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.

7 replies
  1. Maribeth Seaton-Murray says:

    Thank you for sharing this information. As painful as it is to live through fires, we accept that naturally induced fire is a part of a natural life cycle. We also understand that human induced climate change has damaged the natural cycle of Earth’s systems. Our hearts go out to all the people and animals suffering through the devastation and to those who don’t survive. May we all work to reduce our negative human impact on our planet home. We will remain hopeful and grateful for the beauty of California Fall Color.

  2. Geno says:

    Your optimism gave me hope. This has been such a terrible year and fall foliage was the one bright spot I was looking forward to. I will continue to keep the faith and watch this blog for updates. Thank you!

    • John Poimiroo says:

      Maribeth, Robert and Geno – thanks for your support and views. We plan to stay positive, yet pragmatic, during a difficult year. This experience is testing our collective mettle. As for CaliforniaFallColor.com, we will never stop searching for the beauty of autumn.

      • Robert B says:

        Thanks John…My wife and I will still take our annual Eastern Sierra trip in Oct and if the color is not as good as other years it will still be a nice trip! Keep up the great work here on your site, looking forward to more reports!

  3. RM says:

    Thank you for this info. I have wanting to take a fall color trip to the Eastern Sierra Nevada from LA for years now and was planning on taking the trip this year, but see that it might not be the best year to do it. I will keep an eye on updates, but wanted to say thank you for this site. I love this site and look at every year often during the fall months.

    • John Poimiroo says:

      Right now, it’s not the best time, but give it a day and it could be one of the most unbelievably beautiful years, ever. The reason it’s so disappointing for the moment are: forest closures (due to smoke and to allow USFS staff to focus entirely on firefighting) and haze. However, both those conditions will change. Yesterday was the first clear day in a month in the Sacramento Valley, with an actual sunset seen along the Coast Range. If I’ve learned anything in more than 40 years writing about California’s fall color it’s what Heraclitus of Ephesus wrote 2,520 years ago, “the only constant is change.”

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