Little ponds, large impact


IF YOU SOUGHT out the heart of the forest, where would it be? What would it look like? Would you even know if you found it?

Most of us would tramp by, uncomprehending the tiny but potent wellsprings of life known as autumnal-vernal ponds. Unfortunately, the ignorance extends to a lack of protection from drainage, development and timbering.

In summer, these woodland wetlands aren't even damp. Only an expert might note their grayish soils, a slightly more open understory than the surrounding woods and a bulge to the trunks of trees there.

Even when full of water, they're easily missed - seldom much more than 120 feet across, rarely more than a few feet at their deepest, says Gene Wingert, a Dickinson College professor who has studied them for decades.

Yet, scattered throughout the Chesapeake Bay watershed, these inauspicious woodland "hearts" pump out masses of frogs, toads and salamanders that by weight surpass all the birds and mammals in the forests together.

These pond-spawned amphibians are critical links in the forest ecosystem.

They eat the plankton, insects and other invertebrates teeming in the richly decaying litter of the forest floor.

Leaf litter might not appear that energetic, but Wingert says a square yard, decomposed by bacteria, can yield 5 million calories.

Amphibians, feeding there almost invisibly, translate that into flesh which in turn nourishes wild turkeys, raccoons, skunks, snakes, owls, foxes, bear and others.

In sum, nothing more bespeaks a vibrant forest than soils that are well-salamandered, toadsome and frogful.

And it all emanates from autumnal-vernal ponds, Wingert explains.

The show begins on rainy nights in September when masses of black-and-white mottled, marble salamanders home in on the little ponds, traveling from up to half a mile away. No one knows what guides them. The ponds often are still dry.

There, they perform a "waltz," male-female pairs positioning themselves so that they move in roughly circular fashion as he proffers his packet of sperm, and she inserts it into her cloaca.

Wingert, who has spent many a lonely, wet, dark hour videotaping such rituals, says the resulting eggs are so well-hidden that only once in 15 years has he been able to find them.

By October or November the ponds have filled, as trees go dormant and cease transpiring moisture from the soil. From eggs that had lain dried out all summer appear hosts of delicate, frilly, fairy shrimp.

Subtle "earth tides" knead the ponds. The moon's pull tugs apart soil particles in their bottoms, letting water intrude deeper.

Unlike ocean tides, earth tides rise and fall infinitesimally - but enough to create a moist, micro-niche for specialized bacteria in the pond's bottoms that free nutrients for travel up the forest food ladder.

November sees waves of Jefferson salamanders barge into the ponds, only to retreat and bury in the forest floor dozens of yards back from water's edge.

In deepest winter, scampering across snow and ice, they re-emerge to spawn.

No one knows why they do this two-step; but Wingert has used his knowledge of it to foster rules in Pennsylvania establishing protective timbering practices around the ponds. Maryland has no such regulations, and Pennsylvania only in state forestland.

The stampede of the wood frog chuckles raucously into the vernal ponds in February and March, with up to 5,000 crowding into a single small pond, Wingert has observed.

They sound, he says, like ducks quacking at a distance. Wood frogs are of interest to health researchers, as they freeze solid in winter without damage to the heart or cells.

The waves and sounds of life - masses of spotted salamanders, shrill calliopes of spring peepers, elongate trills of the American toad and shorter utterances of the gray tree frog. By June, the ponds shimmer as if riffled by breeze, but they're simply aquiver with life, chockablock with tadpoles.

By July, on rainy nights, young salamanders are emerging and scattering into the woods. There they will live as long as a century, returning to their natal ponds to spawn.

Their memories of home are long. Wingert knows of a pond, destroyed and 50 years later supplanted by a swimming pool. That spring, salamanders emerged from the woods to try to spawn there.

Threats to the woodland autumnal-vernal ponds come from farm drainage, housing projects and timbering that fragments the forest, letting different plants and animals intrude.

Arnold Norden, a vernal ponds expert with Maryland's Department of Natural Resources, says: "There's no question we're losing them, we just don't know how fast."

A task force in Maryland, he says, is wrestling with how to protect the ponds, which "don't fit into the state's classification of wetlands."

Nonetheless, Norden says, "These are very special habitats." They have been a stable feature of the landscape for thousands of years, allowing evolution of specialized life forms dependent on their existence.

He concedes "life would go on" with fewer amphibians, and all the other unique life of the woodland pond. "But doggone it, life won't be as much fun," he says. "It won't be as interesting for our kids and grandkids."

Copyright © 2019, The Baltimore Sun, a Baltimore Sun Media Group publication | Place an Ad