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Our Dynamic Forest

By Bruce Rottink, Volunteer Nature Guide & Retired Research Forester


This year January brought us an unusually wet, heavy snow.  In my Lake Oswego backyard, it amounted to just over 7-1/2 inches of the white stuff.  The snow at Tryon Creek State Natural Area (TCSNA) was roughly similar.  As with so many other unusual events, it was a great opportunity to learn more about our forest.


The wet, heavy snow brought many changes.  Some that we humans, entranced with the visual wonder that is our forest, tend to regard as tragic.  But Nature may have a different view.  Let’s take a look at some of the things that happened.


Look out below! 

All kinds of trees fell down.  As shown in the photo below, the top snapped off from this red alder (Alnus rubra) growing near Red Fox Bridge.  You can see the top lying on the ground.  For the alder, this is a horrific setback, if not death.

Photo 1

Top of alder broken off near Red Fox Bridge.


However, the plants growing on the ground under this alder may have a different perspective.  I stood right over the alder trunk lying on the ground, pointed my camera upwards and took this picture of a significant hole in the canopy.

Photo 2

View of the sky where the alder fell down.


Do you suppose the plants growing on the ground are looking up and thinking, “Oh what a tragedy.  Now we’re going to be growing in full, life-giving sunlight, and we won’t have competition from the alder.”  No matter what kind of tragedy it was for the tree that fell down, many of the neighboring plants will be celebrating because of the extra sunlight they will be receiving.


And if the existing plants already on the ground aren’t able to jump in and take advantage of the newly sunny spot, rest assured that some new plants will.  The photo below shows numerous red alder seeds (two are marked with red arrows) on the Middle Creek Trail the very same day I photographed the broken alder.  Finding these tiny seeds in the forested area would be very difficult, but have no doubt, they are there!

Photo 3

Red alder seeds on the trail (green Douglas-fir needle at bottom provides perspective).


Death Cleanses the Forest

Perhaps you mourn the loss of so many good trees.  In at least some cases, your tears are wasted.  A storm like the one we had can be viewed in part as Nature cleaning up the forest.  For example, as part of a human cleanup effort, I spent some time cutting through the trunk of a western redcedar (Thuja plicata) that was lying across the Cedar Trail so the trail would become passable (see photo below).

Photo 4

Western redcedar stem lying across the trail (note pen for scale).


It was sad because it was a young tree, with potential to become one of the esteemed elders of the forest.  Or so I thought.  As I dragged some of the branches off the trail, I noticed the top of this tree (pictured below).

Photo 5

Dead top of the fallen western redcedar tree.


The top four to five feet of this tree had already been dead for some time.  So the real story was that this tree was already having problems of one kind or another, and the storm just ended its struggle.  Since it already had a dead top, its long term potential was not as great as I originally thought.


In another case, a very tall (about 115 foot) Douglas-fir (Pseudotsuga menziesii) fell down across the Old Main Trail.  This is another tree that I cleared off the trail (Note:  The clean-up work I did after the storm proved very educational.  You might want to give it a try!)  The top was forked due to some damage many years ago, as indicated in the picture below.

Photo 6

Fork-topped Douglas-fir on the ground after a heavy snowstorm.


But this is another example of a tree that was already in trouble.  The smaller branch on the right side of the picture shown above had been damaged many years before this year’s storm, as you can see below.

Photo 7

Broken, semi-rotten top end of one of the major stems on a Douglas-fir.


I sawed off the top 12” of this stub, and inserted a pencil into the soft rotten area in the center of the stem.  The results are shown below.

Photo 8

Pencil stuck in stub of tree trunk.


Photo 9

This is how far I could stick the pencil in.


I could easily stick the pencil a couple inches into the rotten wood.  I cut 2 more feet off the end of this stub, and was still able to stick the pencil about ½” into the rotten center of the branch.  Once the fungus gains this much of a foothold in a tree, it’s only a matter of time before it seriously weakens the tree.

So once again, the storm felled a tree that was already in trouble.


Dead Trees Can be Useful

And if you mourn for the dying trees, rest assured that not all of the forest inhabitants share your grief.  Bark beetles lay eggs under the bark, and their larvae start burrowing through and eating the soft nutritious tissues that are right under the bark.  Of the hundreds of species of bark beetles, at least some attack after the tree is dead.  These beetles leave the kind of tracks like those you can see after the bark has been removed from this branch collected at TCSNA.

Photo 10

Tracks left by bark beetles eating the soft tissues of the branches.


And of course, once insects get into a tree, can woodpeckers be far behind?  The photo below shows a heavily “wood-peckered” long-dead tree along Old Main Trail.

Photo 11

Heavily woodpecker-ed dead tree along Old Main Trail.


And Some Weird Stuff…

The snow also brought at least one unique observational opportunity!  Down near the creek in one area, I noticed that the snow had patches of yellow color.  (No, it’s not THAT!)  There were no animal tracks in this area, so I seriously doubt the yellow patches were from dogs or coyotes.  According to reports on the internet, yellow snow in this context is frequently the result of pollen getting mixed in with the snow.  Sadly, I got a picture, but never collected a snow sample for microscopic examination.  The storm was roughly at the time that some hazel (Corylus spp.) would be shedding its pollen, but I have no proof that’s what it is.

Photo 12

Yellow patches of pollen (?) on fresh snow near Beaver Bridge.


Assuming this is pollen, I have no doubt that pollen is shed like this on the ground every year.  However, it takes a snow covered forest floor before we will ever notice it.


Our Ever Changing Forest

Our forest is an ever changing ecosystem.  If we could see this forest in 400 years, much of it would look unfamiliar.  Most often the change is very slow, but a catastrophic event like a dramatic storm puts the changes in a time context we humans can relate to.  Enjoy our forest today, because when you come back tomorrow, it will be different.




Native American Uses of the Forest

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester


For thousands of years before settlers from the eastern United States or Europe arrived in the vicinity of what is now Tryon Creek State Natural Area (TCSNA), Native Americans called this forest home. The Native Americans used resources ranging from rocks to trees to animals. However, the basis for much of the Native American life was the plant life of this area. They relied on the forest and waterways for everything; food, medicine, tools, clothes, everything!

What kinds of plants did they eat?

There were lots of plants and fruits the Native Americans ate. Some of the more tasty items were the berries from the forest, like the salal (Gaultheria shallon) berries. Pictured below are the plant and berries. I’ve planted salal in my front yard, and they are delicious on my morning cereal!


Salal plant, with salal berries in the inset at lower left


Another food the Native Americans sometimes ate were the berries of the Oregon grape (Mahonia nervosa). In the photo below, the blue-colored berries are almost ready to eat, while the greenish ones have a way to go before they are ripe.


Oregon grape berries starting to ripen


I’ve tasted Oregon grape berries too. My taste buds’ response was, o-o-o-o-kay! I think they’re about half way between yummy and yucky. According to ethnobotanists, people who study how different groups of people use plants, the Native Americans would sometimes mash the fruits of the salal and Oregon grape together. In this way, they had a greater total quantity of food, which still tasted “kind of” good.


Another category of food plants is represented by the skunk cabbage (Lysichitum americanus) pictured below. This plant has a large underground tuber (note: potatoes are also tubers). Unfortunately, the skunk cabbage tuber tastes awful. It had to be specially prepared to become even edible. Ethnobotanists refer to this as a “starvation food” meaning that you only ate it when the alternative was starvation. If you’ve ever smelled a skunk cabbage in the spring, you understand why it wouldn’t necessarily pop into your mind as a good food item!


Skunk cabbage plant and flower

What kind of medicine is in the forest?

For the Native Americans, the forest was their drugstore. Just one of the many medicinal plants used by some Native Americans was the licorice fern (Polypodium glycyrrhiza). The pictures below show the licorice fern growing on the side of a tree at TCSNA and the second photo shows a cleaned-up licorice fern plant that was growing on a branch that was blown down during a windstorm. The rhizome can be thought of as a perennial stem, while the leaves come and go with the seasons.


Licorice fern growing on a tree trunk



Licorice fern after removing the surrounding moss


The Native Americans cleaned up the rhizome of the licorice fern and chewed it as a cough and sore throat remedy. Once when I was not at TCSNA, I cleaned up a licorice fern rhizome and chewed it a bit. It does taste faintly like licorice. Within 30 seconds of starting to chew the rhizome, I got a tingle right in the back of my throat. Although I was perfectly healthy at the time, the fern was definitely affecting me. It would have been interesting to see the effect if I’d had a cold or sore throat.


What kind of tools did they find in the forest?

One of the tools the Native Americans found in the forest was the horsetail (Equisetum spp.), pictured below. This primitive plant contains a lot of silica crystals. Silica is the most common material found in sand. The Native Americans used this as a “natural sandpaper” for finishing their wooden tools. The effectiveness of this tool can be demonstrated by using it to polish a penny.


Equisetum and polishing a penny with Equisetum


The effectiveness of polishing is shown in the “before and after” photos below.


Two unpolished pennies (left)        Far right polished for 2 min. with Equisetum.


What kind of clothes did they make from forest plants?

The western redcedar tree (Thuja plicata) had many uses. To give just one example, its bark is very fibrous. With careful harvesting and care it can be used to produce everything from rope to clothes. Pictured below is a cedar bark rain hat. These were widely made and used by the Native Americans on the Pacific coast. According to some sources, they would sometimes treat this hat with pitch to make it even more water repellent.



Native American cedar bark rain hat


But of all the clothing that the Native Americans made from forest plants, the one that always intrigued me was that they used moss for baby diapers. I wondered how well those would work. Strictly as a public service, I decided to run an experiment and find out.

You personally tested moss as diapers? Seriously?

Before your imagination runs wild (it may already be too late), let me explain. I took samples of five water-absorbing things:

  • A major brand of modern disposable diaper
  • A sponge
  • A pile of moss
  • A traditional cloth diaper
  • A bunch of paper towels


I weighed each item dry, making sure I had between 60 grams and 90 grams of each material (this is about 2 to 3 ounces). I then soaked each item (separately) in water completely covering the test material with water for 15 minutes. Then I put each material on a sheet of screen to drain. When the drops of water falling out of the material were 10 or more seconds apart, I considered the material to be completely drained. I then weighed each item wet. I calculated “absorbency” by dividing the weight of water absorbed by the dry weight of the material.


The results are displayed in the chart below.



Modern diapers with their SAP (Super Absorbent Polymer) ingredient can absorb more than 80 times their weight in liquid! But let’s cut to the chase. I was fascinated to see that moss, the key ingredient in the Native American diaper could absorb 7.4 times its dry weight in water. In contrast, a classic 100% cotton, all-cloth diaper can only absorb 3.5 times its own dry weight in water. So the Native Americans were using the superior diapering material! Wow!


At home in the forest!

To the Native Americans, the forest was their home, their grocery store, their pharmacy, their hardware store, their everything! They adapted to their environment to meet all their needs.


Fighting Flora

The Plants Fight Back!

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester


Plants may seem like passive members of the Tryon Creek State Natural Area (TCSNA) forest community. They stand in one place for many years, stoically enduring every insult the ecosystem throws at them. Their reactions are neither flashy like birds, nor noisy like squirrels. Their efforts at survival are more subtle, yet often very effective.

Plants are subject to a wide range of diseases, primarily caused by fungi or bacteria. Unlike many animals, plants don’t have an immune system to fight off infections. Still, over many generations, plants have developed some defensive tricks that might not be obvious to humans.


Okay, how do plants cope with infections?

One method of dealing with disease is to just give up and start over again! For example, by early August of 2013, all the leaves of one particular vine maple (Acer circinatum) near Obie’s Bridge were heavily infected and damaged by a microorganism. The photo below shows the extent of damage to typical leaves.


Heavily infected leaves on a vine maple


Damaged as the leaves were, the plant reacted by dropping all of the diseased leaves in early August, and growing a new set of uninfected leaves. The uninfected leaves served it well through the remainder of the growing season. The new leaves are shown in the photo below. You’ll note in the photo that the leaves on the lower portion of this branch have not yet grown out, and may not grow out this year.


Second set of leaves in a single year

Wow, that seems like overkill!

Yes, this is a radical approach to dealing with leaf diseases, but when all other defenses fail, the plant has little choice. More often, plants deal with leaf infections by a process known as “compartmentalization.” This is illustrated in the photo of the Oregon grape (Mahonia sp.) leaf below. This leaf has been attacked by a fungus. The fungal attack has killed the leaf tissue, as indicated by the pale circular (and now fractured) area of leaf tissue. In response to the infection, the leaf has created a barrier, seen as a thin black line, to stop the infection from spreading. The black spots within this area are places where the fungus has produced spores.


Fungal infection on Oregon grape leaf

Actually, the leaf has responded to the fungal attack in two ways. First, it has created a physical/chemical barrier to the fungus, which is the black ring surrounding the infected spot. This will stop the fungus from spreading any further into the leaf. Secondly, the reddish areas of the leaf are colored by the natural chemical called anthocyanin. Scientists have discovered two very cool things about anthocyanin. First, scientists have shown that anthocyanin interferes with the growth of fungus. Second, scientists have discovered that many plants start producing anthocyanin when they sense a fungal infection. So the production of anthocyanin is the plant’s form of chemical warfare, triggered by the presence of fungus.

In the interests of full disclosure, the anthocyanin may “appear” for one of two reasons. First, it may have been there all along, and only becomes visible when the normal green pigment (chlorophyll) disappears. Or secondly, it may have been synthesized by the plant in response to the attack. While it is not definitive proof, the photo below of a leaf attacked by fungus shows the (red) anthocyanin only near the region of fungal attack. This in spite of the fact that the chlorophyll has disappeared from the leaf. This suggests to me that the leaf was not filled with anthocyanin that was revealed when the chlorophyll disappeared, but rather the anthocyanin was specifically synthesized in response to the fungal attack.


Senescing leaf of Oregon grape


What happens when decay gets into a tree’s trunk?

When a tree is dealing with a fungal attack on its main stem, or trunk, just giving up is NOT an option. Once wood has started to decay, it doesn’t “heal.” And plants, as far as we know, don’t have immune systems. So instead, the tree uses the same compartmentalization technique as it uses with leaves. It isolates the fungus to make sure it doesn’t spread throughout the entire tree trunk.

Below is a picture of the cross section of an alder (Alnus rubra) tree that was growing near the Tryon Creek Nature Center. It was cut down because it was a hazard to folks using the park. The picture clearly shows the solid reddish-brown wood, the gray-ish area of rotten wood probably caused by a fungus, and the thin black barrier the tree has developed to compartmentalize the infection.


Cross section of a red alder which has compartmentalized fungal rot

Park Ranger Dan Quigley found another very interesting rotten tree while cleaning up some “tree messes” around TCSNA. He cut me a “tree cookie” (a cross-sectional slice of the main trunk) and hauled it back to the shop. THANKS, DAN! This specimen of bigleaf maple (Acer macrophyllum) is interesting in that this tree appears to have been attacked by rot twice. It probably was wounded and infected once, and then sometime later, it was wounded and infected again. In older trees this is not uncommon. Again the black lines are the barriers created by the tree. (For size purposes, note that the tree cookie is overlapping both edges of the 29” wide picnic table it is resting on).

The wood at the very center of the tree, inside the first barrier, was so rotten that it has disappeared (probably in the cutting/handling process, if not prior to that). Most of the barrier was destroyed too. However, one small section of the first barrier is still present.


Slice of a hollow bigleaf maple trunk from TCSNA

This specimen provides a rare opportunity to view the “barrier” up close. I scraped away some of the rotten wood inside of the 1st attack barrier. The photo below shows a side view of the barrier, with the barrier being a darker color than the rest of the wood.


Side view of one section of the barrier strip in a partially rotten tree trunk











I carefully dug out some of the rotten wood between the first barrier strip and the bark. Then I took the photo below looking pretty much straight down the tree trunk. In this photo, you can see that the barrier strip is a real physical entity. It is approximately the thickness of, and as strong as, the material in a standard manila file folder.


Looking from the top down at the tree’s barrier to the 1st attack


Plants are tough!

Plants are rich storehouses of the energy that fungus and other disease-causing organisms need for their own success. Plants are under constant attack. While their defense mechanisms generally allow the whole plant to survive, it is often at the cost of sacrificing a part of themselves to the disease. Somehow, both the plants and the fungus have survived for millions of years, making our forest the home to some of the toughest organisms that you can imagine.



* Thanks to Jay W. Pscheidt, Extension Plant Pathology Specialist and Professor of Botany and Plant Pathology at Oregon State University for his input on this post. He both confirmed some things I thought I knew, and provided some new information on this topic! This exemplifies one of my favorite quotes, “None of us is as smart as all of us!” That said, I take full responsibility for any errors in this note! — Bruce Rottink


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