Bishop Field Office

Fall Color Hot Spots 2013


September 17, 2013 Fall Color Update

Photo of Aspens displaying their orange Fall color with Lake Sabrina in the background. 

Photo of aspens displaying their orange fall color with Lake Sabrina in the background (2011). 

 

 
Aspen, willow and other deciduous trees are beginning to change color near the Sierra Crest and at higher elevations of the Eastern Sierra.
 
On September 14 – 15, 2013 I drove over Sonora Pass (Hwy 108). The aspen and willow at the upper elevations along both sides of the pass are beginning to turn yellow and orange. I would expect that peak color is still a week or two off, but the color is still worth a visit.
 
On Sunday I was up along the South Fork of Bishop Creek. At lower elevations (below 8,000’) the trees are still green but above 8,000’ many patches of aspen are starting to change.
 
Another place I noticed the start of some fall color was in the Crowley Lake area. While I was driving I noticed little bits of color in the upper portions of the Hilton Creek drainage. I was also told that the trees along McGee Creek are changing color at higher elevations. I would expect the lower elevation locations to start to change soon. The McGee Creek trail can be a great place for a hike with lots of fall color.
 
The weather for above 8,000 feet for the next several days should continue to be mostly sunny during the day with cool nights; this weather pattern should help contribute to a colorful fall. However, by next weekend, below freezing temperatures are predicted at the higher elevations; there is also rumor of a chance of snow. Below freezing temps could lead to leaves turning black or trees dropping their leaves.
 

It is always a little hard to predict when the “peak” color will be in the Eastern Sierra. I generally suggest sometime between the last week in September and first week in October. However, it is worth keeping an eye on the weather because if we get a cold snap, significant moisture or windy conditions, the leaves may turn black or fall from the trees.

Martin Oliver, botanist

You can also visit the Inyo National Forest website for reports of fall color on National Forest lands.

For more information contact BLM botanist Martin Oliver, mpoliver@blm.gov  (760) 872-5035.

Please check back at this site in the spring for wildflower reports in Mono and Inyo counties! 


Why do leaves change color in the fall?

Every autumn, cottonwood, quaking aspen and willow are transformed into colorful hues of gold, orange and russet. Before long, their leaves will fall and again become part of another cycle that feeds the soil. What causes this yearly cycle, and what determines which color the leaves turn?   

During spring and summer, leaves actively produce foods necessary for plant growth. This food-making process takes place in the many cells within the leaf. Within these cells are chloroplasts, which contain the chlorophyll pigments that are responsible for the green color of plants. The leaves also contain lesser amounts of other pigments, primarily xanthophylls (yellows) and carotenoids (yellows, oranges, and reds).

Photo of Orange and Yellow AspenMost of the year, these other pigments are masked by the greater amounts of chlorophyll in the leaves. But in fall, when changes in temperature and the period of daylight occur, the leaves stop their food-producing activity. Soon the chlorophyll begins to break down, the green color disappears, and the yellows, oranges and reds slowly begin to emerge, giving the leaves their fall splendor.

The intensity of color is determined by the plant's response to complex gradients of temperature and moisture. Fall weather conditions favoring formation of brilliant autumn color are warm, sunny days followed by cool nights with temperatures below 45F (7C). Sugar production increases during the daytime, but cool nights prevent movement of sugar from the leaves.

From the sugars trapped in leaves, the pigment called anthocyanin is formed. When fall weather is consistently cloudy or rainy, and the nights warm, the leaves usually have less intense coloration. The smaller amount of sugar made during periods of less sunlight moves out of the leaves during the warm nights, reducing the conversion of excess sugars into pigments.

Before the leaves can gracefully spin from their leafstalks, a special layer of cells develops and gradually severs the tissues that support the leaf. A small leaf scar is the only evidence that leaves once adorned these deciduous plants. --Anne Halford, Botanist