Grazing Investigation

We know that grasses survive continuous grazing by cows, or buffalo, or zebras. Take some time to speculate about this. What features of grasses make it possible for grasslands to support large herds of grazers? Why doesn't the grass run out in the face of such heavy grazing pressures?

Think about grazing in terms of our two familiar questions:

• What kinds of (environmental) pressures do we think that grazers might impose on grasses?

• What would we expect from grasses in terms of being adapted to this kind of pressure?

In this investigation, you employ modeling, an investigative technique often used by scientists. You will model or simulate grazing by using scissors to "graze" your plants.

But first, think about what kind of grazer you want to model—for example, a cow, an antelope, a buffalo. What grazing action does this animal use? What effect will it have on the grass as it grazes? How far down will it bite?

Use these questions to decide where and how to cut your plants, then cut the radish and grass in your grazing planting.

During the rest of the week, spend a few minutes each day to observe the plants closely with the magnifying glass. What patterns do you see as the plants regrow? For example, where does new growth occur? Do the cut leaves change with time? What happens to the damaged edges?

Optional, yet encouraged—if you do several observational drawings periodically over the course of the week, you may be rewarded with more nuanced insights about grazing!

In your journal:

• Make an annotated drawing to show exactly where you cut the plants, and why.

• Predict what will happen to both the grass and the radish plants. Will the plants grow back? If so, how? Justify your prediction in terms of what you know now about adaptation.

• Record your observations.