All photographs copyright Elizabeth Farnsworth
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Table of Contents:
Keywords: Traprock, Metacomet Range, Connecticut, Massachusetts, Corydalis flavula, plant conservation, oak-hickory glades |
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Amid the modern roar of traffic coursing along Route 91, a bit of prehistory surfaces in southern New England. The Triassic-aged ridges that make up the Metacomet Range from northern Massachusetts to Long Island Sound hold dinosaur footprints and contemporary treasures of rare species, once and now a concentrated hotspot of biological diversity. As an all-too-frequent commuter on Route 91, I breathe a sigh of relief when the familiar and dramatic profile of Mount Tom rears up into view beside the Connecticut River -- I am almost home. As a conservation biologist, I have come to recognize the significance of these mountains for unique assemblages of plants and animals and as stolid landmarks for the human communities that increasingly value them.
Map of the Metacomet Range from Colbert 1970 |
The Metacomet Range attests to a time of violent geological upheaval at the boundary of the Triassic and Jurassic period, 200 to 240 million years ago (Bell 1985, Little 1986). Dinosaurs roamed this part of New England, and were first described by Edward Hitchcock (1858). Working in the Connecticut River valley, he realized, probably uneasily at first, that the region had once hosted a startlingly different, now extinct fauna. Likewise, such a realization sparked Darwin's early thinking on the possibilities of evolution. Imagine yourself a dinosaur, perhaps a six-footer of the genus "Yaleosaurus," named somewhat pompously for the University that houses its skeleton (Colbert 1970). As you slog through the mucky borders of humid, tropical swamps patrolled by giant dragonflies and the occasional pterodactyl, volcanoes spew lava and earthquakes punctuate your days. This lava is the stuff of which the Metacomets are made.
As the great, unified continent of Pangaea began to separate into the African and North American plates we recognize today, rifts appeared in the landscape. These faults became wider and deeper, and the subsiding land gradually was torn into a rift valley over 100 miles long (Wetherell 1992). Lava burbled up through cracks in the valley or was extruded underground to cool in place. Three major eruption episodes, resulting in three hard layers of basalt, are expressed in the rocks of the Metacomet Range; from oldest to youngest, they are the Talcott basalt, the Holyoke basalt, and the Hampden basalt. Interbedded with these tough bedrock shelves are layers of re-worked arkose sandstone and shales -- sand, mud, and tuff eroded and deposited by water from the uplands. Raindrop impressions, mud cracks, ripples, fern fragments, fish scales, and even armored mud balls (Little 1986) are retained in the rock. Dinosaur footprints criss-cross these Triassic "red-beds" like gigantic turkey tracks. In riverside fossil beds protected by the Trustees of Reservations in Holyoke, Massachusetts, the tracks of young dinosaurs stick close to those of the adults, and it is possible to visualize a herd moving together, perhaps fleeing an eruption.
 Yaleosaurus (from Colbert 1970). |
 Dinosaur footprint meets human sneaker, Holyoke, Massachusetts |
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Dense, crystalline basalt is hard and weathers slowly. Hence, the Metacomet Range persists as a resistant ridge, surviving the actions of glaciers and water for the past 200 million years. This basalt is commonly fractured into columns due to the fact that it was extruded and cooled underground (Bell 1985). Resembling staircases, the columnar basalt is dubbed "trap" rock, a term adapted from the Swedish word for "step." The summits of the Range contain breathtaking exposures of columnar basalt, like the cliffs shown in the photograph of the Hanging Hills in Meriden, Connecticut. |
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The Metacomet layer cake is distinctly tilted. Continued splitting of Pangaea caused faulting and subsidence of the east side of the nascent river valley (Roberts 1996); thus, the ridge slumps to the east. For most of its length, the ridge parallels the west bank of the Connecticut River (see map), with a seemingly rogue outcropping of trap rock to the west in Southbury, Connecticut. However, toward New Haven in the south, the range trends lopsidedly northeast. Most strikingly, the "seven sisters" of the Mt. Holyoke range in Hadley, Massachusetts, veer off east toward Boston. Weather can differ dramatically on either side of the range, east to west or north to south. Together with stark elevational gradients in temperature, this variation in microclimate contributes to the diversity of forests found on the Metacomet Range.
Patterns of DiversityThe sheer topography of the Metacomet ridge and its curious bedrock geology shape the natural plant communities along the Range. The western and southern aspects of the Range are significantly drier and warmer than the eastern and northern flanks. Moist air, arriving in weather fronts from the west, rises along the range. Air is coolest in the Connecticut River valley, and upon contacting the dark, open basalt balds at the summit actually warms (unlike many mountain summits, like the frigid, wind-worn top of Mount Washington, that are much colder than lower elevations). Heating of the basalt balances adiabatic cooling of the rising air. Thus, the Metacomet summits can warm considerably earlier and experience longer seasons of extended warm temperatures than the surrounding valley (Brumbach 1965). Air spilling over the eastern and northern flanks of the ridge cools and, often, drops its load of moisture as rain and mist. Thus, the leeward slopes are cooler and wetter than the warm windward hillsides and the dry, hot summit. Today's "pterodactyls," the large raptors -- hawks, vultures, and eagles -- soar on the thermals and use the Metacomet Range as a critical flyway during their annual migrations. From a bird's eye view, the relatively unfragmented woodlands along these ranges, comprising thousands of acres of forest habitat, provide the largest and best nesting areas along the lower half of the Connecticut River (Anderson and Merrill 1998).
Oak-hickory forests, more reminiscent of southern woodlands, characterize the western and southern slopes of the Metacomet Range. By contrast, hemlock, birch, and maple forests more boreal in their affinity, tend to cover cooler northern and eastern slopes and are particularly well developed in central and northern Massachusetts. The knife-edge summits of the Range support another highly unusual forest type -- a park-like glade of stunted oaks, hickories and ash trees, with a low understory dominated by the Pennsylvania sedge, Carex penslyvanica. These unique "grassy" glades on traprock balds are recognized as one of the most species-rich and imperiled ecosystems of Connecticut by the Connecticut Natural Diversity Data Base. In Massachusetts, these well-studied balds and glades are continually yielding new botanical discoveries, according to botanist Karen Searcy of the University of Massachusetts. Rare herbaceous plant species dot these ridges: over ten listed species have been reported in Connecticut and more still in Massachusetts (fact sheets on some of these species are available on the web, such as glaucescent sedge (Carex glaucodea var. flaccosperma)).
Why are these hills so chock-full of rarities? Several plant species, whose seeds find their way into the fissures and talus that hold sparse soil, are specialized on the unique chemistry of the bedrock. Holyoke basalt commonly contains calcium-plagioclase and pyroxene (a mineral containing oxides of calcium, magnesium, iron, and sodium; Bell 1985); consequently, the meager soils from this parent rock are nearly neutral in pH. Magnesium and calcium, in particular, are essential, limiting nutrients for plants (Salisbury and Ross 1992). Although soil deeper than 0.5 m is generally not found on the bare summits of these trap-rock ridges, a surprising diversity of plants exploit the mineral-rich, subacidic chemistry of the habitat, and many species are restricted to areas where these physical conditions prevail.
Yellow corydalis (Corydalis flavula), a delicate, diminutive inhabitant of the southern Metacomets, exemplifies many of the specialized features of the region’s rare plants. I have been fascinated with this plant for two years. The species reaches the northeastern edge of its range in Connecticut. In the heart of its range in midwestern and southeastern North America, yellow corydalis occurs in mesic to damp woods, floodplains, and bottomlands. Where it moves north and up in elevation along the Alleghenies, Blue Ridge, and southern Appalachian belt, the species occupies cliffs, rocky outcrops, ledges, and other comparatively dry habitats (reviewed by Farnsworth 2001). The common denominator among all these habitats appears to be the presence of circumneutral or rich soils.
It is a mystery how or when yellow corydalis first showed up in Connecticut; the earliest herbarium collections date from the 1920's (Clark 1926). The nearest known populations of yellow corydalis occur in the Hudson Highlands of New York, hundreds of miles away. Perhaps the Connecticut populations are newcomers or relicts, or perhaps we have yet to discover pockets of these inconspicuous plants throughout the state. In any case, it is clear that the far-flung clusters of plants in Connecticut carry with them the traits of plants adapted to conditions farther south -- traits that create both problems and opportunities. For example, this annual plant produces seeds that germinate in late fall and overwinter as seedlings (Baskin & Baskin 1994, Farnsworth, unpublished data). In the comparatively mild winters of the south, such a feature allows the plants to take advantage of an early spring flush of water and nutrients before the tree canopy leafs out. In New England, harsh winters can spell trouble for vulnerable seedlings, and the majority may die. As winters warm in New England due to global change (U. S. Global Change Research Program 2001), yellow corydalis may yet flourish. However, the plant is also highly susceptible to drought (recall its happy home in southern mesic and alluvial woods). The past year has been among the driest on record in New England, and another El Niño event is imminent. In 2001, yellow corydalis plants died in significant numbers due to drought at one Connecticut site (see photo below). Their ability to recover in 2002 will be contingent on a bank of seeds or hardy seedlings. Yellow corydalis thrives in sun (plant size correlates significantly with light availability, according to my data), but pays a price when the rains fail.
The patchy local distribution of yellow corydalis may reflect a peculiar feature of its biology. Its tiny, black seeds bear a protein-rich elaiosome and are dispersed by ants (Beattie et al. 1979, Beattie & Culver 1981). The majority of mature plants of yellow corydalis on Connecticut traprock ridges are associated with pockets of intense ant activity near nests, particularly those of Myrmica punctiventris and Leptothorax longispinosus (Farnsworth, unpublished data).
Other insects are important to the plant's survival and reproduction as well. Corydalis species usually require insect vectors for pollination (Ohara & Higashi 1994); bumble bees, honey bees, flies, and butterflies are the usual pollinators. Overwintering bumblebee queens may complicate matters by robbing nectar from corydalis plants, reducing the efficiency of pollination (Higashi et al. 1988). Yellow corydalis is one of the earliest plants to flower on the traprock ridges of Connecticut, blooming in April when insects are few and frequently hampered by variable spring weather. Do most yellow corydalis in these isolated populations self-pollinate, with attendant erosion of genetic variation? Or, could an unlikely insect opportunistically visit? The rare falcate orange-tip butterfly (Anthocaris midea) flits through the traprock glades in April and appears to visit yellow corydalis (Farnsworth, personal observation). This skittish white butterfly with bright orange wingtips does not range north of the middle Metacomets in Connecticut. Yellow corydalis and the falcate orange-tip would make strange bedfellows and their relationship has yet to be confirmed. But more than one rare plant species in New England depends on rare partners -- pollinators, fungi, hosts -- and these subtle ecological webs need to be understood in order to develop sound conservation strategies.
The dissected hillsides of the Metacomet Range are topographically complex, with narrow gorges cut by fault lines and streams, sheltered "coves," and talus slopes. The jumbled rocks and hollows of talus, plucked by glaciers from the summits and dumped in a skirt at the base of cliffs, serve as drains for cold air and hold ice late into the spring. Here, northern species like mountain maple (Acer spicatum) and mountain ash (Sorbus americana) gain a foothold. Groundwater seeps out of fissures in the basalt, and vernal pools appear magically in the spring. Pocket wetlands and tiny gorges harbor still more rare plants, from orchids like autumn puttyroot (Corallorrhiza odontorhiza), to trees like Swamp Cottonwood (Populus heterophylla), a new state record for Massachusetts recently found by botanists searching Mount Holyoke (Searcy and Ascher 2001).
Likewise, Karen Searcy, Curator of the Herbarium at the University of Massachusetts at Amherst, has found that certain species of plants prefer to inhabit the arkose deposits of the Metacomet Range, while others specialize on the basalt. Such subtle plant pickiness results in still more intricate patterns of species diversity within the broad climatic zones of the range. In 2000, twenty biologists counted over 270 species of plants on peaks of the Mt. Holyoke Range in Hadley in one day. In the same year, several days of searching around Mount Tom in Holyoke yielded more than 750 species.
Plants obviously are not the only organisms that inhabit these wetlands. During warm rains, flashy Marbled Salamanders (Ambystoma opacum) migrate by night among vernal pools nestled in the ridges; numerous populations have been located and tracked around the Metacomets. Turtles, frogs, and toads lay their eggs in and around these ephemeral wet areas. Snakes are legendary inhabitants of the Metacomet Range.
Northern black racers (Coluber constrictor constrictor) hunt other snakes. Likewise, the Metacomet Range is one of the last hold-outs in New England of the timber rattlesnake (Crotalus horridus) and copperhead (Agkistrodon contortrix mokasen), that sun themselves on warm rocky outcrops and prowl the forest understory for mates and prey (Peterson & Fritsch 1986). These large snakes are declining precipitously throughout their North American range due to poaching, encounters with cars, and land conversion, and find a critical refuge in the Metacomets. Lest these reptiles go the way of the dinosaurs before them on these hills, their dens and territories need to be safeguarded through concerted land protection and public education.
Humans have used these mountains in two primary ways: for inspiration and for resources. Native Americans hunted the ridges and may have used fire creatively to draw and trap wildlife (Cronon 1983, Sinton 2001). Indeed, the Metacomet Range was named for the sachem Metacomet, (second son of Massasoit, called "King Philip" by colonialists) of the Wampanoag Indians and confederation of Algonkin tribes. The Connecticut River Valley was shaken for thirteen years of attacks and bloody reprisals between his forces and colonists, and some of these pitched battles occurred in these mountains. Seeking both a bounty of food and communion, tribes gathered at notable landmarks on the range, including the towering basalt columns of Titan's Piazza overlooking the Connecticut River in what is now South Hadley, Massachusetts.
Later settlers harvested timber from woodlots that often extended in narrow strips from the river's edge up the steep escarpment. Celebrating a new-found appreciation for the "wilderness" still inherent in these altered landscapes, a generation of romantic artists and writers immortalized the beauty of the range. Thomas Cole's 1836 painting, "View from Mount Holyoke, Massachusetts, after a Thunderstorm," captured a panorama that inspired a new movement of idealized naturalism in painting, the Hudson River School. Victorian tourists made their way to the summits to enjoy picnics and scenery. Funicular railways were run up the mountainsides to transport them, and elaborate hotels were built to accommodate them in finery. Some of these buildings, like the Summit House (Joseph Skinner's summer estate) remain; others failed, burned, or gave way to communications towers.
Today, roads and footpaths conduct visitors along the Range, who enjoy the view, rock-climb, mountain-bike, and (occasionally) camp. The Metacomet-Monadnock Trail runs over one hundred miles from Monadnock Mountain in New Hampshire through the Metacomets in north-central Connecticut. It meets up with the Blue Trail system in Connecticut, on which the dedicated hiker can traipse from summit to summit nearly to Long Island Sound. Together, these trails are being considered for federal designation as a National Scenic Trail. Most hikers bring with them a picnic lunch and a sense of appreciation for the Range. Others, however, dump litter (an increasing problem in recent years, despite annual Earth Day reminders), spray graffiti, and start fires.
The latter issue, fire, poses an ecological dilemma. The incidence of historical fire, and its signature on the natural forests of the Metacomet mountains today is poorly understood. Sparse charcoal layers indicate that fire occurred infrequently on traprock ridges. Oak forests may be an artefact of selective cutting in the 19th century, followed by selection for fire-resistant species (Crow 1988, Abrams 1992). Is fire needed to maintain open canopies and soil communities that support a rich understory flora? Are the already rare New England traprock summit forests succeeding to maple (Acer) species as fires continue to be suppressed, as suggested by studies in New Jersey (Dodge 1997)? Campfires escaped to engulf hundreds of acres of the Mt. Holyoke Range in Massachusetts during the parched fall of 2001. Observations of forest recovery following these fires will enrich our understanding of the role of human and natural disturbance in maintaining traprock communities.
Traprock also provides a handy raw material for gravel and pavement; thus, quarries have exploited the Metacomet Range for decades. Large quarries scour rock from Lamentation Mountain, Mount Tom, and Skinner Mountain. They may provide a significant source of town revenue, but their expansion has become a bone of contention over the years among neighbors and conservationists who seek to limit the area damaged by quarrying (Libby 1991).
Another source of alarm has been the increasing pace of development and home-building in and around the Metacomet Range. One would think the sheer cliffs and dense forests would discourage enthusiastic developers, but the views and close proximity of the mountains to major routes (like Route 91) are a strong temptation. Local citizens' organizations have teamed with municipal, state and private conservation organizations throughout the region to ward off specific development projects. For example, a proposal to build dozens of houses on the flank of Mt. Holyoke was narrowly averted in 2001 by a hastily-assembled but well-organized group, Save the Mountain, what garnered public support for protection of the Range, distributed countless bumper stickers and lawn signs, carefully researched existing law regulating such development, examined and articulated the pros and cons of new home construction for the community, sought private donations to acquire the 100-acre parcel, rallied state government to help, and negotiated conservation restrictions non-confrontationally with the landowner. At the same time, the Mount Holyoke Range and Mount Tom were hailed as one of America's "Last Chance Landscapes" by a national organization, Scenic America. Another collaborative effort among three towns in Connecticut afforded protection to Lamentation Mountain, and educational web sites express an ardent vision for the values of an enduring Metacomet Range (White 1991).
Thousands of small parcels (each skyrocketing in cost) line these mountains, however, and conservation cannot continue to proceed piecemeal. Recognizing this, groups are beginning to address the Range as a whole entity and to recognize its hydrological and biotic linkages with the Connecticut River watershed. Save the Mountain, for example, has evolved from a dedicated cadre of a few dozen people to a community-wide effort called the Connecticut Valley Summit. The Summit is a coalition crossing nine towns in west-central Massachusetts, whose self-described mission is to: "convene the residents of the Connecticut River Valley so they can share their visions of the Valley's future, find common views, uncover common viewpoints and help resolve incompatible uses of land and resources." Individual task forces are accomplishing specific objectives: for example, passing the Community Preservation Act in a local town, gathering ecological research on the Range, and training volunteers to track mammal movements around the mountains. Can such a grassroots effort serve as a model for proactive conservation of the natural and human values of the Metacomet Range?
Karl Meyer articulated the imperative eloquently in a 1998 essay: "Dozens of people pore over the essential elements of this landscape daily -- weighing the pieces, great and small, of biodiversity, open space, history, culture, and cultivation...In the aggregate, these people and the environmental groups they are associated with constitute a critical public trust working to maintain a place that will nourish all of its denizens well into the future." As conservation biologists search the hills for new and ancient treasures, working to reveal the ecology of the Metacomet system, all of us become better versed in the wonders of rugged, scarred, and beautiful backbone of southern New England.
[Editor’s Note:
Sometimes preservation perserverance pays off! According to the following press release issued by the Trustees of Reservations, more than 350 acres of the Mt. Holyoke Range, which include several of the traprock ridge communities highlighted in Elizabeth Farnsworth’s article, will be saved from developers. See below:
Date posted/modified: 08/02/2002
Connecticut Valley Conservation Partnership Protects Mt. Tom
Holyoke, MA--The Trustees of Reservations announced today that a conservation partnership has completed its purchase of most of the former Mt. Tom ski area in Holyoke. Permanently protected are 359 acres, which will be managed by the state’s Department of Environment Management, the U.S. Fish and Wildlife Service, and The Trustees.
The closing on a fourth, 22-acre parcel, to be purchased by the Holyoke Boys and Girls Club, was postponed until the current owners can complete a Title V septic system inspection. In addition, the owners retained a 16-acre parcel containing the existing quarry, which must shut down operations no later than 2012. At that time the parcel will be conveyed to the state at no additional charge.
The 73-acre parcel acquired by The Trustees includes most of the hill known as "Little Tom," located between the base lodge and Interstate 91. The property is a relatively undisturbed natural area that offers invigorating hiking, stunning views of the Connecticut Valley, and a fascinating educational experience in the unique geology, ecology and history of the Mt. Tom area. Little Tom will become a new reservation of The Trustees, complete with parking, trails, and maps for visitors. A fundraising campaign is now underway to meet the $520,000 in acquisition, transaction, "start-up," and management costs of the new reservation.
The former ski area property, arguably the most significant threatened open space in the Connecticut Valley, had been for sale for some time. Home to a controversial traprock quarry and vulnerable to further development, this property at the heart of Mt. Tom is critical to the ecological integrity of the mountain and its scenic and recreational pleasures. Efforts to purchase and protect the parcel had collapsed twice in the last 15 months.
For more information, please contact Pamela Barnes or Charlie Wyman at 413-587-0716, or email them at pbarnes@ttor.org or cwyman@ttor.org.]
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