Habitat Logs: How to Help the Creepy Crawlies on the Forest Floor

rough-skinned newt
Downed logs provide shelter to many forest species, including the rough-skinned newt, which sometimes overwinters in old logs. Photo: Ken Bevis/DNR.

The forest floor is rich with life, largely unseen, largely small. Salamanders and small mammals creep and crawl about in the great struggle for survival that is nature. While battling with red teeth and claws, they need quiet places to rest, reproduce, feed and regroup. All of this drama quietly unfolds beneath our very feet, and downed logs play an integral role.

These creatures live beneath and within the rich decayed material that is derived from our forests. Wood and leaves break down mostly through fungus, enhanced by the actions of insects, amphibians, reptiles and small mammals that chew wood, and move spores about. Dead trees that have fallen over and become down logs offer some of the richest habitats in this universe of decay.

Many amphibians and small mammals make use of cavities in down wood for important life history phases. For example, many salamanders breed and feed in decayed wood and use spaces in rotting logs for critical cover. Red-backed voles and deer mice use interstitial spaces in dead logs and snags for cover and places to look for food. Douglas squirrels cache cones in down logs and use cavities large enough for them to enter. Pine marten and snowshoe hares covet large cavities in, and cover under, down logs.

Tim Brown and Tara Chestnut
Tim Brown shows Tara Chestnut, a landowner, how he is turning a recently downed log into a home for wildlife. Photo: Ken Bevis/DNR.

Yet, the down log can be a solid eminence for many years, and these animals sometimes have to wait for time to open up the logs to allow their entrance. Breaks, cracks and holes created by physical damage, animals or the action of fungus can take a long time to appear, or might never exist at all, before the log crumbles away into soil.

Can we help? Of course! Targeted management action can enhance this process and provide immediate habitat for these small, unheralded but essential organisms. The normal tools of forestry applied in the cause of habitat creation will suffice; in other words, a chainsaw and a thoughtful operator.

Tim Brown has been creating wildlife habitats out of trees for over 42 years. He got his start as a logger and firefighter, and progressed to become a nationally recognized leader in wildlife tree habitat techniques*. Tim recently spent a day with me in western Washington and we created a habitat log on a small forest landowner’s property near Mt. Rainier.

We located a recently toppled hemlock behind the home of Tara Chestnut, a local landowner, and with her permission we “worked it up” using Tim’s chainsaw and expertise. I asked Tim some questions as the work progressed.

What wildlife species will benefit from this work?

Lots. Including: salamanders, mollusks (snails and slugs), beetles and other arthropods, ants, spiders and many small mammals such as mice or voles.

What ecological process are you trying to imitate or encourage?

“I am trying to expedite the processes where the animals can get inside of the log to propagate, feed and hide.”

What species and type of log works the best?

“I look for logs that are still sound and not too soft. Any species is good, but in western Washington the best are, (in order), cedar, fir, hemlock and then any hardwoods like alder or cottonwood. Bigger is better, always.”

What about slope position or landscape location?

“Since many of these creatures we are targeting like moist places, the closer to the riparian areas the better.” Lying across, rather than down, a slope is preferred, as the uphill portion of the log will collect soil and moisture.

How do you make a habitat log?

Tim used his saw to cut into the log at various angles and provide entrances and cavities within the log for the use of small wildlife. He used his saw like a knife, plunging into the log at various angles. He prefers a 24-inch or larger blade for this kind of carving work.

“I make a series of slits and slashes into the log to allow wildlife to access the inside of the log right away. I put some cuts down low so that creatures on the ground can access the interior of the log. Slits should be about three times the saw’s width to be large enough for these small critters to enter.”

Making a habiutat log
Left: Tim Brown cuts a slab from a hemlock log. Center: Duff and vegetation are placed into chambers and slits carved into the log. Right: The finished product. Note the entrance on top. Similar slits on the lower edges allow for an alternate entrance.

Tim explained that the middle of the log was accessed by taking a big slab out of the top, about one-third of the way through, in an arc pattern. This works well, as it is a single cut, and then it sits back on top without having to fasten it on. Water will infiltrate and collect in the log along the cracks created by the cuts. Sometimes, people will nail the slab on. If you use steel nails make sure the log will never be cut up for wood; a heavy rock placed on top could do the trick.

After the slab is removed, slits and chambers are created in the center of the log. Chambers inside of the log are accessed by the slits that go all the way through, some out the bottom and side of the log. For small mammals, try to make the slits slightly wider by pushing the saw through three times or more.

Remove as much sawdust as possible so passages are not clogged.

For amphibians and mollusks, Tim adds soil and some organic material to give a jump-start to decay. He thinks small mammals prefer dry habitat, so try to keep the chambers clear for them; they will bring in nesting material.

“I often cut a suspended log so that it falls into contact with the ground. If it is hanging above ground, or there are branch stubs holding it up, decay won’t work as quickly. We want it to decay, and now we have instant habitat value from the entrances we created into the log.”

Tim has gone back and monitored logs like this one he has created over the years, and reports plentiful wildlife use of these created log habitats, including small rodents, marten and salamanders. He has even hollowed out larger logs to create bear dens. (Subject of a future article).

Down logs benefit many forest wildlife species, and provide opportunity for the small forest landowner to enhance habitats. Be creative. Use your saw to hollow out solid logs and help the little critters use them more, and sooner, in the decay process.

Let us know what you try, and send some pictures of your project!

There’s life in dead wood.

Contact us for more information or training on Tim’s wildlife tree techniques.

By Tim Brown, wildlife tree creation expert, 206-271-2020

and Ken Bevis, DNR stewardship wildlife biologist, Ken.Bevis@dnr.wa.gov, 360-489-4802

*(Material used with copyright permission from Timothy K. Brown)

 

Citizen Science Tools for Washington’s Forest Landowners

Like many of you, my family treasures our four-generation ownership of a small patch of forest. Each summer, we watch a rufous hummingbird sitting on a lichen-cup nest, listen for the sound of squirrel-cut western larch cones bouncing off the roof, and await the July ripening of the first huckleberries, hoping we beat a bear to the crop. Our private stewardship also helps protect habitat and supports conservation beyond our property boundary. We actively work to maintain forest health that ensures the continuation of excellent habitat for nesting songbirds, burrowing mammals, and a host of native trees, shrubs, and wildflowers.

We live in an exciting time where the internet has birthed a new field: citizen science. The Oxford English Dictionary recently defined citizen science as “scientific work undertaken by members of the general public, often in collaboration with or under the direction of professional scientists and scientific institutions.” Rapidly growing world-wide, public participation in research enables all of us to engage in the process of scientific investigation, right in our own backyards.

Citizen science tools allow observations made on private lands to aid the scientific community to learn about habitat needs and population trends of our native flora and fauna. People like us use websites or phone apps to collect and report data—easy as pie! In this article, I’d like to share several programs that can help Washington forest landowners identify and learn about plants and animals who share their land.

The Cornell Lab of Ornithology eBird makes it easy for citizens to report bird observations so scientists can analyze movements, distributions, and numbers of bird through time. Individuals can use eBird to view barcharts, range maps, and time period and location for any given species in a given region. eBird data supports Merlin — a bird identification learning app-that allows an observer to enter a few observations about an unknown bird and offers limited choices so the user can say “That’s my bird!” and immediately see its range map, photos, and key ID traits.

Similarly, the University of Washington Burke Museum Herbarium helped launch a low-cost phone app to help users identify Washington wildflowers. The app includes images, species descriptions, range maps, bloom period, and technical descriptions for more than 850 common wildflowers, shrubs, and vines that occur in Washington. To identify an unknown flower, users enter a series of observations and are then offered a small subset of possible matches, based on location. Getting to say “That’s my flower,” takes just a few minutes and doesn’t require an internet connection.

Have you ever seen milkweed or a monarch butterfly on your land? The Washington Dept. of Fish and Wildlife invites you can join an exciting new citizen science project, the Western Monarch Milkweed Mapper. This project is the first-ever effort to document locations for both monarch adults, larvae, and eggs found on milkweed, helping WSU researchers learn about monarch migration from Washington to coastal California over-wintering sites.

The Xerces Society for Invertebrate Conservation is an international nonprofit organization that protects wildlife through the conservation of invertebrates and their habitats. They offer several citizen science programs for pollination species, including Bumblebee Watch. The website offers detailed species identification guides so the user can say “That’s my bee!”

The Xerces Society also offers landowners resources to improve habitats for native pollinators. Their book, Attracting Native Pollinators (2003), is packed with information about natural history of bees, butterflies, flies, beetles and wasps. Book Sections include ways to take action to create nest and foraging habitat in all kinds of landscapes. You can purchase and post their attractive Pollinator Habitat sign, to inform neighbors about your conservation efforts.

It is personally rewarding for me to share what I’ve learned on my own property with the wider community of scientists. The websites and phone apps make it easy and fun to both learn and share while I enjoy my family’s forest patch. Consider becoming a Washington citizen scientist today!

By Susan Ballinger, conservation fellow with the Chelan-Douglas Land Trust, educator and active citizen scientist advocate. Her website is Wenatcheenaturalist.com

Who was here? Clues from Wildlife Sign

wolf track by Ken Bevis
Wolf track in road mud in northeast Washington state. This log scale ruler marks tenths of a foot, so the track is about 5 and a half inches long. Photo: Ken Bevis/DNR.

The bull elk stalks through the forest, holding his enormous antlers back so he doesn’t tangle in the brush. The tiny warbler flits through the canopy, seldom letting us have a good look. The woodpecker chisels for food and cavities in dead wood. Small mammals creep along under the edge of down logs. Cougar and bobcat slink around the forest edges.

Wildlife captures our imagination, filling the forest with life, but can be difficult to observe directly. Yet, we can discover some of what wildlife use our lands through keen observation.

Keep a Record

I encourage small forest landowners to keep some kind of record of what sort of wildlife they observe and encounter on their property.

Excerpt from a wildlife journal
Excerpt from a wildlife journal kept by a family living near the town of Curlew in northeast Washington state.

It could be as simple as a journal entry with species, specific location, behavior and numbers, all written in a notebook or hard bound book. Some keep an electronic record on their computer or mobile phone. Any method is good, because it gives you a chance to compare notes from year to year, while reminding us all to try to become experts on the kinds of wildlife using our property.

Look for “Sign”

Sign is an old word and expression referring to physical things telling us about our environment.

Many animals will leave behind sign, telling us of their presence and their lives.

Droppings (poop or scat) are a sign that can usually be identified to species. We often find some poop along our walks, and sometimes wonder what it is and what it can tell us. Note the shape, location, freshness. Don’t touch too much (wash afterwards), but pull it apart and see what is in it.

A good reference for thinking about scat is the Internet Center for Wildlife Damage Management at www.icwdm.org.

Once on the website you’ll find several questions whose answers can help to narrow the possibilities for what sort of scat you’ve observed. These questions include:

  • White in the droppings? This is from a bird, or even a reptile
  • Size: Length? Width? Consider the expected size of the anus of the animal it came from.
  • Shape: Is it like a pellet? Tubular? What are the ends shaped like?
  • Where did you find it? Under a tree? On the trail?
  • Are there pieces of bone or hair? Seeds or fruit pits?
  • Where are you? What kind of habitat is it? What are the possible animals?

Use these clues to figure it out. Become familiar with the different forms of deer poop, and what bear or coyote scat looks like.

Tracks

Deer and elk leave tracks (and rubbed small trees in the fall). Moose have big feet and distinctive tracks. Bear and cougar are very different.

It’s more difficult to find tracks of smaller animals but it can be done. Tracks are often distinctive, but need to be put down in the right substrate. Mud along roadside puddles is perfect medium for track impressions. Walking with a landowner east of Colville, we found the print of a lone wolf in a muddy puddle on a remote forest road. Location, shape and size tell us it was wolf. The landowner’s big golden retriever was along and the dog’s track was only two-thirds the size of this one.

Light snow on a hard surface also is a great way to find tracks. We all remember the day when the snow was just right and we could suddenly see what animals had passed by. Dusty roads can work too. Ever see insect tracks in the dust?

Critter Parts

Sometimes bones or feathers we find can give us clues. Think about the body structure of an animal. Hard and white larger bones are mammal. Bird bones are delicate, and even the largest birds (eagles, ravens, or geese) have relatively small bones compared to a raccoon or snowshoe hare. These fine bones degrade quickly in the outdoors. Reptile bones are rarely found, and never amphibian bones. All animals share the same basic anatomy, and a great exercise is trying to reconstruct the body of the creature from the small clue of a bone, or collection of bones. Call it CSI wildlife.

Another important clue is the setting. Did the animal die from predation? Was it scavenged? How many pieces did you find and how old are they?

shrew mole
A shrew mole found dead. Photo: Ken Bevis/DNR.

Individual feathers are usually molted, or shed, in the normal course of the bird replacing its resplendent covering. Try to figure out the species by color, pattern and size. Which part of the bird did it come from? A pile of feathers, often on a log, can indicate a kill by a hawk, usually an accipiter like a Cooper’s, sharp-shinned or goshawk. They will pluck breast feathers, and some tail feathers, and either eat the rest right there, or carry the carcass to a favored feeding spot.

Rarely do we find whole dead animals because the forces of scavenging and rot are so formidable.

Recently, however, I did find a dead shrew-mole (an unusual mammal) on a forest road near Mt. Rainier. It was still floppy, and I do not know why the animal was dead. But it did give open up a teachable moment, and I learned about Neurotrichus gibbsii, and this amazing little critter’s lifestyle.

Song and Call

In the springtime, territorial songs and calls of birds will reveal species and defended territories, but it takes a trained ear to differentiate between the subtle calls. There are several good apps now that link song to bird species. Go out early in the day with someone who is good at “birding by ear,” and you will be amazed at what is out there.

Mammals don’t vocalize very much. Coyotes call often in the late spring and summer when pups are exploring. Elk bugle in September and October. Deer sometimes bleat. But in general, hearing a mammal is uncommon.

Tree Sign

beaver sign on tree
Clear sign that a beaver was here. Photo Ken Bevis/DNR

Beavers are the only critter to chew through large tree stems. Deer and elk rub saplings leaving bald areas on the tree’s lower trunk. Woodpeckers leave distinctive holes in trees for feeding and nesting. Bears can strip the cambium off of small diameter saplings in wet forests. Tree sign is among the best because it lasts a long time!

Wildlife is elusive but not invisible if we are alert to all of the ways of detecting and understanding the amazing animals we share our forest with. Open your senses to the little pieces of evidence all around us as we walk in the woods!

Bear sign
Bear sign is hard to miss Photo: DNR.

Send me your wildlife photos, pictures of sign and stories so I can share them when teaching our Coached Planning classes this year. And consider signing up for a Coached Planning course when one is help near you, or take part in our online version of the course this winter.

By Ken Bevis, stewardship wildlife biologist, Washington Department of Natural Resources, ken.bevis@dnr.wa.gov

My, What Big Teeth You Have! Living with Big Predators on Small Forest Lands

Methow Valley cougar: Photo: Ken Bevis/DNR.
A trail camera with remote sensors captured this image of a mother cougar in the Methow Valley. Photo: Don McIvor (see more of this cougar and her cubs in McIvor’s video linked in this article).

“Lions and tigers and bears. Oh my!” Remember in the Wizard of Oz how Dorothy and her three companions (four if you count Toto), chanted this phrase in the creepy forest while looking over their shoulders nervously for certain doom?

Sometimes people who have moved out to their own little piece of paradise in a rural area feel this same trepidation, particularly after hearing a neighbor or news story about a predator encounter. It’s important to consider that we now live in someone else’s neighborhood, namely that of our rich Washington wildlife. This includes some significant predators. But don’t worry too much. With knowledge and good habits, we can peacefully coexist with these animals.

Worries over these big toothy critters include indirect effects, such as losing livestock or pets, or seeing damage to infrastructure from bears getting into garbage or destroying bee hives. These also may be sparked by fears of direct encounters with these animals. Here I will present a few facts, stories, and some links to good resources.

Territory

Predators tend to have large territories, and will continually cross ownerships in their quest for survival. This means that the home ranges of predators usually cover far more land than our average small forest landowner. If you see one, it probably is either passing through, or has found just what it needs there for a limited time (See cougar story below).

We have a rich variety of meat eaters across our landscape, with varying species and populations depending on where you are. Black bears, cougar, wolves, coyote, bobcat and fox all live with us, and sometimes thrive on our forest lands. Their life histories require killing of prey, and the size of prey generally correlates with the size of the predator. For example, coyotes eat mice and voles, cougars eat deer.

Mostly, we coexist with these animals and never even know they are there. But sometimes we notice. Smaller predators generally cause small scale problems, such as the occasional loss of pets (cats and small dogs) or small livestock (such as chickens). Those causing the deepest consternation for landowners are the larger predators, particularly black bear, and cougar. (Wolves are large and wide ranging, sometimes taking range livestock, but rarely causing problems for small forest landowners or threatening people directly. Hence I won’t discuss wolves here. Check the Washington State Department of Fish and Wildlife’s website for useful information about dealing with wolves and all sorts of other wildlife.)

Cougars

Cougars occur in most forested regions of our state, in varying populations, but basically can occur wherever prey, mostly deer, occur. Some of the Puget Sound islands are currently without cougars, perhaps due to historic extirpation, but one recently appeared on Vashon Island and has been quite the phenomenon there.

Cougar along Skagit River
Cougar along Skagit River. Used with permission of landowner

Cougar observations are rare, and those of us who have been fortunate enough to see one in the wild remember it vividly. Even rarer events are attacks on people (and pets) but they do occur. Precautions can be taken, particularly if active cougar sign is about. They are outlined in the WDFW publication, Living with Cougars. Remember, cougars prey primarily on deer. If you choose to feed deer, you may also be inadvertently attracting cougars.

I heard a landowner near Spokane tell me a story from his neighborhood of part time landowners, (where he lives full time), with seven deer feeders. These were the barrel variety with a timer that causes the noisy machine to come on at a set time. The deer would come running for the spray of delicious corn. Needless to say, the neighborhood has a healthy population of resident whitetail deer. There is also a resident mother cougar and her cubs. Nearly everyone had seen this big cat and several youngsters following her around. The neighborhood alarm was substantial. It was exciting but probably dangerous for all concerned, the cougar in particular. To my knowledge, the situation has not changed at the time of this writing.

Here is an interesting story about cougars from by my good friend, Don McIvor. He provided this transcript and wonderful video to add to this topic.

I received a trail camera for Christmas a few years ago and put it out on our 20-acre property near Twisp, Wash., in early January. A fresh snowfall blanketed the ground, wiping the forest floor clean and leaving few clues as to a good spot to mount the camera. I found a faint set of tracks, almost completely obscured by the new snow, and strapped the camera to a nearby tree. The photograph here (see above) is the very first image captured by the camera; you could have knocked me over with a feather! What followed was about a 10-day visit from this female cougar and her three cubs. I repositioned the camera to a nearby spot where the snow was so compacted I couldn’t distinguish the tracks. Turns out this area was immediately adjacent to a deer the mother had killed, and the packed-down snow was the cubs’ playground. I managed to document much of the visit with video and still photography. This was probably a once-in-a-lifetime event and I am pleased our small property could host the big cats, even if only for the short-term. This rare glimpse into the lives of these graceful creatures also illustrates our property’s role in the broader landscape where we help to maintain populations of animals that need large blocks of habitat to survive.

Black Bear

Black bears are big, cute, roly-poly, cartoonish characters; and are also the other big predator we may encounter on our small forest lands. Most of us have bears about. They are omnivorous but opportunistic predators, and will eat most anything they can find, including the occasional deer fawn or elk calf. They tend to be solitary and shy, avoiding humans whenever possible. They can be aggressive towards humans, but it is very rare and usually associated with a mother bear with cubs. Black bears are a game animal and may be taken during legal hunting seasons.

Black bear over carcass remains; image captured by remote sensor camera about 100 yards from Ken Bevis’ house. Photo: Ken Bevis.

Black bears are famous as scavengers and will take advantage of free food. Avoid leaving pet food or garbage out in bear country. Bird feeders can also lead to bear attention. If bears find your feeders, take them down until the bear moves on. “A fed bear is a dead bear” is a saying among wildlife control folks. Habituating bears to human food will lead to trouble, especially for the bear. “Problem” bears are sometimes relocated by WDFW but this is a last resort in situations where the bear has become habitual to a location and human safety is at issue.

Trail cameras are an excellent tool for viewing wildlife on your property. They are a subject for a future article!

The Washington State Department of Fish and Wildlife has an excellent source of information on these critters in its Living with Wildlife Series

The message here is, if you live in wild lands, expect wild animals. Live accordingly.

And please send me good stories and photos!

By Ken Bevis, DNR stewardship wildlife biologist, Washington Department of Natural Resources, ken.bevis@dnr.wa.gov

Fall is Tree Thinning Time for Forest Landowners

Ponderosa pine stand thinned and pruned
Ponderosa pine stand thinned and pruned to prevent spread of low-intensity ground-level fires into the crowns. Photo: US Forest Service.

Fall is just around the corner and for those who own forested land, if you have not already done so, you may want to consider thinning some trees out. People who own forested property are often hesitant to remove trees for various reasons. Why should you thin? What are the advantages?

Forest health

Many people think of a forest as a stand of trees existing together in harmony. In reality, a forest, particularly a young forest, contains trees competing with one another for their life-sustaining resources: sunlight, water, and nutrients.

There’s even a priority list of sorts within individual trees. It varies depending on the species but, in general, the order in which resources are allocated is, from highest priority to lowest priority:

  1. Maintenance of respiration
  2. Production of fine roots
  3. Reproduction
  4. Height growth
  5. Diameter growth
  6. Insect and disease resistance mechanisms, and
  7. Storage

A dense stand of tall, thin lodgepole pine, is a good example of a stand where there are enough available resources to allocate up to priority number 4, height growth, but not enough resources to allocate much to priority number 5, diameter growth, or beyond. This lack of resources will affect overall forest health, as the trees will not be able to allocate resources to insect and disease resistance mechanisms.

What sort of insect and disease resistance mechanisms do trees have? Let’s use bark beetles as an example, since certain species of bark beetles can cause extensive tree mortality.

In most coniferous species a resin duct system produces oleoresin when the tree is wounded, such as a broken branch. Oleoresin is basically a mixture of essential oil (turpentine) and nonvolatile solids (rosin). Oleoresin is considered the primary defense of conifers against bark beetle attack. Beetles that attempt to attack a conifer that is in good health and capable of producing adequate, pressurized oleoresin are typically immobilized in the resin or killed by drowning in it. The chemical makeup of the oleoresin is important as well, as some of the volatiles released from the oleoresin are toxic to bark beetles.

Dense stands, which tend to grow slowly, are consistently associated with bark beetle infestations. The susceptibility of a stand to bark beetle infestations may be changed by reducing competition between trees; in other words, thinning. In western North America, thinning has long been advocated as a preventative measure to reduce or alleviate the amount of bark beetle caused tree mortality. Thinning improves tree vigor and growth. It also decreases the likelihood of bark beetle attacks on individual trees by allowing the site’s available resources to be concentrated on fewer stems, which means trees will have enough resources to allocate to priority number 6 (insect and disease resistance mechanisms).

Wildfire risk reduction

Successful fire exclusion over the past 60 to 70 years has resulted in greater stand densities and a change in species composition. In that span of time, many forests in dry ecosystems, such as eastern Washington, have transitioned from fire-adapted, open ponderosa pine stands to dense pine and Douglas-fir stands. In moist forests, the change has been from open stands of western white pine and western larch to relatively short, closed stands of grand fir, western hemlock and western redcedar. These changes have led to an increase in the occurrence of crown fires (fire that spreads from treetop to treetop), the most intense type of wildfire, and often the most difficult to contain.

Thin from below
Example of thin from below. Photo A: Before thinning. Photo B: After thinning. Photos: Michelle Ensminger.

 

Ponderosa pine, western white pine and western larch all tend to be tall and self-prune (the natural removal of lower limbs that don’t receive enough sunlight to survive). Western white pine and western larch have lower volume crowns and carry their crowns well above surface fuels compared to true firs, Douglas-fir, western hemlock, and western redcedar. Because of these attributes, western white pine and western larch do not carry crown fires well and tend not to create ladder fuels (fuels in the lower canopy that carry fire up into the crowns of trees). In contrast, stands dominated by true firs, Douglas-fir, western hemlock, and/ or western redcedar do not self-prune well. They tend to carry large branches low in the canopy and have relatively voluminous crowns. Stands dominated by these species usually support crown fires.

Thinning cannot alter all variables that influence fire behavior, but it can influence factors such as species composition, available fuel, fuel arrangement, fuel moisture and surface winds. The objective of thinning in wildfire risk reduction is usually to prevent or slow the spread of crown fire by reducing surface and ladder fuels. Thinning also raises the height of overstory crowns and breaks up the connectedness of crowns, which reduces tree-to-tree spread of crown fires.

Wildlife management

Species associated with fairly open canopies and an open forest floor may benefit from thinning treatments. Thinning a stand of trees increases the amount of sunlight reaching the understory, which stimulates the growth of grasses, wildflowers and native shrubs. Elk, deer, and moose will likely benefit from the increase in forage quantity and quality. Small mammals such as chipmunks and deer mice may increase in number, particularly after thinning in Douglas-fir and ponderosa pine forests. This may be advantageous to species of hawks, owls and eagles that prey on small mammals in open forests and small clearings. Although not often considered as part of the wildlife community, pollinators such as moths and butterflies may also benefit from changes in structural diversity as a result of fuel reduction treatments that increase the amount of light reaching foliage and the forest floor.

Timber production

If you are managing your forested land for future timber production, thinning will be an important part of your management plan. Thinning releases resources to the residual trees allowing them to allocate to their fifth priority, diameter growth, which leads to an increase in tree volume. This increase in diameter growth results in an increase in overall stand value.

Thinning techniques

The tools and methods by which thinning is implemented are quite varied, and can result in significantly different stand structures. The type of thinning you select may depend on your objectives and on individual stand characteristics, such as species composition.

When managing for forest health and fuel reduction, private landowners typically use the “thin from below” method. Thinning from below consists of removing trees from the lower canopy, leaving larger trees to occupy the site. This method mimics mortality caused by competition or surface fires and concentrates available resources on larger, healthier, fire-adapted trees, while removing the stagnant, unhealthy trees.

Thinning is best accomplished in the late summer and early fall if possible. At this time trees will be least susceptible to damage from the thinning operation and the populations of insects that may be attracted to the slash created will be low. Winter also is an acceptable time to thin, but can lead to soil compaction and erosion if done at the wrong time. Thinning in spring and summer is not recommended as it can attract insects such as bark beetles and can affect wildlife, particularly nestlings.

For more information about thinning your property, please visit the Forest Stewardship Program and the Landowner Assistance Center pages on the Washington State Department of Natural Resources website.

By Melissa Fischer, Forest Health Specialist, DNR Northeast Region, Washington State Department of Natural Resources

 

Resources to  learn more:

Fettig, C.J., Klepzig, K.D., Billings, R.F., Munson, A.S., Nebeker, T.E., Negron, J.F., and Nowak, J.T. 2007. The effectiveness of vegetation management practices for prevention and control of bark beetle infestations in coniferous forests of the western and southern United States. Forest Ecology and Management. 238: 24-53.

Graham, R.T., Harvey, A.E., Jain, T.B. and Tonn, J.R. 1999. The effects of thinning and similar stand treatments on fire behavior in western forests. U.S. Forest Service, Pacific Northwest Research Station. PNW-GTR-463.

Pilliod, D.S., Bull, E.L., Hayes, J.L. and Wales, B.C. 2006. Wildlife and invertebrate response to fuel reduction treatments in dry coniferous forests of the western United States: A synthesis. U.S. Forest Service, Rocky Mountain Research Station. RMRS-GTR-173.