Using Drones for Better Forest Access and Management

drone hovering
An Autel Robotics X-Star Premium drone hovering over land trust property. Photo: Mark Gray

The Chehalis River Basin Land Trust owns or holds conservation easements on over 4,400 acres of forest land in southwest Washington. Land Trust representatives visit these lands each year to develop restoration plans, and monitor for invasive species, garbage dumping and other damage. Many of the land trust’s holdings lack roads and are accessible only by foot or boat. Some of the lands contain extensive wetlands that are not accessible even by foot.

To improve the value of their monitoring efforts and to facilitate long term observations of site conditions, the Land Trust has been using an Android tablet loaded with GIS and GPS software. With these tools examiners have access to maps, as well as photos and GPS tracks of previous site visits in the field. QGIS ( and Handy GPS ( are two great free software solutions for field mapping. Free is an important consideration for non-profit, volunteer organization like the Chehalis River Basin Land Trust.

However, these tools don’t help with access to areas that are too wet or steep to be reached by foot. To overcome this challenge the land trust has been investigating the use of an unmanned aerial vehicle (or drone) as a relatively low-cost way to access areas ground based observers can’t reach.

Land Trust board members and volunteers recently had an opportunity to experience a drone in action when Grays Harbor College forestry instructor Alex Bastos provided a demo of the College’s drone at a site east of Aberdeen in the Chehalis River Surge Plain. The site is a wetland, dissected by a network of sloughs draining into the Chehalis River and is not accessible by foot or boat. The Autel Robotics X-Star Premium drone provided high resolution video and still photos of areas that the land owners had never seen. The drone flies at a height of up to 400 feet and has a range of about 1,800 feet from the controller providing plenty of range to cover much of the parcel. The drone can stay airborne for only fifteen minutes but can cover a lot of ground in this short time.  You can see a video of the drone in action at

While using a drone requires a certain level of skill to make the best use of its range and flight time is limited by battery life, it has the potential to be a useful tool to survey inaccessible lands quickly and cost effectively.

The Chehalis River Basin Land Trust holds over 4,400 acres for conservation, protection, and restoration in our beautiful Basin. From the rolling hills and prairies south of Puget Sound to the saltwater estuaries on the Pacific coast, the Chehalis River watershed stretches across 2,660 square miles. Waters from five different counties flow into Grays Harbor by way of the Chehalis River, forming the second largest river basin in Washington State. To learn more about the Chehalis River Basin Land Trust, visit their website at

By Mark Gray, board member, Chehalis River Basin Land Trust

Beaver: The benefits and the problems

Adult beaver
Adult beaver feeding. Photo: Forestry Images

Beaver (Castor canadensis) are North America’s largest rodent (they have reached weights of up to 100 pounds but adults are usually from 30 plus to just over 60 pounds) and as such have voracious appetites and are very prolific. They are found throughout the continent and occur in every county in Washington. They are semi-aquatic in that most of their life is spent in or immediately adjacent to water. They forage primarily on bark, twigs, leaves, buds, and cambium of hardwood trees and shrubs that grow in moist or wet soils and found in riparian zones. Species such as the maples, willows, cottonwood, aspen, dogwood, birch, and cascara, among others are favored foods. Conifers are not a favored food with the exception of western red cedar, although they utilize many conifers for dam and lodge building. Some aquatic plants and riparian forbs and grasses are also consumed.

Beavers form colonies usually consisting of the older adult parents, juveniles, and young of the year. The juveniles usually disperse when about two years of age and form their own colonies if suitable habitat can be found. At times, several generations and colonies will be in close proximity to each other if food and space is available.

Beavers build lodges out of sticks and mud in shallow water of ponds and lakes and on banks of slow-moving streams. They will dig bank dens or tunnels below the water line and back into the bank in deep and faster flowing streams. Dams are constructed from mud, rocks, sticks, and small logs in slow moving streams in order to flood an area within or adjacent to a food source.

Beaver typically swim to their food and even cache large piles of branches in deeper water so a food source is available in the winter when water freezes over. They are quite clumsy on land making them very susceptible to predators (coyotes, wolves, bobcats, lynx, cougars, dogs, and any other carnivore that can catch them). They will build a series of dams up and down a stream if necessary to access food sources. When food runs out they must move to better areas (if available) or succumb to starvation and predation. They are quite ephemeral but their “workings” may last for long periods on the landscape.

Abandoned beaver dams and ponds are quite common. When the dams collapse from lack of repair or are washed out from spring snowmelt the ensuing debris flow can be devastating to downstream habitats and structures. Typically, the newly exposed wet soils can be quickly recolonized by their primary riparian food resources and a new colony will eventually establish on that site. However, in more recent times the invasion of noxious weeds such as canary grass, Himalayan blackberries, and others may take over the site first, rendering it all but useless for most native wildlife.

Beaver are common in Washington and their numbers are high. They have been classified and managed as a furbearer in Washington and all other states with established harvest seasons and rules administered by the state fish and wildlife agencies for many decades.

When beavers move in

When beaver establish residency on a landowner’s property there is little middle ground—it’s either a love or hate attitude. Both viewpoints are understandable considering the aesthetic, ecological, and financial pros and cons associated with their presence. Beaver ponds established behind their dams can be excellent sources of fish and wildlife habitat while acting as silt traps and small flood control structures. Their foraging and feeding activities may result in setting succession of hardwood trees and shrubs back and invigorating sprouting and reestablishment of many early or pioneering riparian and wetland plant species when the older tree canopy is removed. On the other hand, their activities result in flooding and killing valuable timber and orchards, flooding roads, blocking culverts, bank deterioration and collapse, destruction of croplands, and even moving the riparian management zone of designated timberlands further back resulting in even greater loss of timber. These traits do not endear themselves to most landowners who rely on stewardship and harvest of timber and agricultural crops as part of their livelihood.

beaver damage
The tell-tale gnawing of a beaver is easy to spot on felled trees.

So what’s a landowner to do? You can sit back and enjoy the beaver or have some or all (if a small colony) removed to stop the damage. Licensed trappers can harvest them during the winter open season and sell the pelts (and consume the meat—it is tender and with good flavor). However, the passage of the citizens’ initiative more than a decade ago has changed the rules on this to the detriment of the landowners. Prior to the initiative several thousand beaver were harvested each season by licensed trappers and the pelts were sold to licensed fur buyers. This was done at no cost to the landowner. With the passage of the initiative, instant-kill type traps and snares were outlawed and only live traps can now be used (and then the catch must be killed by whatever means available). Live traps cost several hundred dollars each and weigh over fifty pounds. The annual legal harvest during the winter trapping season has declined to a fourth to a half of the earlier harvest levels. Most licensed trappers responding to damage complaints will charge the landowner, and the hides and meat cannot be utilized but are thrown away.

Damage control

Damage control trapping may be done at any month—even when young are in the den. Landowners experiencing damage and wanting removal must contact the Washington Department of Fish and Wildlife (WDFW) for certification of their damage and to request permits to kill beaver. That Department can also give contact information of licensed damage control trappers.

Live trapping and translocation of live beavers to other areas is seldom done. A permit and suitable release site with landowner’s or manager’s permission must be acquired. Suitable sites are those with sufficient food, water, and space that are presently unoccupied by beaver (a rare situation). Adjacent landowners do not want to inherit someone’s “problem animals”. There may be a cost associated with hiring a live trapper to do the catching and translocation with your permit. Removal of dams is seldom successful in the long term, can be expensive, and is illegal without a permit from the WDFW.

Obviously, these are not the most desirable approaches to managing a valuable resource—but when emotions guide natural resource management this can be the result. The high expense associated with timber, crop, and road loss, and with hiring a licensed trapper under permit to remove offending animals quite often leads to reducing them (in the mind of the landowner) to pest status and the ‘shoot, shovel, and shutup’ approach to management of an otherwise important public resource.

Exclusion devices

There are other approaches including screening or barricading culvert inlets and outlets to exclude beaver from damming or plugging those facilities. The openings in these barricades must be large enough to allow adult fish passage. Beaver excluders—perforated pipes passing through the dam and well into the pond— have proven successful in some applications. Plans are available for these from numerous sources. You must remember however why the beaver have built the dam (to access food in safety) and that by keeping them from increasing the size of the dam, and subsequently the size of the pond, limits or eliminates their ability to access food. This will likely force them to move elsewhere or result in their eventual starvation.

Beaver, like other species of wildlife as well as trees and crops, cannot be stockpiled—available space and resources limit the population size. The choice on management of this valuable and interesting animal resides with the landowner.

Why maintain riparian buffers

stream shaded by forest riparian buffer
Forested riparian buffers help cool the water temperature in streams. Photo Andy Perleberg

Over Thanksgiving, I had the privilege to visit with family. There was a lot to be thankful for, not the least of which is my mother’s renewed health after a recent illness, and the bright eyes of our next generation shining from my young cousins. It turns out, all the things for which we are really thankful are those that allow us to all move forward together as a family and as a community.

In returning from a holiday to my professional community, these thoughts stay in my mind and I am filled with pride because we, as a community of foresters, move forward together. We have overcome so many technical challenges. Perhaps the most significant challenge we faced — protecting water quality — is resolved by maintaining forested riparian buffers. These buffers tie together the forestry community with everybody else in Washington State before any timber even reaches a mill. This practice protects water quality and salmon productivity while allowing our uplands to provide timber. These basic resources are all essential to a healthy, prosperous community.

But, how do forested buffers protect water quality and salmon populations? Well, it’s actually pretty simple. We tend to describe the ways that riparian forests provide clean water and productive fish habitat in terms of the ecological functions of these streamside forests, which are the mechanical ways that the forest interacts with streams.

Forested buffers intercept the loose soils that erode, or flow down the hillside when it rains and provide root strength in the slopes nearest streams to keep streambanks from eroding. Road use and timber harvesting often loosen soils in the uplands. Eroded soils, which are primarily mud, can fill in all the spaces between the cobbles, gravels, and larger rocks in a streambed. These are the only spaces where salmon eggs can incubate. When large amounts of mud flow into a stream, it’s possible to smother every salmon egg in the neighborhood, even downstream on other properties. Mud also prevents adult salmon from reproducing. Soils loosened from timber harvest activities can also erode slowly, leaving continuous source of soil particles in the water that must be cleaned before it is suitable for people to drink.

By maintaining shade over streams, we maintain water temperature. Cool streams are more important than they sound because high water temperatures stress fish, preventing adult salmon from surviving their challenging upriver journey and decreasing the survival rates of juvenile salmon. Warm streams also incubate bacteria and diseases that again must be treated before it is drinkable.

By providing litterfall and nutrients to streams, riparian forests supply the basic building blocks of a food web for salmon, especially for young salmon whose initial growth and survival depends on having great food in the form of small insects that decompose the litterfall and other raw nutrients. This food web extends into the Puget Sound and the Pacific Ocean where the salmon travel, feeding orca whales and countless other species. The food web that starts with riparian forests also feeds land-based species, like bears and people.

By providing large woody debris, riparian forests create the physical structure of instream habitat. The gravels, cobbles, and large rocks that I described above as being essential to salmon reproduction would all move downstream if the streams were straight, steep chutes. Instead, streams in the Pacific Northwest tend to be stepped with intermittent pools and riffles, resulting from changes in the slope of the streambed. This habitat is a result of wood that fell into the stream and blocked the downstream movement of gravels. As gravels build up behind a log in a stream, the slope of the streambed becomes more gradual. The pattern of small calm pools dotted along a stream with clean flowing water allows for the diverse habitat needs of fish. Salmon use pools to rest and feed. The riffles of slightly faster flowing water downstream of the logs provide well-oxygenated waters excellent for reproduction.

I am constantly amazed that forests provide such important resources like sustainable food and clean water. It’s an expensive practice to retain riparian forests during a timber harvest, but we cannot live without food and water. I’m thankful that we, as a community of foresters, have committed to responsible forest management. I’m thankful that we have the best information to protect public resources. I’m thankful for clean water and healthy food. I hope you take pride in every riparian area you protect because everybody in Washington, whether they know it or not, is thankful for clean water and healthy food.

Marty Acker, ESA Ecologist
NOAA, National Marine Fisheries, Washington State Habitat Office


Why fish need forests and why forests need fish

logs in stream help fish habitat
Logs and other large woody debris help regulating the movement of material through streams and provides a variety of habitats for the fish and other wildlife that live and along the stream.

Why fish need forests

Stream habitat can be evaluated as a product of the various input factors that come in from the surrounding watershed. These can be divided up in various ways, and one way is to segregate them as geologic input of sediments to the stream, hydrologic delivery of water, and biological or chemical delivery of wood and nutrients to the stream. It is these characters together that define instream habitat and determine fish productivity, salmon productivity, and biological characteristics within the stream. Habitat and fish are the product of these inputs from the surrounding watershed, and it is through this approach that we can evaluate how forests influence fish.

The place where these interactions occur most is in the riparian zone, forests next to the stream. Three major interactions include:

  • Input of litter
  • Input of shade
  • Input of large woody debris

These are among the most significant when the issue of regulations is discussed. Input of litter is the delivery of the finer (smaller) types of organic matter from the forest to the stream: needles and leaves. This material serves as an important food source for invertebrates in the stream. For example, when one compares the inputs from early and late succession forests, about 60 grams per square meter per year of input occurred in the young (7 yr old) forest compared to 300 in the older forest. Some of the reduction in the young forest was compensated for by plant (algal) production in the stream channel of the young forest. Total organic matter availability in the stream of the older forest was about 80 percent greater. Forests do deliver a significant amount of organic matter to streams.

Shade and the role it plays in thermal regulation of streams is probably the riparian function that most people are familiar with. Studies have shown that presence of forests keeps the average temperature lower. Forest cover also keeps the day-to-day and day-to-night fluctuations lower as well during warm periods of the year.

Input of large wood to streams has become a very hot topic in scientific and management circles over the last 10 to 20 years. Wood has a variety of effects on stream systems: 

  • Impacts on channel form
  • Physical characteristics of stream channels
  • Wood plays a key role in regulating movement of material through stream systems
  • It provides a variety of habitats for stream biota

Wood has a dramatic effect on the shape of the channel, helping to form pools. In small to moderate streams 60-80 percent of the pools can be related to coarse woody debris. Local scour around the piece of wood creates a pool with deeper water. For a long time, people thought that large woody debris did not play much of a role in determining channel form in large river systems, but in recent years we have found that wood does play a significant role in channel form in these large streams. Pieces that play such a role are invariably large trees with intact root wads, introduced into the channel from bank erosion. These trees get deposited fairly close to the channel bank, with the root wad oriented upstream and the rest of the tree trailing downstream. It begins to trap more coarse woody debris on its upstream side that creates slow flow on the downstream side and creates sites for sediment deposition and vegetation establishment. Wood influences channel form and successional dynamics in the riparian zone.

Sediment is retained by large woody debris and influences its movement through the stream system. The transport of fine and coarse sediment increases twofold in the absence of wood. Increase efficiency of transport, and mobilization of stored sediment, will both occur. Wood can also retain organic material in the stream longer than if wood is not present to trap smaller material. Not only needles and leaves, but also salmon carcasses can be retained by wood in the channel. Up to 60 percent of salmon carcasses can be associated with presence of coarse woody debris.

Wood plays a key role in providing habitat for animals. Spawning adult salmon will typically will use large pools, many of which are associated with woody debris, for holding areas prior to spawning. Many of the fish species of high interest will use similar pools while juveniles are rearing in fresh water. Comparison of cutthroat trout and coho salmon biomass (abundance X body weight) in British Columbia showed far higher biomass in sites with high amounts of large woody debris.

The entire watershed interacts with the stream channel. The delivery of water to stream channels will change, for example, with development of a forested watershed. As a result, peak flows will increase. In King County the average flow expected once every five years in a forested watershed was occurring once every year in an urbanized watershed. Biological consequences of this are increased bed scour, and reduced fish egg survival. Emerging fish are more likely to be flushed downstream, and food availability may also be less. Productivity of streams for coho salmon declines rapidly, so that in streams in King County with 10 percent impervious surfaces, salmon productivity had declined 70 percent from forested watersheds. At 40 percent to 50 percent impervious surface, these streams are essentially inconsequential in terms of salmon production.

Why forests need fish

The reason forests in the Pacific Northwest need fish is because of the kinds of fish we have here. Pacific salmon exhibit two characteristics that enable them to impact the habitats and forests of the streams they live in:

  • They return to spawn in the same place, and in large numbers
  • They die after they spawn

 So they transport marine-derived nutrients to generally nutrient-poor headwater areas where they were born, and leave them there by dying. The kinds of effects salmon have on freshwater habitats include:

  • Alteration in channel form as a result of the physical act of constructing redds, and this is particularly true for species that spawn in high densities, like chum and pink salmon.
  • Changes in the characteristics of gravels, by removing large quantities of fine sediments.
  • They are a food resource for wildlife as well as other fish and invertebrates in the stream.
  • They are a significant nutrient source for riparian forests, too.

About 20-40 percent of the nitrogen and carbon in the body tissues of cutthroat trout, coho salmon, and steel-head are derived from marine sources. About 18 percent of the nitrogen in the tree foliage is also of marine origin, directly attributable to salmon. Subsequent work has shown that leaves of salmonberry, a riparian-oriented shrub, that nitrogen content is higher in streams that contain salmon than in streams without salmon. Increased understory cover and species diversity has been associated with streams where salmon spawn, and tree growth may also be increased significantly. This, of course, has a positive feedback in that potential pieces of large woody debris are being developed faster and fall into the stream to improve habitat quality.

We have been trying to understand fish utilization as a function of the primary land use in a watershed. The Snohomish River watershed shows that median coho salmon abundance declines significantly from forested watersheds to rural residential use to agriculture and urban areas. The only locations with consistent high utilization by salmon are the forested watersheds.

Salmon recovery should pay special attention to retaining lands in forest cover. Because of the way we currently manage these other lands, they tend to be very incapable of supporting high populations of salmon.

 Robert Bilby, Ph.D.