Mother Nature: Master Recycler
By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester
Recycling has become a “big deal” for humans in the years since I was born! As a kid, I remember burning newspapers in the burn-barrel by our garden, and throwing a massive number of tin cans in the garbage which doubtless wound up in some landfill. Now, the Oregon Department of Environmental Quality (DEQ) proudly reports that in 2013, Oregonians recycled 53.9% of our post-consumer waste. Nice try, but we don’t even come close to Mother Nature’s record of recycling: 100%!
Here at Tryon Creek State Natural Area (TCSNA) the forest constantly recycles biomass like leaves, logs and dead animals. Sometimes it’s fast, and sometimes it’s slow, but it’s always thorough!
We need look no further than some of the TCSNA’s old logs and stumps to see that sometimes recycling takes quite a while. This rotting log is approximately 18” in diameter. It is on the side of Old Main Trail and hasn’t changed much in the last 5 years, and I don’t expect it to completely disintegrate any time soon. In fact, research foresters report that fallen Douglas-fir (Pseudotsuga menziesii) logs sometimes take almost 200 years to completely decay!
But other stuff “recycles” faster, doesn’t it?
Absolutely! In order to see how fast things are recycling (“decaying”) at TCSNA, I set up a small study. Scientists who want to study recycling in the forest often use things called “litter bags.” (The term “litter” here refers to the fallen leaves, twigs and branches on the ground, not to candy wrappers and used Kleenex!) I collected the plant material for this study off the ground, so this material was ready to start decaying.
I cut square pieces of window screen to make my bags. I placed the plant material on half of each piece of screen, and then folded the other half over the top, and stapled it shut. I fastened each bag to the ground using four big nails, one in each corner. I set up the bags in an area of TCSNA where they wouldn’t be disturbed. I put out some bags on September 11 and others on September 13, 2014.
In each bag, I put one of five things; Alder (Alnus rubra) leaves, bigleaf maple (Acer macrophyllum) leaves, western redcedar (Thuja plicata) twigs with their green scaly leaves, Douglas-fir twigs with needles, and finally, the scales from a Douglas-fir cone. I had two bags of each type of material. Then I fastened the bags to the ground.
So what happened?
This is what it looked like on September 13, 2014, after the full study was installed. You can see some of the green leaves inside the bags.
I took pictures of every bag each month. When I took pictures I brushed off the top of the bag, loosened two of the nails holding it to the ground, and slipped a piece of white plastic underneath the bag to provide contrast to the material inside the bag. I refastened the bags and replaced the litter following each photo. Below are some highlights.
By October 3, 2014 some natural forest litter had fallen on the bags. This is totally realistic. There were times when the litter bags were almost completely covered with natural litter from the trees.
Having the litter inside bags did create a certain amount of unrealism. This point was made dramatically during my March 2015 visit to the litter bags, when the little critter pictured below was crawling over them. To the extent that snails might accelerate litter decomposition, my study was only an approximation of reality.
So let’s see the decay process!
The decay rates for the samples in my litter bags varied a lot between species, and sometimes between particular leaves of the same species.
The alder leaves decayed dramatically over the course of a year. After 79 days, the leaves had lost their color, but had only just started to disintegrate. By the end of March, the leaf in the upper half of the photos was pretty much reduced to the mid-rib (the tough “vein” going from the base of the leaf right through to the tip) and the lateral veins. In contrast, the leaf in the lower right hand corner still had a lot of the leaf blade left.
Once again, the maple leaves were significantly decayed after the first year, but the petiole (the stalk that attaches the leaf to the branch) being more “woody” than the leaf blade is still largely intact.
Western redcedar is loaded with hydrocarbon molecules that impart decay resistance. The most amazing thing was that in November 2015, after more than two months on the ground, most of the redcedar branch was still green! (Confession time: The other redcedar branch had turned completely brown at this point.) After over a year on the forest floor, this branch, and its needles, was still largely intact.
Unlike the alder and maple samples, this bag includes the woody twig in addition to the foliage. The Douglas-fir twig rapidly shed all its needles, producing an un-photogenic combination of a bare twig, and clumps of dead needles. The slight movement of the bags in preparation for taking photos is what caused the needles to gather in clumps. The needles, though brown and scattered, are individually maintaining their structural integrity. As with the western redcedar discussed earlier, the presence of hydrocarbon molecules in the needles and stem are helping resist decay.
Douglas-fir cone scales
The Douglas-fir cone scales are tough and woody. To tell the story of their decay in the first year, we only need two photos. In the 12+ months in the litter bag, there was no perceptible change in the Douglas-fir cone scales, except they are now slightly darker! Again, shifting the bag for photos results in shifting the scales around within the bag.
The Cycle: Life > Death > Life
As organic matter decays, important chemicals like nitrogen and phosphorus are slowly released to soil for growing plants. The partially decayed organic matter in the soil dramatically increases its moisture holding capacity, and water infiltration rates, among other things. Better than most of us, Mother Nature knows that the rotting leaves and stems of today are the key to the towering trees of tomorrow! Without recycling, there would be no forest as we know it.
Energizing the Forest
By Bruce Rottink, Volunteer Nature Guide and Retired Research Forester
Every living thing needs energy. Plants and some microorganisms use the process of photosynthesis to directly capture the energy of sunlight to meet this need. These organisms are called autotrophs, meaning “self-feeders.” Almost all other organisms rely on “eating” energy-containing organic matter produced by the autotrophs (see a previous Naturalist’s Note, “What’s the Yucky Stuff in the Creek” to read about one exception). These creatures are called heterotrophs, which roughly means “feeding on others.” Heterotrophs might eat autotrophs or other heterotrophs.
How does the energy move through the forest?
Ecologists have long been interested in studying how energy flows through the whole complex of autotrophs and heterotrophs in the forest. In “the old days” we were taught about food chains. In a food chain, trees captured the energy of the sun, and produced seeds, squirrels ate the seeds, and then hawks ate the squirrels. That’s correct as far as it goes, but is a bit too linear. Scientists now advocate a concept they call a “food web.” It’s pretty much the same idea, but recognizes that lots of heterotrophs have a varied diet and that a linear chain is too simplistic. For example, a tree produces seeds and a thimbleberry produces leaves. The seeds are eaten by squirrels. The leaves are eaten by insects. Birds eat the insects, and owls eat both the birds and the squirrels. For simplicity, in this posting I’ll stick with the food chain concept.
Each organism is the source of energy for the next organism up the food chain. However, there is one big factor to consider. Every organism uses up a certain amount of the energy it acquires to perform vital functions which might include staying warm or moving around. This “maintenance” energy is being used, or lost, at every level in the food chain. Thus, there is more energy available to the insects eating the plants than there is to birds eating the insects.
What effect does this maintenance energy loss have?
The most obvious effect of energy loss at each level in the food chain is that there is “more” of the organisms at the lower level of the food chain than at the upper level. Let’s look at a simple food chain at Tryon Creek State Natural Area (TCSNA). For this example I’ll use the chain of plant-worm-mole-owl.
At the very bottom, think of it as the “foundation,” are plants, which capture solar energy to make sugar. One example at TCSNA is the vine maple shown below.
The next step is the earthworms, pictured below, which feed on dead plant matter.
The next step in our example is a mole, which eats the earthworms.
The next link in the chain is an owl. This owl’s ready for a nice mole dinner!
To recap, our sample food chain is: plants capture energy from the sun, worms eat dead plant material, moles eat worms and owls eat moles. Owls are an example of what’s called an “apex predator,” meaning it is at the top of the food chain.
When you start thinking about food chains, you might develop a different perspective about the creatures you see in the forest. When you think of owls as eating moles you might view them differently. Take the great horned owl in the photo below:
Click on the owl’s picture to reveal a different perspective on owls.
An owl is just earthworms which have been reconfigured to fly.
How does the “maintenance energy” loss effect the food chain?
As mentioned above, each link in the food chain uses up some of the energy it captures just to stay alive. So each link up the food chain contains less biomass (weight) than the link just below it. It is useful to think in terms of biomass per unit area of land. For this discussion, the area of land is TCSNA.
Based on recent TCSNA citizen science project owl numbers (thanks to Matthew Collins), and the estimates of weights of the different species, there are approximately 20 lbs. of owls living at TCSNA.
They are represented by this red square with an area of 1 square inch.
Biomass numbers for some of the forest organisms aren’t easy to come by. Apparently everyone figures they had something better to do than find out how many pounds of moles there are in an acre of forest. So instead of moles, I’ll use some biomass numbers for mice found in a study at the H. J. Andrews Experimental Forest near Corvallis. Owls eat mice, and other things, as well as moles.
Using the same scale as the red square for the owls, the weight of mice at TCSNA is estimated at 506 lbs. It is represented by the gray square below. One caution should be noted. The biomass numbers always represent just one point in time (“the standing crop” in ecology-speak). In reality, these mice are constantly having babies and some of the babies and adults are constantly being eaten. Therefore, over the course of the year, the heterotrophs of TCSNA probably have the opportunity to eat a lot more than 506 lbs. of mice.
Numbers for the standing crop of worms that I could find were so wildly variable, that I decided to skip those.
Extrapolating from plant biomass data collected at several Pacific Northwest forests, there are approximately 197 million lbs. of trees and shrubs at TCSNA. Using the same scale as for the owls and mice, this would be a square approximately the area of 6 or 7 average city lots. Think about cutting out the 1 inch red square representing owls, and laying it out on your front yard, and comparing the size of that red square to the sum total of the sizes of your lot, your neighbor’s lots on both sides, and the three lots across the street. When comparing the biomass of the plants to the biomass of the owls, owls almost don’t exist.
But owls are the top of the food chain, right?
As I said before, owls are considered to be an apex predator in our forest. In an area the size of TCSNA they would provide very little food for the next link up the chain. In order for a predator to survive by eating owls, it would have to cover a huge territory to get enough food. Think of a good size hawk hunting over a big chunk of the Willamette Valley!
But there’s another option!
We’ve probably all watched too many movies of lions killing gazelles on the plains of Africa. This has created a sense of “prey” and “predator” that has limited usefulness when we think about the flow of energy in an ecosystem. Rather than think about a large owl-eating predator that covers huge areas, let’s look at an alternative.
Since there are only enough owls to support a small weight of the next level up the food chain, what if the organisms at the next level of the food chain were really small? When scientists studied owls in northern Idaho, they found something very interesting!
Click on the blood drop below to find out what the scientists discovered.
Owl’s blood containing red blood cells AND blood parasites (the horned demons)
That’s right, blood parasites were found in more than half of the northern saw-whet owls (a species we have at TCSNA). The parasites were getting energy from the owl’s blood. This isn’t the traditional view of “eating” something, but for energy flow purposes, it’s the same thing. The biomass of the blood parasites that are probably in owls at TCSNA is incredibly small, which fits into the pattern we have seen so far in the food chain. I am reluctant to declare that the blood parasites are the final link in the energy flow of our forest. However I will stop here, you get the idea!
All organisms in the forest need energy. As you can see, Mother Nature has been very creative in developing a variety of ways in which energy flows through our ecosystem. Enjoy the many manifestations of that energy as you, a child of the sun, hike through TCSNA.
Mother Nature’s Mistakes: Trilliums, Quadliums, and More
By Bruce Rottink, Volunteer Nature Guide
Have you ever had a day, when you were so tired, that you started making mistakes? When you look around, and see some of Mother Nature’s mistakes, you begin to wonder if maybe she gets tired too.
At Tryon Creek State Natural Area you can see many of Mother Nature’s mistakes. Everyone knows, for example, that trilliums (Trillium ovatum) have three petals, like the picture below. That’s why they’re called trilliums; the “tri” stands for “three.”
But when you pay attention, you see that every now and then there is a trillium that doesn’t quite follow the rules, like this trillium I found on Middle Creek Trail. Four petals! So is it a quadlium?
Not only does it have 4 petals, it has four leaves too!
As if that’s not weird enough…
Take a close look at the number of stamens (those long fuzzy yellow things that make the pollen) and the number of styles (the white things in the very center that look like tiny, curved octopus arms, which are female parts of the trillium). A normal trillium has six stamens and three styles, but not this one!
Curiouser and curiouser
How about this trillium (pictured below) that popped up along Old Main trail a couple of years ago with two conjoined ovaries; six stamens and six styles, instead of the normal three styles.
It doesn’t end there
Later on in the season, this flower produced a conjoined pair of seed capsules.
Compare the normal seed capsule on the left to the capsule which developed from the two conjoined ovaries on the right.
Any guesses as to why?
These “mistakes” aren’t necessarily genetic mutations, but might be just developmental anomalies. Developmental anomalies are the result of abnormal things that happened during plant development. The anomalies can be the result of a variety of environmental factors, like water stress or cold shock, or even an infection with certain types of bacteria or plant viruses.
And more…maple mishaps
Mother Nature’s mistakes aren’t limited to trilliums. Normally, the seed of the bigleaf maple (Acer macrophyllum) is born in pairs, as you see in the picture on the left.
However, on occasion, the seeds will be produced as triplets, as you see on the right.
1 in 500
During a recent check at Tryon Creek, I found that slightly less than 1 in 500 maple fruits was a triplet. All the rest were double-seeded. However, keep your eyes open; years ago in the Oregon coast range, I found a bigleaf maple fruit consisting of 7 seeds all joined together.
These oddities are interesting of course, but can they do more than just gratify our idle curiosity?
Yes! As Francois Jacob, winner of the 1965 Nobel Prize in Physiology or Medicine said,
“One of the most effective ways of determining the normal mechanisms of the cell is to explore abnormalities in suitably selected monsters.”
By “monsters” of course he meant abnormal specimens. For example, if we only looked at normal trilliums, or even the four-petaled trillium, we might conclude that there was some process in the plant which ensured that there were always twice as many stamens as styles. However a single glance at the trillium with conjoined ovaries shows that isn’t true.
So if you think you’ve “seen it all” at Tryon Creek, just keep your eyes open for more of Mother Nature’s “mistakes.” They open up a whole new world of wonder.