By Roger Rittmaster Vernal pools are an important feature of the Maine woods, but what are they, and why are they so valuable? Vernal pools are temporary bodies of water that fill up from autumn through the spring and usually dry up during the summer. Because they are not permanent, fish and predators such as bullfrog tadpoles cannot survive in them. This creates a niche in which the larvae of amphibians and insects that don’t require year-round water, but are easily consumed