Hemlock

Hemlock: A Forest Giant on the Edge

DAVID R. FOSTER Editor
BENJAMIN BAISER
AUDREY BARKER PLOTKIN
ANTHONY D’AMATO
AARON ELLISON
DAVID FOSTER
DAVID ORWIG
WYATT OSWALD
JONATHAN THOMPSON
STEPHEN LONG Consulting Editor
Copyright Date: 2014
Published by: Yale University Press
Pages: 352
https://www.jstor.org/stable/j.ctt5vkxb3
  • Cite this Item
  • Book Info
    Hemlock
    Book Description:

    The Eastern Hemlock, massive and majestic, has played a unique role in structuring northeastern forest environments, from Nova Scotia to Wisconsin and through the Appalachian Mountains to North Carolina, Tennessee, and Alabama. A "foundation species" influencing all the species in the ecosystem surrounding it, this iconic North American tree has long inspired poets and artists as well as naturalists and scientists.Five thousand years ago, the hemlock collapsed as a result of abrupt global climate change. Now this iconic tree faces extinction once again because of an invasive insect, the hemlock woolly adelgid. Drawing from a century of studies at Harvard University's Harvard Forest, one of the most well-regarded long-term ecological research programs in North America, the authors explore what hemlock's modern decline can tell us about the challenges facing nature and society in an era of habitat changes and fragmentation, as well as global change.

    eISBN: 978-0-300-18677-2
    Subjects: Ecology & Evolutionary Biology, Botany & Plant Sciences

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. FOREWORD
    (pp. ix-xx)
    Robert Sullivan

    We have gathered together today, in a still-dark grove on the side of a hill, to say a few words about hemlock. We have gathered, in fact, in a hemlock forest to say these few words, though we are a small group and there are not many words, and nothing anyone can say can possibly sum up the long life of hemlock on the eastern seaboard of North America, which began shortly after the last ice age and thus included a long stretch of difficult-to-sum-up-time that runs from the late Pleistocene epoch through the Revolutionary War and up to the...

  4. PREFACE
    (pp. xxi-xxvi)
  5. ACKNOWLEDGMENTS
    (pp. xxvii-xxix)
  6. ONE HEMLOCK’S FUTURE IN THE CONTEXT OF ITS PAST
    (pp. 1-10)

    The long-term history of the forests of the northeastern United States is one of resilience, loss, and recovery. No species—not even American chestnut—captures those dynamics, or the associated lessons for ecology and conservation, like eastern hemlock. Long before chestnut was crippled by an exotic fungal blight, indeed thousands of years before chestnut migrated onto the New England scene following the last ice age, hemlock suffered a range-wide collapse and then recovered as a dominant species.

    By the time European explorers arrived in the New World, hemlock and American beech, its broad-leafed counterpart in shade tolerance and longevity, dominated...

  7. TWO AN ICONIC SPECIES
    (pp. 11-24)

    No other tree species in our eastern landscape exerts such a widespread and profound influence on the environment and other organisms, including ourselves. When we enter a hemlock forest on a sunny day, we sense a change and immediately recognize that we are in a different and special place. The light dims perceptibly, the wind dissipates, and the temperature drops. The ground beneath our feet turns soft and spongy, and the understory opens up around us as the abundance of other plants declines. Stillness reigns. The wooded environment quiets, and singular sounds stand out clearly. Such is a hemlock forest....

  8. Lessons from Harvard Forests and Ecologists I. The Pisgah Forest
    (pp. 25-43)

    One irony of ancient forests and wilderness areas—known for their absence of human imprint—is that the names of many of these great natural areas often conjure up associations with people. Generally, these are individuals who protected the landscape or documented its qualities in ways that enable us to appreciate them today. In these associations there is much to be learned, for although we value nature by itself as a source of inspiration and insight, many lessons and much enjoyment also come from the stories of the people whose lives are entwined with it.

    Nationally, there are many examples...

  9. THREE PREHISTORY TO PRESENT
    (pp. 44-63)

    Some of us never seem to lose the joy of playing in the mud and on the water. Picture a remote New England pond on a beautiful, breezy summer day. The sky is a deep blue and filled with those puffy but solid clouds that may get larger and angrier later in the day. An unlikely research vessel is anchored in the deep center of the pond and tethered in three directions, floating beyond the reach of the mosquitoes buzzing through the red maples and sedges along the shoreline. This makeshift catamaran, constructed by strapping a sheet of plywood across...

  10. FOUR TREE-FALLS AND TANBARK
    (pp. 64-76)

    The dark-crowned groves of hemlock stippling the landscape of southern New England form repositories of a critical forest history, yielding stories of the natural and human-induced destruction and rebirth of these majestic forests. Most tell a familiar second-growth story of hemlock’s devastation by the ax and subsequent resilience, but a select few yield old-growth tomes with lessons of how these forests may have looked and functioned prior to European settlement and how they have weathered the past few centuries of natural dynamics and climate change.

    The last century witnessed an amazing period of interpretation of both of these story lines...

  11. Lessons from Harvard Forests and Ecologists II. Bob Marshall’s Plot
    (pp. 77-92)

    Al Cline gave me your article about the Adirondack Forest Preserve, and I have read it with entire sympathy and agreement. There is no argument about the proposition that to furnish the highest kinds of enjoyment a forest should be left strictly alone. With so little real primeval forest now left, sparing the remnants that still exist in the Adirondacks does not seem too much to ask.

    Your argument gave me a thought about a project, which I have long had in mind, and which might interest you for your investigative work next autumn at Petersham. Not far from there...

  12. FIVE HEMLOCK AS A FOUNDATION SPECIES
    (pp. 93-104)

    We share the earth with approximately ten million other species. Many of these are widespread but infrequently seen: bacteria, fungi, and many insects, along with organisms that live in places that we are unlikely to visit, such as the deep oceans or the canopy of tropical rainforests. Others are superabundant and visible all around us: the common reed, ragweed, kudzu, and many aggressively spreading “invasive species.” Other species are less threatening but no less abundant, such as corn, cows, and potatoes, which have been transported worldwide by people and have established large populations outside their native ranges. But the vast...

  13. SIX A RANGE-WIDE HEMLOCK DECLINE
    (pp. 105-119)

    If you were to look at lake-sediment pollen records from places as far apart as Rogers Lake in southern Connecticut and Gould Pond in central Maine, you’d see similar patterns. Indeed, the records from most New England lakes feature a common sequence of shifts in vegetation that accompanied the changes in regional climate since the last glacier receded. Most of the transitions from one type of vegetation to another happened quite slowly, but a few were abrupt and involved dramatic reorganizations of plant and animal communities and their associated ecological processes.

    Using pollen analysis, paleoecologists have documented these broad trends...

  14. SEVEN INVASION OF AN EXOTIC PEST
    (pp. 120-135)

    In today’s world of global commerce, organisms move freely to new continents and novel ecological settings. At last count, more than 400 forest insects had arrived in North America during the last couple of centuries, a few with devastating consequences. The eastern United States lays unfortunate claim to having experienced many of the textbook collapses of tree species from introduced insects and diseases. The majestic American chestnut, which provided timber, firewood, and nuts to communities from Alabama to Maine, became little more than an understory shrub because of a fungal pathogen from Asia in the early 1900s. Oak trees have...

  15. EIGHT CUT OR GIRDLE
    (pp. 136-152)

    The long-term observational studies of forest change described in the preceding chapter have enabled us to document in detail the natural dynamics and decline of hemlock forests throughout New England. These observations continue to be critical for understanding possible future conditions of our forests. They also provide a wealth of insights that can guide land managers and policy makers, and that we regularly use in discussions with owners, foresters, and conservation organizations. By their nature, we have had little control over the timing and logistics of these studies other than making the commitment to undertake them. We cannot decide when...

  16. NINE MODELING THE DYNAMICS OF A FOREST GIANT
    (pp. 153-164)

    In 1997 University of New Hampshire professor and longtime Harvard Forest collaborator John Aber wrote an editorial in theBulletin of the Ecological Society of Americawith the title “Why Don’t We Believe the Models?” He lamented that insights gleaned from ecological models rarely interested his colleagues, who were mostly field researchers. When he initiated discussions “from a modeling perspective,” they often deteriorated into what he termed “the glazed-model-gaze.” The ambivalence to and distrust of models differed from attitudes in most other scientific fields, where quantitative model predictions and verification of those predictions are central to the whole research endeavor....

  17. TEN REPRISE: EASTERN HEMLOCK AS A FOUNDATION SPECIES
    (pp. 165-171)

    Throughout this book, we have referred to eastern hemlock as a foundation species—a species that creates its own ecosystem literally from the ground up; dominates the system in terms of numbers and mass; and is intimately linked to the majority of other species in the system. These characteristics of a foundation species lead us to perceive and recognize it as an inseparable part of the system—we know it when we see it—but for scientists there is an important difference between thinking (or hypothesizing) that something is so and demonstrating that it is indeed so. Strictly speaking, in...

  18. Lessons from Harvard Forests and Ecologists III. The Earl Stephens Plot
    (pp. 172-180)

    These days, hikers tromp right by the spot on the heavily shaded path. With eyes drawn not to the dark depths of the old hemlock woods but toward the bright expanse of Harvard Pond just a few feet off the trail, most people miss the thirty-five-foot-wide strip of paper birch and red maple that heads upslope through the woods. Only in the winter does this narrow stand jump out. Then, on sunny days when the snow catches in the canopy of the ancient hemlocks and leaves the ground beneath them a dull gray brown, the narrow band of young hardwoods...

  19. ELEVEN WHEN DOING NOTHING IS A VIABLE ALTERNATIVE: INSIGHTS INTO CONSERVATION AND MANAGEMENT
    (pp. 181-203)

    It is a poignant image. The date is late September 1938, just days after the Great Hurricane swept across New England, laying forests flat, ripping roofs, cupolas, and steeples from buildings, and turning thousands of boats into flotsam. Most of the timber visible on the Harvard Forest was uprooted or damaged, and the fate of three decades of research and experiments lay in uncertain condition, deep and inaccessible in the tangle of ravaged woods. The photograph captures Al Cline, the Forest’s acting director, leaning against an immense prostrate white pine, gazing across a scene of unimaginable chaos. While he clearly...

  20. Lessons from Harvard Forests and Ecologists IV. Three Views from John Sanderson’s Woodlot
    (pp. 204-223)

    It is likely the most famous farm in the scholarly fields of ecology and environmental history. When Hugh Raup transformed the slide show–based lecture that he had presented to enthusiastic audiences for years and published it in 1966 as “The View from John Sanderson’s Farm: A Perspective for the Use of the Land,” he produced an instant success for the journalForest Historyand opened the eyes of people in many disciplines. The article used the Harvard Forest dioramas and the history of colonial management of the farm that became the Harvard Forest to insist on the critical need...

  21. TWELVE LAMENT
    (pp. 224-230)

    Every hike through the hemlocks at the Harvard Forest these days lends to an ongoing voyage in self-exploration. Like all groves of this great species, the environment is still and inspiring: cool in the heat of summer; eerie with a low mist hanging above the snow on a warm winter morning; and thick with darkness cut by shafts of bright light whenever the sun shines brilliant above the dense foliage. The magic of these woods persists, and the awareness of their past as primeval forest, colonial woodlot, and inspiration for creative people of all types adds a deep temporal dimension...

  22. BIBLIOGRAPHIC ESSAYS
    (pp. 231-268)
  23. REFERENCES
    (pp. 269-292)
  24. List of Contributors
    (pp. 293-294)
  25. INDEX
    (pp. 295-306)