Tree Mortality & Falling Hazards

Dead and dying trees in the Tahoe National Forest and Nevada County is a fact of contemporary life. Being aware of hazards that dead trees cause and hyperconscious of fire starting activities will help keep families and neighbors safer.


From 66 million dead trees in 2010 to 129 million in 2017, the State of California is losing trees at a rate that no one has previously seen.

An effective response is beyond what the US Forest Service and CalFire can handle.

Keeping populated areas safe from wildfires and falling trees, as well as aiding in forest recovery will take cooperation between homeowners, PG&E, NID, recreation facility managers, environmental, nonprofit, and government agencies.”

“Though California received record-breaking rains in the winter of 2016-2017, the effects of five consecutive years of severe drought, a dramatic rise in bark beetle infestation, and rising temperatures have led to historic levels of tree die-off. ” – Tree Mortality Task Force – News Release 12/12/17

“The Tree Mortality Taskforce has provided an essential venue for coordination of response efforts, exchange of ideas, reporting, and accountability for the ongoing statewide response to this incident,” says Supervisor Nathan Magsig of Fresno County. – News Release 12/12/17 Tree Mortality Taskforce. 

In Executive Order B-42-17, Governor Brown relaxed regulations so that anyone licensed for timber and tree service operations can perform tree removal in high-risk areas.

California’s ‘New Normal’ Fire Safety Strategies

“Approximately 95% of all wildfires in California are caused by people,” says the California Wildland Fire Coordinating Group (CWCG).

Roadway, Burn Pile, and Camping Safety

Sparks Along Roadways

Burn Pile Safety

Putting out Campfires

Falling Trees

  • stay clear of large stands of dead trees, especially if it is windy
  • look up and around before parking near dead trees, don’t park in the potential path of a tree fall
  • if traveling to remote areas, keep a chainsaw or ax in your vehicle in case a tree fall blocks the road
  • Tree Mortality – Watch Out – PDF

Defensible Space Around Homes

“The importance of removing dead and diseased trees cannot be overstated. Addressing widespread tree mortality is a crucial first step to not only safeguarding our forest communities but also in creating a healthier and more resilient Sierra Nevada forest – which provides more than 60 percent of the state’s water supply.” – Tom Berryhill, Tree Mortality Update – 3/2016

  •  Remove dead trees
  • Create defensible space around your home
  • Call PG&E (1-800-743-5000) if you have a dead tree threatening a power line
  • Create a home evacuation plan and ‘go-kit.’ Check kit supplies monthly

After the McCourtney and Lobo fires in October 2017, Nevada County residents were harshly reminded about how quickly wildfires can move through communities.

We also have an opportunity to witness the adaptations that nature makes in response to drought, global warming, and pest infestations.


If you liked this post, check out Native Plants for Healing the Land after Fire or bark Miniscule Mountain Beetle Turning Forests Red


Forest Research and Outreach – University of California

Homeowner Responsibilities – USDA

Nevada County FireSafe Council – 2018-2019 Fire Season Guide + Emergency Preparedness and Evacuation Guide

One Less Spark – One Less Wildfire – fire prevention

Ongoing hazards from trees affected by drought – PG&E

Our Forests are Changing  – USDA

Prepare for Bark Beetle – CalFire

USDA Forest Service – Aerial Detection Survey Results

With California Drought Over, Fewer Sierra Pines Dying –  10/24/17 – 

Miniscule Mountain Beetle Turning Forests Red

“It’s about the size of a mouse turd,” says Diana Six, Professor of Forest Entomology/Pathology at University of Montana, when describing the Mountain Pine Beetle.

Historically, the Mountain Pine Beetle contributed to a healthy forest by eliminating weakened trees, making room for new growth. Cold temperatures kept populations in check, only 20% of larvae would survive a winter.

Beetle Lifespan

At higher altitudes, Pine Beetles may live for up to two years; however, most beetles complete a life cycle within one year. They go through egg, larva and pupa stages beneath the bark of a tree. When summer temperatures warmed sufficiently, adults emerged in search of a new host. Females lead the charge, emitting pheromones that beckon males to follow.

Carrying a fungus in mouth pockets, it is released inside the tree when the beetles begin boring into it. The fungus grows, gathering nitrogen that supplies the beetles with needed food. A female will lay approximately 60 eggs. The fungus supplies nutrients to the growing offspring.

Fungus Kills the Tree

The fungus invades the sapwood, preventing the tree from using pitch to repel beetles.  It also blocks water and nutrient transport inside the tree.

Pine Beetles are opportunists. When conditions are right, they colonize and reproduce. Now might be the beetle’s greatest moment in history.

Contributing Factors to Widespread Beetle Success

  • Managed forest landscapes – the practice of replanting only a single species
  • Years of fire suppression procedures
  • Climate change – low night temperatures at night don’t drop enough to kill larvae
  • Forest trees weakened by years of drought 2014 – 2017

Mountain Pine Beetles have been devastating forests in Canada, trees at higher altitudes with no natural resistance.  The insects aren’t picky when food source areas are depleted, they move on to another one. Ponderosa and other pines in Nevada County, stressed and weakened by drought, are feeling the bite.

It may be the largest forest insect blight
ever seen in North America. – Wikipedia

Unfortunately, by the time tree needles turn red, the beetles have already settled in another host. A single besieged tree will nourish enough beetles to infect seven more. With numbers like that, they cut a wide swath through a forest quickly. Aside from keeping dead trees from becoming a hazard to humans or buildings, there is no effective method to halt or control the infestation…

Infestation Evidence

  • Reddish dust and “boreholes”
  • “Pitch tubes” resing globules the tree produced in an attempt to protect itself
  • Leaves / needles turning yellow, then red
  • Horizontal larvae egg galleries under the bark
  • A blue-gray color in sapwood, caused by beetle introduced fungus

As disturbing as it is to see huge areas of forest turning red, a bright spot may be the survivors – genetic adaptors. These are trees that struggled in cooler, wetter conditions. The beetle blight is giving them an opportunity to flourish. Mountain Pine Beetles don’t ‘see’ those trees as food.

It is too soon to tell the effects that these species will have on animal habitats, water retention, and snow packs.

“Insects are expected to be one of the first indicators of climate change in terrestrial ecosystems because they are cold blooded.  Everything they do – everything – is dependent on temperature.”  -Andrew Nikiforuk, author of Empire of the Beetle

 Sound as Pest Control





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If you liked this post, check out Tree Mortality State of Emergency


Bark and Wood Boring Beetles of the World

Mercury News – Why tiny insects are tearing up Sierra forests

National Geographic 4/2015 – Pine Beetle Epidemic

Nature of Things with David Suzuki 8/2014 – The Beetles are Coming

San Francisco Chronicle – Bark beetles ravaging droughtstricken forests in California

University of Montana – Diana Six, Professor of Forest Entomology / Pathology

USDA – Bark Beetle Management

YubaNet – Tree Mortality in Nevada County 9/9/16

Wikipedia –  Dendroctonus ponderosae

(beetle discussion with Diana Six 0-14:33)

Sierran Tree Frog with Chemical Sensitivities

Even though it has ‘tree’ in its name, the Sierran Tree Frog is mostly found near the ground.


Tree frogs live in bushes and grass. Their preference is for damp, moist areas.


Large toe pads that allow it to walk on vertical surfaces. The toe pads are also useful for clinging to sticks and twigs.

To avoid being eaten, the Sierran Tree Frog is fast! It can jump long distances and swim quickly to hide.  It also remains perfectly still and changes color to stay camouflaged. Sierran Tree Frogs can change from green and gray to brown.

The Sierran Tree Frog is more often heard than it is seen. Males call to advertise availability and attract mates. Breeding and egg-laying occur from November through July. During this time, males establish a territory that they defend with encounter calls, butting, or wrestling with rivals.


Worms, small invertebrates, and flying insects are the frog’s dietary staples.

Tadpoles feed on algae, bacteria and organic debris. Their feeding activities help keep streams and waterways clear of slippery plant material.

Global Amphibian Issues

Scientists say that we are living in the Anthropocene epoch, a time when human activity is the dominant influence on climate and the environment. Unfortunately, the consequences of this are that many habitats and species will disappear.

Frogs and newts are indicator species because they have thin skin that easily absorbs pollutants. Since they live both in water and on land, they absorb toxins from both environments. Like the miners who used canaries to warn when toxic gas was present, amphibian health determines the quality of the environment.

There are a number of factors that affect amphibian populations. Not unique to Nevada County, these conditions are happening globally.

Factors Contributing to Amphibian Decline

  • Housing and Habitat Loss

“We’re running out of places where frogs are healthy,” Amphibian Study Volunteer

“It doesn’t matter how many frogs we save if there is no place to put them back in the wild,” Edgardo Griffith, El Valle Amphibian Conservation Center

  • Chytridiomycosis (Batrachochytrim dendrobatidis) Skin Fungus – A Global Epidemic
  • Pesticide Runoff & Flushed Prescription Medications

California agriculture is the number one consumer of pesticides in the United States.

The state produces half of the US agricultural produce.

  • 99 percent of artichokes
  • 99 percent of walnuts
  • 97 percent of kiwis
  • 95 percent of garlic
  • 89 percent of cauliflower
  • 85% of the lettuce
  • 71 percent of spinach, and
  • 69 percent of carrots

Contaminated agricultural water runoff affects the entire ecosystem.

“Atrazine (an herbicide) is the most common contaminant in our drinking water. It causes male frogs to turn into females.” – Tyrone Hayes, UC Berkeley Biologist

  • Invasive Bullfrogs

“Bullfrogs pose several threats to the native amphibians of California, many of which are endangered. When bullfrogs—the largest frogs in North America—escape or are released into the wild, they have a tendency to eat other amphibians and any other wildlife that will fit in their mouths. Their size also allows them to outcompete native species for food. Even worse, a large portion of the bullfrogs imported into this country—62 percent according to one study—are infected with the deadly chytrid fungus (Batrachochytrium dendrobatidis), a lethal skin disease which has already been blamed for extinctions of about 100 amphibian species around the globe.” – Should California Ban American Bullfrogs? Scientific American Blog

 How to Help

Speak up for Nevada County frogs, toads, and salamanders.


If you liked this post, check out Miniscule Mountain Beetle Turning Forests Red

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Discovering Sierra Reptiles and Amphibians, Basey, H. E.

The Audubon Society Field Guide to North American Reptiles & Amphibians, Behler, J. L., King

Peterson Field Guide to Western Reptiles and Amphibians, Third Edition, Stebbins, R. C.


AmphibianWeb – Overview of Chytridiomycosis

California Tree Frog identification

Chytrid in Nevada County – Sierra Streams Institute

El Valle Amphibian Conservation Center

Frogs Need Our Help –

Hazards of Atrazine herbicide – Clear Health Centers video

Indicator Species –

Nevada County Resource Conservation District – Amphibians

Reproductive problems linked to atrazine – Tyrone Hayes, UC Berkeley Biologist– Sierran Tree Frog

Service Working to Combat Killer Chytrid in California Frog Populations – Sacramento Fish & Wildlife Office

State of Sierra Frogs (2008) PDF – Sierra Nevada Alliance– Sierran Tree Frog

What if there is no happy ending? – Scientific American, 2013

Worldwide Amphibian Declines 2017

Hungry Bears Losing Ground & Helping Humans Burn Fat

First published September 24, 2017

As of 2012, the American Black Bear population living in the Sierra Nevada Mountain Range was estimated at 10,000 bears. Mostly, they live at higher elevation levels, 3,000 feet and above, in areas managed by the U.S. Forest Service or the National Parks. There is about one bear per square mile.

A rough estimate of Nevada County’s high elevation habitat puts our bear population count at around 500 bears.

Coat Variation Colors

Brown, cinnamon, yellow-brown, grey-blue and white


Full Grown Females: 100-200 pounds
Full Grown Males: 150-350 pounds


Ninety-five percent of a bear’s diet is plant-based.

  • acorns
  • manzanita berries
  • insects (Snag logs, left to decompose, are sources for insects and used as dens.)
  • sometimes grass.

Bears are omnivores. They will eat whatever is available, including human garbage and pet food.


  • Excellent sense of smell
  • Good climbers
  • Avoids confrontation
  • Good swimmers
  • Shy


Female bear fertility is directly linked to nutrition and food availability. They must have high-quality berries and acorns to successfully reproduce.

Bears mate in June & July (females begin to breed at age four-and-a-half).

Typically females have litters every other year, producing two to four cubs in early spring while the mother is in the den.

Unusual Adaptation

Delayed implantation.
Adult females can hold fertilized eggs for months. The zygote doesn’t attach to the uterine wall unless the female has gained adequate fat by hibernation time. If the female is undernourished, the zygotes will not develop.

Hibernation & Human Health Studies

During hibernation, bears don’t defecate. Scientists believe that reabsorbing nitrogen-rich urea, helps them to maintain muscle mass while losing between 15 to 30 percent of their body fat. Studies of this phenomena may one day lead to weight loss aids for humans.

Accumulated fat and high cholesterol levels sustain them through the winter. A bile acid that bears generate during hibernations has been found to dissolve gallstones in humans.

Another interesting hibernation fact is that, while in that state, bears repair and regenerate bones. Researchers are studying this with the hope of curing human bone diseases and degenerative arthritis.


Bear cubs are the most vulnerable to predators such as coyotes, bobcats, and mountain lions.

Largest Threat: Habitat Loss

Humans and habitat loss is the biggest threat to bears.

In the wild, American Black Bears can live to 30 years. Unfortunately, when a bear is drawn into human territory, their lifespan shrinks to about ten years.

Long range relocation studies have shown that relocation efforts are unsuccessful.

Relocated bears will:

  • return to the original scene of the disturbance
  • apply learned behavior in new areas
  • or are killed by territorial bears already living in resettlement zones.

Bears & Humans

Most interactions between bears and humans occur when bears are hungry in spring and late summer/fall.

Once bears become a nuisance to humans, they continue to be a problem.
Problem bears are put down.

The best way to live successfully in high elevation zones, is to discourage bears from establishing bad habits.

*Keep a tidy home and be conscious of items that act as attractant odors.

Guidelines for Bear-Proofing a Home, Property, or Campsite

  • Use ammonia or bleach to deodorize trash cans.
  • Put garbage containers in a shed or garage when not out for pick-up.
  • Freeze smelly food waste and only put it out for collection close to the time it will be picked up.
  • Use a garbage disposal when possible.
  • Keep outdoor grills clean and free of meat drippings.
  • Bring in bird food and pet food at night.
  • Pick up fallen fruit from around trees.
  • Install bear-proof compost containers.
  • Use bear-proof garbage boxes.
  • Keep food and other fragrant items out of your car.
  • Close and secure ground level doors and windows at night.
  • Survey your property for potential hibernation sites; under decks or buildings. Block those places so animals can not access them.


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California Department of
Fish & Game Offices
Northern California-North Coast Region
(530) 225-2300

California Department of Fish and Wildlife – Black Bear Biology

California Department of Fish and Wildlife – Black Bear Keep Me Wild Campaign

California Department of Fish and Wildlife – Black Bear Population

California Department of Fish and Wildlife – Statewide Black Bear Policy

California Department of Fish and Wildlife –Living with California Black Bears PDF

KNCO – 6/2015 – Bears On the Move in Nevada County

KVIE Nature – Black Bear Fact Sheet

North American Bear Center

Untamed Science – American Black Bear

Dammed Disrupted Salmon

When responding to the urge to spawn, Salmon become a powerful delivery system. If allowed to move freely through rivers and streams, they transport ocean nitrogen and other nutrients thousands of miles inland while providing humans and animals with a rich source of food. They did this successfully until man decided to industrialize their reproduction.

Now billions are spent each year attempting to repair a disrupted cycle of nature.

“In 1851, we could observe a great decrease. Like the poor Indian, they are being driven westward into the sea. During hydraulic mining in the 1870s and 80s the salmon population of California was reduced to near extinction” – C. A. Kirkpatrick reporting on the fate of the salmon

Ocean Fertilizer Transport

Conditions necessary for successful spawning;

  • access to inland rivers and streams
  • cool water temperatures (45° – 58° F)
  • highly oxygenated water
  • correct sized gravel
  • not being eaten

“Salmon and steelhead are indicators of river health, from the headwaters to the ocean, when a watershed is able to support strong salmon and steelhead populations, the entire ecosystem can thrive.” – SRYCL and Partners

“West coast salmon runs have been in decline for decades… Analysts estimate that only 0.1 percent of the tens of millions of salmon that used to darken rivers every summer and fall up and down the west coast before white settlement still exist.” – Scientific American

According to the National Oceanic and Atmospheric Administration, the Chinook salmon population along the California coast is declining due to;

  • overfishing
  • loss of freshwater habitat
  • loss of estuarine habitat
  • hydropower development
  • poor ocean conditions
  • and hatchery practices

Fish hatchery managed salmon reproduction has weakened the species.

The video below shows numerous corrective attempts that have been made to restore the salmon along the Columbia River.

Salmon Running the Gauntlet  | National Geographic

Deer Creek Salmon Restoration Efforts

April 2017 – 1:29 – A partnership between the South Yuba River Citizens League and the United States Fish and Wildlife Service has resulted in leadership and funding for adding spawning gravels to the Yuba River near the confluence with Deer Creek.

Salmon & Steelhead in Deer Creek

“SSI has been monitoring salmon and steelhead in Deer Creek since 2009. From 2011-2013 we implemented three gravel augmentation projects to increase the availability of spawning habitat in Deer Creek, resulting in over a 500% increase in salmon redds observed in Deer Creek in 2013.” – Sierra Streams Institute report

Humbolt Restoration

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California Fisheries – Yuba River Steelhead
Crow’s Range: An Environmental History of the Sierra Nevada, by David Beesley [KXJZ, Insight interview 35:46]January 2008  – UC Davis panel on Salmon and Tribes – Klamath River System
Native People along rivers have been affected by dams and loss of natural salmon runs.

South Yuba River Citizens League – Species Profile: Rainbow Trout, Steelhead

South Yuba River Citizens League – Yuba Salmon Now

Wikipedia – Chinook salmon

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