Catlin Gabel 7th Graders Share Their Results

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(Editor’s Note – The Hyla Woods Team is thrilled to have an ongoing partnership with the 7th grade students and faculty from Catlin Gabel School in Portland.  Each year, with the excellent leadership of their teacher, Jesse Lowes, and other adults, the students do important and useful scientific investigations in the forests.  The report below is just one of the many summary reports that the students have produced.  The class cooperatively made the decision that Hannah’s report would be shared.  We thank all involved for their hard and careful work.)


Into the Woods – A Report on a Scientific Investigation:

By Hannah Renee Langer

It was drizzling. The skies looked overcast and positively cranky, clouds bumbling about and bumping against each other grumpily. We all stood underneath the awning outside of the gym, bundled up in rain jackets. Though the benefits of tromping in the soggy forest for hours may not have been immediately discernible, we all knew that the environment – and us, to a certain extent – would greatly profit from our hard work and the extensive evaluation we did on the water quality of a little creek in the Coast Range.


We, one of the four science classes that make up 65 students total, were about to board a school bus to leave for Hyla Woods, an experimental forest plopped down right in the middle of Oregon. Tall trees of all different sorts reached towards the sky, awe-inducing, like decorated church spires. The moment I stepped off the bus and took a deep lungful of the crisp autumn air, I knew this environment was nothing like the one I was living in. Hyla Woods had a certain quality about it that made everything about it seem even more enchanting: the assorted bird calls that echoed throughout the treetops mournfully, the feeling of a soft pad of moss underneath the sole of my rubber boots, and the simple quiet of the place. Almost immediately after arriving, we all stood in a circle, closed our eyes, and simply focused on the noises of the forest. Instead of hearing construction, cars whirring by, and the busy hubbub of the city that we had just tuned out and accepted as everyday white noise, we were exposed to a magical forest almost out of a storybook where birds gossiped, a distant creek burbled, and stray raindrops hit the ground, twirling and falling helplessly from the verdant boughs of nearby trees and rich vegetation.

At this forest, we tracked the question “How can we tell if an ecosystem is healthy?” and did so by investigating the stream that sauntered through the forest, Louisignont Creek. We completed many tests on the water quality of the stream, including an inventory of the organisms that were folded inside of the stray leaf packs that were scattered and rooted in the silt. Though I wasn’t used to getting mud everywhere (everywhere, I tell you!) and shielding myself from the drizzling rain for hours on end, while I was there, in the moment, I felt like I was completing important work – and I was!

This important work was completed over two days in October and November. To ensure that our evidence and findings were meaningful, there were 12 research sites in total that different groups worked at along the bank of the creek. Our topic question, how can we tell if an ecosystem is healthy?, is very important because we live in one! It’s very important to know how to tell whether an ecosystem is healthy or not, and how to improve and measure that health, because this information is necessary in order to take care of the big, wet rocky sphere we inhabit.


While visiting Hyla Woods, we conducted tests on the creek that bubbled through the woods. We tested the temperature of the water, as well as the pH of the water, the amount of dissolved oxygen (DO) in the water, and the turbidity (cloudiness) of the water. A good water temperature for Northwest aquatic life is 5-15 degrees Celsius, and the class of 2020 tested the water to be 11 degrees, which is perfect! The air temperature was also around 11 degrees Celsius that day. If the water temperature was too hot, some organisms would not be able to thrive in the environment, and it’d throw the whole food web out of whack! The optimal pH range is 6.5-8.3, and our class measured the pH to be 6.7 (the average from 12 research sites over two days), which means there’s a healthy pH value in the stream. If the pH value weren’t in this optimal range, however, it may impair the vision of fish or prevent fish eggs from hatching. The DO (dissolved oxygen) range that is most suitable for Northwest aquatic life is at least 8-12 ppm (parts per million), and our class measured the DO to be 9.1 ppm, suggesting that the stream is right in the ‘healthy’ range. If the DO was lower, the water may not be suitable to the organisms, because they may not be able to breathe in water with less dissolved oxygen. Finally, our class measured the turbidity (cloudiness) of the water to be 10 NTUs (Nephelometric Turbidity Units), which is healthy! To find this information, we filled a tube with water from the creek until we couldn’t see the bottom anymore. Many groups kept filling it until it overflowed, and they were still able to see the bottom of the tube, meaning the water was very clear. 10 NTUs means that the water isn’t so cloudy that it disrupts the organisms or their homes.


After testing the water, we planted an artificial leaf pack. Leaf packs are natural clumps of leaves that form in streams and act as perfect homes for assorted aquatic macroinvertebrates, tiny little creatures that dwell in ecosystems like the stream we investigated at Hyla woods. Some examples of these are caddisflies, midges, and aquatic sow bugs. Based on how sensitive the organisms we discovered living in our leaf packs were, we could then determine whether or not the ecosystem was healthy. For example, if many sensitive macroinvertebrates like alderflies and mayflies are living in the stream and thriving, it means the stream is healthy. But, if there are many tolerant species living in the leaf packs like leeches or midges and not many sensitive species, it means the stream is somewhat or very unhealthy. To efficiently measure the amount of sensitive and tolerant species living in our leaf packs, we plugged the species we discovered at all twelve sites into an equation and came out with a number, the Biotic Index, that we could then use to judge the healthiness of the stream. Our class average for the Biotic Index was 3.76. This data comes from the artificial leaf packs we placed, but some leaf packs were either lost or compromised. This means the water quality was good (nearly excellent) because the range for excellent water quality is 3.75 or more.


From what I’ve learned, I’ve come to the conclusion that a healthy ecosystem is an ecosystem that is balanced and thriving. A healthy ecosystem should be filled with many different organisms that work together synergistically to support their environment. In class, we studied food webs, which perfectly sums up invertebrates in an environment and how they all connect and help each other out. We also interviewed different people in our lives outside of school, asking them about what they considered a healthy ecosystem to be. My mom pointed out the fact that an ecosystem should be rooted and connected, sometimes so much so that when one piece falls from the puzzle, the whole construction collapses. Ecosystems should be tightly woven, like a quilt made up of a wide plethora of different kinds of organisms. After completing many tests on the water quality and examining the organisms that live in the Louisignont creek, this year’s Catlin Gabel 7th graders have come to the conclusion that Hyla Woods continues to be a healthy, thriving ecosystem.