Chapter 12. Chapter 12: Grasslands

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Guiding Question 12.3

How do overgrazing and undergrazing affect grasslands?

Why You Should Care

There can be both too much and too little of a good thing, especially with grasslands. The grasses that form grasslands are often stimulated to grow by various forms of damage, like fire and grazing, but too much of this damage will kill them. When overgrazing kills grass, there is no longer an anchor for the soil and it is more likely to erode or simply blow away. Grasslands that are degraded this way are difficult to regenerate because of the compromised soil. Grazing animals aren’t just eating grass, however; they are also eating tree and shrub seedlings that would otherwise colonize the grassland and convert it to forest. Not only does woody vegetation overshadow grass, remove animal habitat, and alter the structure of the soil, but it also serves as extra fuel for fires. Short and dense or thicket-like woody vegetation burns hotter and longer than grasses, so fires in grasslands that have been undergrazed often cause much more damage to the ecosystem and surrounding human property.

Infographic 12.2: Desertification

1.

The continents with the most area under a very high threat of desertification are:

A.
B.
C.
D.
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How does overgrazing compare to natural grazing? Arrange the blocks below in the proper order.

4.

Desertification always happens in response to grazing when:

A.
B.
C.
D.
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Correct.
Incorrect.

7.

Thought Question: How could the grazing regimen portrayed above be altered to prevent the palatable grasses from dying out?
The best strategy would be to leave animals in the grazed area long enough to eat the palatable grass and then have to resort to eating the weeds. Care would have to be taken not to force the animals to overgraze, however, since that would lead to a die-off of most plants, the loss of their roots to stabilize the soil, and the inability to grow back much of anything for the animals to eat.

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