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Open Grassland

opengrasslandsClick on each section to find out about species found in open grasslands


Mammals

Birds

Amphibians/Reptiles

Arthropods

Plants

Bryophytes/Lichens


Open Grasslands are the flowing landscapes of open areas where grasses are the dominant vegetation and where relatively few trees or shrubs grow. Trees are not able to grow in these hot and dry conditions, but grasses have adapted to deal with the drought. Many grasses take advantage of moisture in the soil in early spring to complete their growing cycle before it becomes too hot.

Bunchgrasses are the most widespread grasses in British Columbia grasslands. The tufted shape of the plant enables it to collect rain water, directing it into the middle of the fine roots below ground; the outward curving leaves also help shade the ground around the plant from the hot sun. Bunchgrasses have shallow, fibrous root systems that survive on surface moisture, or moisture not far below the surface. They often stop growing and their leaves will turn brown during drought periods, but they will grow again when summer rain retures. Their large root systems provide effective winter storage for nutrients for the next year's growth.

Bluebunch wheatgrass is common in the low elevations of the Fraser, Thompson, and Okanagan valleys and in the southern Rocky Mountain trench. Rough fescue thrives in the mid to upper elevations and only occurs south of Barriere and Clinton (51°N). It needs more moisture than bluebunch wheatgrass and so is found in moist sites and on north-facing slopes.

Idaho fescue occurs in the southern Rocky Mountain Trench, southern Okanagan valley and in the Garry oak meadows of southern Vancouver Island and the Gulf Islands. The grasslands of the Cariboo-Chilcotin are dominated by bluebunch wheatgrass and needlegrasses, and those of the Peace River country by slender and western wheatgrass. Many other grass species occur throughout the open grasslands.

Big sagebrush and rabbitbrush are common shrubs of all the lower grasslands areas of the middle and southern interior of the province. Antelope-brush, a third shrub, cannot tolerate cold winters and is confined to the southern grassland areas of the Rocky Mountain trench and the South Okanagan. All three species are covered with tiny white hairs that help to reduce evapotranspiration in the summer heat and have deep roots to capture moisture. In the Peace River Region, big sagebrush is replaced by the prairie sagewort.

Scattered trees such as Ponderosa pine and Douglas-fir dot the open grasslands landscape where small differences in topography, aspect and soils provide moister growing conditions.

Forbs, or non-grassy flowering plants, are a very important component of open grasslands, and are especially noticeable at higher elevations. Many species, such as yellow bells and arrow-leaved balsamroot grow at a variety of elevations. In some cases, plants at lower elevations may already be producing seeds while their counterparts at higher elevations are just beginning to bloom.

Some of the forbs, such as the sagebrush buttercup, grow through the melting snow adding welcome splashes of bright yellow to the early spring grassland. In June the upper grasslands are awash in the colours of blooming Nuttall’s larkspur, sticky geranium, chocolate lily, silky lupine and old man’s whiskers. The sagebrush mariposa lily, grows from a deep-underground bulb, and often blooms well into July. By August the grasslands turn a soft yellow-brown as the plants become dormant.

An important element of healthy open grasslands at lower elevations is the biological crust, a layer of lichens, mosses, liverworts, fungi and cyanobacteria that covers the ground between well-spaced grassland plants. The crust forms a protective cover for the soil, helps retain moisture in the soil, prevents weedy species from becoming established and adds to the diversity in the ecosystem. The cyanobacteria absorb nitrogen from the atmosphere and convert it to nitrates, a natural fertilizer for the soil.

Open grasslands are home to a variety of animals and birds, many of which are found only in grasslands. Others, such as Mule Deer, rely on both grasslands and forests for their annual needs. Many bird species, such as Western Meadowlark and Common Nighthawk, use the open grasslands only for breeding and raising their young, migrating to warmer climates for the winter. Some bats, such as the Western Small-footed Myotis, hunt only in grasslands. In the Cariboo-Chilcotin, the Western Small-footed Myotis is the most common bat species that hunts for insects over lower grasslands.

Some resident species, such as snakes, avoid the winter cold by congregating underground in communal dens, while others, such as the Badger and Yellow-bellied Marmot hibernate in burrows underground. The Great Basin Spadefoot Toad uses spade-like flanges on their back feet to dig themselves into loose soil where they may stay for many years until favourably moist conditions trigger them to re-emerge.

Because open grasslands are so restricted in their extent in forest-dominated British Columbia, many grassland-dependent species are among the BC and Canadian Species at Risk. The grasslands of the Southern Okanagan have the largest concentration of species at risk of anywhere in Canada. These species are often associated with particular plant communities: Sage Thrashers and Brewer’s Sparrows prefer sagebrush steppe areas, Lark Sparrows are associated with antelope-brush, while Grasshopper Sparrows prefer bunchgrass habitats.

Want to find out more about nutrient cycling in grasslands?
Go to Ecosystem Processes.

Want to find out more about open coniferous forest areas?
Go to Communities and Habitats.

Photos:
Paul Sanborn (Cryptogamic Crust)
Paul Sanborn (Open grasslands)