When hiking along a forest trail, fish are probably not the first thing that comes to mind. What do fish have to do with forests? And forests with fish?
It may not be obvious, but the connection between land and water is deep—as deep as a pool scoured by the fast action of water cascading over a fallen log. So when I met with Tony Spitzack, Fish Biologist for BLM, at the Valley of the Giants Outstanding Natural Area for a short hike through a late-successional forest, I was excited to discuss these connections.
The Hike
- Trailhead: Valley of the Giants Trailhead
- Distance: 1.4 miles
- Elevation Gain: about 500 feet
- Details: Traveling to the Valley of the Giants trailhead requires patience. It is a long drive on logging roads. I recommend that you check with the district BLM office to check for closures and directions. However, the trailhead is well signed and there is a good amount of parking available.
Timber Time
The Valley of the Giants (VOG) Outstanding Natural Area lies just outside the deserted timber company town of Valsetz, west of Falls City in the Oregon Coast Range.
Small logging towns were once common in Oregon’s coastal mountains. As the logging industry of the late 19th and early 20th century boomed, and people were needed to support the growth. Then by the late 20th century, the industry changed, timber production declined, and the labor force required for logging was diminished. However, by this time, much of Oregon’s Coastal forests had already been logged.
As for Valsetz, In 1984, it was shut down and many of the buildings removed. It is now a tree farm.
Out with the Old
The impacts of this era of logging can still be seen today—the forests were altered and so were the rivers. Most of Oregon’s coastal old-growth was removed during that time. Coastal streams were channelized and disconnected from flood plains. Logs and natural barriers were removed and streams were cleared for transportation. According to Tony, splash dams were commonly used back then. A splash dam is a temporary wooden dam built to raise water levels enough to float timber downstream to sawmills. Few places remain in the Oregon Coast Range that didn’t experience these impacts.
The Valley of the Giants (VOG) is one of these few places. The VOG is a 51-acre piece of land that has never been logged. There is also no record of splash damming on the North Fork of the Siletz that runs through the VOG either (though it is unlikely that it has been untouched). Making the VOG a special place— a functional late-successional forest in a sea of mostly secondary growth.
Something Fishy
As we started along the trail, Tony told me a bit about the fish populations that inhabit the area. The trail crosses over the North Fork of the Siletz River, which supports chinook, summer steelhead, and cutthroat trout, among other fish species.
Each species of fish found in the Siletz has a unique ecological niche. This means that they have different habits and take advantage of different habitats within the stream. For example, some species (or variants of species) of fish migrate to the ocean, like Chinook and Steelhead, while others will take up residence in freshwater streams or migrate to estuaries, like most cutthroat trout.
According to Tony, the summer steelhead run is really unique. He said, “the North Fork of the Siletz River is the only native summer steelhead run within the Oregon Coastal steelhead population.” The reason being that downstream a boulder cascade waterfall, Siletz Falls, blocks the passage of steelhead during high winter flows. So the steelhead adapted to a summer run, creating a genetically unique population from winter steelhead.
Cutthroat trout also distinguish themselves from other fish by their home range. One of Tony’s jobs is to determine upper fish limits for streams. Compared to other species, he finds cutthroat very high upstream. Making use of upper reaches of streams allows cutthroat to avoid competition with other fish and take advantage of this otherwise unreachable habitat. However, cutthroat populations sometimes move so high upstream that they become isolated when flows become low in these upper reaches. Tony has even found cutthroat trout that have permanently lost connectivity with their home stream. What happens to these populations is still being studied.
Riparian Feast
Gradually Tony and I made our way through the forest and closer to the stream edge. The corridor of vegetation along the stream is known as the Riparian area. Besides large conifer trees, deciduous trees and shrubs dominated the area.
Here, Tony reached out for a salmonberry to munch on.
Besides providing delicious berries to eat, salmonberry and other deciduous trees and shrubs provide food to fish. No, fish don’t eat the plants or berries, but leaves in various states of decay provide food for the insects and other invertebrates that feed fish. A large amount of energy is supplied by the riparian area through leaf fall to the aquatic food web in this way.
Heterogeneity
Tony also talked about how the riparian area also influences light availability and stream productivity. He mentioned a study that showed that when riparian plants are removed, productivity increases, making more energy available to the stream food web. However, the result is only temporary. In the years that follow, fast-growing riparian plants grow and shade out the stream reducing productivity significantly. [1]
According to Tony, patchy cover that you get in a natural forest cycle is best. Tree fall creates patches of light to increase productivity, while other trees provide shade and other habitat needs to fish. A dynamic system is a resilient system, as change is a natural part of the ebb and flow of the ecosystem.
Sort It Out
Shortly after crossing a bridge over the N. Fork of the Siletz, Tony and I reached the junction for the lollipop loop. We followed the trail to the right and soon reached a short spur that led to a small side channel.
Tony told me that he had scouted out the area earlier and decided the small channel was a great place to look at sediment sorting. The velocity of water in a stream determines how sediments sort. Smaller sediments, like sand, will move even in low velocity conditions, while gravel requires a higher velocity. Boulders are often found in the highest reaches of a stream system because they require higher velocity flows.
Even in our small side channel, you could see sorting take place. Bigger rocks remained in the center, or thalweg, of the straight channel where the water traveled fastest. While smaller sediments collected along the edges where the water was moving slower.
The way that sediments sort themselves within a channel of water is really important to fish. In particular, salmonid species rely on gravel beds for spawning habitat. Fish need complex streams with sediments that are sorted to create these gravel beds and other features, like pools, where sediments are scoured away.
Falling Logs
Tony placed a stick in the small channel to block the flow. He explained that as water poured over the stick it would start to wear away sediment creating a pool below it. He then moved the stick so that it entered the stream at 45 degrees. In this case, Tony said, “water hits the stick and turns perpendicular to the stick,” such that it will be directed toward the opposite bank and may undercut the bank.
These same processes occur on a larger scale in big streams and rivers as well and are important to fish. Undercut banks provide excellent cover for fish, while pools are for resting and keeping cool. In addition, logjams trap sediments and aid in the formation of gravel beds needed for spawning. “The more you put wood in, the more dynamic the system is,” said Tony. And the more dynamic the system, the greater the complexity and availability of different habitat features for fish.
Networking
As we continued around the forested loop, I looked around at all the trees, shrubs, and forbs, and at the down logs with new growth sprouting from their rotting bodies— and I felt admiration. These trees supplied so many benefits to fish—shelter, food, and rearing habitat—was there any reciprocation?
Tony pointed at one of the larger down logs with shrubs and seedlings growing out it. He explained how the trees of the forest are connected by a mycorrhizal fungi network. Fungi gather nutrients and water from the soil and pass it to trees in exchange for carbon-rich sugars produced by trees through photosynthesis.
This network reaches anywhere the forest grows, even into the nursery log before us. There are studies that show, shared Tony, that the mycorrhizal network is vast and far-reaching and fungi will carry nutrients and water over large distances in order to get the carbon they need. So even though we were a good distance from the river’s edge, our seedlings could benefit from the water and nutrients carried through the network— from the stream to the riparian area to our rotting log to our seedling.
Fish Feed Forests
As mentioned earlier, many of the fish that live in Oregon’s rivers migrate to the ocean to grow. Later, they return to their natal stream to spawn and die. Consequently, anadromous fish end up supplying marine nutrients to their freshwater home—a benefit to the ecosystem overall.
This may seem like a small contribution, but when you consider the extent of Oregon’s native salmon runs—historically numbering in the 10s of millions— the magnitude of the transfer of nutrients is substantial.
And don’t forget the mycorrhizae! The effects of these nutrients are far-reaching. Tony told me, “some people have suggested trees will grow three times as fast on a stream that has salmon coming back to it.” Clearly, fish do help trees.
Lost Fish
However, as we dammed and altered our river systems during the 20th century, salmonid populations plummeted. And the nutrient connection between marine and freshwater ecosystems was diminished greatly.
Of course, that only counts fish that western culture historically paid any attention to. Tony told me about recent efforts to study Pacific Lamprey— a parasitic species with a tube-like body and round suctioning mouth-part—that has largely been ignored by western science. He has been using eDNA methodology to better understand the distribution of Lamprey in the Marys Peak Field Office. This non-invasive technique allows researchers to gather water samples from a body of water and run tests to see if the DNA of a fish is present in the water.
We don’t know what Pacific Lamprey fish populations were historically. We don’t even know what they are now. But we do know that Pacific Lamprey were probably just as important, if not more important ecologically, as other anadromous fish. Pacific Lamprey have high-fat content and are easier to prey on than salmonids. Tony suggested, “by biomass, they are probably more important.”
Either way, when considering the loss of salmonid and lamprey populations— “the amount of nutrients we have lost from the riparian area is astronomical,” said Tony.
Disturbed
As we finished the loop, crossed over the river and made our way back to our cars, I asked Tony what he thought were the biggest issues when it comes to fish. He was quick to respond: “The biggest thing humans have an issue with is that resilience depends on disturbance and not stability.”
I asked him to elaborate. He explained that humans want things to be neat and tidy—we don’t want ecosystems to change. We often see it as a bad thing. For example, landslides or forest fires are often seen as purely negative forces on an ecosystem. But the truth is, though perhaps destructive locally, the changes that result are overall positive.
Tony mentioned a study that looked at landslide-prone areas. At first glance, you might think that landslides would be bad for fish. However, in this study, it was found that these areas not only had three important habitat types (spawning, summer -earing, and winter-refuge habitat) but connectivity between the habitat types. [2] Why? Because the landslides likely provide new materials, like sediment and wood to the stream, developing all the different habitat requirements Coho need, and in close proximity.
This is how nature works. Fish (and other wildlife) thrive in dynamic, heterogeneous environments.
Lessening Our Impact
Of course, not all disturbances are positive. Too much change can throw natural systems out of balance. So before we parted ways, I asked Tony what he thought about human disturbances in the lives of fish and forests.
Tony offered a hopeful stance. He talked about how we have learned a lot about how to lessen our impacts on ecosystems over the years, while still benefiting from the products and services they provide. He used the example of roads. We need roads, he explained, to access timber, recreation areas like the VOC, and other natural resources. But roads are going to impact the environment. However, not all roads are equal. Roads are now built with cross drains to divert runoff before reaching the stream, allowing sediment to settle in vegetated side-slopes. Also, new road construction now incorporates large culverts that allow streams to freely flow and fish to move up and downstream. Roads are necessary if we want access, according to Tony, but that doesn’t mean there isn’t a lot we can do to improve them and mitigate their impact.
Driving Home
As I drove the many miles of gravel roads back to civilization, I thought a lot about what Tony said.
It is apparent that humans are connected by a complex transportation network— we can easily see and experience this connection, as I did on the dusty, bumpy ride home. But there is another complex network that we are a part of that often remains hidden—the web of life. Like fish and trees in a forest—we too are dependent on the natural world—ecosystems provide us with clean air, water, food, medicine, and many more products and services.
So what do we do? We lay bare these connections. We study them and respect them. And by doing so, we build better roads—and perhaps a better world.
Tony Spitzack is a Fish Biologist with the Bureau of Land Management in the Northwest Oregon District. Tony has also worked as a Natural Resource Technician for the Forest Service. He has a Masters Degree from Eastern New Mexico University and studied marine ecology at Washington State University Vancouver.
References
- Warren, D.R., Keeton, W.S., Bechtold, H.A. et al. Comparing streambed light availability and canopy cover in streams with old-growth versus early-mature riparian forests in western Oregon. Aquat Sci 75, 547–558 (2013). https://doi.org/10.1007/s00027-013-0299-2
- Beeson, Helen & Flitcroft, Rebecca & Fonstad, Mark & Roering, Josh. (2018). Deep‐Seated Landslides Drive Variability in Valley Width and Increase Connectivity of Salmon Habitat in the Oregon Coast Range. JAWRA Journal of the American Water Resources Association. 10.1111/1752-1688.12693.