Animal Angles: Frogs' Friends

Frogs have amphibian classmates—Eastern red-backed salamanders (Plethodon cinereus)—whose eating habits help them, and perhaps us too, to survive.

The bad news is that Eastern red-backed salamanders are also threatened, like frogs, by acid rain and global warming. Like all Plethodons, they live on land, have no lungs, and breathe through moist skin. Acid rain lowers the sodium content of soil, making it harder for the red-backed salamanders to get the amount of sodium they need to survive. With less sodium, these salamanders excrete water so that they can maintain the right sodium-to-water ratio in their bodies. That dries their skin and makes it harder for oxygen to pass through. Global warming also dries out the soil, making it still harder for them to breathe.

The good news is that Eastern red-backed salamanders eat leaf-fragmenting animals, such as beetles. Leaf fragmenters break leaves into smaller bits, making it easier—with the help of fungi and bacteria—for the leaves to decompose and release carbon into the air as carbon dioxide, a greenhouse gas. Leaf fragmenters also eat the nitrogen-rich parts of leaves. By eating leaf fragmenters, Eastern red-backed salamanders slow the leaf decomposition process and help to keep nitrogen on the forest floor, too.

More good news: Eastern red-backed salamanders are still the most abundant terrestrial vertebrates in the northeastern United States. They thrive in forests over 80 years old. According to Richard Wyman, who studies them at the E.N. Huyck Preserve in Rensselaerville, NY, there are 18 billion red-backed salamanders in New York State alone. Dr. Wyman estimates that they keep 400 million tons of carbon on New York's forest floors every year!


The decaying or rotting of something.

To discharge from the blood, tissues, or organs.

greenhouse gas:
Any of the atmospheric gases that contribute to the greenhouse effect.

Living or growing on land.

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  1. What effect does acid rain have on the pH of soil? How does this change affect the red-backed salamander?
    [anno: Acid rain makes soil more acidic and lowers the soil's sodium content. When this happens, the red-backed salamander cannot absorb the sodium it needs to keep its sodium-to-water ratio balanced in its body, and the salamander excretes more water. This dries out its skin and hinders oxygen absorption.]
  2. If the amount of acid rain falling in an area cannot be changed, would it make sense to add salt to the soil in certain areas? What might be the benefit of doing this? What might be the drawbacks? What else might be affected by the addition of salt to soil? Write a short paragraph describing the benefits and drawbacks of adding salt to the soil in areas where acid rain falls.
    [anno: Answers will vary but could include that the addition of salt to the soil in areas where acid rain falls would help red-backed salamanders. The drawbacks to such an action might include that the salt content of the soil might be difficult to monitor and continually adjust. The runoff from the area could adversely affect other plant and animal life by raising the salt content of streams, lakes, and rivers.]