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Students Measure Growth Trends in the School Woods
The need to sustainably manage our global natural resources has never been greater. According to the UN Department of Economic and Social Affairs (2017), the human population is expected to increase from 7.4 billion to an estimated 11 bfflion by 2100. Yet, the Earth lost about 29.4 million hectares of forest in 2017 (Hansen et al. 2013), a trend that is not only unsustainable but also contributes to climate change because healthy forests are one of the planet's primary engines for removing carbon from the atmosphere (Canadell and Raupach 2008).
This unit teaches students about the value of sustainable forest management. First, students go into a sugar maple stand to measure the diameter of trees greater than 10 cm (4 in.) across (Figure 1, p. 86). To measure the main trunk of the tree, or stem, students wrap diameter tape around the tree 1.3 m (4.5 ft.) from the ground and read in inches to 1/100th of an inch. (For an excellent description of this process, see the July 2018 Science Scope article by Mann, Petrosino, and Jenevein, titled "Where Does a Tree Get Its Mass?") Then, students take these data to their computer technology class, where they calculate its basal area (the amount of tree stems, typically measured in square feet per acre). They proceed to combine their findings with data collected in previous years and review harvest methodologies. For more information about each lesson covered in this unit, see Figure 2, P. 87.
Ultimately, students will determine when and how the sugar maples should be harvested using established management practices they learn in other lessons, which address wildlife, climate change, and silviculture (the growing and cultivation of trees). In the case of a sugar maple stand, the best approach is an uneven-aged management plan, which removes mature and undesired trees as the forest grows (Neumann 2015). When their 10 acres are ready to harvest, my students will present their findings to the governing boards of our township and school district. Everybody wins: The community and the schools get a great management plan, the sugar maple forest is managed sustainably, and the wildlife and watershed are protected. Most importantly, my students develop a deep understanding...
