Sierra forests threatened

It’s not good news according to the experts. Forests in the Sierra Nevada are threatened by unnatural tree densities, fire and climate change, and it’s going to be an uphill battle making them safer.

The good news is that, given the right resources and the right decisions, some of these forests can be returned to a more natural state and made safer.

Magnificent Trees

The first of three speakers to present at a well-attended talk put on by Feather River College at the West End Theater on Feb. 15 was Ryan Tompkins, chief silviculturist with Plumas National Forest.

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When European-Americans first saw the magnificent trees of California they assumed that if they could just stop fires, they could have even more big trees. After a firestorm in northern Washington, Idaho and Montana in 1910 destroyed 10 million acres and another catastrophic fire in Minnesota in 1918 killed 500 people in a single day, it was decided that fires couldn’t be allowed to burn.

This assumption and strategy turned out to be catastrophic for many western forests.Tompkins pointed out that after decades of putting out all fires, scientists learned that trees compete for water and light. If there are too many trees, none of them get big.

Need for low intensity fires

In most forests, especially those in lower elevations, frequent low intensity fires reduced the number of trees to relatively few and kept the accumulation of heavy fuels low.

By putting out low severity fires, forests ended up with a lot of trees, but most of these trees were small. Competition between these small trees for limited moisture weakened many of them, setting the stage for insect attack, disease and catastrophic fire.

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Therefore, age does not make for large trees; reducing competition makes for large trees.

Prior knowledge

Native people had already learned this lesson and had set many of the frequent low intensity fires that resulted in the giant trees that the early European settlers saw when they arrived. And many learned from the native people and set low intensity fires to protect their forests. 

However, they were overruled by people back east, shocked by the massive loss of forests and human life in the two fires mentioned.

Local forests are dense, homogeneous and unstable

Today, trees are burning at a much faster rate than they can grow into mature trees. With high fuel loads, many mature trees are going to burn in high severity fires.

Tompkins said that two-thirds of forest stands in Plumas County have not burned in 100 years. These densely forested areas are set up for burning.

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Droughts further weaken overcrowded trees, making them more susceptible to diseases, insects and eventually catastrophic fire.

Tompkins noted that the area may have dodged a catastrophic fire bullet during this drought, but unless fuel levels are reduced, overcrowded forests will burn catastrophically at some point.

Tompkins also pointed out that recent high severity fires have homogenized forests, making them both less diverse and more ecologically unstable.

  He also noted that when repeatedly burned by high intensity fires, forest soils become sterilized, more erodible and are no longer able to regenerate on their own.

Forests are out of whack

Danny Cluck, a leading forest entomologist with the Forest Service, was next to present. Cluck described the role played by bark beetles in forests, which are a normal part, but usually found in relatively small numbers.

However, during long droughts they attack trees weakened by drought, competition and old age. Weak trees are no longer able to push the beetles back out. Once inside a tree, the beetles multiply rapidly.

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With more stressed trees, there are more beetles attacking more trees. With so much more fuel from dead and dying trees in the understories of overcrowded forests, fires become hotter and burn higher up into the crowns of mature trees, spreading rapidly from crown to crown.

Instead of reducing competition for large trees, catastrophic fires burn nearly all trees, including old growth trees that have survived low intensity fires for hundreds of years.

Cluck summarized what he and Tompkins had been saying by declaring, “Our forests are completely out of whack. There are too many trees for the soil water resources available.”

Forests and climate change

Kyle Merriam, forest ecologist for the Sierra Cascade Province of the Forest Service, spoke last.

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If overcrowded forests, severe outbreaks of bark beetles and catastrophic fires weren’t enough, Merriam described how changing climates are impacting forests.

Merriam pointed out that average yearly temperatures in the area have risen an average of 2 to 2.5F since 1895.

That doesn’t sound like much, but it has had enormous impacts on forests.

This region used to have eight months of below freezing temperatures. Those eight months are now down to approximately five.

With less precipitation as snow, more precipitation runs off as water in the winter.

Less snow means less soil moisture available for trees during the growing season in the spring and less water for trees to get through the summer.

Less snow also means higher air and soil temperatures in the summer and less groundwater.

Plants are programmed to start growing by temperature and length of daylight.

Spring is coming about two weeks earlier now than it used to. This is affecting plant growth and making already normally dry summers longer and more severe.

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Fuels are also drying out sooner, making the fire season almost three months longer than it was in the 1960s.

Consequently, forests are experiencing more fires, more severe fires and much larger fires than normal.

The economic costs

Not only did the U.S. pay for 100 years to put out low severity fires, it is going to cost much more now to thin and lightly burn forests in order to return them to the healthier condition prior to fire suppression.

Fire suppression in an age of dense understories cost the Forest Service a full 50 percent of its budget in 2015, reducing its ability to do other things.

Indeed, there may never be enough money available to thin and lightly burn much of the local forests. Moreover, it is hard to burn dense forests safely.

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In addition, citizens have become used to summers of smokeless days. Burning, whether due to wildfire or prescribed fire, creates smoke.

Tompkins pointed out that Plumas National Forest has 1.2 million acres. The Forest Service currently treats 1 percent of the forest a year. Therefore, at current treatments levels, the forest will be right back where it started 100 years from now.Assuming catastrophic fires don’t burn the forests before then.

As Tompkins summarized as an understatement at the end of the talk, “We have a scale issue.”

Future presentations

The FRC Sustainability Series is presented by the FRC Sustainability Action Team as an effort to promote sustainability and environmental awareness.

The series continues on March 15, at 7 p.m., with “Sierra Meadow Restoration: How does it affect you?” `

The film, “Love Thy Nature,” will be shown at the Town Hall Theatre on Thursday, April 20, at 7 p.m., in conjunction with Plumas Earth Days.

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Darla DeRuiter, who teaches in both the Outdoor Recreation Leadership and Environmental Studies programs at FRC, organized the series.