Fall Colors on the Prescott National Forest

Trees in Haywood Canyon turn bright yellow, orange, and red during the peak fall colorsAspens leaves turning gold along Copper Basin RoadBlazing gold leaves against a bright blue sky at Lynx Lake South ShoreLynx Lake South Shore on a crisp, clear autumn dayFetid Goosefoot bursts with reds, oranges, and golds in Granite BasinClose up of fetid goosefoot in Granite Basin during the fallHumphrey's Peak near Flagstaff and red rock views from Mingus MountainBright red virginia creeper vines cling to ponderosa pine and oaksClose up of bright red virginia creeperGranite Mountain reflected in Granite Basin LakeGreen, red, orange, and gold trees line Mount Vernon Street in Prescott

 

Fall colors in Arizona?  Seriously?

Come visit the Prescott National Forest this fall and you might be surprised by what you find!  Pockets of ash, maple, oaks, cottonwoods, aspen, poplars, and sycamore sprinkled throughout the forest explode in color during the autumn.  These traditional displays of fall color are usually found near lakes, waterways, and drainages, but perhaps the most surprising fall colors on the forest are found closer to the ground:  Fetid goosefoot covers the foothills and bursts with golds, oranges, and reds in the fall, and Virginia Creeper (a tree-climbing vine) goes unnoticed all summer, but turns a vivid red before losing its leaves for the  winter.  If you're set on seeing a concentration of fall colors in one place, you can always swing through any of the towns or cities adjacent to the forest where you'll find abundant ornamental trees in a dazzling array of bright fall colors rivaling those found in the North Woods. 

When do fall colors peak on the Prescott?

 Like in other parts of the country, it is impossible to say exactly when fall colors will peak--but as a general rule, trees and bushes at the highest elevations start changing from mid- to late September with leaves falling around mid- to late October.  Trees at lower elevations begin changing a couple weeks to a month later, and you can still find signs of autumn into mid-December in the Verde Valley and other low elevation parts of the forest.  So, think about an autumn trip to see the sights on the Prescott National Forest.  If you miss peak colors, you're sure to find plenty of beauty and color such as the red rock views as you drop off Mingus Mountain headed towards the Verde Valley, or blue sky, clouds, trees, and rock formations reflected off of any of the Forest's lakes or waterways.  If you're hankering to get out of town and see natural beauty this fall, the Prescott National Forest will not dissappoint! 

Additional Resources

 

The Science Behind Fall Colors

What Makes Leaves Turn Colors?

The leaves on deciduous trees do not really “turn” colors. They just lose their green. Leaves actually begin to prepare for autumn in the spring. At the base of each leaf is a layer of cells called the “abscission” or separation layer. All summer, small tubes pass through the abscission to carry water into the leaf. The leaf uses this water with carbon dioxide, sunlight and chlorophyll to produce food. This process is called photosynthesis.

The word photosynthesis means “putting together with light.” The food, or “sugar,” is carried back out through the tubes in the abscission into the tree. 

In the fall, the cells of this abscission layer begin to swell and form a cork-like material, reducing and finally cutting off flow between the leaf (leaves) and the rest of the tree. Also, because of cool nights, the sugar still produced in the bright fall sun is not readily transported from the leaves to the stems and roots. The less sunlight (shorter days at the end of summer, beginning of autumn), the less green chlorophyll is produced, and is, in fact, broken down.

This is when you begin to see the yellow xanthophyll and orange carotene that are present in the leaf all year around but are covered by the green chlorophyll. No one is sure what purpose these other elements serve, but scientists believe they also have something to do with photosynthesis. Certain species of deciduous trees will begin, at this time of warm days and cool nights, to produce anthocyanins. Anthocyanins are the reds and purples and are produced only in autumn; they are not present in the leaves all year.

During this dormant period, the trees use the reserves they have stored up over the summer to stay alive. They need this time to take a rest from producing.

What do autumn leaves and bananas have in common?

The green color in unripe bananas comes from chlorophyll, the same pigment that gives green leaves their color. As bananas ripen, the chlorophyll breaks down and disappears, revealing the yellow color, which has been there all along. The yellows and oranges of autumn leaves are also revealed as their chlorophyll breaks down.

Why Are Some Years More Colorful Than Others?

Good reds are produced when the days are warm and sunny and the nights are cool (45°F or less, but not a frost), coming one after another. In this setting, the leaves produce lots of sugar using the abundant sunlight, but the cool nights prevent the sugar from flowing through the leaf veins. At this point, anthocyanins (the reds and purples) are produced. Yellow and orange are fairly constant, because they are already in the leaf and do not require specific weather situations.

A warm, wet period in the fall will cause the changing to be not so brilliant because sunny days producing the sugar and cool nights halting it’s spread produce the best color. A severe frost will kill the leaves, ending the show immediately.


Why Are Some Areas More Colorful Than Others?

Sunshine is the key. The more sunshine, the more sugar is produced. While there will not be enough sunshine to produce chlorophyll, some sugar and anthocyanins (the red/purple/blue colors) will be produced as a last ditch effort to bring nutrition to the leaves. In trees where anthocyanins are not produced, we will see only the yellows and oranges.

The sunnier spots of the mountains and less-shaded trees in town will become reddish/purplish, if they are predisposed to do so. In addition, a single tree may be red on one side, the side more exposed to the sun, and yellow and orange on the other.

When Do The Leaves Typically Change Color on the Prescott National Forest?

Typically, trees in the highest elevations begin to change mid-September. Then, like a slow-moving wave, the color descends into the valleys where signs of autumn last into December.

What Are The Types Of Trees In Central Arizona That Turn Colors?

Aspen (yellow), Maple (yellow, orange, red), Oak (yellow, orange, brown), Cottonwood (yellow), Various fruit trees (red, orange, yellow), Elm (yellow), ash (yellow), poplar (yellow), willow (yellow), and even weeds and bushes like sumacs (Orange, red) and poison ivy will change colors and decorate the roadsides.

What Makes Evergreens…Well, Evergreen?

Evergreen trees (pines, spruces, cedars and firs) don’t lose their leaves in the fall. They are covered with a heavy wax coating and the fluids inside the cells contain substances that resist freezing. Evergreen leaves can last for several years before they fall and are replaced by new growth. They may, however, become brownish if the winter is particularly cold.
 





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