Climate, Conditions and Color

Smoke from the Rough Fire obscured aspen turning yellow at Lake Sabrina (8/24/15) John Poimiroo

Environmental changes affect fall color. California is experiencing a prolonged spate of hot, dry and smoky air. That dehydrates the soil and reduces photosynthesis, which affects fall color.

CaliforniaFallColor.com has been monitoring news reports of whether this autumn is predicted to be more colorful or less than in previous years. Sources in New Hampshire, Minnesota and Southwest Colorado predict dull color due to drought. North Carolina is getting mixed reviews. Wisconsin is estimated to have a normal autumn, and Maryland is optimistic for a vibrant Autumn due to moisture and hot days.

As for California, we conclude that the beauty of our show will depend upon conditions at specific locations and that no overall prediction for a given region with the state or California as a whole can be made with any reliability. Nevertheless, late summer hot, dry days and smoky air will dull fall color in many places.

“Soil moisture is essential to tree health, obviously, so if there has not been enough moisture at fall color time, color could be delayed, just plain dull, or leaves can die early without changing color,’’ Val Cervenka, forest health program coordinator for the Minnesota Department of Natural Resources was reported in the Duluth News Tribune, this week, as saying. “Trees that are under stress usually show it first in their leaves. Since so much of a tree’s energy goes into producing leaves, the tree can conserve energy by simply dropping the leaves, like it does before it goes dormant in the winter,” he continued.

Marissa Y. Thompson, Ph.D. of New Mexico State University wrote on the university’s website in 2001 that, “Plants can be affected in both a positive and negative manner by smoke.” She continued that “Smoke, produced by combustion of some material, means that there is increased carbon dioxide over a limited area. This is good for the plants and can increase their growth if there is sufficient light.

“The smoke particles that we see, however, are particulate pollution which can coat the leaf surface, reducing photosynthesis. These particulates can also clog stomatal pores, reducing gas exchange in the leaf. These effects are bad for plants,” Thompson concluded.

Science is often torn between two conclusions, i.e., more CO2 resulting from combustion is good for plants, however smoke particles can reduce photosynthesis which is not good for plants.

Our conclusion is that the smoke caused by this autumn’s earlier-than-usual wildfire season will, on the whole, not be good for fall color. Combined with hot, dry days it has desiccated the leaves on many trees – particularly those that were stressed from disease or localized drought. That means, less dramatic fall color.

Further, smoke particulates – should they remain soiling our air – will reduce the beauty of whatever fall color appears, because fewer light waves will make it through the smoky atmosphere to illuminate the leaves.

That’s a dismal prediction for this early in the year. So, we should note that it’s still two weeks from the Autumnal equinox and a lot can happen that could change this within the next month.

  1. It could rain. Some long-range forecasts predict rain at the end of September. Where moisture falls, forests will thrive, leaves will remain fresh and fall color will appear in dazzling displays.
  2. The air could clear. The number and ferocity of California’s wildfires have exceeded normality. They’ve been fed by lightning strikes, high temperatures and wind. A drop in any of these influences could return the state to a more normal fire season.

So, be informed, but don’t lose your enthusiasm. Despite the disappointing present, there will be bright spots of gorgeous fall color to find along the backroads and byways of California. And, when they can be seen, we will report them.

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500 Years of Beauty

Makoto Fujimoto shares these pictures of a massive Gingko biloba tree standing near Koukokuji Temple in the Shinjuku district of Tokyo.

Mike reports that the tree is 500 years old, yet its early December color still shines brightly.

  • Tokyo (131′) – Past Peak, YOU MISSED IT.

The Gift of Nature

First Fall Color Day (10/19/19) Dan Varvais

Few gifts last a lifetime. Nature is one of them.

However, with each generation, fewer Americans are passing this gift to their children.

Well documented concerns about youth detachment from outdoor activities, lack of physical exercise, and increased obesity and health risks, have alarmed many who believe American children are being hurt by the erosion of our country’s cultural connection to nature and outdoor recreation.

Numerous studies have shown that children who participate in outdoor recreational activities are healthier, do better in school, have better social skills and self image, and lead more fulfilled lives.

In response, California became the first state to establish a Children’s Outdoor Bill of Rights. It states that every child should, before their 15th birthday, have had the opportunity to:

  • Discover California’s past
  • Splash in the water
  • Play in a safe place
  • Camp under the stars
  • Explore nature
  • Learn to swim
  • Play on a team
  • Follow a trail
  • Catch a fish, and
  • Celebrate their heritage.

It’s a pretty simple, flexible and achievable list of outdoor rights. Fundamentally, they embody the right to experience the outdoors, outdoor play and outdoor learning. The idea is that family and guardians provide these experiences to children more than once, though many children never get the chance to do all of them, or perhaps even any of them.

Considering the mesmerizing enticements of digital distractions (e.g., video games, TV, social media), if parents, grandparents, guardians and family members don’t introduce children to nature and outdoor activities, this generation will be entirely disassociated from the outdoors.

Color spotters Dan and Connie Varvais checked off several of the above rights for their grandson when they took to Lundy Canyon in the Eastern Sierra for his first fall color day … one they’ve allowed us to share.


Special Report: Yellowstone

Bison, Yellowstone National Park (9/20/19) Alena Nicholas

Autumn arrived two weeks ago at Yellowstone National Park. Southern California color spotter Alena Nicholas was there to record its sparce beginnings.

Yellowstone’s fall color is limited to grasses and willows, as a cone-bearing forest (fir, pine juniper and spruce) covers 80% of the national park.

Nevertheless, in autumn, visual excitement is provided by the park’s abundant wildlife.

Rocky Mountain Elk were rutting and American Bison were grazing its plains. Alena even saw emaciated wolves in desperate search of sustenance.

At this point, the national park would be peaking, though fall color is limited to grasses, ground cover, shrubs and a few trees near the river.

  • Yellowstone National Park – Peak (75-100%) GO NOW!

Autumn in the Tetons

Grand Tetons (9/19/19) Alena Nicholas

Autumn has arrived early in the Tetons at Jackson, Wyoming.

California color spotter Alena Nicholas is photographing Grand Teton National Park and sent these images.

She’s been photographing the Jackson area for the past week and the change of color has evolved rapidly from lime to yellow and, today, to orange and red.

Daytime temperatures there are in the 60s, overnight temps in the low 30s. That’s a good combination to develop vibrant color.

At the beginning of the week, about 25% of the aspen and cottonwood had begun showing color. Now, it’s about 40%.

Autumn happens quickly in the Tetons.

Sunrise, Grand Teton NP, Wyoming (9/19/19) Alena Nicholas
  • Grand Teton National Park, WY (6,800′) – Patchy (10-50%)

Why don’t evergreens lose their leaves?

Coastal Redwood, El Dorado Hills (9/7/17) John Poimiroo

Actually, they do.  It just doesn’t happen all at once, with few exceptions.

Evergreen trees have both broad leafs and needles. Madrone, magnolia and photinia are examples of broadleaved evergreens, while pine, fir, cedar, spruce, and redwood have needled leaves.

Evergreen needles can last anywhere from a year to 20 years, but eventually they are replaced by new leaves. When that happens, the old needles turn color and drop, but not all together and not as dramatically as deciduous trees (e.g., maple, oak, dogwood, alder, birch).

The reason needles are green is that they are full of chlorophyll which photosynthesizes sunlight into food for the tree. It also reflects green light waves, making the needles look green.

Needles, just like deciduous leaves, contain carotenoid and anthocyanin pigments. You just don’t see them until the green chlorophyll stops being produced. Once that happens, hidden carotenoids (yellow, orange and brown) emerge, as is seen in the above photograph.

Additionally, red, blue and purple Anthocyanins – produced in autumn from the combination of bright light and and excess sugars in the leaf cells – also emerge once the chlorophyll subsides.

Yes, even evergreen leaves change color… eventually.

Evergreens that drop leaves at one time include the: Conifers Larch, Bald Cyprus and Dawn Redwood.

In snowy regions, evergreen trees are able to carry snow because the waxy coating on needles, along with their narrow shape, allows them to retain water better by keeping it from freezing inside (which would otherwise destroy the leaf).

Needles also prevent snow from weighing down and breaking branches. Finally, needles allow an evergreen tree to sustain the production (though slowed) of chlorophyll through winter. Whereas, broadleaved deciduous trees would be damaged if they kept producing chlorophyll and didn’t drop their leaves.

Evergreen trees do lose their leaves and the leaves do change color. It just isn’t as spectacular. 

Why do deciduous trees lose their leaves?

Snowcreek (11/2/15) Alicia Vennos

It’s survival not just of the fittest, but of the wisest.

Deciduous trees drop their leaves in order to survive.  As days grow shorter and colder, deciduous trees shut down veins and capillaries (that carry water and nutrients) with a barrier of cells that form at the leaf’s stem.

Called “abscission” cells, the barrier prevents the leaf from being nourished. Eventually, like scissors, the abscission cells close the connection between leaf and branch and the leaf falls.

Had the leaves remained on branches, the leaves would have continued to drink and, once temperatures drop to freezing, the water in the tree’s veins would freeze, killing the tree.

Further, with leaves fallen, bare branches are able to carry what little snow collects on them, protecting them from being broken under the weight of the snow. So, by cutting off their food supply (leaves), deciduous trees survive winter.

The fallen leaves continue to benefit the tree through winter, spring and summer by creating a humus on the forest floor that insulates roots from winter cold and summer heat, collect dew and rainfall, and decompose to enrich the soil and nurture life.

It’s a cycle of survival, planned wisely. 

Why do leaves change color?

Chlorophyll Molecule (Wikipedia)

Leaves on deciduous trees change color in autumn from green to various hues of lime, yellow, gold, orange, red and brown because of a combination of shorter days and colder temperatures.

Throughout spring and summer, green chlorophyll (which allows trees to absorb sunlight and produce nutrients) is made and replaced constantly.

However, as days grow shorter, “cells near the juncture of the leaf and stem divide rapidly but do not expand,” reports Accuweather.com. “This action of the cells form a layer called the abscission layer.

“The abscission layer blocks the transportation of materials from the leaf to the branch and from the roots to the leaves. As Chlorophyll is blocked from the leaves, it disappears completely from them.”

That’s when vivid yellow xanthophylls, orange carotenoids and, due to a different process, red and purple anthocyanins emerge.

Orange is found in leaves with lots of beta-carotene, a compound that absorbs blue and green light and reflects yellow and red light, giving the leaves their orange color.

Yellow comes from Xanthophylls and Flavonols that reflect yellow light. Xanthophylls are compounds and Flavonols are proteins.  They’re what give egg yolks their color.

Though always present in the leaves, Carotenoids and Xanthophylls are not visible until Chlorophyll production slows.

Red comes from the Anthocyanin compound. It protects the leaf in autumn, prolonging its life. Anthocyanins are pigments manufactured from the sugars trapped in the leaf, giving term to the vernacular expression, “the leaves are sugaring up.”

The best fall color occurs when days are warm and nights are clear and cold. California’s cloudless skies and extreme range of elevations (sea level to 14,000′) provide ideal conditions for the development of consistently vivid fall color, as seen in these reports. 

The Science of Changing Leaves

Is red a defensive color? (November 22, 2018) John Poimiroo

Smithsonian.com has posted a fascinating time-lapse video of leaves transforming from chlorophyll-filled green to tones of yellow, red and brown, accompanied by an article explaining how leaves change color and some misconceptions about the process.

The video was created by Owen Reiser, a mathematics and biology student at Southern Illinois University Edwardsville. Reiser, Smithsonian.com reports, took 6,000 photos of leaves to weave together the video.

CaliforniaFallColor.com has reported previously how the change of leaf color results from the loss of chlorophyl, due to shorter days and fewer nutrients. Though, David Lee, Professor Emeritus of biological sciences at Florida International University and author of Nature’s Palette, The Science of Plant Color, says many (including us) have misreported (we won’t make the mistake again) that yellow and red leaves change the same way, when they do not.

Lee states in the Smithsonian.com article that the breakdown of chlorophyll in the leaves does reveal yellow and orange (carotenoids) hidden beneath, but that red (anthocyanin) pigments are produced within the leaves as they die.

There are two schools of thought as to why this happens. One is that the red color is a defensive measure to make the plants look an unhealthy red as the leaf dies, protecting it from plant-eating bugs and animals which are conditioned not to eat red foliage.

The other thought is that red is a form of photo protection. Horticulturist Bill Hoch, Smithsonian.com reports, believes red’s wavelength helps shield the leaf by absorbing excess light allowing the plant to more efficiently remove nitrogen from the proteins that are breaking down and send that nutrient back to tree limbs and roots, saving as much of it as possible before winter.

Whatever the cause, the result is spectacular and less than a month away from being seen in California.


Scouting Report: Siskiyou

Mt. Shasta, Autumn (File Photo)

Whenever I visit Siskiyou County, I question why it took so long to return. The county is so beautiful and loaded with tantalizing outdoor things to do that it’s a wonder it’s so lightly populated and traveled.

Siskiyou is the frosting atop California’s layer cake of spectacular places, and Mount Shasta is its grandest decoration.

What’s kept me from visiting more often has been my perception that it’s too far away. However, on a recent scouting trip up north, time melted away and anticipation built as I drove north on I-5.

Near Red Bluff, big, beautiful, frosted Mt. Shasta rose above the horizon, beckoning and reminding me why Siskiyou is so irresistible.

CaliforniaFallColor.com posts far too few reports from locations north of Shasta Lake, but when we do, they glitter with gold.

Among my favorites for fall color are the Klamath River, McCloud River, Hedge Creek, Mossbrae Falls, Faery Falls and any spot that contrasts fall color with Mt. Shasta.

Greenhorn Rd., Etna, Autumn (File Photo)

I asked Siskiyou County’s Megan Peterson where locals go when the color begins sparkling. She likes the Scott Valley where bigleaf maple populate the twisting edges of the Scott River. Good one.

Megan also likes the Gateway Trail system near Yreka. Dogwood and Bigleaf Maple are the dominant deciduous trees and part of the Foundation Trail (part of the Gateway) has tightly bunched dogwood that “put on a great show” in autumn.

Hiker Jane Cohn of Mt. Shasta City lists the Castle Lake Shore Trail, Lake Siskiyou Trail, Box Canyon Trail, Ney Springs Canyon Trail, McCloud River Fall Trail, Sisson Meadow Trail, Dunsmuir Trail, Sacramento River Trail, Pine Tree Hollow Loop, Kelsey Creek Trail and Cabin Creek as all being flanked with pockets of bold color in autumn.

Hikemtshasta.com recommends the Cliff Lake Trail and Spring Hill Trail. 

Mt Shasta Resort, Autumn (File Photo)

Then, of course, the Mt. Shasta Resort’s golf links are lined with trees that shine bright orange in autumn.

In late May, driving along the McCloud Road, dogwood were abloom with their floral white bracts, hinting at the display of yellow sure to appear once autumn arrives.

Autumn is, however, still a season away, but then don’t put off visiting, as I had. There’s just too much to see, enjoy and explore atop the state in Siskiyou County that is downright irresistible.