Ecological studies are often conducted in a field environment that poses different challenges than a lab environment. To begin studying different variables that affect an ecosystem, students will need to understand some of the basic relationships and processes in that ecosystem. While the specific relationships and processes vary from ecosystem to ecosystem, the general types of ecological relationships are similar from ecosystem to ecosystem. For example, students will need to learn about the variety of predator and prey relationships in an ecosystem. They will need to understand the annual climatic patterns of the area and the ways in which plants and animals have adapted to these patterns. They will need to understand how the particular ecosystem that they are studying tends to change over time.
After they pinpoint some of the main ecological relationships and processes in the ecosystem, students will be ready to create hypotheses that can be tested. Help the students create hypotheses that are specific and testable. Ecological field studies often need to occur over time frames that do not suit a school term. Choose ecological processes that occur in the short term in the field or are replicable in a lab setting. These might include cold temperatures, wet soil and other abiotic factors.
The change in predator-prey relationships and population numbers is something a student can examine over a school term in a lab or field setting, especially if the predators and prey are small and easy to find. For example, students could hypothesize that a change in oxygen levels would impact the population of invertebrates in a small stream. After testing this hypothesis as the days get warmer and oxygen becomes more scarce, students can then test another hypothesis. They can determine whether the relative abundance of prey impacts the population numbers of larger predators such as fish and frogs.
Studying the changes in an ecosystem over the course of a season or two is another project suited to a school term. The ecological changes that occur as fall changes to winter or winter changes to spring are profound for the animals that live through them. This field study also provides students with an opportunity to discover how changes in climate could affect animal or plant populations. Students can hypothesize about what will happen to the behavior of a particular animal as the weather gets colder or warmer. They can observe the animal population in a particular area as the temperature changes during the year and report on their observations. To create an experiment on warm or cold temperatures in a lab setting, observe the effects of temperature on plants kept in very warm or very cold indoor spaces.
Water flow also affects an ecosystem. If there is a season that is particularly rainy in your area, it will provide a good opportunity for students to undertake a lab based on water flow and plants. Students can observe the health of the plants when the ground is dry or moist, then they can observe different health indicators of the plants when the ground is saturated. They can hypothesize how rainfall impacts particular plants in the ecosystem.