Plant Diversity in Yukon

Yukon's Plant History

During the last ice age (30,000 - 10,000 years ago) most of Canada was covered in kilometre-thick sheets of ice. During that time most of Yukon, Alaska, and parts of the Northwest Territories remained ice free in a sub-continent called Beringia. While most of Canada had to be recolonized from plants that survived south of the ice sheets, Yukon already had a rich flora. Many of these plants survived and today Yukon is known to be home to 1242 species of plants (1348 including subspecies and varieties) from 84 families.

During the ice age, glacier-free Yukon was connected to Asia via a landbridge, exposed due to low sea levels. As a result, Yukon contains rich areas of plant biodiversity. The north coast is home to 1/5 of the world's arctic flora, perhaps the richest arctic coastline for its size. The Mackenzie Mountains host the richest areas of plant biodiversity in Canada, while more than 10 per cent of all plants native to Canada can be found in the LaBiche Valley in the south.

Yukon's Plant Diversity

Yukon surpasses the Maritime Provinces and the other territories for native plant diversity, and is second only to BC and Ontario for the number of plants found nowhere else in Canada. Yukon is second only to Nunavut and the Northwest Territories for the fewest numbers of introduced plants.

Yukon is a contact zone for plants from 3 different regions: Beringia, the Western Cordilleran mountain ranges, and the Boreal forest. Three regions in Yukon contain higher levels of plant diversity:

• Southeast Yukon near the LaBiche and Beaver Rivers - is the northwest edge of the range for many boreal forest plants. Large Ostrich Ferns (Matteucia struthriopteris) give an almost tropical appearance to these lush northern forests. Hotsprings are abundant in this region and provide warmer refugia for some plants typically found further south.

• Southwest Yukon (e.g. Kluane National Park and Reserve) - contains a mosaic of plant species typically associated with Beringia, Western Cordilleran Mountains and the boreal forest.

• Yukon's portion of Beringia - contains a large number of species found nowhere else in Canada as well as several species found nowhere else on earth.

Yukon Endemic Plant Species:

• Yukon Draba (Draba yukonensis)
  
• Kluane Draba (Draba kluanensis)
  
• Scotter's Draba (Draba scotteri)
  
• Ogilvie Spring Beauty (Claytonia ogilviensis)
  
• Maclean's Goldenweed (Nestotus macleanii)

Yukon Endemic Subspecies and Varieties:

• Artemisia rupestris ssp. woodii
  
• Oxytropis arctica var. murrayi
  
• Oxytropis nigrescens var. lonchopoda
  
• Pedicularis labradorica var. sulphurea

At-Risk Plant Species:

• Yukon has only one species of plant that is considered to be "at risk" under federal legislation ; the Baikal Sedge (Carex sabulosa).

Unique Yukon Plant Communities

• Grasslands in the southwest Yukon
• Salt Flats
• Beringian calcareous mountaintops
• The North Coast

Biodiversity is Important

There is still much to be learned about the flora of Yukon. As one component in maintaining ecological integrity and protecting the natural heritage of Yukon, we need to have good information about the location and health of unique plant populations.

Environment Yukon's Role

Environment Yukon is trying to maintain and update a list of plant species in the Yukon as well as track the health of rare populations of plants. This information can be used in land use planning and management decisions and environmental assessments.

Additional Resources

• Yukon Biodiversity Database
• Yukon Plant Photographs
• Cody, W. 1996. Flora of the Yukon Territory - a good list of botanical references that can be found within the Yukon