Have you ever walked in a forest in the early spring and seen all the beautiful little ponds that dot the landscape? Have you gone there again in July and wondered where they went? Well, read on and I can explain what’s happening here.
Vernal pools, also known as ephemeral, autumnal, spring or temporary woodland ponds typically fill with water in the autumn or winter and remain ponded through the spring and into early summer. The advantage they have for species that utilize them is they don’t contain permanent water, so insects, amphibians and reptiles using them for breeding, don’t have to face predation from fish species who can’t survive in these non-permanent waters.
Myriad wildlife utilizes this habitat, as frogs, toads, salamanders, insects and other invertebrates teem in vernal pools. Strings of floating herptile eggs can be seen in its depths. Fairy shrimp and other invertebrates abound. Wood Frogs sing out their spring songs, sounding like a flock of ducks from its banks, while Gray Tree Frogs, American Toads and Green Frogs lay eggs, live and feed here. Soon we will hear the peeping of the Spring Peeper, who breeds in vernal ponds, small lakes and bogs. Juvenile stages of dragonflies, caddisflies, mosquitoes, backswimmers and diving beetles breed in its depths as well. These ponds are a magnet for many salamanders, such as the Spotted Salamander and Red-spotted Newt, who lay their eggs masses along small twigs in the water.
Of course all this food attracts predators, so it is not uncommon to find turtles feasting on the eggs of the various frogs and salamanders. Nor is it unlikely you might find a Green Heron, a snake or raccoon coming to dine on the adult frogs and salamanders which might still be nearby.
By late spring or early summer, hundreds of young frogs and salamanders leave the pond and complete their life cycle in the surrounding forests, and the cycle begins anew. Meanwhile the pond dries up slowly and when the fall rains come again, it slowly recharges, ready for next year!
So how do you know if it’s a vernal pond or not? Well, you really don’t but wildlife does. Again it’s a temporary water body which seems to have no beginning or end. It’s not stream fed nor does it rely on a lake’s overflow. It is filled with water from rainfall or spring melt, simply collecting in a hollow or depression, slowly evaporating until gone. Local geology makes it possible for these to persist, as shallow depressions in the landscape are essential so the water has somewhere to collect.
In North Durham, we have been heavily glaciated and are forested, so we have many of these spots where water can pool. Generally, these ponds are quite small (e.g. 15-20 meters wide and 1-1.5 meters deep). Often the edges are heavily foliated with small shrubs and flowering plants. Can you still find them late in the summer? Well, yes, sort of, but they likely won’t have water in them. Look for compressed black leaf litter, grayish coloured soil, watermarks on surrounding tree trunks and moisture-tolerant vegetation. All these indicators can lead you to these ponds.
So how important are these ponds? One source indicates, the amphibian species developing in ponds generally amount to more vertebrate biomass than the mass of all the birds and mammals in a forest! Most of our salamanders and many of our frogs can’t survive without them. As we continue to develop our lands they will become increasingly important and unfortunately rare. It may not be long before we simply can’t find salamanders in southern Durham, nor enjoy the spring frog chorus.
Here’s what you can do, if you own land that hosts a pond: (1) Avoid using chemicals and fertilizers; (2) Maintain forest canopy; (3) Do not add or remove plant debris from the ponds; (4) Do not add fish or other animals; and, (5) Do not drain ponds or alter the surrounding watershed. These may sound like small things but they can have a huge impact.
Geoff Carpentier is a published author, expedition guide and environmental consultant. Visit Geoff on-line at www.avocetnatureservices.com and on LinkedIn and Facebook.
We reserve the right to remove any and all comments for any reason. Comments with swearing will be deleted without exception.
Geoff Carpentier is a published author, ecotour guide and environmental consultant. Visit Geoff on-line, at www.avocetnatureservices.com and on LinkedIn and Facebook.