Aspen Parkland - Flora

Flora

Four significantly different habitats are common in the aspen parklands: The fescue prairie, the woodlands, the ravines and the wetlands and lakes. A rarer habitat type, tallgrass aspen parkland, occurs only in the extreme southeastern corner of the aspen parklands biome (southeastern Manitoba/northwestern Minnesota). The fescue prairie is a meadowland rich in vegetation variety which forms the cover for the development of the richer soils that underlie the parklands. The close association with woodlands and wetlands makes this a choice location for many plants and a preferred range or home site for a wide diversity of wildlife. The richer soil and increased precipitation favours the natural growth of fescue grass. However, varying conditions such as moisture level and grazing pressures allow for the invasion of secondary plant species.

There are numerous grasses and sedges in the fescue prairie. Gravelly and rocky terrain is a good location for parry oat grass. Dry areas favour June, porcupine and spear grass. Wet areas are often covered with slender wheat grass and timber oat grass. Prairie rose and snowberry are common shrubs found in these grasslands.

The forested, or woodlands area is dominated by trembling aspen Populus tremuloides, balsam poplar (Populus balsamifera), other poplars and spruces, although other species of trees do occur. Pines, mostly jack pine and lodgepole pine will often grow in areas that have sandy soil conditions. Other native species may include box elder, tamarack and willow, while the foothills area in the southeast of the region, such as Turtle Mountain or Spruce Woods Provincial Park, have woodland of white spruce and balsam fir but quaking aspen will domninate where the woodland has been cleared by fire. The proportion of forests to grasslands has increased somewhat over the prairie in areas not affected by agriculture in the last 100 years. This increase is partly due to the reduction of prairie fires which used to destroy the new saplings on the fringes of the aspen groves. Also, it was a common practice for farmers to plant stands of trees as windbreaks.

Aspen woodlands support an extensive understory consisting of mid-sized and small shrubs, some herbs and ground cover. Spruce-dominated woodlands usually do not support a dense understory due to more acidic and nutrient-poor soils and a denser canopy, which reduces sunlight reaching the forest floor below. However, in areas where a mixture of aspen and spruce occur, a fairly dense understory can still thrive. In fact, the mixed wood understory, as it is called, supports the greatest diversity of forest wildlife in the aspen parkland.

Large shrubs such as red-osier dogwood, beaked willow, saskatoon, chokecherry and pincherry, along with the smaller shrubs including prickly rose, snowberry, beaked hazelnut and low bush cranberry, form a dense entangled understory. Dense shrubbery is a typical feature in aspen-dominated forests. Common herbs found in the woodlands include: Lindley’s aster (Aster ciliolatus), northern bedstraw (Galium boreale), pea vine, Western Canada violet (Viola canadensis), dewberry and bunchberry. Mosses appear at the base of trees and on the ground.

Wetlands are very common in this biome, including lakes, shallow open water, marshes, and grassy wetlands. Glacial erosion has contributed to such features by creating depressions in which standing water can collect. In the larger depressions, permanent lakes or ponds of water remain. Many of the lakes have a saline character, thus most shore vegetation has a high tolerance of salty soils. These lakes are known as alkali lakes. Wet meadows are flooded in the spring and dry by fall. They contain rushes, sedges and grasses and provide excellent opportunities to study the similarities and differences of these forms of vegetation.

Rivers and streams erode valleys throughout the parkland ecoregion. Steep hills and ravines result in a unique topography. Southwest slopes with increased exposure to the sun are dry and often more grass covered while the shaded north and east exposures retain more moisture and tend to have greater forest cover. Some forms of vegetation unique to the ravines include: poplar, spruce, birch, willow, and river alder.

Wildflowers are an important component of the grassland association of the parkland. Look for common yarrow, cut-leaf anemone, rock cress, creeping white prairie aster, milk vetch, late yellow loco weed, goldenrod, prairie rose, prairie crocus, and tiger lily.