There are consequences to setting a river free, ranging from impacts on aesthetics, history, and recreation, to the possible reduction of hydropower (a non-fossil source of energy), to changes in property values. The ecological repercussions of removing a dam are far-reaching and profound.

There are more than 75,000 dams in the United States that are at least 6 feet high. Vermont has about 1,200 dams – one quarter of the number found in New Hampshire. Most of these dams were originally built from the late 1700s through the 1800s in order to supply water power gristmills or sawmills, provide for recreation, and, later, to generate hydroelectric energy.

Dams transform river environments into ponds or lakes – still waters that form layers with different levels of temperature, clarity, and oxygen content. Water lilies and pondweed grow in the shallows, with arrowhead and cattails near the shore. I’ve angled these environments for sunfish, perch, pike, and the elusive lunker bass, casting the limpid idylls of historic millponds while dragonflies patrolled, ducklings wove through fragrant water lilies, and yellow warblers sang, Sweet, sweet, sweet, I’m so sweet!

But some old dams have outlived their original purposes, may be too expensive to repair, and may no longer be wanted by their owners. What happens when a dam is removed? Most dramatically, removing a dam physically re-opens a river to migratory fish, perhaps including American shad, Atlantic salmon, and blueback herring.

Removing a dam also tends to cool a river’s temperature, favoring the many species of fish that require consistently cool water in order to migrate. Warm water signals to many migratory fish that the spawning season is over. Even where dams are equipped with fish ladders, unnaturally warm water above the dam can create a thermal barrier that triggers an end to migration and spawning behavior in American shad.

On a smaller scale, insects such as stoneflies, water pennies, and certain mayflies, craneflies, and caddisflies thrive in a free-flowing river. Gravel bottoms are ideal because water flushes through the minute spaces, providing oxygen and nutrients while removing wastes.

Spring floods scour the river to maintain gravel, cobble, and rocky bottoms. Water tumbles and mixes over rocks and riffles, which balances the temperature from top to bottom and blends in oxygen. Shade from overhanging trees and shrubs keeps water cool, enabling it to hold more of the dissolved oxygen that is so essential for species such as trout and alewives. Some species—like the endangered cobblestone tiger beetle of the Connecticut River—require the scouring action of springtime flows to maintain critical habitat.

Removing a dam restores water flow to within the historic channel and reestablishes interconnections between stretches of river and bordering riparian habitats. Gradually, plants and animals of the open river return, and the ecological community harbors a growing diversity of species.

The free flow of water also re-establishes the process of nutrient production and recycling. With natural flow, the algae that grow on rocks in riffles produce most of the ecosystem’s energy and become food for other species. Nutrients, meanwhile, settle out and decompose in quiet pools. This cycle of production and decomposition occurs repeatedly along the course of a free-ranging river.

Dam removal does pose risks, like opening the upper reaches of a river to invasive species, where newly exposed shorelines provide fertile and available habitat. Planting native species will stabilize these areas. During the breaching itself, the impounded water needs to be released slowly to mitigate downstream flooding and riverbank erosion. In addition, the silt behind old dams may contain toxic sediment left over from our industrial heritage, and this silt may need to be dredged or captured with filters to reduce the possibility of poisoning habitat downstream. Finally dams must be removed at times of year that minimize the effect on migratory fish.

The Peterson Dam along the Lamoille River and the Dufresne Dam on the Batten Kill are two Vermont structures currently being considered for removal. Taking down the Peterson Dam could restore the Lamoille’s migratory runs of sturgeon, walleye, and landlocked salmon, while the Dufresne is the only dam along the main channel of the Batten Kill, one of the region’s celebrated trout-fishing rivers.

Done carefully, the long-term benefits to aquatic ecosystems that accrue from removing dams can outweigh the short-term disruptions of the removal process, especially when the dam in question is no longer being used for its intended purpose. 

I recently found a slug waiting out the daylight hours under a flat stone, far from vegetation. Day after day, the slug would be there whenever I lifted the stone. At night, however, when I lifted up the stone to check on it, the slug would be gone.

Another nocturnal slug undertaking is mating. A single individual is both male and female, so getting together with another slug involves a mutual exchange of sperm. Both will go on to lay eggs, which are small and opaque at first, then increasingly transparent, and laid in bunches of 20 or 30 in the soil and other protected places. When conditions are right, slug populations seem to explode, for an ordinary slug can produce 500 eggs in a single year.

In this contradictory world, there is room enough for even those creatures that creep around in the dark, repelling us with their soft and slimy ways. Except when they’re crawling on the lettuce.

For example, what does the color of a bird’s egg tell us? Many scientists believe that the default color of birds’ eggs is white, and indeed many birds’ eggs are white, including, in some cases, that most familiar of eggs, the hen’s egg.

The eggs of birds that nest in tree cavities, such as woodpeckers and kingfishers, also tend to be white. Scientists think this may be because the eggs are well hidden from predators, and since it’s kind of dark in those holes, the bird parents can more easily see bright white than they could a duller color.

Birds that lay their nests on the ground, such as shorebirds and game birds (for example, turkeys), tend to have eggs that are colored to blend in with their surroundings. Killdeer are technically shorebirds but are found throughout Vermont and New Hampshire, far from water, in open spaces on farms and even in parking lots. Their sandy-colored, speckled eggs are nicely camouflaged on a beach and don’t seem to do a bad job being inconspicuous in the other bare places the killdeer nest either.

But some ground-nesting birds, such as the pied-billed grebe, lay white eggs. Over time, the eggs grow dirty and stained, becoming somewhat camouflaged in that way.

Why are the eggs of so many birds, particularly thrushes, including robins, bluebirds, and hermit thrushes, a beautiful sky blue? I haven’t heard an explanation worth repeating – scientists don’t know. What scientists do know, though, is that the blue color comes from pigments closely related to the pigment that makes blood cells red, so perhaps there’s a connection there somewhere.

I remember learning as a kid that eggs are egg-shaped so that they will roll in a circle, and not in a straight line off a cliff. Sure enough, some of the pointiest bird eggs in the world are laid by birds that nest on cliffs. I’m thinking of murres, which are found on the northern coasts of North America, both Atlantic and Pacific. But there is evidence that pointy eggs and cliff dwelling don’t have to go together. For example, peregrine falcons nest on bare ledges, or on perhaps a scrape on a cliff, but their eggs are no pointier than a hen’s egg, and in some cases a bit rounder.

As it turns out, it’s those shorebirds again that in general seem to lay pointy eggs. The eggs are carefully arranged in the nest so that the pointy ends are together. That allows the eggs to be packed closer together in the nest than round eggs, an advantage if you are a small bird trying to keep a lot of eggs warm.

Having round eggs, though, does offer an advantage. A sphere, or ball shape, is the way to have the most inside (volume) with the least outside (surface area). That’s a benefit if you want to pack as much good stuff as possible inside your egg but limit its exposure to the elements.

The great long-horned owl, which nests in our area, is known for having nearly spherical eggs. This bird might take over a nest from a crow or a hawk, but also, especially in the western U.S., may lay its eggs on the bare ground of a cliff. So much for round eggs rolling off.

The relative size of a bird’s egg does tell you something about the bird that laid it but not necessarily its size. Birds whose young hatch out of the egg ready to walk, and perhaps even swim, are called “precocial.” Waterfowl, such as ducks and geese, are precocial and lay larger eggs than other birds the same size whose young are born helpless.

Becky Suomala says that she and the other biologists at New Hampshire Audubon are sometimes asked to identify eggs that people find. “It’s difficult because so many eggs have similar colorations and sizes,” she says. Sometimes she can narrow it down to a family of birds. For example, looking at her field guide to nests and nestlings, she says, “On the woodpecker page, all the eggs are white and about the same size.”

Besides size and shape, she goes by other clues, such as where an egg was found, in a nest or on the ground, in a forest or in a field. It seems that eggs can tell us a lot, but can’t always tell us the bird that made them.

Two walks a couple of days apart produced nothing, though the dog and I both valued the exercise. Then, on a beastly hot day not long after, I was off on a birding hike of my woods with Vermont Audubon‘s Steve Hagenbuch. Vermont Audubon has a great program where they help landowners evaluate their land as habitat for birds. A walk with a good birder is such a treat, and as we were listening to a hermit thrush and an ovenbird, I came upon 4 morels in an unlikely place, scattered in a patch of almost pure hemlock. Two of them were huge, the largest I’ve ever seen. Which didn’t bother me until I happened to mention those two facts to a mushroom-loving friend, that they were found in hemlocks and they were huge.

“Hmmm,” was all she said.

Morels are the one mushroom that I know for certain. They are undeniably phallic, they are hollow, and their tops look like brain matter. I couldn’t be wrong. But I have to admit that my friend’s “Hmmm” made me wonder if my wife and I were going to die from eating some previously undocumented huge faux-morels.

I remained confident, they were delicious, and we’re still here. And you can bet I’ll go back to the hemlocks next time I’m looking for morels. 

Fields that are no longer being hayed or pastured regularly become populated with a tangle of plants and, eventually, the beginnings of a forest. Because they are such changeable environments, these old fields disappear if not maintained and are one of least-common habitats in New Hampshire and Vermont. In the mid-1800s, when farming in northern New England was at its peak, nearly four out of every five acres of land had been cleared. Over time, as agriculture declined, this trend reversed until trees now cover 80 percent of the landscape. In recent decades, old fields have become scarce.

Native and introduced species of plants quickly populate old fields. Timothy, alfalfa, and orchard grass become interspersed with sedges and the wild grasses of foxtail, little bluestem, and reed canary. Seeds arrive via parasols, burrs, springs, catapults, and glider-like wings. Apple trees and other fruit-bearers wrap seeds inside tasty flesh that is deposited wherever birds, deer, and other fruitarians leave droppings.

Ox-eye daisy and toadflax (butter-and-eggs) are among the early season flowers. Mid-summer blossoms include black-eyed Susan, milkweed, and Queen Anne’s lace. Late summer and early autumn come alive with the rich hues of goldenrods, the bright rays of asters, and the down of thistle seeds, food of the American goldfinch. My favorite is the tiny white flower of old-field balsam, whose autumn scent evokes calico and old lace.

Insects are drawn to these farms gone wild. Grasshoppers and crickets sing from the greenery. Leafhoppers, or “spittle bugs,” exude foamy white shelters. June’s eastern black swallowtails are followed by the monarchs of July that famously lay eggs on milkweed. Flower spiders ambush pollinating insects with a toxic bite. These pale arachnids slowly color-shift to match white or yellow flowers.

About 40 percent of our local wildlife species rely on old-field habitats at some stage of their lives – from red foxes and white-tailed deer to eastern coyotes, woodchucks, and cottontails. Weasels and garter snakes hunt here for the ubiquitous mice and meadow voles.

Ironically, old-field plants create conditions less suitable for their own progeny but beneficial for those species that follow in their wake, by providing deeper shade, taller shrubs, greater soil moisture, moderated temperature swings, and protection from the elements. Annuals and perennials eventually yield to shrubs and trees of a young forest. Raspberries and blackberries appear, along with sumac and sun-loving trees such as aspen, white pine, and black cherry. Wet meadows sport pussy willow, highbush blueberry, alder, and elderberry. Over time, a succession of ecological changes transforms open land into mature forest.

As the plants come and go, so do the animals. When grassland matures into an old field, eastern meadowlarks and bobolinks give way to melodious song sparrows and field sparrows whose voice recalls the quickening beats of a bouncing ping-pong ball. Eastern loggerhead shrikes impale prey on hawthorn spikes. In early springtime, American woodcocks launch aerial displays from hedgerows. Damp, shrub-studded fields attract the vociferous common yellowthroat and the rapidly disappearing golden-winged warbler.

Well-planned and timely cuttings are needed to create or maintain diverse old-field habitats. Years ago, when I was a novice mower, I circled fields and cut in toward the center. But this technique herded everything from crickets to voles into the ever-shrinking, uncut portion until, with the last pass of the singing blades, I became Jack the Reaper. Now I divide fields into sections and mow back and forth along one edge, driving animals to the other sections instead of corralling them in the middle.

I aim to mow each section once every four to five years on a rotating schedule that maintains varied stages of growth. My sections are about a quarter-acre in size, and I mow in late August, when the young of ground nesting birds have fledged. Curves, scallops, and other irregular shapes create longer edges between sections of varying ages, which increases diversity and enhances the field’s value as wildlife habitat. I also maintain a few small islands of shrubs and tall trees where birds of prey, such as red-tailed hawks, can perch, and where kestrels can nest and other animals find shade.

I mow every year in areas wherever invasive species, such as Japanese honeysuckle, common buckthorn and glossy buckthorn, have appeared. These fast-growing species can be eradicated only if the mowing is done regularly.

The effort required to maintain old fields is well rewarded. When wind forms waves of grasses and blossoms, we are as sailors scanning the swells in a sea of flowers. We are Gullivers in this colorful land of Lilliput – witnessing the minute mysteries of a knee-deep ecosystem.

How many times have Sox fans heard this call after that tell-tale crack of bat on ball? Until recently, the wooden bat that struck that ball would have been made of ash from the Northeast. (Some players now use maple, too.) Red Sox third baseman Mike Lowell loves the sound of ash striking a baseball. He has said that he can instantly tell by the sound of the ball hitting the bat if a player is using maple or ash. But if the emerald ash borer has its way, all ballplayers might soon be swinging maple, or something other than ash.

The emerald ash borer (EAB) is a small beetle (it easily fits on a penny) discovered in 2002 in Michigan and Windsor, Ontario. The insect kills North American ash trees, those in the genus Fraxinus. This includes green, white, and black ash, all native to Vermont and New Hampshire. The larvae create tunnels called galleries just below the bark in the phloem layer of the tree. These galleries stop water and nutrients from being transported up the tree. Branches begin to die first, and finally the entire tree goes. Large trees may die within three to four years of initial infestation, and saplings or small trees may die after just a single year.

The emerald ash borer is an exotic accidentally introduced from the Far East. It probably arrived in Detroit stowed away in a wooden pallet from China, perhaps as long ago as the late 1980s or early 1990s. With worldwide trade occurring at the highest rate in human history, it is not surprising that exotic pests are also arriving at records rates. The economic and ecological troubles they cause are enormous.

Over 50 million ash trees have been killed in the United States since EAB was discovered. In just the first two years after discovery, the United States Department of Agriculture spent nearly $50 million on eradication. Ohio estimates it has 2.1 billion board feet of ash exposed to EAB in its forests, worth almost $1 billion at the sawmill.

New England is free of EAB for now. Since its original detection in Michigan and Ontario, the beetle has been found in Ohio in 2003, northern Indiana in 2004, northern Illinois and Maryland in 2006, and in western Pennsylvania and West Virginia in 2007.

The emerald ash borer spreads in North America through a combination of local range extension, associated with local flights by adult beetles of up to a half-mile, and by long-distance “jump dispersal,” caused by human movement of infested saplings or contaminated firewood. The borers arrived in Maryland when a nursery imported ash saplings from Michigan despite a quarantine.

The initial discovery of EAB and its subsequent identification took several months. Little was known about this relatively obscure Asian insect at the time. In the Asian scientific literature, there were species descriptions and only two brief accounts with general information about its biology in China.

Recent research shows that the beetle can have a one- or two-year life cycle. Adults begin emerging in mid- to late May, with peak emergence in late June. Females usually begin laying eggs about two weeks after emergence. Eggs hatch in one to two weeks, and the tiny larvae bore through the bark and into the cambium – the area between the bark and wood where nutrient levels are high. The larvae feed under the bark for several weeks, usually from late July or early August through October. They typically pass through four stages, reaching a size of roughly an inch long. Most EAB larvae over-winter in a small chamber in the outer bark or in the outer inch of wood. Pupation occurs in spring, and the new generation of adults will emerge in May or early June to continue the life cycle.

Quick identification of infestation areas is key to halting the EAB’s spread. Adult beetles leave distinctive D-shaped exit holes in the outer bark of the branches and the trunk. Adults are roughly a half-inch long with metallic-green wing covers and a coppery red or purple abdomen. They may be present from late May through early September but are most common in June and July. Signs of infestation include tree canopy dieback and yellowing or browning of leaves, by which time there are hundreds of beetles that have already reproduced.

State and federal agencies are trying to stop EAB through education, identification of infestations, quarantines, and eradication, though the prognosis is not good. If we can all help keep EAB out of New England, the only thing “going, going, gone” will be another Red Sox home run, not our valuable ash trees. 

Why is it important to know this for a region? Many studies have shown that, first, the amount of impervious surface in a region has a direct correlation with water quality. The rule of thumb has been that after a region is more than 10 percent paved or impervious, water quality starts to decline rapidly due largely to road runoff: a messy mixture of oil, grease, heavy metals, and nitrogen. The second reason is that with more imperviousness, there is more flooding, as rainfall is diverted from areas that could have absorbed rain and instead rushes directly and rapidly into rivers and streams, guided there by carefully engineered networks of storm drains and pipes.

How much of our land is impervious? Nationally, the current estimate is that for the U.S., an area the size of Ohio (41,000 square miles) is now paved. It is no surprise then that around the country, more and more flooding occurs each year due to the increasing impermeability of the landscape. Hundred-year floods, those that have a one percent chance of happening in any given year, are occurring with greater frequency. The flooding we see on the evening news is perhaps as likely to be due to increased imperviousness as from climate change or from weather extremes. U.S. Geological Survey scientists have noted that peak flooding increases downstream of development due to increased flows over greater areas of impervious surfaces.

The mid-May 2006 flooding in southeastern New Hampshire and in Massachusetts and Maine that equaled or exceeded local, 100-year flood levels was due to a powerful storm coupled with more and more impervious surfaces. The area of New Hampshire with the heaviest flooding is also where population growth has been fastest and where construction and paving have been the heaviest. A pre-flood study by University of New Hampshire researchers that focused on southeastern New Hampshire showed that the imperviousness of the region had increased by 46 percent from 1990 to 2000, growing from 4.3 percent to 6.3 percent paved, on average. Also, the acres of imperviousness increased from 0.15 acres to 0.20 acres per person. Paving is not the root cause of flooding, of course, but worsens it effects - speeding runoff and preventing water infiltration into the ground.

When the 10 counties of New Hampshire are compared with a new national map of paved areas, the four counties with the highest average imperviousness, Merrimack, Stafford, Hillsboro, and Rockingham (ranging from 2 to 6 percent) are also those where the most severe flooding occurred, according to the U.S. Geological Survey.

Image by Thomas A. Stone. Data courtesy of NOAA,
Dartmouth Flood Observatory, USGS EROS Data Center, & ESRI
This map shows seven days of rainfall
ending May 18, 2006. Flooded rivers are bright
blue and correspond directly with the pattern of impermeable
surfaces (in black), particularly in southeastern
New Hampshire and northern Massachusetts.

Positive changes would be: reducing the number of parking places required for new office buildings, using alternative surfacing methods such as crushed stone or open pavers where appropriate, diverting storm waters into dry wells, catch basins, or man-made sinks before they have chance to reach streams and rivers, and surrounding paved parking areas with grassy swales that slow exiting waters. All these allow for some infiltration of rainwater into the ground.

The abilities of forests and other natural lands to retain and clean rainfall and runoff are called “ecosystems services” by ecologists. Other ecosystems services include: cleaning the air, building soil, taking carbon dioxide out of the atmosphere, providing habitat, protecting diversity, and stabilizing the climate. Ecosystem services are provided free by nature and, because of that, most people take them for granted. Paving eliminates ecosystem services, requires more and more infrastructure to handle storm runoff, and degrades water quality. If we can retain forests, woodlands, and other natural lands, we’ll have cleaner air and water, less flood damage, and reduced costs of maintaining our infrastructure. 

Food is one of our basic needs, so it makes sense that many of these movements focus on it. No less essential to society, however, are other goods and services, which small groups of people in communities across the nation are trying to encourage with “buy local” campaigns. It makes sense that our other basic needs – water and shelter – can also be met locally.

That’s the basic premise behind the Vermont Town Forest Project, which was founded by the Northern Forest Alliance in 2004 “to help communities across Vermont maximize the community benefits derived from their town forests and to help support the creation of new town forests statewide.”

These benefits include everything from watershed protection, forest products, and wildlife habitat to public recreation and community rallying points. They function in the same way town commons have for centuries in New England and New York. Every community member is responsible for their stewardship, and every member also benefits from their presence.

The concept of town commons, and even town forests, is not a new one. In fact, the enabling legislation for creating town forests in Vermont was enacted in 1915. But these forests haven’t been on the top of everyone’s mind. At least until lately. Now, thanks to projects such as the Vermont Town Forest Project, they are experiencing an exciting revival.

The excitement was palpable this spring at the Vermont Town Forest Project’s third annual summit, held in Hinesburg. Hinesburg is fortunate to own not one but two town forests: the “older” (it dates to 1940), composed of 837 acres of mixed woodlands, and the “newer” (just purchased), with 301 acres boasting extensive wetlands and calcium-rich soils.

Hinesburg’s forests exemplify town forest potential. They have recreation: world-class mountain biking trails, along with skiing, hiking, and horseback riding. They also serve as outdoor classrooms, both for local teachers and for the University of Vermont, whose students have conducted dozens of projects there.

And the older forest also has active forest management: one recent harvest took out white ash, which was then milled and kiln-dried locally and installed to replace the floor of the Hinesburg Town Hall, which had been sanded so many times that the tongue of each tongue-and-groove board was exposed. All this at a total cost of $2.48 per square foot, about what you’d pay commercially.

The great thing is, Hinesburg is only one of many Vermont communities with town forests. Some towns have had forests for years, while others are just now acquiring them – a task made easier by the assistance provided by the Vermont Town Forest Project and the federal Community Forest and Open Space Conservation Program, which will provide 50-50 matching grants for towns to acquire town forests.

The momentum is building. Old town forests are being looked at in a new light – as providers of essential ecosystem services, as outdoor classrooms, as places of solace and recreational pursuits, and as providers of locally sourced wood products. New town forests are popping up all over the place, including the Brushwood Community Forest in West Fairlee, which has been designated top priority for federal Forest Legacy Program funding in Vermont.

Town forests are reminders of a time of town commons, poor farms, and public lots – when people collaborated on stewardship, made decisions as a group, and reaped the rewards of all that work together. That kind of model doesn’t have to fade into the landscape like an old stone wall. It just needs a renewal – board for board, like an old town hall floor, replaced with thought and care, each board a piece of a tree that was just an eager seedling when the original floor was laid down.

For more information on the Vermont Town Forest Project, and to obtain a copy of their new Town Forest Stewardship Guide for communities, visit www.northernforestalliance.org/townforest.htm.  More information about urban and community forestry is also available at the Vermont Division of Forestry.