Category Archives: Tryon Creek

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.

 

 

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Nature’s Patterns

By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester

At the most basic level, the universe is orderly, although sometimes that order is not immediately apparent.  Albert Einstein famously remarked, “God does not play dice with the universe.”  Fortunately, in the forests of Tryon Creek State Natural Area (TCSNA) we have many wonderful examples of the orderliness of the universe.  For this article I will focus on the symmetry that we see in so many of the organisms in the forest.

 

The most common types of symmetry we can see at TCSNA are typically referred to as spherical, radial and bilateral symmetry.  Another way to think about these kinds of symmetry is symmetry around a point, symmetry around a line and symmetry around a plane.

 

Spherical Symmetry (Symmetry around a point)   

With spherical symmetry, there is one point in the middle of an object, and no matter which direction you go from that point, everything is the same.  If you’ve already guessed that all the examples are spheres, you’re right!  The seeds and fruits of some plants are the best examples of this at TCSNA.  For example, the picture below shows the fruit of a bedstraw (a.k.a. “cleaver”) plant (Gallium spp.)  The scar in the middle of the picture is where the fruit was attached to the stem.

photo-1

Bedstraw seed with spherical symmetry

 

Other forms of symmetry get a little more interesting.

 

Radial Symmetry (Symmetry around a line)

A second type of symmetry is radial, where there is a central axis to the object, and the parts all stick out equally in any direction from that central axis.  One of the best examples can be seen in this mushroom fruiting body.  Imagine the red dashed line going down the center of the stem of the mushroom.  At a given distance from the ground, if you travel out at any 90° angle to that red line the mushroom structure is identical.

photo-2

A mushroom with radial symmetry

 

The picture below is of the underside of the mushroom’s cap.  I’ve put in a red dot to indicate the central axis of the fruiting body.  No matter which direction you look out from the center, the structure looks essentially the same.  The edges of the gills that you see as lines, all point to the center of the mushroom.

 

Looking at the underside of the mushroom’s cap provides an additional perspective on radial symmetry.

photo-3

Underside of a mushroom cap, showing radial symmetry

 

 The mushroom above is an example of the simplest kind of radial symmetry.  But radial symmetry can be more complicated, and more interesting.

 

Spirals – A special case of radial symmetry

The mushroom pictured above is a very simple example of radial symmetry, but more complex examples can be easily found at TCSNA.  The most obvious are some of our native conifers.  For example, at first glance the scales on a Douglas-fir (Pseudotsuga menziesii) cone might appear to be arranged in a random pattern.

photo-4

Douglas-fir cone

 

In fact, the scales on a Douglas-fir cone are arranged in a definite spiral pattern around a central stalk.  The scales are actually arranged in multiple spiral patterns.  To illustrate this I painted the bracts (the three-pointed papery structure attached to each cone scale) to highlight these spirals.  Each spiral is a different color.  The results can be seen in the movie below.  Since each cone scale is actually part of three different spiral patterns, I have painted three different cones, each illustrating one of the three patterns.  A different color of paint was used to mark each of the spirals.  Watch first one cone and then the others to see these three different spiral patterns.

 

 

You can see in the movie that there are a set of three spirals of cone scales going in one direction around the cone axis at a very gradual angle.  There is a second set of five spirals going around the cone at a steeper angle in the opposite direction.  Finally, there is a third set of eight very steep spirals going about the cone in the same direction as the first set of spirals.  So each scale is part of all three spirals going around the cone’s central axis.

 

In any given plant, the number of spirals are a part of a set of numbers known as the Fibonacci sequence of numbers.  The Fibonacci numbers were described by an Italian mathematician more than 800 years ago (and Indian mathematicians had apparently described them even before that).  Starting with the number 1, each subsequent number is the sum of the two previous numbers.  Below is the start of the original Fibonacci sequence (the “modern” version starts with zero, which has no impact on the rest of the sequence):

 

1, 1, 2, 3, 5, 8, 13, 21, 34, etc, etc, ad infinitum.

 

In the botanical literature, it is traditionally reported that the number of spirals in any plant are always two consecutive numbers of the Fibonacci sequence.  With one exception.  The pineapple fruit is almost always described as having three spirals.  I present here the possibility that the Douglas-fir cone, like the pineapple, is composed of three spirals, not the traditionally recognized two.  But, whether it’s two spirals or three, it represents an example of order in nature.

 

Bilateral Symmetry (Symmetry around a plane)

Finally, there is bilateral symmetry, which is symmetry with respect to a plane (think of a sheet of glass).  The structure is identical on both sides of the plane.  The butterfly below is a beautiful example of bilateral symmetry.  Think of an imaginary sheet of glass running vertically through the butterfly’s body.  Each side of the body is an identical mirror image of the other side.  The easiest feature to see in the photo below are the patterns on the wings.

photo-5

Red admiral butterfly (Vanessa atalanta) near the Middle Creek Trail

 

Plants often exhibit bilateral symmetry, as exemplified by the bigleaf maple (Acer macrophyllum) fruit shown below.  In fact there are two different planes of symmetry.  The first one is centered around the red line drawn on the picture.  The second plane of symmetry is represented by the paper on which this picture could be printed.  The front and back sides of the seed are identical.

photo-6

Bigleaf maple seed with two planes of bilateral symmetry

 

But wait… Not everything in the forest is symmetrical!

My favorite example of a non-symmetric organism in the forest is the banana slug (Ariolimax columbianus).  Below are two pictures of the same slug.  One picture is of the right side of the forward part of its body, and the other is of the left side of the forward part of its body.  As you can see, the slug only has one breathing hole, and it is on the right side of its body.  Thus, the slug does not display symmetry in this regard, it is asymmetrical.  Every slug has its breathing hole on the right hand side of the body.

photo-7

Photo left: right side of slug’s body (arrow points to breathing hole). Photo right: left side of slug’s body (no breathing hole)

 

But that’s not the only way a slug is asymmetrical!  Look at the coloration on the body of the slug pictured below.  A black spot on one side of the slug is not matched with an equal sized, or shaped black spot on the other side of its body.

photo-8

Banana slug showing asymmetrical coloration patterns

 

Why symmetry?

Symmetry is often useful, such as birds having one wing on each side of its body.  Imagine a bird trying to fly with both wings on the same side of its body.  But In truth, while nature has intended many things to be symmetrical, oftentimes the symmetry is not perfect.  These imperfections may result from mutations during development, or accidents.  So what you ask?  Scientists have discovered that some animals, like female peahens and barn swallows, prefer males with symmetrical tails.  To the birds, symmetry could be proof of a potential mate’s normalcy, which is often the safe choice.

 

The symmetrical patterns that we see in much of the flora and fauna of TCSNA provide some reassurance in the orderliness of the universe.  It suggests that perhaps Einstein was correct!

Slime Molds: The Weirdos of the Forest

By Bruce Rottink, Volunteer Nature Guide & Retired Research Forester

 

Some strange things live in the forest at Tryon Creek State Natural Area (TCSNA) but for my money, none is stranger than the organisms known as slime molds. Taxonomists, folks who specialize in classifying organisms, haven’t all agreed on how to classify slime molds. They do, however, all agree that slime molds are clearly neither plants, animals, fungi nor bacteria. Slime molds are fascinating creatures because they have a very strange life cycle, and a highly unusual “body”. This note focuses only on the plasmodial slime molds, which are the type you will probably see at TCSNA. [Important: The slime mold names used in this note represent my best efforts at identifying these creatures, based on their strong similarity to photos on the internet.]

 

Where do slime molds grow?

The best place to find slime molds at TCSNA is on rotting wood. Old logs, tree stumps, or dead standing trees are prime candidates. This is because the primary foods for slime molds are bacteria and fungi. These are abundant in dead wood. Experts say the best times to find these slime molds is either spring or fall, when the forest is fairly damp. The slime molds pictured in this note were found at TCSNA in April, July, September and November.

 

What’s so weird about slime molds?

The weirdest thing about slime molds is their dramatic changes in shape over the course of their life cycle. Let’s start with the point in the life cycle which gives these organisms their name. The most active adult stage of the slime mold is when it looks like (surprise, surprise) slime! This nearly formless stage is called the plasmodial stage. At the risk of being indelicate, the adult slime mold in this stage looks like someone with serious nasal congestion blew their nose onto a log. This stage looks a little “blob-y” and has a distinct “wet” appearance. The plasmodium stage of life is the diploid stage where the slime mold has chromosomes from both parents, just like you. The example pictured below was on a decaying tree trunk that was lying on the ground near the West Horse Loop Trail.

 

Photo 1

Unknown species of slime mold in plasmodial stage on rotting log

 

These blobs of life are unusual in that they are giant cells with many thousands of nuclei in each cell. For most life forms, one nucleus per cell is the rule. Also, at this stage, there is a thin cell membrane, but no rigid cell wall. The big advantage to having giant wall free cells is that these plasmodia can move by streaming the cell contents (cytoplasm) from one end of the plasmodium to the other end. The plasmodium will move in the direction that the streaming cytoplasm is heading. Laboratory studies have observed slime molds moving at approximately 1 inch per day towards concentrations of food.

When food starts to become scarce, the slime mold moves into the next stage of life. This stage is called a sporangium. The sporangium, as you might guess, is the stage that produces the spores. The forms of the sporangium differ greatly, depending on the species of slime mold.

 

How does the sporangium develop?

There are many different sizes, shapes and colors of sporangia, depending on the species of slime mold. Examples I’ve found at TCSNA are included below.

The series of photos below shows the development of a single sporangium found on a standing dead tree along the Trillium Trail is shown. Unfortunately, I found the sporangium when it was completely developed. This was formed by a plasmodial mass similar to the one pictured above. A tough shell develops to protect the developing spores on the inside. This sporangium is the species of slime mold called “false puffball”. Its scientific name is Enteridium lycoperdon. The most striking thing about this sporangium is that in my entire life I have never seen a natural object that has looked so much like plastic. Measured vertically along the trunk of the tree, it is about 3 inches long.

 

Photo 2

Slime mold near Trillium Trail– April 02, 2016

 

Just one day later, the surface of the sporangium has started to crack apart. The interior of the sporangium is filled with small brown spores. This particular sporangium was growing very close to the trail. I suspect the yellowish area which is oozing just a little yellow fluid is in fact a wound inflicted by a curious visitor to the park!

 

Photo 3

Trillium Trail slime mold– April 03, 2016– red arrows point to apparent wound

 

After three additional days, the surface of the sporangium is starting to seriously deteriorate, exposing even more brown spores.

 

Photo 4

Trillium Trail slime mold– April 06, 2016

 

In just an additional 3 days, the surface of the sporangium is almost completely gone, and many of the spores have been washed or blown away. Now the spores will germinate and produce     single celled amoeba-like cells that crawl around. These cells are the functional equivalent of human egg and sperm cells. These amoeba-like cells will find and fuse with a compatible amoeba-like cell. Then this fused cell will grow to become a new plasmodium, restarting the cycle.

 

Photo 5

Trillium Trail slime mold– April 09, 2016

 

The photo below gives you an idea of what the interior of this slime mold sporangia contains.

 

Photo 6

Brown powdery spots from inside the sporangium

 

While observing the above slime mold, I noticed some insects on its surface. As I approached quite close to take photos, the insects boldly maintained their positions. I sent this picture to Josh Vlach, an entomologist with the Oregon Department of Agriculture. He indicated this insect “looks like a Mycetophilidae possibly a species of Mycetophila”. Mycetophilidae is a family of insects, while the Mycetophila is a genus within that family. The common name for this group of insects is “fungus gnats.” This type of insects oftentimes lay their eggs in either mushrooms or slime molds. The developing larvae eat the mushroom or slime mold. One of these insects appears in the picture below.

 

Photo 7

A fungus gnat investigating a slime mold sporangium

 

Are there other kinds of slime mold at TCSNA?

Yes, I’ve spotted several other kinds of slime molds at Tryon Creek. Below is an example of a slime mold in an advanced stage of spore production. It was on the side of a downed log just off the Old Main Trail. The cluster of spore producing bodies seem to be resting on a thin sheet of shiny material that looks like dried slug slime. The entire cluster is 9 inches horizontally, and 6-1/2 inches vertically. The thickness of these spore clusters is less than 1 inch. When touched, they easily broke into a dark brown powder. These appear to be the species Tubifera ferruginosa, the red raspberry slime mold. In a younger stage, which I clearly missed, they are bright red.

 

Photo 8

Mature patch of ‘red raspberry’ slime mold– July 06, 2015

 

In the close-up below, you can see more detail of the structure of this slime mold.

 

Photo 9

Close-up of mature red raspberry slime mold reproductive structures

 

Next is the dog vomit slime mold. (I don’t name ‘em, I just report ‘em!) For once, you might like the Latin name better – Fuligo septica. Below is the sporangium of this colorful slime mold, which I found on a fallen log next to the Middle Creek Trail. The outer covering of the sporangium is just starting to break apart, revealing the brown spore bearing parts of the slime mold. On the moss just below the sporangium, you can see a few remnants of plasmodial strands that didn’t quite make it into the sporangium.

 

Photo 10

“Dog vomit” slime mold on fallen log on the side of Middle Creek Trail– September 13, 2014

 

Below is a close-up of the surface of the dog vomit slime mold. It is substantially different in both color and texture from the first slime mold pictured in this note.

 

Photo 11

Close-up of surface of dog vomit slime mold

 

Slime molds are an amazingly diverse group of organisms, and the next species testifies to that. The photo below appears to be a slime mold in the genus Trichia. The plasmodium, the white slimy part, and the sporangia, the orange balls on a stalk, coexist. The orange blobs bear the spores for this slime mold.

 

Photo 12

Slime mold found on an old stump on Middle Creek Trail– November 20, 2014

 

Not only are the sporangia of this species dramatically different in appearance, they also differ in size. The next photo compares the sporangia to my thumbnail.

 

Photo 13

My thumbnail provides size perspective

 

So what’s the lesson here?

The slime molds really are the weirdos of the forest, and trust me, this note only scratches the surface of that weirdness. They remind us that there are many ways to be successful. The slime molds eat the bacteria, and the larvae of the gnat fly eat the slime molds, and many things eat the gnat files. Every creature in creation is linked together, and we would be wise to remember that.

 

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