How Climate Change is Affecting the Forests of the Sierra Nevada

The forests of the Sierra Nevada have inspired poets, artists, and wanderers. John Muir himself was often found in the Sierra Nevada along with others who were searching for the peace of the wilderness. Modern times have mostly left the Sierrra Nevada unchanged, but some key species of trees in the mountain region are reacting to global warming in interesting ways.

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Climate change is causing certain key species in the Sierra Nevada mountains to change where they are growing according to a study published by the journal California Fish and Game. Lodge pole pines, red firs, and western white pines, among others, are shifting their growing zones to higher elevations. These kinds of trees typically grow in cooler temperatures, which are now moving increasingly higher up mountains as the earth grows warmer.

The trees have moved nearly 500 feet higher into the mountains in the last 80 years all along the Sierra Nevada range, from south of Lake Tahoe to the north. Scientists who conducted the research are glad to see that the trees are adapting to a warming world, but worry that the trees will eventually have nowhere else to move to.

Map showing the study area in the northern Sierra Nevada ecoregion, California, USA, above 914 m elevation (3000 feet).

Map showing the study area in the northern Sierra Nevada ecoregion, California, USA, above 914 m elevation (3000 feet). Source: Wright et al., 2016.

Temperatures in the Sierra Nevada have risen approximately 2.34 degrees Fahrenheit in the last century. As trees and other species migrate to cooler temperatures, especially in areas like the Sierra Nevada mountains, they will find an increasingly crowded environment as the mountaintops only get smaller and smaller as you move up. Species will eventually begin to die off with nowhere else to go.

Other tree species in the Sierra Nevada are more resilient to global warming, like the Douglas fir. Although the Douglas fir trees haven’t seen a discernible shift up the mountainsides, researchers wonder how long it will be before these trees too begin an exodus away from hotter temperatures. Rather than leave it until it’s too late to save these vital tree species, researchers emphasize the need to curb the manmade problems associated with global warming sooner rather than later.

More:

Wright, D.H., Nguyen, C.V., and Anderson, S. (2016).  Upward shifts in recruitment of high-elevation tree species in the northern Sierra Nevada, California.  California Fish and Game 102(1):17-31; 2016

Study: Sierra Nevada forests shifting to higher elevations as temperatures warm, Mercury News, May 25, 2016.

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