Category Archives: Plants & Wildlife

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.

 

 

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!

Fungi: The Amazing Ancients

By Bruce Rottink, Volunteer Nature Guide & Retired Research Forester

 

Fungi (singular = fungus) are one of the oldest types of living organisms on earth, dating back approximately 1 Billion years. It may be slightly easier to grasp if I say that fungi have been around approximately 12 times longer than the earliest primate ancestors of humans. The fungi have used their time to develop diverse, and sometimes complex lifestyles!

The basic building block of fungi is a hypha (plural = hyphae) which is basically a long branching fungal thread. They can be seen in the picture below. This growth was on the underside of a leaf that was lying on the damp soil. The hyphae are attached to both the cottonwood (Populus balsamifera ssp. trichocarpa) leaf and a Douglas-fir (Pseudotsuga menziesii) needle. The hyphae are sometimes collectively referred to as mycelium (plural = mycelia).

photo-1

White fungal hyphae on the underside of a decaying black cottonwood leaf

 

Fungi, unlike plants, do not make their own food. This has led many fungi to adopt one of three lifestyles; a) a decayer of non-living organic matter; b) a parasite/disease of living organisms; c) a helpful life-partner of another organism. All three of these life styles can be found at Tryon Creek State Natural Area (TSCNA).

 

Fungi as Recyclers

Fungi at TCSNA recycle (“decay”) many things, as pointed out in my Naturalist Note of October 2015. This can be thought of as their “rotting” function. This is nicely illustrated in the above photo, where the fungi are probably rotting both the leaf and the needle. Rotting releases nutrients in the organic matter to be re-used by other organisms. Unfortunately, some of the most obvious examples of this at TCSNA are fungi which are decaying dog feces (a. k. a. “poop”) left behind by dogs tended by those few people with apparently little regard for either the park or other visitors.

Fungi decaying dog feces alongside Old Main Trail

Fungi decaying dog feces alongside Old Main Trail

 

Fungi as parasites or disease

Attacking dead things is one lifestyle, being a parasite, or disease, is quite another. If you’ve ever had “athlete’s foot” you know first-hand about fungi causing diseases. Some of the fungi at TCSNA are diseases too. One tree disease is caused by the honey fungus (Armillaria mellea). They produce thick black shoestring-like structures called “rhizomorphs” under the bark of this log (see below) alongside Old Main Trail. Rhizomorphs are typical of the honey fungus. Species that are rated as “highly susceptible” to this fungal disease include our grand fir (Abies amabilis), Douglas-fir and western hemlock (Tsuga heterophylla).

Black rhizomorphs of Armillaria mellea often grow between the wood and the bark

Black rhizomorphs of Armillaria mellea often grow between the wood and the bark

 

Fungi as life partners

Sometimes fungi will form a close, often physically interwoven relationship with another organism that benefits both of them. A relationship that benefits both partners is called “mutualism” which is a specific type of symbiosis. One of the most common mutualistic relationships fungi form is with forest plants, including most trees. Fungi will grow on, or sometimes into, the roots of plants, forming structures called “mycorrhizae” (from the Greek “fungus root”).” Long fungal hyphae will extend out from the mycorrhizae into the soil. In this relationship, the plant provides the fungi with food (think “sugar”). In return, using chemical means the plant does not have, the fungi very efficiently extracts nutrients from the soil, especially phosphorus, and transports it to the plant.

Another advantage to the plant is that mycorrhizal fungal mycelium are dramatically smaller in diameter than the plant’s own roots. It takes less energy to build the mycelium than it would take to build its own roots. Thus for the same expenditure of energy on the part of the plant, it can tap into a much greater volume of soil by using the finer fungal threads. Over 2,000 species of fungus have been identified as potential mycorrhizal partners of Douglas-fir.

The coral fungus shown below is one of the fungi found at TCSNA that can have a mycorrhizal relationship with many tree species.

Coral fungus fruiting bodies

Coral fungus fruiting bodies

 

Another totally different kind of symbiosis, is when a fungus lives with an algae to form what we call a lichen. The fungus does a great job of providing moisture for the algae and the algae is able to photosynthesize (create sugar) which supports the fungus. There are thousands of species of lichen world-wide, but they have been grouped by their form into several different types. The fruticose lichen has lots of branch-like structures. The crustose lichen often looks like a thick layer of paint, and the foliose types have what looks like primitive leaves.

Fruticose lichen on a stick

 

Crustose lichen on tree bark

Crustose lichen on tree bark

 

Foliose lichen on a branch which is resting on a log

Foliose lichen on a branch which is resting on a log

                                                

In the lichen, only the fungus reproduces sexually, and if some algae cells happen to cling to the spore as it floats away, great; otherwise, when the fungus lands, it will have to find some new algae with which to start a new lichen.

 

Fungi use chemical warfare

You don’t survive a billion years without picking up a few tricks along the way. Fungi have developed a broad array of chemical weapons in their fight for survival. Some fungi have been found to produce chemicals which inhibit competing organisms, like bacteria and other fungi, from growing near the fungus. Recall that the medicine penicillin was originally isolated from a fungus.

Some of these chemicals are also very effective in killing cancer cells. A chemical extracted from yew bark, taxol, has been known for years to effectively treat some breast cancers. Researchers have recently discovered that a fungus growing inside the yew bark, Taxomyces andreanae, produces the chemical taxol. Whether or not the yew tree itself also produces the chemical is not clear.

“By the sword you did your work, and by the sword you die”

The sentiment above, expressed by the Greek playwright Aeschylus in the 5th century BCE, applies to fungi as well as people. Just as fungi sometimes use chemical warfare against other organisms, sometimes chemical warfare is used against fungi too. TCSNA’s garlic mustard (Alliaria petiolata), an invasive plant native to Europe, produces and releases chemicals to stifle fungal growth. Since an overwhelming majority of plants are mycorrhizal, killing fungi interferes with the growth of plants that would otherwise compete with garlic mustard. Garlic mustard itself is one of a small group of plants that doesn’t have mycorrhizae.

 

Garlic mustard – First year plants near the North Horse Trail

Garlic mustard – First year plants near the North Horse Trail

 

One the principal chemicals released by the garlic mustard is allyl isothiocyanate. This chemical is released into the soil, and is toxic to the fungi located in the soil. Interestingly enough, in garlic mustard’s native Europe, the soil fungi are resistant to the garlic mustard’s chemical. Apparently our native fungi haven’t developed that resistance yet.

 

And sometimes life gets complicated!

There are a few fungi which have a lifestyle which is one of the most complicated of any organism on earth. These are called “heteroecious rust fungi.” These fungi are plant diseases. Their unique characteristic is that they need to use two species of plants to complete their life cycle. One of these fungal species that we may have at TCSNA is the “common fir-bracken rust” (Uredinopsis pteridis). This fungi spends part of its life cycle growing on bracken fern (Pteridium aquilinum) and the other part on grand fir.

 

Left: Bracken fern near TCSNA bike path. Right: Needles and cones of grand fir near Cedar Trail

Left: Bracken fern near TCSNA bike path. Right: Needles and cones of grand fir near Cedar Trail

 

I have no proof that we have this disease at TCSNA, but since we have both hosts here, it is a distinct possibility. Furthermore, this fungus sequentially produces not one, not two, but five different kinds of spores during its life cycle. Of the different spore types, some are produced only on the fern, and the others are produced only on the grand fir. Frankly, this complicated a life cycle boggles my mind. The two questions that plague me are: 1) How did this complicated life cycle ever get started? and 2) What conceivable advantage is there to the fungi in needing two hosts? The answers have eluded me.

 

The fungal internet

Human’s internet is a johnny-come-lately compared to the “internet” that fungi developed long ago. Strands of fungus often connect the root systems of two trees in the forest. The trees don’t even have to be the same species. The overall results is that fungi of one species or another, connect almost all the trees in the forest. Something like this:

photo-10

 

It appears that fungi connect nearly every tree in the forest with other trees. While there is clear evidence that some small amount of sugars are passed from tree to tree, this fungal internet may have a far more interesting function.

Two different studies have found that plants apparently transfer “information” from one to another via their interconnecting fungi. In one study, some plants were deliberately infected with a fungal disease (not one that creates mycorrhizae). Researchers found that if a neighboring uninfected plant was connected via mycelium to the infected plant, it was dramatically less likely to catch the disease, than if the uninfected plant was NOT connected to an infected plant. It appeared that the mycelium was passing along a message that said, “Hey this disease is coming around, better get ready to resist!”

In a second study, the same basic effect was found when one plant was infected with aphids. The uninfected plants appear to get some signal through the mycelium from the infected plants, and its anti-aphid defenses kicked into gear before they were actually attacked by the aphids.

 

Fascinating Fungi

As you can see, the fungi of TCSNA are themselves complex and terrifically creative organisms. They play many important roles in our forest, by decomposing organic matter, acting as diseases, and forming mutually beneficial relationships with other organisms. They are the hidden partners in making our park a great place to enjoy nature.

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