Of Spring Ephemerals and Vernal Pools

The season is upon us and all around you can see (and hear) signs of Spring. Tomorrow marks the beginning of March, during which the Vernal (or Spring) Equinox occurs. We are nearing 12 hours of sunlight with our Sunrise occurring at 6:29am this morning and setting at 5:45pm this evening. Life is returning to the north. Today I’d like to talk about two phenomena that are characteristic of this time of year: Spring Ephemerals and Vernal Pools.

The word “ephemeral” means “lasting for a very short time,” which is certainly an appropriate moniker for these very special and increasingly rare species. But the term Spring Ephemerial doesn’t speak to a scientific, or botanical, classification but rather a simple description of various, unrelated, species that have all evolved a similar mechanism to capitalize on the continually strengthening rays of sunlight, before the forest canopy closes in. Most of these plants carry out their entire reproductive and growth habits during these few short months of early spring, with some holding onto their leaves or fruit until the heat of the summer forces them back into dormancy. Species such as Bloodroot (Sanguinaria canadensis), Virginia Bluebells (Mertensia virginica), and Yellow Trout Lily (Erythronium americanum), are all Spring Ephemerals that quickly leaf out, bloom, and go dormant again while other species such as Wild Violets (Viola spp.), Mayapple (Podophyllum peltatum), and Woodland Phlox (Phlox divaricata), flower in the early spring but may hold onto their foliage or fruit throughout the growing season if conditions permit.

These species are increasingly rare in the wild, and all but ignored in the home landscape - which is a shame as exotic ephemerals such as Tulips or Snowdrops are quite popular. These species are extremely important for our pollinators, especially Queen Bumblebees, who are freshly emergent and close to starvation this time of year as they set out on their journey to feast and mate. Many are diminutive and are best used en masse for optimal effect both aesthetically as well as ecologically as this will ensure there is enough nectar and pollen to go around.

Vernal Pools are another unique, but often overlooked, wetland habitat of our forested lands that are extremely important to local ecology. With the word “Vernal” meaning “of, in, or appropriate to spring,” these wetland habitats, like the Ephemerals mentioned above, are also a fleeting characteristic of the season. Composed of snowmelt and early spring rains, these depressions (many of which originating during glaciation, similar to kettle-ponds) are often the sole reproductive habitat of many of our native Amphibians. Beginning in February, Yellow Spotted Salamanders, Tiger Salamanders, and other Caudates all emerge from their subterranean lives and make the overland trek to the ephemeral pool of their own birth, to find a mate and continue their bloodline. In a similar manner members of the order Anura, like Wood Frogs, American Toads, and Spring Peepers, just to name a few, also utilize these pools. Within a forest, Vernal Pools offer a safe aquatic nursery for amphibians, away from predators like fish, which would otherwise make a meal out of their eggs or larvae.

Yet, this safety has its limitations and as Spring turns to Summer these pools almost always dry up, leaving only a slight depression layered with moist fallen leaves and mud. This means that there is always a race against time for these amphibians to metamorphose as quickly as possible in order to begin their more terrestrial life, away from the confines of their nursery pools. In the interim these wetlands host a myriad of other lifeforms, from Dragonflies and their kin to Pond Snails, Fairy Shrimp, and even Clams that are able to wait out the dry summer months until the rains fall again in Fall which usually allows water to collect in them once again. Vernal Pools are also an increasingly rare feature of our landscape, as they are not permanent and often don’t have the same protections as other wetlands. Often they are filled in, bulldozed over, or simply no longer capable of supporting life due to the removal of the tree canopy or becoming polluted from fertilizer or road salt runoff.

Together, Vernal Pools and Spring Ephemerals form intricate parts of our local ecology, being a meeting point for various terrestrial and aquatic ecosystems and in turn allowing for a nutrient exchange between the two. Fallen leaves from last year feed herbivorous tadpoles, fairy shrimp and mollusks, while Salamander and Newts feed on various crustaceans and aquatic insects like mosquito larvae. As they feed and grow and begin to metamorphose they will leave their pools for dry land further controlling “pests” species while acting as prey themselves to many higher carnivores. Many of our Spring Ephemerals such as Virginia Bluebells, can also be found growing within or around Vernal Pools as the microclimates they create are ideal. If you are lucky enough to have either of these harbingers of spring on your property or within your community please do what you can to continue their preservation and ecological function for the future.