7. Habitat Survey - Background

Teacher Background
Most of us are familiar with the threats to ecosystems such as rainforests, wetlands, and oceans. Naturally, anything that is a concern on a large scale such as global warming or clear cutting should be studied and researched. However, many organisms do not use an entire ecosystem. Most live in a relatively tiny portion of a larger ecosystem, a microhabitat. In fact many organisms spend their entire lives within a 1 meter square area. It is essential to recognize that organisms do not need an entire ecosystem to be damaged to find that their little microhabitat has been destroyed.

I believe that science skills such as water quality monitoring or soil analysis are of little interest to students unless these skills are applied in the real world to real problems that may not have ready-made solutions. Therefore, after teaching them how to make observations and analyze soil samples in the classroom, I take my students to apply these skills to a real world problem – invasive English ivy that has taken over the bank of a nearby creek. This problem gives students an opportunity to carefully monitor a microhabitat, recognize that ecology happens on a small scale (as well as a larger scale) that an individual person can make a difference on, and create a plan of action to help their microhabitat.

Invasive species are organisms that not only are non-native, but which take over a habitat and out-compete the native organisms. There are many examples of invasive species. Each has a story about where the invasive species came from, how it got to the area, and what adaptations allow this species to out-compete the native species that typically occupy that niche of the food web. English ivy is just one example. It was brought over to America by Europeans who decorated their houses and gardens with this robust, fast-growing vine. In Europe, ivy does not out-compete the plants in the local ecosystems, however, in California, ivy will quickly invade and cover large areas to the exclusion of all other plants.

For middle school students, it is important to draw the distinction between non-native species and invasive species. Not all non-natives are “bad”. One can think of it like diversity in a community of people. Newcomers to a community are welcome and bring new points of view and new ways of doing things. However, if a small group of newcomers start killing off all of the “natives” by crowding them out and taking all the resources then those newcomers are no longer welcome.

This activity plays a role in that the microhabitat survey allows students to observe that there is an extreme difference between those students who have a microhabitat in the ivy covered area and those who have a microhabitat elsewhere along the creek bank. They observe first hand how ivy is invasive and can come to the definition of a native species, non-native species, and invasive species through their own observations. We then decide upon an action plan to restore the ivy area to a more native state and begin our restoration activities. At the end of the year we repeated the microhabitat survey to see how well we did with our goals.

Depending on the message you wish to convey with your own students, the focus of this investigation will vary. I chose to assign half the students sites in the ivy area that we plan to restore and the other half sites in a previously restored area. Other ideas include investigating shaded versus sunny microhabitats, schoolyard versus garden habitats, organic versus fertilized garden habitats, and virtually any other comparison you can imagine.

Student Prerequisites
Soil analysis skills (see Soil Analysis Lesson).
Basic understanding of habitats and ecosystems (see Terraqua Columns, Food Chains, Food Webs, and Ecosystem Organization Lessons).
Ability to use a field guide (see Food Webs Lesson).