. Löve) is the most dominant species within both grassland and ponderosa pine parkland, whereas pinegrass (Calamagrostis rubescens Buckley) is more abundant at higher elevations. Bunchgrasses are perennial grasses that grow in tufts or bunches, using a single root system, rather than growing in sod or mats as do most prairie grasses (Caldwell et al. 1983; Sinclair et al. 2006). As the stems of bunchgrasses grow up and outward from a narrow base, they form an “umbrella,” protecting the base and root system from sun and evaporation. The leaf bundles act as funnels, gathering rainwater from above and guiding it into the middle of the fine roots below ground. The outward curving leaves help shade the ground around the plant from the hot sun. Leaves of bunchgrass also contain dry support tissues, and rather than wilting during droughts like other grasses do, bunchgrasses become dormant. 88 J. D. Shorthouse

In contrast to the sod-forming grasses of the prairies, which grow from networks of rhizomes, bunchgrass grows as bunches of numerous, tightly packed growing points. Individual leaves and flower stems of bunchgrasses grow from these points above the soil. Bunchgrass leaves die each year, but the plants regrow from the same root system and base each spring. The older the plant, the more growing points it accumulates and the larger the bunch becomes, some exceeding 15 cm in diameter. Because of these characteristics, bunchgrasses are particularly well adapted to the dry conditions found in parts of the Thompson-Okanagan region. Other flora that commonly grows with bluebunch wheat grass includes big sagebrush (Artemisia tridentata Nutt.). Big sagebrush is an aromatic, woody shrub, freely branched above, and from 0.5 to 1.5 m in height (Cawker 1983). Young stems are silver-gray, whereas the older stems are grayish brown. In the far south of the Okanagan Valley where winters are mildest, antelope brush (Purshia tridentata (Pursh) DC.), also known as bitterbrush or greasewood, is the dominant shrub. Antelope brush is an erect, stiff, and abundantly branched shrub up to 2 m tall. It is freely branched, although under constant grazing, it may be more compact and globose. Antelope brush is an important browse species for hoofed mammals such as mule deer. Other important grasses in British Columbia include the introduced crested wheat grass (Agropyron cristatum (L.) Gaertn.), giant wild rye (Elymus condensatus J. Presl.), June grass (Koeleria macrantha (Ledeb.) Schult.), Kentucky bluegrass (Poa pratensis L.), and needle-and-thread grass (Hesperostipa comata (Trin. and Rupr.)) (Nicholson et al. 1991). British Columbia’s grasslands are unique in Canada not only because they are dominated by bunchgrass, but also because many other plant species occur only here or are rarely found east of the Rocky Mountains (Harding and McCullum 1994). In addition, less BC grasslands have been converted to crop production than have grasslands of the prairie provinces. However, most of British Columbia’s grasslands have been used for raising livestock. Besides being affected by livestock grazing, many species of plants and animals in the interior grasslands are currently endangered because of urban sprawl and the conversion of land to orchards and vineyards (Harding and McCullum 1994). Cattle grazing is also known to alter species composition (Pitt and Hooper 1994; Cannings and Cannings 1996). Riparian habitats beside the edges of rivers, lakes, ponds, and wetlands occur in the valleys of British Columbia’s grasslands and are just as important for a wide variety of flora and fauna here as they are on the prairies. Riparian areas in southern British Columbia vary in width from small patches of shrubs beside a small wetland to broad stands of cottonwood (Populus balsamifera (Torr. and A. Gray ex Hook.)) along the larger rivers (Harding and McCullum 1994). Cottonwood and trembling aspen (Populus tremuloides Michx.) are the most common tree species in riparian areas; willows (Salix spp.) red osier dogwood (Cornus stolonifera Michx.), common snowberry (Symphoricarpos albus (L.) S.F. Blake), and wild roses (Rosa woodsii Lindl. and R. nutkana C. Presl) are common shrubs; rushes and sedges are found on the water’s edge; and a variety of flowering plants occur in the drier areas away from the water. Fire was an important factor in the past for sustaining BC grasslands, just as it was on the prairies. It is a natural ecological disturbance, especially in the dry interior forests of British Columbia (Daubenmire 1968; Cawker 1983; Gayton 2003). In the past, forest fires were suppressed, but foresters now view fire as essential for forest regeneration, contributing to a greater diversity of flora and fauna. Fire causes more damage to shrubs than grasses, and thus can allow grasses to encroach on areas once occupied by shrubs. Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 89

In contrast, heavy grazing on grasses reduces their competitive ability, allowing shrubs to invade the grasslands (Brayshaw 1965).

Ecoregions with Grasslands within the Montane Cordillera Ecozone Ecoregion Most of the material included in this review of ecoregions comes from the Ecological Stratification Working Group (1995). The Fraser Plateau Ecoregion is south of the Fraser Basin Ecoregion and covers the Interior Plateau and interior foothills of the Coast Mountains of central British Columbia (Fig. 2). The Fraser Plateau Ecoregion is a broad, rolling plateau ranging in elevation from 1,150 to 1,800 m. Surface deposits include glacial till with well- developed drumlinoid features, pitted terraces, eskers, and areas of glacial lake deposits. The mean annual temperature for the area is approximately 3 °C, with a summer mean of 12.5 °C and a winter mean of −7 °C. Mean annual precipitation ranges from 250 to 600 mm. The ecoregion is dominated by white spruce (Picea glauca (Moench)), lodgepole pine (Pinus contorta Dougl. ex Loud), trembling aspen, and Douglas-fir forests. Open-growing lodgepole pine and Douglas fir occur on drier mid-elevation sites. Bunchgrass-dominated grasslands occur at valley bottoms along the Fraser and Chilcotin rivers. Major communities include Williams Lake, Vanderhoof, and 100 Mile House.

Eastern Ecoregion The long, thin Eastern Continental Ranges Ecoregion covers the Rocky Mountains of Alberta, incorporating the eastern flanks of the Continental Ranges (Fig. 2). The mean annual temperature varies from north to south, with typical values for major valley systems of about 2.5 °C. The mean summer temperature is 12 °C and the winter mean is −7.5 °C. The mean annual precipitation ranges from 600 to 800 mm, increasing with elevation. Climatic conditions in the major valleys are marked by warm, dry summers and mild, snowy winters. Stands of Douglas fir intermixed with trembling aspen and grassland ecosystems occur on the warmest, driest sites. Major communities are Jasper, Banff, and .

Interior Transition Ranges Ecoregion The mountainous upland of the Interior Transition Ranges Ecoregion ranges in elevation from 300 to 3,000 m and lies to the southwest of the Fraser Plateau Ecoregion within the eastern portion of the southern Pacific Ranges (Fig. 2). A strong gradient runs from the moist maritime climate of the coast to the semi-arid continental climate of the southern interior of British Columbia. The mean annual temperature is approximately 6 °C, with a summer mean of 15 °C and a winter mean of −3.5 °C. A strong gradient in the mean annual precipitation occurs through the Fraser Canyon, ranging from 300 mm in the south to 500 mm in the north. This ecoregion contains ecosystems ranging from alpine and subalpine to montane forests of lodgepole pine, trembling aspen, white spruce, and Douglas fir. At the lowest elevations in the eastern portions of the ecoregion is parkland of scattered ponderosa pine in a matrix of bluebunch wheat grass and sagebrush grasslands. The main communities are Lillooet and Lytton.

Thompson-Okanagan Plateau Ecoregion The Thompson-Okanagan Plateau Ecoregion in the southern part of the Montane Cordillera ecozone (Fig. 2) is one of the warmest and dries ecoregions in Canada. This ecoregion is 90 J. D. Shorthouse

characterized by rolling plateaux and drainage from the Okanagan, Thompson, and Nicola rivers. The region has a gently rolling surface covered mainly by glacial deposits into which rivers are incised (Fig. 3). Glacial deposits include hummocky moraines, well- developed drumlinoid features, glaciofluvial terraces, eskers, and glacial lake deposits. The mean annual temperature of the major valleys is approximately 6 °C, with a summer mean of 15 °C and a winter mean of −3.5 °C. Kamloops, located on the Thompson River, has the highest average daytime temperature of all Canadian cities at 27.2 °C. The mean annual precipitation ranges from 250 to 300 mm in the major valleys to over 1,000 mm in subalpine and alpine areas. A strong increase in precipitation occurs with elevation. Lower elevations support forests of lodgepole pine with pinegrass understory, mixed with trembling aspen, white spruce, and Douglas fir. Valley bottoms support open stands of Douglas fir and pinegrass, or parklands of scattered ponderosa pine in a matrix of bluebunch wheat grass and sagebrush. Trees are absent in the driest areas, such as near Cache Creek, north of Kamloops, and thus valleys are dominated by grasses (Fig. 3). The major communities are Kelowna and Kamloops.

Okanagan Range Ecoregion The small, rugged Okanagan Range Ecoregion lies south of the Thompson-Okanagan Plateau Ecoregion and abuts against the border with the United States. The Okanagan Range Ecoregion incorporates the southeastern portions of the Cascade Mountains and Okanagan Range, which are some of the warmest and driest mountain ranges in British Columbia. The mean annual temperature for the ecoregion is approximately 7 °C, with a summer mean of 15 °C and a winter mean of −1 °C. There is a strong gradient in the mean annual precipitation of about 500 mm in the east to about 1,000 mm to the west. Subalpine forests dominate the ecoregion and are composed of Engelmann spruce, subalpine fir, and lodgepole pine forests. Douglas fir, occasional ponderosa pine, and pinegrass parklands cover the bottoms of the major valleys. The main communities are Keremeos and Hedley.

Okanagan Highland Ecoregion The Ecoregion, also south of the Thompson-Okanagan Plateau Ecoregion, is to the east of the Okanagan Range and also abuts the USA border. The Okanagan Highland is the smallest ecoregion in the ecozone and, like most of the dry interior ecoregions of southern British Columbia, lies within a rain shadow of the Cascade Mountains to the west. This ecoregion is composed of long, rounded ridges of moderate relief and deep, wide valleys often occupied by large elongated lakes (Fig. 4). This is one of the hottest and driest regions. The climate is characterized by warm-to-hot, dry summers and moderately cool winters with relatively little snowfall. Summer drought, enhanced by warm temperatures, is the primary factor promoting the development of grassland vegetation below 700 mm asl in the valley bottoms. The mean annual temperature for the major valleys of the ecoregion is approximately 7.5 °C, with a summer mean of 16.5 °C and a winter mean of −1.5 °C. The mean annual precipitation ranges from 250 mm in the dry valleys to 300–400 mm on the plateau surface. The climate varies with elevation and topography. Forest cover ranges from lodgepole pine with trembling aspen, white spruce, and Douglas fir on the plateau to Douglas fir and pinegrass at moderate elevations. Valley bottoms are covered by parkland of scattered ponderosa pine in a matrix of bluebunch wheat grass and sagebrush and at the lowest elevations by antelope brush, bluebunch wheat grass, bluegrass, and June grass (Fig. 5). The main communities are Oliver and Osoyoos. Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 91

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Figs. 3 and 4. Grasslands in southern British Columbia. Fig. 3. Grasslands in the valley of the Thompson River about 15 km southeast of Cache Creek, British Columbia. Fig. 4. Southern Okanagan Valley near the border with Washington overlooking the community of Osoyoos, British Columbia. Note the grasslands in the foreground and on the plains beside Osoyoos Lake in the background. Photographs by the author. 92 J. D. Shorthouse

Southern Rocky Mountain Trench Ecoregion The small and narrow south–north Southern Mountain Trench Ecoregion in the southwest part of the province is a complex of ecosystems that occupy the valley of this major geological fault that runs between the and the Rocky Mountains. This ecoregion is a linear, steep-walled, faulted valley about 480 km long. The valley floor is relatively level and can vary in width from less than 1 km to 20 km. Climate tends to become colder and moister from north to south. The mean annual temperature for the ecoregion is approximately 4.5 °C, with a summer mean of 14 °C and a winter mean of −5.5 °C. The mean annual precipitation is less than 500 mm in the southern end of the ecoregion around Windermere and Cranbrook, and 800–1,000 mm farther north near Kinbasket Lake. Vegetation in the valley bottom ranges from bunchgrass, ponderosa pine, and Douglas fir in the south (Fig. 6), to western red cedar (Thuja plicata Donn ex D. Don) and western hemlock (Tsuga heterophylla (Raf.) Sarg.) in the central portion and white and black spruce and lodgepole pine in the northern portions. Large flood plains and wetlands have been formed by several large rivers that drain and meander along the valley floor of the trench. The main communities are Cranbrook, Kimberley, Invermere, and Golden.

Arthropod Studies in the Montane Cordillera Ecozone The report by Smith and Scudder (1998) summarizes the findings for several major invertebrate taxa, nearly all of which showed the greatest species diversity in the Montane Cordillera Ecozone relative to other ecozones in Canada. Most of these taxa attained their highest diversity in the ecozone’s grassland ecoregions. The ecozone includes about 3,000 of Canada’s estimated 10,000 species of mites (Acari), and 76 of British Columbia’s 83 species of Odonata (dragonflies and damselflies). It is the richest ecozone in western Canada for orthopteroid insects, with a total of 125 species, 80 of which are grasshoppers. The total encompasses 11 species that are confined to the Okanagan Valley and considered rare or endangered, including Canada’s only native mantid, Litaneutria minor (Scudder). Of British Columbia’s 697 described species of Heteroptera, 88.4% occur in this ecozone. Further, 19 species of Heteroptera occur only in the Alberta part of the ecozone, having not yet been reported from British Columbia. Of Canadian totals, about 52% (n = 140) of diving beetle (Dytiscidae) species, 51% (n = 101) of robber fly (Asilidae) species, 45% (n = 406) of aculeate wasps, and 44% (n = approximately 2,000) of Lepidoptera occur here. Lists of the various species are provided in Smith and Scudder (1998). Even with this report, it is apparent that much remains to be learned about the arthropod fauna of the grassland portions of the Montane Cordillera Ecozone.

Grasslands in the Yukon Small and isolated grasslands are found in northwestern Canada in the Boreal Cordillera Ecozone, an ecozone that lies north of the Montane Cordillera Ecozone in British Columbia and west of the Taiga Plains Ecozone of the (Ecological Stratification Working Group 1995). The Boreal Cordillera Ecozone is located in the midsection of the Cordilleran system encompassing northern British Columbia and the southern Yukon. This ecozone is characterized by mountain ranges with numerous high peaks and extensive plateaux separated by wide valleys and lowlands. The valleys have been modified by glaciation, erosion, solifluction, and volcanic ash deposition. Of the 12 ecoregions in this ecozone, only three, Ruby Ranges, -Central, and Yukon Southern Lakes, Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 93

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Figs. 5 and 6. Grasslands in southern British Columbia. Fig. 5. Grassland in southern Okanagan Valley north of Osoyoos, British Columbia, on one of the plains to the east of Osoyoos Lake shown in Fig. 4. Fig. 6. Grasslands near Cranbrook, British Columbia. Note the scattered ponderosa pine among the bunchgrass grasslands. Photographs by the author. 94 J. D. Shorthouse

have significant grasslands. These grasslands are intermittent and are found only on warm south-facing slopes (Figs. 7 and 8), with boreal forest vegetation on the north-facing slopes. Many of these grasslands occur in distinctive xeric habitats in the south and central Yukon and along the Yukon River (Scudder 1997; Vetter 2000) and have sagewort (Artemisia frigida Willd.) and grass communities comprising threadleaf sedge (Carex filifolia Nutt.), glaucous bluegrass (Poa glauca Vahl), and alpine fescue (Festuca brachyphylla Schult. ex Schult. and Schult.). Communities of trembling aspen (Populus tremuloides) and prickly rose (Rosa acicularis), and bearberry (Arctostaphylos uva-ursi (L). Spreng.) define the lower and lateral edges of these grasslands (Vetter 2000). Vetter (2000) has suggested that the P. tremuloides, R. acicularis, and A. uva-ursi communities are invading the grasslands but are held in check by browsing hares. The climate of the Boreal Cordillera Ecozone ranges from cold and subhumid to semi- arid. It is marked by long, cold winters and short, warm summers and is modified by vertical zonation and aspect. Mean annual temperatures range from 1 °C to 5.5 °C, with mean summer temperatures from 9.5 °C to 11.5 °C and mean winter temperatures from −13 °C to −23 °C. The Pacific maritime influence moderates temperatures over most of the ecozone. The following descriptions are taken from the Ecological Stratification Working Group (1995).

Ecoregions with Grasslands within the Boreal Cordillera Ecozone Ruby Ranges Ecoregion The Ruby Ranges Ecoregion covers the Kluane, Ruby, and Nisling ranges, the Shakwak Valley (Trench), and the Kluane Plateau. The climate is characterized by short, cool summers and long, cold winters. Maritime air from the Gulf of Alaska periodically invades the region during the winter, resulting in mild spells with near-thawing temperatures. The mean annual temperature for the area is −3 °C, with a summer mean of 10 °C and a winter mean of −17 °C. The mean annual precipitation ranges from 250 to 300 mm. The terrain consists of rolling to undulating hills above 900 m elevation. Northern boreal forests occupy lower slopes and valley bottoms, with grasslands found on south-facing slopes (Fig. 7). The main community in the region is Haines Junction along the Alaska Highway. Many of the grasslands near Kluane Lake and the Aishihik-Sekulmun Lake area are relatively accessible from the Alaska Highway (Vetter 2000).

Yukon Plateau-Central Ecoregion The Yukon Plateau-Central Ecoregion extends northward from Lake Laberge to the lower Stewart River in the central Yukon. This ecoregion is composed of several groups of rolling hills and plateaux separated by deeply cut, broad valleys. The climate is cold and semi-arid. The mean annual temperature for the area is approximately −3.5 °C, with a summer mean of 12 °C and a winter mean of −19 °C. Mean annual precipitation varies from 250 mm in the southern areas near Carmacks to 400 mm at higher elevations in the north and east. White and black spruce form the most common forest types. Lodgepole pine frequently invades burn-over areas and dry sites. The presence of extensive grasslands on lower elevation south-facing slopes (Fig. 8) is a significant vegetative feature of this ecoregion. Major communities in the region are Carmacks and Pelly Crossing.

Yukon Southern Lakes Ecoregion The Yukon Southern Lakes Ecoregion extends from Lake Laberge south to the boundary with British Columbia. It covers parts of the Lewes and Nisutlin plateaux and all of the Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 95

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Figs. 7 and 8. Patches of grasses on hillsides in the southern Yukon. Fig. 7. Grassy hillside on a south-facing slope east of Kluane Lake on the Alaska Highway. Photograph courtesy of M.A. Vetter. Fig. 8. Grassy hillside on a south-facing slope beside the Klondike Highway in the Yukon near the community of Carmacks. Photograph courtesy of T.A. Wheeler. 96 J. D. Shorthouse

Teslin Plateau. The climate is cold and semi-arid. Within major valleys, the mean annual temperature is approximately −2.5 °C, with a summer mean of 10 °C and a winter mean of −16.5 °C. In the major valleys that lie within the rain shadow of the St. Elias Mountains, the mean annual precipitation ranges from 225 to 300 mm (Keenan and Cwynar 1992). Boreal forests are composed of open white spruce (Picea glauca (Moench) Voss) and lodgepole pine (Pinus contorta Douglas ex Louden) intermixed with aspen poplar. Grasslands are found on south-facing slopes at low elevations. , Carcross, and Teslin are the major communities.

Insect Studies in the Yukon The Biological Survey of Canada made a significant contribution to our knowledge of the environment, paleoecology, and invertebrate fauna of the Yukon with the publication of Insects of the Yukon (Danks and Downes 1997). This publication documents the many diverse habitats for insects in the Yukon, including the intermittent grasslands on the south- facing slopes, even though it has far fewer species of insects than has southern Canada. Furthermore, entomological research in the Yukon provides insight into the nature and development of the insect fauna of Canada. This is because part of the region, known as Beringia, remained ice-free during the Pleistocene and was a refugium for many organisms (Hopkins et al. 1982). Further, because the Yukon is the most northern range of the fauna that moved up from the south as the continental ice sheets dissipated, it is an area where southern fauna comes in contact with surviving Beringia fauna. Finally, the land corridor that appeared across the Bering and Chukchi seas during the glacial periods allowed for an exchange of Palearctic and Nearctic flora and fauna (Matthews and Telka 1997). Thus, knowledge of Yukon fauna is central not only to our understanding of the flora and fauna of Canada, but also to our understanding of the origins of the whole North American biota (Downes and Kavanaugh 1988). The Yukon grasslands have a distinctive insect fauna, many with southern affinities and some being Pleistocene refugial species (Anderson 1984; Lafontaine and Wood 1988; Scudder 1993, 1997). Seventeen species of grasshoppers have been found in the Yukon and many of these are on south-facing slopes (Vickery 1997). One of these, the migratory grasshopper (Melanoplus sanguinipes (Fabricius)), is a pest of cereals in the prairie grasslands to the south (see Chapter 1). Another, the Yukon grasshopper (Bruneria yukonensis Vickery), is endemic to the Yukon (Vickery 1997). Hamilton (1997) recorded 16 species of leafhoppers on these south-facing grasslands. Anderson (1984) discovered a new species and genus of weevil, Connatichela artemisiae Anderson, found only on dry south-facing slopes in the Yukon and Alaska.

Grasslands in Southern Ontario Extensive grasslands with several tallgrass species were present in southwestern Ontario as recently as 1800 (Szeicz and MacDonald 1991). Settlement and place names such as the town of Prairie Siding (Kent County), Paris Plains Church (Brant County), and Turkey Point Plains (Haldimand-Norfolk region) are reminders of grasslands that today have long since been plowed under or paved over. At present, only about 100 small remnant patches of these grasslands remain to sustain tallgrass species. They are situated in roughly a triangle stretching from the tip of Georgian Bay, southwest to Lake St. Clair, northeast to the Trent River, and west to Georgian Bay (Fig. 9). Tallgrass prairie once occurred in an almost Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 97

Fig. 9. Map of southern Ontario showing current distribution (by dots) of grasslands and savanna remnants. Source of figure: Wasyl Bakowsky of the Ontario Natural Heritage Information Centre.

continuous band from Turkey Point northward to Brantford and Cambridge and eastward to Hamilton (Bakowsky and Riley 1994). Other extensive areas occurred on Walpole Island, near Windsor, and on the Oak Ridges Moraine near Rice Lake south of Peterborough (Catling et al. 1992). There are also remnant grasslands in northwestern Ontario near the border with Minnesota. Grasses such as big bluestem (Andropogon gerardii Vitman), Indian grass (Sorghastrum nutans (L.) Nash), and switch grass (Panicum virgatum L.); shorter grasses such as side-oats grama (Bouteloua curtipendula Link), Canada wild rye (Elymus canadensis L.), and porcupine grass (Stipa spartea Trin.); and numerous species of forbs grow in these remnant patches (Bakowsky and Riley 1994). Ontario’s grasslands are patchy extensions of the tallgrass prairie of the Great Plains of the American Midwest that occur among the Carolinian deciduous forests of Minnesota, Wisconsin, Illinois, Michigan, Indiana, and Ohio (see Chapter 8). The grasslands in southwestern Ontario (Figs. 10 and 11), as well as in a small region north of the Rainy River between Rainy River and Fort Frances in northwestern Ontario (Figs. 12 and 13), are the most northern examples. All of Ontario’s grasslands, like those in the Yukon, are isolated and biogeographically significant. However, in contrast to the grasslands in the Yukon, those in southwestern Ontario are tallgrass and usually grow in association with widely spaced deciduous trees. Grasslands in southern Ontario are thought to be remnants of a “prairie peninsula” that developed about 8,000 years ago when temperatures were approximately 1–2 °C warmer than they are today (Transeau 1935; Wright 1968). Grasslands expanded as eastern forests 98 J. D. Shorthouse

receded during this period as a result of increased winds, decreasing soil moisture, and increased mortality from the fires that accompanied rising temperatures (Wright 1968). After the temperatures returned to modern levels, the prairie peninsula was fragmented as trees recolonized much of their previous range (Wright 1968), leaving tallgrass in only a few favourable sites. The remaining tallgrass sites were further fragmented by human activities such as agriculture and urban sprawl (Szeicz and MacDonald 1991). Bakowsky and Riley (1994) estimated that tallgrass prairie and oak savanna now occupy less than 1% of their former range. Ontario’s grasslands are unique because they are Canada’s only “Savannah Grasslands” (Kline 1997). More commonly used to describe grasslands in Africa, savannas are natural areas of mostly grasses with scattered open-grown trees (Figs. 10–11). Trees that characterize Ontario savannas in the southwest are black oak (Quercus velutina Lam), white oak (Q. alba L.), and pignut hickory (Carya glabra (Mill.) Sweet). On drier sites, there may also be white pine (Pinus strobus L.), red pine (P. resinosa Aiton), and eastern red cedar (Juniperus virginiana L.). The Walpole Island First Nation prairies (approximately 650 ha) to the west of Lake St. Clair (Fig. 9) is one of the largest and best remaining stands of oak savanna grasslands. The Ojibway Prairie Complex (Figs. 10 and 11), a collection of five different sites totalling 320 ha within the city limits of Windsor (see Chapter 9), provides a second such example. The Ojibway Prairie supports a rich Carolinian flora of over 600 species and 116 species of plants that are prairie indicators (Pratt 1989). It is one of the few sites in Ontario where fire is used to sustain the tallgrass prairie (Fig. 11). The reason that areas of grasslands persisted within the deciduous forests of southern Ontario prior to the arrival of European settlers has been the subject of much discussion. However, scientists generally agree that a combination of soil characteristics, microclimate, and fire likely favoured grasslands over forests (Szeicz and MacDonald 1991; Catling et al. 1992). Before the onset of fire suppression, periodic fires set by lightning strikes and those deliberately set by aboriginal peoples shaped and maintained the grassland landscape (Pyne 1982; Pauly 1997). Native peoples on the Manitou Rapids First Nation Reserve near Rainy River in northwestern Ontario, and those associated with the nearby Kay-Nah-Chi-Wah-Nung Historical Centre, with its ancient burial mounds (Fig. 12), claim that their ancestors periodically burned the tallgrass communities, just as is still done annually today. Grasslands near Rainy River in northwestern Ontario are rare examples of western mixed grass, fescue prairie, and open woodlands (Fig. 13). These mixedgrass communities are small and exhibit floristic differences from western grasslands. This region remains largely unexplored by botanists and entomologists and many species likely remain undocumented. The Stanley area along the Kaministikwia River just west of Thunder Bay harbours numerous rare prairie species and northern rough fescue (Festuca altaica Trin.), which is a common member of the Aspen Parkland Ecoregion. The next nearest population of this grass is in Riding Mountain National Park, some 800 km to the west. Paiero et al. (see Chapter 9) recorded about 2,200 species of insects from Ojibway Prairie. This total includes a large number of species restricted to tallgrass habitat, many of which are rare on a national level. Thus, the site is one of the most important biodiversity hotspots in Canada. Further, the presence of disjunct populations of tallgrass-dependent arthropods, particularly species incapable of sustained flight, suggests that the Ojibway Prairie was formerly part of a continuous prairie peninsula connected to the Great Plains (Mlot 1990; Hamilton 1994, 1995, 2005; Paiero et al.: Chapter 9). Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 99

10

11

Figs. 10 and 11. Tallgrass oak savanna in the Ojibway Park near Windsor, Ontario. Fig. 10. Remnant patch of tallgrass surrounded by black oak. Fig. 11. Remnant patch of tallgrass with new shoots sprouting following a spring burn. Photographs by the author. 100 J. D. Shorthouse

12

13

Figs. 12 and 13. Tallgrass remnants in northwest Ontario. Fig. 12. Remnant tallgrass on ancient burial grounds at the Kay-Nah-Chi-Wah-Nung Historical Centre near Fort Frances. Photograph by J.D. Shorthouse. Fig. 13. Grassland dominated by Stipa spartea among a bur oak savanna on the shoreline of the Lake of the Woods, near Budreau’s Beach between Kenora and Fort Frances. Photograph courtesy of Wasyl Bakowsky. Ecoregions with Grasslands in British Columbia, the Yukon, and Southern Ontario 101

The plight of Ontario’s grasslands has caught the attention of the public and several organizations, including the World Wildlife Fund, and government agencies such as the Ontario Ministry of Natural Resources have developed a recovery plan to save and enhance what is left. The Ontario Tallgrass Prairie and Savanna Association is working to raise awareness, coordinate recovery efforts, and help provide local groups with advice on restoration.

Alvars The alvars of southern Ontario are another unique grassland-like community. Alvars are bedrocks of flat limestone with shallow soils and sparse vegetation that were scoured by retreating glaciers. They are surrounded by forested areas, characterized by annual extremes of moisture and temperature, and are dominated by grasses, sedges, shrubs, and stunted trees (Catling and Brownell 1995). When trees are present, they are confined to deep, wide cracks in the bedrock where soil has accumulated such that the canopy is not continuous. Six main alvar regions occur in Ontario, with the most prominent found along the Bruce Peninsula, on Manitoulin Island, near Ottawa, and along a line from Kingston to Lake Simcoe (Catling and Brownwell 1995). The presence of rare species of plants endemic to alvars has been documented (Catling and Brownell 1995), but little is known about the invertebrates of these sites. The leafhoppers and their allies are one exception (Bouchard et al. 2001). Eighteen species of prairie-endemic Auchenorrhyncha are recorded from alvars. This tally includes the red- tailed leafhopper (Aflexia rubranura (DeLong)) and Flexamia delongi Ross and Cooley. Both species are flightless and typically are found in tallgrass prairie in southern Manitoba to the central United States, where the latter species feeds on little bluestem Schizachyrium scoparium (Michx).

Acknowledgements I thank Léo Larivière of the Department of Geography at Laurentian University for drawing the maps and Geoff Scudder and Robert Lalonde for suggestions on improving the text.

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