Pingo, West Blackstone River (Photo: J. Meikle, YTG)
Tundra polygons (Photo: J. Meikle, YTG)
The Peel watershed planning region encompasses approximately 67,000 km2 of the Taiga Cordillera and Taiga Plains ecozones. Ecoregions within the planning region include:
The sedimentary rocks that underlie much of the ecoregion range in age from Early Proterozoic to Middle Jurassic, a 1.6 billion year long sedimentary record exposed only in few other places in Canada. Spectacular landforms are associated with multiple glaciations and periglacial weathering. This ecoregion encompasses a significant ecological transition from the boreal in the south to the taiga in the north. The Yukon portion of the ecoregion is home to some of the largest woodland caribou herds in the territory.
Peel River Plateau
This is the only ecoregion in the Yukon with landscapes almost entirely shaped as the result of Laurentide glaciation. Several canyons testify to rapid northward draining of pro-glacial lakes about 10,500 years ago. Regional drainage was rerouted northward by Laurentide Ice, and in response, Peel River tributaries, such as the Snake, Caribou, Trail and Road Rivers have downcut into the plateau. Most species of large Yukon mammals occur, but only the polar representatives of most small mammal generally inhabit the ecoregion. The extensive wetlands and the broad Peel River valley support considerable bird life.
Fort McPherson Plain
Only a small portion of this low relief, low elevation ecoregion occurs within the Yukon. It includes the only part of the territory that lies on the floor of the Mackenzie Valley. Perennially frozen peatlands are extensive, covering over 25% of the ecoregion. The mean annual runoff is extremely low because of the very low relief. The mean seasonal and summer stream flows of rivers are the lowest per unit area among all the Yukon ecoregions.
North Ogilvie Mountains
Mountains of modest relief formed of sedimentary rock have unvegetated summits and rubble covered slopes, separated by broad valleys. This ecoregion was largely ice-free during the most recent glacial event, but has evidence of older glaciations. Periglacial landforms are common. The coldest daily minimum winter temperatures in the Yukon are often recorded in valleys of this ecoregion. The North Ogilvie Mountains Ecoregion provides wintering grounds for the Porcupine caribou herd and is home to perhaps the only mammal species restricted to the Yukon — the Ogilvie Mountain lemming.
This ecoregion contains the largest extent of unglaciated mountain ranges in Canada. Some excellent examples of periglacial landforms are found within this ecoregion, including solifluction lobes and cryoplanation summits and terraces. The northernmost Richardson Mountains host phosphate minerals, including lazulite, the Yukon gemstone. Vegetation cover, strongly influenced by aspect and elevation, produces a surprising diversity of ecosystems and habitats. This ecoregion contains the Yukon portion of calving habitat along with important migration routes of the Porcupine caribou herd.