Science

Finding Vermont’s Elusive Vernal Pools: High Tech and On the Ground

After a long, cold, quiet Vermont winter, certain sections of the forest explode with life after spring’s first few warm rains. Sunshine glimmers on open water, and the peeps of spring peepers and bloops of wood frogs echo through the trees. These sights and sounds may indicate that you have found a Vernal Pool – a tiny, unique natural community which provides crucial habitat to several species including salamanders and frogs.

The most exciting way to find a vernal pool is through a woods exploration, but biologists can increase their odds of finding one using some new high-tech methods. Among the most exciting of these is LIDAR – a high-tech method of mapping very precise elevations with lasers mounted on a plane.  That’s right – lasers can help find vernal pools!

LIDAR

This is a LIDAR map of a ridge in Hinesburg, with blue and purple at lower elevations, green intermediate elevations, and red indicating higher elevations. This colorful image reveals small basins, mapped in white below.

Of course, not every basin will hold water. Some basins may occur on sand or cracked bedrock, so that water can drain out instead of collecting. We can investigate further with aerial photos taken in early spring, just when the amphibians are at their loudest. The next image is an aerial photo of one of the possible pools, at the base of a cliff. The area outlined in white shows a dark color – in this case water. Note also that another smaller pool is present just to the south, that wasn’t picked up at first glance.

Layer

Aerial photo used to investigate possible vernal pools.

Taken together, these map layers tell a story of a likely vernal pool. But knowing this is not enough. Is the pool used by amphibians? Which species? Is it in good condition? How deep is it? To answer these questions, it’s time to grab your boots and head out into the woods. The field work is as important as ever, but now it is a bit more efficient. The photo below is of the pool we just mapped in the aerial photo.

vernal pool

The vernal pool shown in the aerial photo above.

The Agency of Natural Resources is not the only group working on remotely locating Vernal Pools. The Vermont Center for Ecostudies and Arrowwood Environmental have mapped nearly 5000 potential and known pools using aerial photos and field work, and have recruited citizen scientists to trek into the field and confirm their presence. The increase of LIDAR availability is allowing for even more implementation of this type of work moving forward. And of course, if you find a vernal pool, let us know! There are always some that even the most high tech methods won’t find on their own.