The Number of Shades of Green Is Overwhelming: Hoh Rainforest, WA

Nestled within the Olympic National Park on Washington’s Olympic Peninsula, the Hoh Rain Forest is one of the largest temperate rainforests in the U.S., located on the Olympic Peninsula in western Washington state. It encompasses 24 square miles of low elevation forest along the ever-flowing Hoh River that carves its way from Mount Olympus towards the Pacific Coast.

There are multiple theories where the name Hoh (pronounced ‘hoe’) originates but there is no doubt why more than 400,000 people visit the rainforest each year.

Hoh River Trail

It looks like they need to regularly trim the vegetation to prevent it from covering over the sign.

Hike distance: 11.93 miles

Elevation Gain: 883 ft elevation gain.

TrailsNH Hiking Difficulty Calculator: 141 - Moderately Strenuous

Several years ago, I began using the TrailsNH Hiking Difficulty Calculator to give me a better sense of the challenge a hike presents. The chart below summarizes the rating scale but if you’d like more information about the calculator, follow this link to their website.

The Hoh Rain Forest is situated within the Pacific Northwest rainforest, which originally extended over 2,000 miles along the Pacific coast from southeastern Alaska to California's central coast. Since European settlement, approximately 72% of the original old-growth conifer forest in the Pacific Northwest has been destroyed, mainly due to logging and other human activities such as development and agriculture, resulting in habitat loss. This makes our experience in these remarkable surroundings even more precious.

But First the Hall of Moss Trail - A Forest on a Tree Limb

Before starting our hike on the Hoh Rainforest Trail, we walked along the iconic Hall of Moss Trail, which is 0.8 miles long. Starting early in the morning provided dim lighting and cooler temperatures, creating an ideal setting for a horror movie.

You can see how the eerie beauty of the moss-covered branches can create that feeling of the unknown and the possibility of lurking dangers, but ....

... we pushed on as the sun started to illuminate the tree tops

Moss and lichen cover every surface and ferns carpet the ground. There are hundreds of species of moss and lichen found here. Although they may look like other plants, mosses are distinct from the rest of the forest's undergrowth. This is because mosses are non-vascular, meaning they don't have the specialized tissues needed to transport water throughout their bodies. They also lack true leaves, stems, or roots.

Both the towering giants of the forest and the lower branches of smaller trees provide an ideal habitat for moss to flourish. Mosses grow relatively slowly, and factors like environmental conditions and the specific type of moss can affect their growth rate. While some mosses may grow more rapidly in certain conditions, it's unlikely to see a significant "beard" formation in less than a year.

Although moss and lichen attach themselves to trees, they do not harm their hosts and are not considered parasitic plants. They are epiphytes, which means they grow on the surface of another plant without extracting nutrients from it. Instead, they absorb moisture and nutrients from the air, rain, or surrounding debris.

I was able to capture this picture of clubmoss. It resembles a miniature evergreen forest densely growing on a tree branch. Clubmosses are some of the earliest known vascular plants, having evolved approximately 410 million years ago. Their tree-sized ancestors were prevalent during the Carboniferous period, playing a significant role in the creation of coal deposits. Today’s clubmoss species are much smaller, usually growing as ground-cover plants.

I wish I had enough botanical knowledge to tell moss and lichen apart in my photos, but at least iNaturalist identified species this as Cat's Tail Moss.

Hoh Rainforest Trail: Like Looking at the World Through a Green Lens

Imagine a forest that receives over 12 feet of precipitation each year and typical summer temperature don't reach the mid-70°s F. The results is massive evergreen canopies that are so dense in places that only minimal sunlight reaches the forest floor.

Occasionally when the sun breaks through, the forest takes on a different hue.

Why do Conifers Grow So Tall in the Pacific Northwest

Surrounded by giant trees leads to the obvious question: why do they grow so tall here. Conifers grow so tall in the Pacific Northwest rainforests due to a combination of ideal environmental conditions and evolutionary adaptations that allow them to thrive in unique environment.

These forests receive substantial rainfall throughout the year, accumulating over 140 inches annually, which promotes constant growth and prevents drought stress. Furthermore, the climate is cool and relatively stable. This extended and mild growing season enables trees to grow for many years without suffering damage from extreme heat or cold. In addition, both freezing temperatures and extreme heat can cause a phenomenon known as cavitation, which prevents trees from growing very tall.

Decomposing plant material from dense vegetation creates nutrient-rich soil and the high humidity keeps the soils moist which creates perfect conditions for deep root systems and healthy trees. Moss and mushrooms are symbols of wet and decaying ground cover. Moss thrives in moist, shady environments, while mushrooms are fungi that decompose organic matter. They both indicate a healthy, biodiverse ecosystem where decomposition is actively taking place.

In Hoh, conifers have developed characteristics like straight trunks and narrow crowns, allowing them to effectively compete for light. Their height enables them to reach sunlight in the densely packed forest.

With little competition from deciduous trees, the conifers are free to reach incredible heights. There are four conifers which 'stand out' in the Hoh Rainforest.

The Four Giants

The enormity of the trees here is inescapable. The Hoh hosts some of North America's giants, including Western hemlock, Western Red cedar, Sitka spruce, and Douglas fir. The National Park Service offers a reference chart to assist in identifying these trees based on bark characteristics.

Western Hemlocks Prove Patience is a Virtue

It's easy to feel 'small' next to the these trees. especially when this wasn't even the largest Western hemlock that we saw on this hike. Mature trees are commonly about 4 feet in diameter but can grow as large as 8 feet in diameter and 200 feet tall if they get enough space. They are one of the most shade-tolerant trees in the Pacific Northwest. Once a seedling is established, it can survive for years, growing slowly in the shade of large Douglas firs. A Douglas fir cannot live forever, and it cannot reproduce in a dense forest with no bare soil where the seeds can germinate and not enough sunlight for them to grow. Eventually, the old Douglas firs will die and the western hemlock will have their place in the sun. Then they can grow faster than a Douglas and will eventually prevail, forming the canopy of the mature forest. They always wins in any competition with Douglas fir.

Western Red Cedar is a ‘Fake Cedar’

Only after viewing this photo did I realize the remarkable nature of this location and image on the trail—these three giants overshadow me in the photo, even though I'm centered in the shot. First off, as the title suggests, these are ‘fake’ cedars; the western red cedar actually belongs to the cypress family. In the rainforest, Western Red cedars typically grow to heights of 100 to 150 feet and diameters of 15 to 30 feet when mature but exceptional trees can reach heights up to 200 feet. They may not be the tallest or girthiest but they are survivors; some of the old growth coastal Western Red cedars may be 1400 years old or older.

Sitka Spruce is Considered a 'Mother' Tree

Sitka spruce is known as the “mother tree” and as a female proctor and guardian symbol. In dense areas, such as around Sitka, Alaska, the dense tree canopies could have provided protection from inclement weather. There is another level of protection as well. Fallen trees create perfect environment for new seedlings and become 'nursery logs' during the regeneration process. In some particular poor soil areas, this may be the only viable way to get seedlings to thrive.

Sitka spruce is by far the largest species of spruce and the 5th largest conifer in the world behind giant Sequoias, coastal redwoods, Douglas fir, and Noble fir. They usually growing to heights of 180 to 225 feet but can grow to heights exceeding 300 feet. Sitka spruce are mostly found along a long narrow zone that stretches from southeastern Alaska to northern and central California.

In the rainforest, Sitka spruce trees often have buttressed trunks, meaning the base of the tree is swollen and flared out. This is a common feature, especially in mature trees like this one, which comfortably accommodates Dave and the kids in the spaces between the roots. Buttressing is a smart structural adaptation for surviving in wet, windy, and often unstable environments.

Douglas Fir is the 'Grooviest' Tree in the Forest

Douglas fir is the most common tree in the Pacific Northwest. It can grow into a 1,000-year-old giant with a 15-foot thick trunk and a tall crown that surpasses 300 feet. Young bark is gray and smooth but as the tree matures it grows over a foot thick and begins to turn corky, reddish-brown, and deeply furrowed. While Douglas firs are the tallest of the rainforest giants, they do not typically have buttressed trunks in the same way as many tropical rainforest trees.

While hiking, we observed two peculiar occurrences that happened repeatedly: nurse logs and inosculations

1. Giant Trees Make Great Nurses

A nurse log is a fallen tree, usually due to age, wind, disease or other events, that begins to decay on the forest floor. Over time the decomposing log creates a rich moist and elevated environment that supports the growth of new plants, especially tree seedlings. Decomposing wood is full of nutrients like nitrogen, phosphorous and potassium and combined with the moisture retained in the tree gives younger plants a better chance to survive. In addition, elevated platform provided by the nurse logs provides more access to light and nutrients for seedlings than the dense undergrowth of the forest floor. The boost from the nurse log gives the tree a healthy start — faster early growth, access to nutrients, and reduced competition. This head start increases its long-term survival chances, even after the log is gone.

As the log decays, the young tree’s roots grow down through the rotting wood and eventually reach the soil underneath. These roots thicken and strengthen, forming a “root bridge” that stabilizes the tree even after the log disappears. Mature trees that began on nurse logs often appear to stand on stilts or have exposed roots arched above the ground where the log once was. This photo of Dave standing beside a Sitka spruce, propped up on stilts, is one of the many examples of nurse logs development we saw on the trail.

The impact of nurse logs endures for centuries after they have decayed, as shown by this 'colonnade' of similarly sized Sitka spruce growing in a straight line along the trail. This row of spruces appears as if humans planted them, rather than being a natural occurrence. Likely, a century ago, each of these spruces sprouted on a nurse log. Although the original log has long since decomposed, the alignment of these soon-to-be giant trees mirrors the straight form of that ancient nursery.

2. Giant Trees Occasionally Kiss

Inosculation is a natural phenomenon in which trunks, branches or roots of two trees grow together in a manner biologically similar to the artificial process of grafting. The term is derived from Latin word 'osculum' which translates as 'to kiss.' In this case, these two Sitka spruce grew close together. Once their bark made contact, friction from continued growth wore away the outer bark layers. The cambium cells of both trees fuse together, essentially grafting the two trees together Over time, the fused cambium continues to grow, forming new bark and wood, creating a single, unified tree.

Here are a few photos taken along the trail that tell a story with little need for description or explanation.

How would you even explain the formation of this root system? Maybe a response to growing on a nurse log?

If Dave is 6 feet tall, then this fallen tree has a diameter of at least 7 feet, which translates to a circumference of more than 22 feet.

The number of shades of green is overwhelming.

The perfect setting for a selfie.

After slow hiking for 4 hours we reached the Hoh River and our turn around spot, but first some relaxing time in the river. The water was blue-gray, colored by silt from the glaciers on Mount Olympus that drain into the river.

Cold but refreshing.

The haze visible in this photo is actually smoke from the wildfires that were burning in the national park during our visit. We found the perfect lunch spot.

While back on the trail, we noticed this sign had fallen over...perhaps we should have put back in place.

You can see how quickly this trail can become overgrown.

There were occasional splashes of fall color.

And just like that, six hours later, we returned to the trailhead. It was an incredible day on the Hoh River Trail. While writing this blog, I found a quote that perfectly encapsulates our experiences on the trail.

"Everything in the forests feeds everything else. When trees fall, other trees grow from it, so its life supports the next. Here, the forest consumes everything. And quickly too."