The work is gritty and exhausting but exhilarating: you leave behind a forest with light that reaches the soil surface, ready to awaken a dormant understory layer of voluptuous ferns and berry-bearing shrubs, and gaps in the canopy layer, soon to be filled by grateful trees growing in ferocious profusion.
Once the initial thinning is done, we touch the forest again, with handsaws. This is a pruning pass: cutting limbs flush to the trunk, initially up as high as a person can reach. Pruning transforms a young stand because you can suddenly see through it as tens of thousands of shade-killed limbs drop to the ground. Within a few years of pruning, the trunks will grow over each wound, creating a smooth outer surface. The wood that grows thereafter will be clear—meaning free of knots. Logs with branches, in contrast, produce one of two types of knotty wood. Lumber with the flaws known as knotholes is sawed from trunks that have grown over dead limbs. The wood from the dead branches tends to shrink and drop out of the board, leaving a hole. Lumber with tight knots is sawed from trunks that have grown over live limbs, trapping the tissue growing out from the main stem. But clear, knotless lumber is sawed from limbless trunks. It commands a premium price due to its beauty and strength.
As the years progress, we’ll enter the forest again with pole saws to do lifts—removing additional whorls of branches as the trees get taller and taller. With our tools and our sweat, we simply accelerate the process of creating tall, straight, limbless boles that would otherwise happen naturally.
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Thinning and pruning have spiritual benefits too, for there is no better way to learn a patch of land than to work on it. We’ve found warrens dug by mountain beavers—pug-size offshoots from the base of the rodent evolutionary tree that live only in the Cascade and Olympic mountains. I’ve watched an Anna’s hummingbird follow Susan when she’s wearing her favorite red sweater and virtually land on her shoulder, mistaking her for a blossom. On occasion we see black bear sign: a pile of scat, old rotting logs and stumps that have been torn apart in search of grubs and ants, and Douglas-fir trees with bark ripped off. Bears will bite the bark of young trees in late spring, when the sap is running at its peak, and peel it up the trunk. The effort exposes the sugary cambium layer, which they eat. Bears will even return in subsequent springs to harvest the tissue next to the wound, now swollen with sugars the tree has sent to speed the repair. Although most trees recover from the assaults, some are girdled and die, forming the forest’s first standing dead snags.
Working in the woods has another benefit as well. In Carl’s forest, the work of thinning and pruning is a family affair. We toil together. The discussions and decisions, the scratches and bleeding, tie us to the land and to each other.
Carl’s forest should become more and more valuable over time, producing a sustainable harvest of high-quality logs for market and taking on the four characteristics of an old-growth stand. I can’t think of a better way to honor a man who endured the Great Depression, fought a war, raised a beautiful family, loved music, contributed to science, saved land, and befriended people from all walks of life.
Damnation
When the trees we’d planted along the remeandered sections of creek were just a few years old, I noticed one or two disappearing at a time—usually in the fall. They were western redcedars in every case, and they were cut just above the plastic plant protector tube. I was mystified—the cut point was too smooth to be deer work. Deer have teeth at the front of their top jaw but the matching surface of their bottom jaw is toothless—it’s just a bony ridge. Instead of cutting, they have to tear stems and twigs as they browse, leaving a ragged edge.
I wondered for a time about mountain beavers—the overgrown hamsters we find in the younger stands in Carl’s forest. Their common name is a misnomer, as they aren’t particularly closely related to regular North American beavers. Mountain beavers live in uplands, make mazes of underground burrows, and eat just about any type of plant; they’re particularly fond of ferns. But the little cedar trees had gone missing in the floodplain, next to the creek channel, and there was no sign of soil disturbance save for an occasional molehill.
The answer came to me at last in the form of a stick. An alder branch with the bark chewed off floated on the creek toward me. I fished it out of the stream and looked at it. There were neat, paired grooves circling the stem, making a series of tiny ridges—a miniature version of a Latino band’s percussion instrument, a guiro—and the ends were chewed into triangular points. This was incontrovertible evidence of Castor canadensis. We had a North American beaver on our hands. Up until then, the only beaver activity I’d been aware of was well over a mile away from our remeanders.
At first we didn’t make too much of this. According to our thinking at the time, a beaver might take some willow and alder stems, but plenty were available. During the remeandering operation we’d secured much of the coir matting along the bank with willow stakes, and many of them had sprouted. Alder was seeding in on its own, and the alder pull-ups we’d planted were taking off—growing like weeds. So we had lots of beaver food at the ready. Noticing some beaver activity was like having someone who plays loud music on Saturday nights move in a couple of doors down. You remark on it, but it’s nothing to get that concerned about.
Then one autumn afternoon we found a much bigger cedar sapling cut. Of the thousands of trees we’d planted, this one had grown the most—it was in the pride and joy category. But its 3-inch-wide trunk was cut at the telltale location, just above the plant protector, and the 8-foot-tall stem lay on the ground, stripped of its leaves and branches. With that, the truce was shattered. The beavers were ignoring the willows and alders. They preferred our cedars, and the deep shade and long lifespan of western redcedars were key to the stream’s future. We had to do something.
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Friends and neighbors had advice: get rid of them. Almost universally we heard, “You don’t want beavers. They’re so destructive.”
This advice didn’t sit well. First, there was something ironic about the emotional responses. Humans have dammed the Columbia and its tributaries more than sixty times, along with the Nile, the Yangtze, and the Colorado, to name a few. We have channeled the Mississippi and the Thames and destroyed most of the world’s prairies and old-growth forests. And we call beavers destructive?
Second, neither of the removal options made sense. Urban friends advocated livetrapping the beavers and moving them to a new location. This is a popular thing to do with nuisance squirrels and raccoons in cities; it makes people feel humane. The problem is that dropping animals off in a new location is like knocking on the door of someone you’ve never met, introducing some strangers that you don’t want living in your own neighborhood, and telling the homeowner that the strangers are going to move in. The newcomers are not likely to be welcomed. The transplanters may feel humane and congratulate themselves, but the transplantees are likely to die slowly and painfully, of starvation or wounds from confrontations with the local residents.
The other option, killing the beavers outright, is neither amoral nor unethical. We kill things all the time, from swatting mosquitoes to harvesting the plants and animals we eat every day. There are, however, two strong counterarguments to killing beavers. The first is a practical issue of time and energy. Trapping beavers puts you on a slippery slope, because the individuals you remove will be replaced by other beavers—usually sooner rather than later. Unless we intended to remove beavers from the entire watershed, we’d be committing ourselves to a lifetime of feuding. Second, and much more important, beavers can be critical to the success of a salmon stream restoration. They are what biologists call ecosystem engineers. The problem was that we needed to direct their energy—away from eating trees that also were critical to the success of the salmon stream restoration.
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If your goal is to live with the land instead of just on it, you have to accept the organisms that live there more or less on their own terms. In our neighborhood, this might m
ean not digging a trout pond when river otters are common, or not mowing an acre of lawn and then complaining about molehills in it. It might even mean not moving to a rural area at all—but just visiting.
We’d faced this issue before in another context. Along our section of creek, Bob Harrison used the excavator to plant what we call eagle poles—large logs that stick up a couple of stories aboveground. At the nwi land just downstream from us, there are so many of these artificial snags that Peter Bahls calls it Woodhenge. Both restoration sites have large logs scattered on the ground as well, artfully arranged by Bob’s excavator. The idea here was to kick-start a restoration with two of the four characteristics of an old-growth forest. Two centuries before big trees will have grown and decades before a complex forest structure can develop, you can have standing dead snags and downed wood simply by adding them. So installing snags and scattering logs on the ground were on the task list for Bob and the Hitachi.
The first fall that salmon ran through the new meanders at our place, though, we found skeletons and shreds of flesh at the feet of some of the poles. Eagles were using the poles as hunting perches: monitoring the creek, stooping on fish, and returning to eat their kills. This drove Bob to distraction. “We’re doing all this work to make the stream perfect for salmon, then we plant these damn poles to make it all nice for the eagles to eat the fish!” The only response was to nod. This is what life is like when you’re part of an ecosystem.
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Beavers build dams to create safe zones. On land, they are almost defenseless against attacks by coyotes, cougars, wolves, or bears. But in the water, they’re safe. They are strong swimmers and have fortresslike lodges they can retreat to. If a dam is large enough to pond water into a small lake, beavers will build a lodge in the middle so it’s surrounded by a moat. If the site is far enough north for the water to freeze over in winter, they will also invest in a food cache—a mound of freshly cut trunks and branches piled on the lake bottom—in the vicinity of the lodge. When the surface freezes inches or even feet thick, they can leave their lodge whenever they want and dive down to retrieve a snack. But along smaller streams they build a bank lodge—digging out an entrance tunnel and an exit tunnel so they can’t be trapped inside. The tunnels connect with a snug chamber where the family can rest in peace. Building a dam across a small stream and ponding the water behind it can make it possible to have an underwater, ultra-secure entrance and exit for the bank lodge.
Although beavers drop trees to provide material for making dams, their primary goal in logging is to eat. Their cheeks look puffy because they are distended by massive jaw muscles; their paired front incisors grow continuously and are sharp and hard enough to take down maples and other hardwoods. To cut a tree, they move around the trunk making a V-shaped cut, similar to what a woodsman would do with an ax. When beavers cleared out a grove of vine maples at our place, they left a group of thirty-two gnawed-off stems clumped in the space of a few square yards, each sharpened to a point like a punji stick. Once a stem is down, they buck it up the way a human logger would—in this case, cutting it into segments that can be dragged to the water and eaten in safety.
In summer, beavers eat the leaves of the deciduous trees and shrubs they harvest; all year round they eat conifer needles. The staple of the beaver diet, though, is cambium and vascular tissues. These cell layers, found in the outermost part of a trunk or branch, consist of three major components: stem cells that divide to form new wood, the structures that form a tree’s circulatory system, and bark. As cells in the stem-cell layer divide, the daughter cells move to the inside or outside, steadily increasing the girth of trunks and roots. Some of these cells differentiate to form the vascular system tissues called xylem and phloem—groups of specialized cells that transport water and sap, respectively. Together, the cambium and vascular tissues form a thin, living layer of cells just outside the stem’s woody core and just inside the outer bark.
The wood and bark on either side of the cambium layer consist of dead cells dominated by cellulose and lignin—two molecules that mammals can’t digest. But the cambium and vascular tissues are moist and nutrient rich. They are also sweetened by sugars—molecules that are manufactured by photosynthesis and then transported back and forth between mature or growing leaves and storage areas in the roots. You’ve tasted the sugars in phloem sap if you’ve ever eaten maple syrup; around the world, almost all aboriginal people will list cambium and vascular tissue as traditional food sources. The stuff is so pitchy, though, that it’s almost always eaten as a last resort—a starvation food.
You can tell where beavers have been feeding by spotting branches and logs that are bright from a recent barking: sticks that have had their cambium chewed off lie scattered about like bleached bones. But beavers leave other sign as well. You can look for scent mounds along lake or stream banks—No trespassing signs for other beavers to note—or tracks in mud at the water’s edge. Along both streams and ponds, you’ll find skid roads where beavers have hauled themselves up and out of the water, humped across land to a logging site, and then dragged tree sections back. In marshes or other shallow wetlands, it’s common to find networks of deep ditches, dug to provide a swimmable and safe road network. And you should listen, too, for the slap of a tail hitting the water surface: a warning signal if you happen to surprise a family that’s out and active. It’s extremely rare to find beaver scat, but it’s not hard to recognize if you’re lucky enough to run across some: it looks like sawdust.
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In 2006, a group of paleontologists working in China reported that they’d found the almost-half-meter-long skeleton of a furred animal with a beaverlike tail and evidence of webbed hind feet, in rocks that were laid down 165 million years ago. But neither the skeleton nor the dentition were rodentlike, and its teeth suggested that it was mostly carnivorous, like a river otter. The best evidence available suggests that its close relatives belong to an extinct order of early mammals called the docodontans. The tail, streamlined body, and webbed feet are examples of convergent evolution—adaptations that have arisen in groups as diverse as today’s platypus, otters, and beavers. Platypus lay eggs and are in the mammal lineage called monotremes; otters are in the group called Carnivora and are especially closely related to weasels; beavers are rodents, so have mice and rats as close cousins.
The discovery of this Jurassic animal popped a hole in the idea that mammals were exclusively small bodied and were bit players ecologically until the demise of the dinosaurs. It also suggests that the beaver way of life—having a body specialized for swimming and for eating resources available in streams and wetlands—has something going for it. Aquatic mammals have a long and storied history.
Certainly, beavers have been living in Tarboo Creek for as long as the stream has existed. Even after a century and a half of intensive disturbance, there are still flattened, peaty sites in the valley descended from long-filled beaver ponds. Directly north of Tarboo, the Chimacum Creek watershed was a continuous series of beaver dams and ponds when whites arrived; just to the north and east, settlers called another watershed Beaver Valley.
Beavers frequently dam the small streams that most salmon prefer for nesting. But any and every salmon biologist will also tell you that beavers are among the best things that can happen to those small streams. Instead of having their passage blocked, the fish almost always find a way through, up and over, or around beaver dams. We’ve watched several different tactics. The first is the most direct. If the barrier is leaky enough, the fish will simply wriggle through.
The second may be the most dramatic. In a classic beaver dam, sticks on the downstream side form a wall that slopes at 30 to 45 degrees, strengthening the structure. Coho salmon are accomplished jumpers and will throw themselves on this sloping face and thrash, throwing their bodies up until they flop over the top. Or if the stream is at flood stage, small breaks may open in the top of the dam, forming channels that cascade down and that fish swim up.
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bsp; Third and last is an outmaneuvering approach. If the dam is too high or too steep for the up-and-over strategy to work, the fish will try to outflank it. In low-gradient streams like Tarboo and nearby Chimacum, a dam that blocks the stream’s main flow raises the water level upstream and forces it out to the sides—meaning that in high water, when the salmon are running, the floodplain becomes a network of small braided channels. Salmon find these, follow them against the current, and refind the main channel. With that, their end run is complete.
Once the fish have made it to the other side, they’re in calm, deep water—a safe place to rest before moving on to navigate the next dam or search for nesting sites.
Beaver dams also do important work when breeding is over and the adults die. When the adult fish are spawned out, beaver dams catch their carcasses, preventing the corpses from washing downstream. They hold the rotting tissue long enough that the nutrients are released and begin cycling through young insects, trees, and fish.
Saving Tarboo Creek Page 12