We’ve been pleased to have several groups of students – ranging from 2nd graders to university students – doing serious investigations in the forests this year.
Below is the first of two reports presented by the 7th grade scientists from Catlin Gabel School. We thank them for their good work and encourage you to learn from their findings.
Sydney N’s Report:
The essential question for the Ecology unit was: “How can we tell if an ecosystem is healthy?” I can tell if an ecosystem is healthy by testing the chemistry, animals, and plants of the ecosystem for their health. For example, if the ecosystem was an aquatic ecosystem, I would take water samples, temperatures, and plant and animal samples. I would know the ecosystem was healthy if the chemistry and organisms were healthy. However, there are many more factors that come into play with determining an ecosystem’s health. A healthy, working food chain would be an example of another component of a healthy ecosystem. If the food chain isn’t working properly, there wouldn’t be a diversity of organisms, and some species in that ecosystem could become endangered or extinct.
At Hyla Woods, our group tested site E of Lousignout Creek. We decided to split up the work in order to get all of the requirements finished on time. While a couple of us worked on writing the habitat description, sketching the surroundings, and performing air and water tests, like D.O., pH, temperature, and turbidity, the rest of the group searched for leaves and made the leaf pack for Benthic Macroinvertebrates to live, so we could determine the EPT rating and stream health. Our greatest challenge was the weather because the snow and wind made testing difficult and water levels would rise and fall because of the melting snow.
Habitat Analysis of the First Trip:
Stream habits present logs, wetlands, woody debris, leaves, and aquatic vegetation. The appearance of the water was clear with an oily sheen. Human modification of the site was displayed by a pile of logs that resembled a beaver dam. Evidence of erosion on the left and right banks was less than 20%. The percent of streambank vegetation was less than 20% on the left bank and between 20-50% on the right bank. The stream bottom was mainly composed of sediment, gravel, and cobble. Grasses, trees, and shrubs, were observed along the left bank and the trees were mostly deciduous. Along the right bank there were trees and shrubs and the trees were mainly evergreen. The land-use within 1/4 mile upstream and adjacent to our site was mainly forest. Impervious surfaces occupied less than 20% of the site. There was no presence of litter in the stream. The average width of the stream was about four meters.
Based on our observations and tests, I conclude that Lousignout Creek is a healthy ecosystem. The water tests and EPT ratings present that the animals living in the stream are healthy. The range of a healthy pH is between 6.5 and 8.3, and the average pH of the creek was about 6.8. A healthy range of D.O. is 8-12ppm, and at Hyla Woods, the average D.O. was 10ppm. About 5˚C-13˚C is a healthy water temperature range for most aquatic invertebrates, and the range in temperature for Hyla Woods was from 2˚C-7˚C (because of the snow). The water in Lousignout Creek was not turbid. The turbidity ranged from 117cm-≥190cm, which meant the water was clear and there was very little stirred-up sediment. All of these factors led me to conclude that Lousignout Creek is a healthy ecosystem.