Community Agriculture Alliance: Forest health concerns |

Community Agriculture Alliance: Forest health concerns

John Twitchell
For Steamboat Pilot & Today

Forest health is a prominent topic in the news these days, here in Colorado and across the West. There is a general recognition that the condition of our forests influences fire behavior, water quality, air quality and our ability to recreate and enjoy this important natural resource.

People in Colorado have understood the importance of forests to our quality of life for a long time. In the past couple of decades, we have experienced, up close and personal, forest issues, such as sudden aspen decline, the mountain pine beetle epidemic in lodgepole pine, the spruce bark beetle epidemic in the subalpine spruce forests and larger and more frequent wildfires throughout the range of these forest types. These forest health events can represent dramatic change on a landscape scale and rightfully receive a good deal of attention in the media and by the public.

For a landowner, the most important forest health issue may be the one happening in their backyard. The Colorado State Forest Service received many calls this year about trees dying here in Northwest Colorado. Not just about old, mature trees, but young, apparently healthy trees that should not be dying. Foresters for the U.S. Forest Service and the State Forester Service were seeing this, as well. What was and is still going on?

A decades-long study that was conducted at the University of Colorado at Boulder and published in the May issue of the “Journal of Ecology” provides some clues. There are many factors that drive forest health, but the study found that the hotter and drier conditions we are experiencing in the West are the main cause of tree death in Colorado’s subalpine forests. Even in forests that were not affected by fire or bark beetle outbreaks, tree mortality has more than tripled since the 1980s. According to an article in, the researchers found that 70% of the tree deaths in the 37-year study could be attributed to heat and drought.

We have experienced drought conditions locally over the past several years, and soil moistures were very low going into last winter. An average winter did little to change those conditions, and much of this summer was hot and dry. This simple explanation does seem to be consistent with what local foresters were seeing in the field this summer, but there are often a number of factors that drive tree mortality.

For example, subalpine fir decline has been very common in recent years in Northwest Colorado, and drought stress probably contributed to the subalpine fir mortality we have seen this year. Subalpine fir decline is a broad descriptor for mortality that is usually caused by a fungus and a beetle working together to kill the tree, although sometimes, it is just the fungus, and sometimes, it is just the beetle. Beetle or fungus, the result is the same, and the tree turns red and dies. It usually does not affect a whole stand of trees but impacts individual trees and small groups of trees. We have also seen mortality in young lodgepole pine this year, and drought is the likely suspect.

There are no real practical treatments for subalpine fir decline, but watering can mitigate drought and heat impacts for individual trees in the yard. Dead trees around the home should be removed to mitigate for fire and reduce the potential for insect and disease. Contact your local Colorado State Forest Service office about other ways to help your surrounding vegetation adapt to a hotter and drier climate.

John Twitchell is a district forester at the Colorado State Forest Service.

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