Climate and Ecology

Last Updated on Friday, 28 June 2013 23:47
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This part of Saskatchewan lies within an area referred to as the Palliser Triangle. Captain John Palliser, a nineteenth century explorer and surveyor, considered this region too dry for agriculture. As a continuation of the semi-arid central plain of the United States, the triangle extends from southwestern Manitoba, includes most of southern Saskatchewan, and reaches northwest to the mountains in Alberta. With annual precipitation averaging only 352 mm, July mean temperatures of 18.9 degrees C., and January mean temperatures of –12 degrees C., this territory presented itself to early European travelers as a semi-arid desert of mixed short-grass prairie, few wetlands, and little or no tree cover.

Millennia of periodic intensive grazing by large bison herds and frequent prairie fires built soils covered by a thick, wiry turf commonly called “prairie wool”. This mixture of plants is called “Needlegrass Prairie” by ecologists. It is composed of native grasses and herbaceous plants capable of responding with rapid growth to any available moisture. When rain is lacking, seeds and the plants’ tough roots can remain dormant for lengthy periods. Their dried stalks provide rich, high protein grazing which, up until the mid-nineteenth century, supported vast herds of bison. The deep, furrowed trails of their migrations and the scooped out hollows of their dust baths are still visible in many places. Today smaller species of herbivores including pronghorn antelope, mule deer, white-tailed deer, jackrabbits, gophers and many birds abound. Predatory species include coyotes, foxes, badgers, weasels and several species of hawks, falcons and eagles. Historically, wolves and an extinct sub-species of grizzly bear similar to the Swan Hills Grizzly also hunted these prairies. Most arable acres within the R.M. have been turned to cultivation. Animal and bird populations have changed in adapting to the presence of agriculture. However, large areas of unbroken prairie exist within the municipality. Their age-old mixtures of plants and animals remain relatively unchanged despite the intrusions of foreign species.

In spring, snowmelt fills numerous sloughs, and small creeks drain excess water into lower basins. Smaller ponds often dry up by summer, but in many places manage to provide enough moisture for fringes of aspen poplar, willow, and a variety of herbaceous plants and woody shrubs. Although native species are well adapted to the extremes of temperature and moisture, through agriculture many introduced species have made inroads. Low-lying areas seem particularly vulnerable to the encroachments of often-undesirable foreign plants. Naturally, drought tolerant species from around the world have found it easiest to establish and compete with native plants.

Cycles of wet and dry years produce wildly fluctuating numbers of insect, animal and bird species. Dry periods offer relief from mosquitoes, but often result in plagues of grasshoppers. Wet years fill sloughs and provide rich habitat for many species, which explode in numbers. Migratory waterfowl arrive in spring on their flight north. In fall if sloughs are full, vast numbers of ducks and geese stay until freeze-up, feeding in the fields. If the fields have been unable to be harvested, the feeding birds can wreak great damage.

Farming and ranching have changed the local ecology. Cultivated species find their way into wild areas. Many species of both plants and animals are not intentionally introduced, but flourish none-the-less as new balances are struck. A growing population of moose is a spectacular example of a species new to the area that is rather hard to ignore, particularly when they take up residence in farmyards and shelterbelts.