The ABCs of Forest Ecology

Resprouted Madrone & Snag

Look on the right hand (downhill) side of the trail for a tree with many trunks. This is a Pacific madrone tree, a common species in this region. While most trees reproduce by making seeds, madrones prefer to reproduce by sending up sprouts when an old tree dies due to fire or cutting. Madrones have been known to send up as many as 300 sprouts from the base of a dead tree! These sprouts use the well-established root system from the previous tree, which gives them a major advantage over baby seedlings that have to grow their roots.

Now look across Clay Creek for a big dead tree that’s still standing (image 2). Dead standing trees are called snags, and they are very important to healthy forest ecosystems. Bugs like beetles come to dead trees to find food and to lay their eggs, and they also start to break down the dead wood. In turn, birds like woodpeckers drill holes to find and eat the bugs. Some woodpeckers even make their nests in snags by drilling larger cavities or holes, and when they leave those nests, other animals and birds move in (image 3). Snags provide food and habitat for animals, fungi, and bacteria long after the tree has died.

Trees, and the organisms that use trees both during and after the trees’ lives, are examples of biotic factors in a landscape.

Explore some more:

Take a close look at this cluster of madrone trunks. What other living things are finding a home on or in this tree? Do you see moss or other plants? Signs of animals, like spider webs? Be sure to look up, too, for signs of animals making use of this tree.

In many cases, landowners remove standing dead trees instead of leaving them as snags. Why do you think people do that? What would happen to the bugs and woodpeckers if people removed all of the dead trees from a forest? Describe a compromise that would meet the needs of humans and the needs of the organisms that rely on snags for food and habitat.

Try it:

Open the  The Woods Tree ID Key . Practice using the key to identify the multi-trunked madrone, and then try identifying another nearby tree.

Continue on the trail.

Trail fork; stay right

When you get to a fork in the trail, stay right to follow the signs for “Multi-Use Trail.”

Look for:

Keep your eyes open for a washed-out area on the downhill side of the trail, where there’s an abrupt opening in the shrubs immediately next to the trail. 

Big Erosion Site

The washed-out area downhill of the trail (image 1) is the site of a major erosion event that happened in 1997 during a big flood. An unusually snowy winter had piled deep drifts of snow in the mountains above Ashland, and an unusually warm and heavy rainstorm not only poured rain on the region but also melted the accumulated snow. The combination of very wet weather and steep topography caused major flooding throughout the Bear Creek Valley, just as residents were ringing in the New Year (image 2).

Major flooding is a normal and important part of a stream’s presence in a natural place. Such flooding carries nutrient-rich soil from upstream and deposits it downstream, creating fertile places for plants to grow. However, this cycle becomes more threatening when humans choose to build their farms, towns, and lives nearby to the waterways' fresh water and fertile soil. Not only did the 1997 flood damage natural areas throughout the mountains surrounding Ashland, like the erosion at this site, it also caused significant damage to buildings, roads, bridges, and other infrastructure in town. It also took out all the bridges here in the Woods!

Weather, topography, and flooding are examples of abiotic factors in a landscape.

Explore some more:

What do you think would have happened here if there had only been a little bit of rain in that 1997 storm? Does it take the same amount of rainfall to cause erosion on a steep slope like this one as it does to cause erosion in a flatter area?

Continue about 20 yards further down the trail, and look to the uphill side of the trail for a large resprouted madrone tree with many exposed roots (image 3).

Biotic factors also contribute to erosion. Much of the soil around this tree was carried away during the 1997 flood. Describe what you think might have happened during the flood in this spot if there had been no trees or plants at all on the slope.

Cultural factors can also play a part in creating or reducing erosion. Look around for an example of how humans are creating opportunities for erosion, and how they’re slowing erosion on this steep slope and on other slopes throughout the Woods.

Continue on the trail.

Geologic Contact

Keep going on the trail until you get to an intersection with a set of stairs heading down to the creek and another set going up the opposite bank (image 1). Head down the stairs, cross the creek, and instead of following the stairs and the main trail to the left, take the small footpath to the right, so that the creek is immediately to your right. Follow it for about 15 yards (14 meters) until you get to a small (1 ½ feet tall) waterfall.

The Woods sit at the intersection of two distinct geologic formations. One is called the Ashland Pluton, which is a huge piece of granitic rock that formed about 160 million years ago when magma (melted rocks) pushed up toward the earth’s surface but didn’t break through, and instead cooled slowly underground, forming crystals in the rock. The other is called the Hornbrook Formation, which was created about 100 million years ago when an inland sea dried up and left behind a thick layer of very fine-grained sediments, which squished together and eventually formed rocks like sandstone, mudstone and siltstone.

Geologic formations are so big that it’s unusual to see the exact place where they connect, but in Clay Creek we can see it clearly. The underlying geologic formations and the water in the creek are examples of abiotic factors in this landscape.

Explore some more:

Using the chart above to guide you (image 2), make some observations about the kind of rocks upstream of the waterfall, like the squarish, flat, light grey rock right next to the trail, and the kind of rocks downstream of the waterfall, like the large mossy ones in the creekbed a little ways downstream where the trail drops down to the creek. Also look at how steep the banks around the creek are: the steeper the banks, the more easily the underlying rock erodes. Using your observations, make a guess about which side of the waterfall is the Hornbrook Formation (mudstone) and which side of the waterfall is the Ashland pluton (granite). 

Because of its small grain size and the way it forms in layers, mudstone is an ideal rock for preserving fossils. If you’re willing to risk wet feet, you can hunt for fossils in the creekbed downstream! For a drier fossil search, head to Weisinger Winery, where boulders in the parking area are full of fossils (image 3).

Continue on the trail.

Make your way back to the bridge crossing, but stay on this side of the creek and go straight up the stairs. When you get to the intersection, take the hard left turn to continue uphill. Look for a green “Adopt-A-Trail” sign on the left shortly after you get to the crest of the hill. 

Adopt-A-Park

Ashland Parks and Recreation Commission (APRC) manages, among other facilities, 17 parks and 48 miles of trails! To keep all of these open spaces in prime condition, APRC established the “Adopt-A-Park” program, through which individuals, groups, and businesses can help maintain safe and healthy conditions in the parks (image 1). To learn more about this and other volunteer opportunities in Ashland parks, check out the  Parks website .

Several years ago, Southern Oregon Land Conservancy (SOLC) encouraged the John Muir Outdoor School (JMOS), a K-8 magnet school in Ashland, to adopt the Woods. Under the guidance of Ashland Parks and SOLC staff, JMOS 7th and 8th graders visit the Woods at least four times each school year to improve and chip the trails, remove invasive weeds like ornamental plums, Scotch broom, and Himalayan blackberry, and even perform some ecological forest thinning. SOLC staff also lead the students in natural science lessons to take advantage of this dynamic and exciting classroom (image 2).

While you catch your breath at the top of the hill, take a look around for examples of the things you learned about earlier on the trail. Can you find a snag, a resprouted madrone tree, and an example of erosion?

Explore some more:

Tune in to all of your senses to notice abiotic, biotic, and cultural factors in this spot. What do you see? What do you hear? What do you feel? What do you smell? (Don’t taste anything, unless you brought a snack or water with you. Now would be a great time to rehydrate!)

Pull up the  Tree ID Key  and try identifying a few trees near you.

Continue on the trail.

Continue on the main trail, keeping left at the intersection. After the intersection, look for signs of a fire, including a burned log on the ground, to the right of the trail.

Controlled Burn

After the intersection, look to the right of the trail for signs of a fire (images 2, 3). This is the site of a prescribed burn that took place in 2017. Managed by Ashland Fire & Rescue, this was the first underburn on an Ashland Parks property (image 1). It was also the City’s first fire project that collaborated with private landowners so that the burn could cross property boundaries.

While uncontrolled forest fires can be devastating for humans, fires are a crucial part of many forest ecosystems. Some tree species will only release their seeds in the extreme heat of a fire. Some plant species rely on fire to clear out other nearby plants, reducing competition for resources like water and soil nutrients (image 4). Fires help recycle nutrients back into the soil. Fires also create snags, which are important food and habitat resources for many animals. And some animals prefer to live in areas that burn regularly, because different plants thrive in burned and unburned areas, which means more choices for food and habitat.

Native Americans who lived in this region recognized the importance of fire, and they allowed fires to burn frequently–as often as every 5-7 years. This recurring burning kept fuel levels low, so the fires remained low-intensity. However, when European settlers arrived, they opted to put out wildfires as quickly as possible. Because of this, unusually large amounts of fuel such as downed branches, dense shrubs and trees, and logs have accumulated in nearby forests over the last 150 years, making high-severity fires much more likely.

Today, some western Native American people, including the Shasta and Yurok, continue to use prescribed fire as a land management tool. Local, state, and federal agencies and organizations are learning from these traditional practices, performing carefully-controlled low-intensity burns to balance the human need to preserve life and property with the forests’ need to burn occasionally.

For more information about local fire management plans that balance human needs and healthy forests, visit the  Ashland Forest Resiliency website .

Explore some more:

Do you think an intentional, controlled burn is an example of an abiotic, biotic, or cultural factor in this landscape? How about a fire that starts by a lightning strike?

Compare the spacing of the trees on the right-hand side of the trail (where the controlled burn took place) and on the left-hand side of the trail (which did not burn). What do you notice? What animals do you think might prefer to live in the thinned forest? In the denser forest?

On the side of the trail that was burned, look for evidence of the fire. What signs tell you that the fire was mild, not severe? How might the forest look different if it had been a very hot, high-intensity fire?

Continue on the trail.

Trail fork; stay left

Continue along the trail until you arrive at the intersection with the trail map sign. Turn left at the fork so that you head downhill, toward the creek. At the T, turn right, so that the creek is on your left. Cross the bridge and turn right, toward the exposed granite and the waterfall.

Bridge and Falls

While exploring the Clay Creek waterfall (image 1), please stay on this side of the creek to prevent further erosion of the banks.

This creek’s source is near Lamb Saddle in the Ashland Watershed. After passing through the Woods, this water feeds into Bear Creek, which provides critical habitat for fish and other aquatic animals. Bear Creek is also an important tributary of the Rogue River, which continues all the way to the Pacific Ocean!

The habitat that occurs directly alongside a moving body of water is called a riparian habitat (image 3). Not all plants have the same needs and preferences; plants that need lots of water thrive in the riparian zone. By comparison, plants that prefer drier soil grow further away from the waterways, uphill in the upland zone. And some plants only grow right in the creek itself, also known as the aquatic zone. The abiotic factors of water and slope determine what plants can grow where near a creek. In turn, these plants shape their landscape by minimizing erosion, reducing the temperature of the water and soil with shade, and serving as food and habitat for animals.

Explore some more:

Look closely for macroinvertebrates (small animals without a backbone but that are large enough to be visible to the naked eye) in the water nearby the falls (image 2). What kinds of critters do you see? Where do you find the most: in the falls themselves, in the pool at the bottom of the falls, or where the creek flows gently downhill? Why do you think they’re there, instead of somewhere else along the creek?

Like plants, animals also have diverse needs and preferences for both food and habitat. Name one animal that lives in the aquatic zone, one that lives in the riparian zone, and one that lives in the upland zone. Can you think of an animal that lives in two of the zones, or that moves through all three?

As you continue along the trail, notice how the plant community changes as you climb uphill, away from the creek. If you don’t already have it open, use SOLC’s  Tree Identification Key  to help you identify the tree species living in the different zones.

Continue on the trail.

Big Downed Tree

Follow the trail downstream, zigzagging across the creek first by carefully crossing on rocks and then on another bridge. After the bridge, walk a ways and then look for a large tree that fell across the trail and into the creekbed, and was then cut to make the trail accessible again (image 1).

While some plant species prefer to grow in the shady, cool understory, others need lots of sun and warmth to grow. When a large tree falls, it opens new space in the forest’s canopy, allowing more sunlight to reach the forest floor below and allowing sun-loving plants to thrive. Downed trees not only offer a change in abiotic resources available in a particular spot, like snags they become biotic food and habitat for many, many more living things on the forest floor.

On the outside of the downed tree on the right hand side of the trail, look for grey-green patches that look like paint. (image 2) This is one type of lichen, a symbiotic partnership between fungus, green algae, and cyanobaceteria that grows on trees (alive and dead), rocks, and even sidewalks. Also look for moss and tiny baby trees, all of which are using the dead tree as a growing medium.

Downed trees are also important for many decomposers, which are organisms that feed on dead organic matter and break it down into soil that other plants can then use to grow. The “FBI” decomposers–fungus, bacteria, and invertebrates–are the recycling crew of the forest. On the cut end of the downed tree, look for tiny holes: these are made by invertebrates such as beetles. As beetles chew tunnels through the log, they break down tough wood into sawdust, and they create additional surface area where bacteria can grow. Also look for white splotches on the cut end of the tree: these are a fungus that is using the downed tree as both a home and a food source, breaking down the wood and turning it into soil to nurture surrounding plants.

Explore some more:

Any time something in the forest looks out of place, unusual, or different from normal patterns, there’s a good chance that there’s a story behind it! The tree immediately to the right of the downed log has a very large scar, complete with insect holes in it, but if you look further up the tree you can see that it’s still alive (image 3)! What do you think happened to this tree? Look all around you (including in the creekbed) for clues, and consider abiotic, biotic, and cultural factors that might have played a role. 

Continue on the trail.

Topographic Influence

As you saw in the cross-section of a riparian zone, sunlight and water availability differ on the uphill and downhill parts of a slope, resulting in different plant communities that in turn support different animal communities. Another key abiotic factor that affects which plants grow where is aspect, or the direction (north, south, east, or west) that a hillside faces. 

To explore aspect and slope, find a sunny spot. Hold out your hand like you’re going to shake hands with someone, and then tilt your palm upward slightly. Your palm is now a hillside! To see how aspect affects your hand hillside, keep your arm and hand in the same position relative to your body, and turn slowly in one spot. Are there some points where your entire palm is in the sun? Or in the shade? 

Slope is how steep a hillside is. Test out how slope affects sunlight availability by turning your palm to face completely up (representing a flat area), and then turning it so your thumb is on top and your hand is vertical (representing a cliff). Try this in combination with the exploration of aspect. How many combinations can you find that result in a completely sunny hillside? How many combinations can you find that make a shady one?

Explore some more: 

Pull up the  Tree ID Key  again. Identify the predominant trees uphill from the trail, and the predominant trees downhill from the trail. What kinds of trees seem to prefer the upland zone? The riparian zone? If you’ve been using the ID key throughout your hike, what patterns did you notice about where certain kinds of trees prefer to grow? 

Continue on the trail.

Keep right at all forks to stay uphill, until you get to the intersection with the paved road. There, turn left to head downhill. Look for a pile of rocks at the end of a driveway on the right hand side of the road.

The Big Picture

As you make your way down the paved road, find a spot with a big view of the valley. Look around the valley for patterns of human use in the broader landscape. How did abiotic, biotic, and cultural factors encourage humans to settle in these ways? 

What abiotic factors could change in coming years? How might that affect local biotic factors? How do you think human use of the landscape might change in the future in response to these changes? 

SOLC’s mission is to protect and enhance precious land in this region to benefit our human and natural communities. We do this by working with landowners and the public to conserve land and to share resources and practices that help keep air, water, and soil clean, and that promote biodiversity and long-term sustainability in our region’s unique ecosystems. 

Everyone can support the Southern Oregon Land Conservancy’s mission in their daily lives. For example, as you make your way down the paved road toward the parking area, think about how else you might support this mission.