Growth of Centenarian Whitebark Pine in the Southern Coast Mountains is Affected by Previous Autumn Snowfall
Whitebark Pine (Pinus albicaulis Engelm.) is a tree species found in high-elevation, cold, windy, or snowy areas. They are “often the first tree species to colonize open, treeless areas” with weak soil development such as the higher elevation areas of the Rocky Mountains and the coastal mountains of British Columbia (BC). Whitebark pines are considered a keystone species; keystone species are “an important source of food and shelter for wildlife species.” Factors such as climate change, white pine blister rust, infections, mountain pine beetle outbreaks, and fire exclusion and suppression are threatening the survival of this tree species. Due to the rapid decline of whitebark pine populations, the Committee on the Status of Endangered Wildlife in Canada (COSEWIC) designated this tree species as endangered in 2010.
Kimberley M. Carlson, Bethany Coulthard, and Brian M. Starzomski discuss the effect of climate on radial growth of whitebark pines in the maritime band of the coastal mountains in BC. Radial growth is defined as the change in the thickness of a tree over time. In August of 2011 and 2012, the researchers collected tree ring information at four locations with healthy and mature whitebark pine populations: Blowdown Pass, Downton Creek, McGillivray Pass, and Texas Creek.
The researchers observed and analyzed the tree ring growth and its correlation to climate and precipitation data. They discovered evidence that “previous autumn snowfall
is the primary determinant of whitebark pine annual radial growth in the study region.” From their results, alongside the trend of warmer and wetter conditions in the upcoming decades suggested by the General Circulation Models (GCMs), the researchers predict increased radial growth of whitebark pines. Long term wetter conditions and a decline in snowfall; however, will limit growth because without the protection of snowpacks, the trees become more vulnerable to freezing and wind scouring.
When comparing their study of maritime band whitebark pine to studies of the broader population of whitebark pine, the researchers found that different factors appeared to influence the growth of whitebark pine differently. For this reason, the researchers believe that a changing climate will have different effects on different whitebark pine populations. The researchers believe engaging in more local-scale studies can result in the development of better management and restoration plans for whitebark pines.
As whitebark pines are a keystone species, the changes in their growth patterns caused by climate will affect other species in the area. The study suggests a difference between the effect of climate change on the growth of whitebark pine in the maritime band compared to the broader population in other areas in the coming decades.
This is a summary article written by Imtihan Ahmed. For more information, please access the full document:
Carlson, Kimberly M., Bethany Coulthard, and Brian M. Starzomski. “Autumn snowfall controls the annual radial growth of centenarian whitebark pine (Pinus albicaulis) in the southern Coast Mountains, British Columbia, Canada.” Arctic, Antarctic, and Alpine Research 49.1 (2017): 101-113.