Auyuittuq National Park of Canada
The arctic is famous for its short but intense blooming season. Visitors in July and early August will delight in the bright carpets of color splashed across the tundra by numerous species of tiny, but hardy, wildflowers.
© Sonia Langer
Auyuittuq National Park straddles the Arctic Circle in an ecological transition between the High Arctic and Low Arctic vegetation zones. The park's harsh physical environment, dominated by rock and ice, limits both the diversity and distribution of plants. Only 15% of the park is covered by vegetation, with most of it occurring in valley bottoms and on lower slopes less than 500 m above sea level.
Plant diversity in Auyuittuq is lower than in other parts of the arctic. Only 112 species of vascular plants have been documented, along with 97 species of lichen and 136 species of bryophytes, or mosses. It is likely, though, that additional species of lichens and mosses are present but have not yet been found.
Arctic plants face many challenges for survival, yet are remarkably adapted to their inhospitable environment. Challenges include:
Permafrost, which limits the depth of root systems
Low winter temperatures, which require the plants to withstand solid freezing
Cool, short summers, which reduce productivity and growth by slowing plant metabolism and the activity of pollinating insects.
Low nitrogen supply in the soil, caused by low rates of decomposition of organic matter due to permafrost and cool temperatures
Strong winds, which can result in abrasive damage to plants by particles of blowing sand or ice
There are many different adaptations to these harsh conditions. Some plants preserve heat by growing in rosettes or dense mats. Others have structural adaptations such as hairy stems or woolly seed covers. All arctic plants are small and grow close to the ground.
© Parks Canada
Most arctic plants contain varying degrees of the pigment anthocyanin, a compound which absorbs solar radiation and allows photosynthesis to occur at lower than normal temperatures. Where vegetation is thick, temperatures at ground level can be up to 20º C higher than the air temperatures above due to the heat-absorbing properties of anthocyanin. While dark-colored plants will absorb more heat than light-colored plants, light-colored plants still contain some anthocyanin (masked by other pigments) to compensate.
A variety of reproductive strategies are used. Many species are able to reproduce from existing stems, rhizomes, or root systems (vegetative reproduction). Some plants rely on insect pollination, while others rely on the wind. Species relying on insect pollination may have their male and female flowers growing in close proximity to increase the chances of pollination success. Because wildlife densities are low, few plant species rely on dispersal of seeds by birds or animals.
Another interesting adaptation is the ability of some plants to tolerate unseasonably cold conditions for more than a year, foregoing growth and reproduction until more suitable temperatures return the following year.