Ecosystem ecologists define nutrients as biologically important elements (e.g., C, N. P, S). Nutrients can cycle either within ecosystems or globally
Nitrogen Cycle
We will consider a very simple example of the nitrogen cycle to illustrate how nutrients cycle within an ecosystem (ie., nutrient cycle within a prairie in Kansas or within a rainforest in Brazil).
Plants pick up nitrogen from the soil, herbivores get their nitrogen from eating plants, and carnivores get their nitrogen by eating herbivores. When organisms die there is nitrogen held in their dead bodies. Decomposers get their nitrogen from dead bodies and return nitrogen to the soil where it can be picked up by plants. Thus, it is possible for the same atom of nitrogen to recylce through the ecosystem over and over.
Ecosystem ecologists are interested in understanding how much nitrogen is found in plants, animals, soil, etc. and the rate at which nitrogen moves from one place to another.
What factors can influence the movement of nitrogen through and ecosystem and why is this important? Decomposers are responsible for moving nitrogen from dead bodies of organisms to the soil. The major decomposers, fungi and bacteria, thrive in warm and wet environments. Thus, we might expect the rates of decomposition in tropical rainforests to be much faster than in the desert. Thus, nutrients in dead bodies are quickly returned to the soil in tropical rainforests where they are quickly picked up by plants. Alternatively, the slow rate of decomposition can tie up nitrogen in dead bodies of plants so that nitrogen is not available for plant growth.
Expected Learning Outcomes
At the end of this course a fully engaged student should be able to
- diagram the nitrogen cycle within an ecosystem and explain how the rate of movement from one reservoir to the next can vary between environments (TEKS 112.43. 12A & 12E).
-develop curricular material to illustrate nitrogen cycling withing a chosen environment (TEKS 112.43. 12A & 12E).
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