This lesson focuses on the factors that determine the location of the treeline in different locations in the world. The elevation of treeline is affected by the combined effects of snowpack depth, minimum winter temperatures, aspect, and soil moisture conditions. Treeline varies by latitude, but is also affected by whether it is an arid, temperate, or tropical climate. In addition, in arid regions, aspect and elevation affects soil moisture conditions and determines where the transition from desert to forest occurs on sky islands. In addition, human impacts such as grazing and fires can impact the elevation of treeline.
Review the Essential Question. Introduce the guiding Question.
Students should take a few minutes to respond to the first reflection prompts. Discuss their answers and any questions they've generated.
Hand out the second Reflection Journal Page. Give students time for a final reflection on the lesson.