FAQs
Tree Mortality
Tree mortality means trees have died. Trees dying are a normal occurrence in natural ecosystems. The difference now is that the extended drought has caused an abnormally high number—in the millions—of trees in California’s forests and wildland-urban interface areas to weaken and/or die. Weakened trees are more susceptible to attacks from bark beetles. Once a tree is successfully invaded by bark beetles, there is no recovery for the tree; it will die.
Ponderosa pine, Jeffrey pine, and pinyon pines are most impacted by bark beetles, but many trees have died just from lack of water in the recent drought. Most other pine species, white fir and incense-cedar are also heavily impacted by the prolonged drought and by bark beetles. There is also an increase in tree mortality among oaks, although it is primarily attributed to drought, not bark beetles.
Bark beetles are small insects, generally black, hard-shelled and approximately 5 millimeters in length—about the size of a piece of cooked rice. Bark beetles tunnel under bark, cutting off the tree’s supply of food and water needed to survive. Bark beetles can kill a tree in as little as two to four weeks during warmer months.
In bark: Look for reddish-brown pitch tubes. These ½-¾ inch blobs of sap on the outside of a tree trunk are a sign that bark beetles successfully attacked the tree. Leaves/needles: Needles on dying conifer trees and pines begin to turn a reddish-brown and often start changing color at the top of the tree. The color change gradually moves down the tree. Other trees may slowly fade from green to brown.
Outside of tree: Flaking bark, or holes in the bark caused by woodpeckers, are good indicators that bark beetles or other insects are present.
Under normal conditions, bark beetles renew the forest by killing older trees and those weakened by disease, drought, smog or physical damage. When trees are weakened due to lack of water from prolonged drought, they are more susceptible to bark beetle attacks. Increasingly successful attacks cause the bark beetle population to explode.
Bark beetles attack stressed trees by boring holes into the bark. A normal, healthy tree would be able to fend off attack by exuding pitch into the holes pushing the beetle out. But drought- stressed trees have a difficult time producing enough pitch to fight off insects. Compounding the problem, beetles release pheromones that attract other beetles. This mass influx of beetles can quickly overwhelm a tree. Bark beetles are also attracted to freshly cut wood.
Beetles bore through tree bark and lay their eggs. Larvae feed on the tree’s living tissues, cutting off its natural process for transporting nutrients and water. One bark beetle infestation can create several thousand beetles and easily spread to neighboring trees.
Dead trees need to be removed. They are a fire hazard because they are fuel for wildfire to burn. Standing dead trees will rot, becoming unstable, and will eventually fall. Dead trees can fall on people, homes, buildings and infrastructure, such as power lines. The sooner a tree is removed the better. The more it rots, the more unstable it becomes. For larger trees located near houses and other infrastructure, foresters and arborists prefer to remove them in pieces. However, if the tree is too rotten, it is unsafe to climb and difficult to predict where it will fall.
California’s Tree Mortality Task Force will be looking at resources and funding to help landowners, especially those located near evacuation routes, power lines, public roads and infrastructure. Currently, CAL OES is reviewing potential use of the California Disaster Assistance Act for Tree Mortality to local jurisdictions (counties, cities, and special districts) to help with the identification, removal, and storing of dead trees. Local jurisdictions must apply and show risk to public infrastructures.
You can either leave the dead trees on your property or you can have them removed. If you are leaving the trees on your property they need to be properly handled. If you plan on using the wood for firewood, cut to the appropriate size and store. Wood from bark beetle-infested trees can be covered with plastic, following a specific technique to kill the beetles, and left covered for several months. See Tree Note 3 for more information. If wood is not going to be used, lop—or chip and scatter—the wood. The smaller the pieces the better. Chipping will kill bark beetles and the smaller pieces are less of a fire hazard.
Yes, on permitted burn days. Check with your local fire station, CAL FIRE office, or air quality district for details on burn days and proper burning requirements.
If you plan to use a diseased tree for firewood, follow proper storage techniques and make sure the wood is burned locally. Do not transport firewood to another location as it may introduce detrimental insects and disease into a new area.
It is highly recommended that you hire a professional to cut down your trees, as tree removal can be dangerous. Falling trees can also be hazardous to people, nearby buildings, cars, other trees and infrastructures. It is also a good idea to make sure you, or your contractor, have adequate liability and damage insurance coverage.
An emergency regulation by the California Board of Forestry and Fire Protection in 2015 allows for an exemption to cut dead and dying trees of any size without the normal regulatory requirements such as a timber harvest plan, submission requirements, and completion and stocking report requirements. For more information visit: http://www.ReadyForWildfire.org/Dead_Tree_Removal
No. If the dead trees are in areas surrounding a home, buildings or infrastructure, these trees should be removed first. If the trees are in a forest, some dead trees may be left as snags for wildlife habitat. Dead trees located near fuel breaks, and within 100 feet of all structures, need to be removed.
If you plan to utilize the wood for yourself, such as for firewood, you do not need to file a timber harvest plan with CAL FIRE. However, if you plan to sell logs or chips that result from tree removal, or use their value to offset the cost of removal, you are required to file a timber harvest document with CAL FIRE.
The best way to prevent bark beetles is by following best forest health practices. In order to do this, you need to plan for extreme weather years. Ensure that trees are widely spaced, and that the number of trees growing on your land is appropriate for the acreage in order to reduce competition for limited water, light and soil nutrients. There are some professional chemical treatments that may help trees fight off bark beetles, but they have not always been proven to work.
Bark beetles have destroyed 45 million acres of forest in the western United States in recent years, including 15 million acres of Forest Service land. Studies have shown that trees are dying faster than ever in old-growth forests of California and the mountains of the West. In addition to the drought and bark beetle infestations, some scientists have linked tree mortality to rising temperatures, earlier than normal snowmelt, and forest fires.
As forests shrink, less carbon dioxide is absorbed from the atmosphere and stored in the living tissues of the trees in the forest. This means more greenhouse gases will be released from dead trees and enter the atmosphere, and fewer trees will remain to absorb carbon dioxide.
- Remove dead trees, especially around your home.
- Create 100 feet of “defensible space,” the natural and landscaped area around a structure that has been maintained and designed to reduce fire danger.
- Maintain trees by thinning overgrown trees and watering as necessary.
- Plant a diversity of tree species, including drought tolerant species of trees native to the area.