The World of Northern Evergreens, Second Edition

The World of Northern Evergreens, Second Edition

E. C. Pielou
Copyright Date: 2011
Edition: 2
Published by: Cornell University Press,
Pages: 168
https://www.jstor.org/stable/10.7591/j.ctt7z9q3
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  • Book Info
    The World of Northern Evergreens, Second Edition
    Book Description:

    Global warming and human-driven impacts from logging, natural gas drilling, mining of oil sands, and the development of hydropower increasingly threaten North America's northern forests. These forests are far from being a uniform environment; close inspection reveals that the conifers that thrive there-pines, larches, spruces, hemlocks, firs, Douglas-firs, arborvitaes, false-cypresses, junipers, and yews-support a varied and complex ecosystem. In The World of Northern Evergreens, the noted ecologist E. C. Pielou introduces the biology of the northern forests and provides a unique invitation to naturalists, ecologists, foresters, and everyone living in northern North America who wants to learn about this unique and threatened northern world and the species that make it their home.

    Through identification keys, descriptions, and life histories of the conifer tree species, the author emphasizes how different these plants are both biologically and evolutionarily from the hardwoods we also call "trees." Following this introduction to the essential conifers, the author's perceptive insights expand to include the interactions of conifers with other plants, fungi, mammals, birds, and amphibians.

    The second edition, enriched by new illustrations by the author of woodland features and creatures, updates the text to include new topics including mycorrhizal fungi, soil, woodlice, bats, and invasive insects such as the hemlock woolly adelgid. Emphasis is given to the very real human-driven impacts that threaten the species that live in and depend on the vital and complex forest ecosystem. Pielou provides us with a rich understanding of the northern forests in this work praised for its nontechnical presentation, scientific objectivity, and original illustrations.

    eISBN: 978-0-8014-6303-7
    Subjects: Ecology & Evolutionary Biology

Table of Contents

  1. Front Matter
    (pp. i-vi)
  2. Table of Contents
    (pp. vii-viii)
  3. Preface to the Second Edition
    (pp. ix-x)
    E. C. Pielou
  4. Preface to the First Edition
    (pp. xi-xiv)
    E. C. Pielou
  5. Chapter 1 Origin of the Evergreen Forests
    (pp. 1-6)

    Of all the people who enter a northern forest, only a handful ever ask themselves these two questions: Where has the forest come from? And why are the great majority of its trees conifers rather than deciduous, broadleafed trees—“broadleafs” for short.

    The answers are by no means obvious. The questions have engaged the interests of ecologists and motivated years of research. What has been investigated and measured is not, for the most part, observable on a hike in the woods, but the hike would certainly be more interesting for somebody knowing about the questions, and the answers that have...

  6. Chapter 2 Identifying the Conifers
    (pp. 7-34)

    The trees considered in this book are the evergreen cone-bearing trees of once-glaciated North America, plus the larches (which aren’t evergreen) and the junipers and yews (whose cones resemble berries). The shrub junipers and yews (for not all junipers and yews are trees) are mentioned in passing. What unites these plants in the botanical sense is explained in chapters 3 and 4. That they form a cohesive group, resembling one another much more closely than any of them resembles a broadleaf tree, nobody would deny. The resemblances among some of them are very close, making it necessary to examine them...

  7. Chapter 3 Reproduction of Conifers
    (pp. 35-42)

    An ovule is a seed before it is fertilized by pollen; only after fertilization does the ovule develop into a seed that matures until it is capable of germination. So far we have considered only seed cones. Now we come to pollen cones and pollen.

    Pollen cones (figures 3.1 and 3.2) are smaller than seed cones and do not persist for nearly as long. They shrivel and dry up as soon as the pollen has been shed in spring. Although most of the pollen cones soon fall off the trees, dried up, dark brown pollen cones can still be found...

  8. Chapter 4 The Life and Growth of a Conifer
    (pp. 43-58)

    Conifers and broadleafs differ greatly in their internal organs, most noticeably their wood. In all trees, the trunk and branches contain tubes to carry liquids up and down the tree, from roots to leaves and back. The tubes leading upward, plus (in some trees) strengthening fibers, constitute the wood, technically, the xylem. The tubes leading downward, and carrying dissolved sugars from the leaves to the rest of the tree, constitute the phloem. Unlike xylem, there is no popular name for phloem. It will become clear later why xylem (that is, wood) and phloem, in spite of their being equally necessary...

  9. Chapter 5 Broadleafs Growing among the Conifers
    (pp. 59-66)

    Although evergreens dominate the northern forests, a few broadleafs are found with them, and they are the subject of this chapter. The trees and shrubs considered here are those living in the harsh climate of the true north, not those in the mixed forests of the St. Lawrence valley and southern Great Lakes where climate and soils are hospitable to many broadleafs. The broadleafs described here play an important part in the coniferous forests.

    They belong to four genera: the willows (Salix), the poplars (Populus), the birches (Betula), and the alders (Alnus). Shrubs as well as trees of these genera...

  10. Chapter 6 Two Kinds of Trees: Conifers and Broadleafs
    (pp. 67-73)

    We have now taken a detailed look at the dominant trees in the northern evergreen forests—conifers—and a cursory look at the few deciduous trees that grow there with them—broadleafs. It is time to consider the contrast between the two kinds of tree. Not all conifers are evergreen (think of the larches), and not all broadleafs are deciduous (think holly). The differences between them are profound, so profound that it is ludicrous, nowadays, to lump them collectively as “trees.” Using one word for a combination of two such entirely different entities is inappropriate in the light of modern...

  11. Chapter 7 Life on the Forest Floor
    (pp. 74-83)

    The forest floor consists chiefly of soil, which makes it a good place to start. By tradition, northern forest soil is described as “poor,” which it obviously isn’t for conifers. It simply means poor for agriculture.

    One of the most distinctive soils is podsol, the typical soil in conifer forests. (For brevity, let’s ignore the fact that its modern name is “spodosol.”) This soil is easily recognizable if you expose it by digging a hole, or even more easily by seeing it exposed in an eroding stream bank. It has a thin, dark top layer of packed needle-leaf litter gradually...

  12. Chapter 8 Parasites on the Conifers
    (pp. 84-92)

    Indisputably beneficial fungi, as described in chapters 4 and 7, are those that unite with tree roots to form mycorrhizae. Now we come to wooddestroying fungi, those that cause wood to rot, decompose, or decay—all three words mean the same. These fungi are discussed in innumerable books devoted to tree “diseases,” describing the damage they do to timber. However, they are vitally necessary in the maintenance of living, growing forests. Without them, dead woody debris, fallen trees, logs, branches, and twigs would accumulate on the forest floor year after year without end. Just visualize it—only then can the...

  13. Chapter 9 Insects and Conifers
    (pp. 93-107)

    Coniferous trees are home to a variety of different insects. Their presence adds to the biodiversity of evergreen forest ecosystems, and for that we can be thankful. At the same time, a conifer forest in which nearly all the trees are home to millions of a particular species of bark beetle is a doomed forest that will soon disappear. Such a species is defined, by some people, as a “pest.” That is a judgment, not a definition, but for brevity the quotation marks around “pest” will be omitted in what follows.

    This chapter is primarily concerned with pest insects because...

  14. Chapter 10 Some Mammals and Birds of the Forest
    (pp. 108-124)

    All warm-blooded animals need food and shelter, and some find what they need, in whole or in part, in coniferous forests. What have the forests to offer?

    The most dependable food supplies are seeds and browse for the herbivores. For the carnivores, there are worms, sowbugs, insects, spiders, any vertebrate animals that they can catch and kill, and accessible birds’ eggs.

    Shelter is needed for four purposes: for breeding, for sleeping and resting, for shelter from bad weather, and for concealment. Evergreen trees, both live and dead, provide for these needs. The variety of small animals that can use suitable...

  15. Chapter 11 Natural and Unnatural Interference
    (pp. 125-137)

    Thus far we have considered only the interactions between coniferous trees and other living things. Now we come to their interactions with the nonliving: fires, the weather, and machinery. (Humans without machinery are almost harmless. With it, they are the most serious forest pests on the planet.)

    The effect of fire on individual trees is injury or death; its effect on forests is to bring about forest renewal. Fire, like decay, disposes of dead vegetation. Without fires, as noted in chapter 8, the forest floor would become an impenetrable tangle of fallen trees, broken branches, and withered and rotting vegetation...

  16. Chapter 12 The Big Picture
    (pp. 138-142)

    Now that we have considered in detail the conifers and the ecosystems they create, it is time to see how this can be summarized by mapping the geographic extent of the ecosystems, and coincidentally the areas of dominance of one or more identifying conifer species. The result is a mosaic of “regions.” As ecologists well know, when you try to define boundaries between ecosystems, either in words or graphically on a map, a large number of rather subjective choices have to be made. Usually, there are no clear, natural boundaries, and the ones drawn on a map are unavoidably arbitrary....

  17. Chapter 13 Global Warming and the Forests
    (pp. 143-152)

    The fact that the climate is warming because of the buildup of greenhouse gases in the atmosphere is generally accepted.

    To begin, note that what is happening is called both “climate change” and “global warming.” Take your choice. The merit of the term “climate change” is that it allows for gaps in the warming; it doesn’t sound like nonsense when an unusually cold spell strikes in a limited area. It also emphasizes that rising temperatures in most of the world are not the only change: precipitation and winds are changing too. In any case, there’s no need to use one...

  18. Index
    (pp. 153-156)