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Harvesting the Biosphere

Harvesting the Biosphere: What We Have Taken from Nature

Vaclav Smil
Copyright Date: 2013
Published by: MIT Press
Pages: 320
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  • Book Info
    Harvesting the Biosphere
    Book Description:

    The biosphere -- the Earth's thin layer of life -- dates from nearly four billion years ago, when the first simple organisms appeared. Many species have exerted enormous influence on the biosphere's character and productivity, but none has transformed the Earth in so many ways and on such a scale as Homo sapiens. In Harvesting the Biosphere, Vaclav Smil offers an interdisciplinary and quantitative account of human claims on the biosphere's stores of living matter, from prehistory to the present day. Smil examines all harvests -- from prehistoric man's hunting of megafauna to modern crop production -- and all uses of harvested biomass, including energy, food, and raw materials. Without harvesting of the biomass, Smil points out, there would be no story of human evolution and advancing civilization; but at the same time, the increasing extent and intensity of present-day biomass harvests are changing the very foundations of civilization's well-being.In his detailed and comprehensive account, Smil presents the best possible quantifications of past and current global losses in order to assess the evolution and extent of biomass harvests. Drawing on the latest work in disciplines ranging from anthropology to environmental science, Smil offers a valuable long-term, planet-wide perspective on human-caused environmental change.

    eISBN: 978-0-262-31226-4
    Subjects: General Science, Environmental Science

Table of Contents

  1. Front Matter
    (pp. i-iv)
  2. Table of Contents
    (pp. v-vi)
  3. Preface
    (pp. vii-viii)
  4. I The Earth’s Biomass:: Stores, Productivity, Harvests

    • [I Introduction]
      (pp. 1-4)

      In December 1990, theGalileospacecraft came as close as 960 km to the Earth’s surface in order to get a gravitational assist from the planet on its way to Jupiter. This flyby was used by Sagan et al. (1993) as an experiment in the remote detection of life on Earth: just imagine that the spacecraft, equipped with assorted detection devices, belonged to another civilization, and registers what its beings could sense. The three phenomena indicating that this planet was very different from all others in its star system were a widespread distribution of a pigment, with a sharp absorption...

    • 1 Biomass: Definitions and Compositions
      (pp. 5-14)

      The classic life sciences—botany, zoology, plant and animal anatomy and physiology—were for centuries preoccupied with classification. This concern was later extended to life’s assemblages, that is (in ascending order), communities, ecosystems, and biomes. Such a focus is now seen as antiquated: the preoccupation has shifted to the intricacies of genetic makeup and metabolism and to the dynamic processes of evolution and adaptation. An undesirable side effect of this shift has been a lack of attention to the precise meanings of many variables used to describe organisms and their evolution. This declining rigor is not a trivial matter, as...

    • 2 Biomass Stores: Means and Extremes
      (pp. 15-30)

      In contrast to regularly conducted inventories of wood volumes in commercially exploited forests and the frequent (now satellite-aided) monitoring of crop productivity, accurate quantifications of phytomass in natural ecosystems remain relatively uncommon. But they do support some easily defensible generalizations, illustrate some important exceptions, and help correct some stereotypes. These assessments are usually presented in units of dry matter per unit area (g/m² or t/ha) or as the total mass of carbon (g C/m² or t C/ha). Our knowledge also remains highly uneven in spatial terms as temperate ecosystems have been studied much more intensively than the tropics. Integrations on...

    • 3 Biomass Productivities
      (pp. 31-40)

      The biosphere’s productivity can be quantified as a cascading series of variables: the most inclusive ones, the two rates at the cascade’s top, gross and net primary productivity, cannot be measured directly and can be quantified (far from accurately) only thanks to our improved understanding of photosynthetic processes, the environmental responses of autotrophs, and the properties of plant metabolism. In contrast, the rates at the cascade’s end can be readily measured in mass or energy terms (although in practice they are often estimated on the basis of limited field sampling): crop yields (expressed mostly in t/ha) and timber harvests (commonly...

    • 4 Phytomass Harvests
      (pp. 41-50)

      Modern phytomass harvests fit mostly into four distinct categories. Food harvests have been transformed as humans have evolved from simple foragers collecting edible plants, hunting animals, and catching aquatic species to agriculturalists relying first on extensive shifting cultivation and later on intensive methods of farming, including large-scale domestication of animals and worldwide fishing efforts. Phytomass use as fuel was relatively limited in all foraging societies, but it increased with a sedentary existence and with the use of wood and charcoal in the production of metals. Because the evolution of agriculture also involved the domestication of animals, the third major purpose...

    • 5 Zoomass Harvests
      (pp. 51-58)

      Terrestrial trophic pyramids are invariably broadly based, with phytomass (primary producers) being commonly 20 times more abundant than the mass of herbivores (primary consumers), and the zoomass in the highest trophic level (this may be the third level in the simplest ecosystems, and only a few terrestrial communities go beyond the fifth level) may be equal to just 0.001% of the phytomass. These realities limit the mass of heterotrophs that could be profitably hunted (or collected): many small herbivores (insects, rodents) are not worth the effort, while the largest carnivores are too scarce and too dangerous to hunt. The situation...

    • 6 Land Cover and Productivity Changes
      (pp. 59-64)

      For a few million years of their early evolution, hominins made a limited claim on the biosphere, as they foraged for food and ate it raw. This began to change with the controlled use of fire for cooking and defense against predatory animals. Inevitably, this led to accidental fires, whose unchecked progress added to the phytomass destruction that had been taking place naturally by fires ignited by lightning. Eventually, humans began to use fire for other than immediate food and security needs, above all to clear forested land for shifting cultivation and later to open up new areas for permanent...

  5. II History of the Harvests:: From Foraging to Globalization

    • [II Introduction]
      (pp. 65-70)

      The predecessor species belonging to our genus—starting withHomo habilis,who appeared nearly 2.5 million years ago—spent all of their evolution as simple heterotrophs. Our species,Homo sapiens, has spent no less than 95% of its evolution (assuming it evolved by about 200,000 years ago) in a similarly simple foraging mode. All of these hominins gathered edible phytomass (tubers, stalks, leaves, fruits, grains, nuts), collected small heterotrophs (mushrooms, insects, small invertebrates, mollusks), hunted a variety of animals (mainly herbivorous species), and caught fish and aquatic mammals. Given the length of these experiences and the variety of environments they...

    • 7 The Evolution of Foraging
      (pp. 71-102)

      A reliable quantification of the resulting impact on the biosphere is impossible, as we lack any realistic assessments of total populations engaged in specific foraging activities, but there can be no doubt that in parts of several biomes (in the richest tropical rain forests and in boreal forests), it remained marginal for millennia. The relative richness of the coastal aquatic zoomass meant that some maritime regions were among the most intensively exploited environments. Cold and hot deserts and their neighboring transitional zones to more vegetated environments were at the other end of the diversity spectrum: a paucity of both collectible...

    • 8 Crops and Animals
      (pp. 103-130)

      The most important force driving the evolution from foraging to crop cultivation and the domestication of animals is clear: gathering and hunting cannot support population densities higher than about one person per square kilometer, even in benign environments with abundant standing biomass. As the numbers of early Holocene humans began to increase, they gradually turned to more intensive ways of food procurement, to what are—in comparison with later traditional agricultures, and even more so with modern farming—still rather extensive ways of growing crops and rearing animals for meat and milk. Given the enormous variety of environments and dominant...

    • 9 Biomass Fuels and Raw Materials
      (pp. 131-150)

      Wood supplied virtually all the energy needed for space and water heating, cooking, and a growing range of artisanal manufactures and industrial processes for far longer than most people think. Fossil fuels were known, both in Asia and in Europe, since antiquity, but the first society in which coal became more important than wood was England of the early seventeenth century—and that remained a great exception. Reasonably reliable estimates and actual output statistics show that in France, coal began to supply more than half of all fuel needs only sometime during the mid-1870s, and in the United States the...

  6. III Adding Up the Claims:: Harvests, Losses, and Trends

    • [III Introduction]
      (pp. 151-156)

      Three fundamental limitations make any large-scale, long-term accounting of human claims on the biosphere’s production challenging—and uncertain. First, these claims belong to three different categories that might simply be labeled extraction, management, and destruction, but a closer look shows that there are overlaps and blurred boundaries. Second, no single measure can adequately express the increasing extent and the overall magnitude of human claims on the biosphere. Third, although a combination of several revealing variables provides a better assessment of these claims, it does not bring a fully satisfactory appraisal because of the many uncertainties in quantifying the natural baselines...

    • 10 Changing Land Cover and Land Use
      (pp. 157-182)

      The most obvious, and conceptually the simplest, indicator of the human impact on the biosphere’s productivity and phytomass storage is the total area of the natural ecosystems that have been transformed by human action. To put these changes into an evolutionary context, I will begin with a brief review of phytomass storage during the past 20 millennia, since the last glacial maximum (LGM), when North America north of 50°N and much of Europe beginning at only a slightly higher latitude were covered by massive continental glaciers. Primary productivity and carbon strongly rebounded during the next 15 millennia, reaching maxima by...

    • 11 Harvesting the Biosphere
      (pp. 183-220)

      In an attempt to quantify what clearly appeared to be a disproportionate share of the Earth’s photosynthetic production that is claimed (directly and indirectly) by its most sapient species, Vitousek et al. (1986) chose net primary productivity (NPP) as the baseline and expressed the overall effect of harvests and modifications as the fraction of NPP appropriated by humans. A very wide range of possible appropriations offered by that paper—from as little as 3% for their low calculation to as much as 40% for their high estimate—made its use for any heuristic purposes, and even more so for any...

    • 12 Long-Term Trends and Possible Worlds
      (pp. 221-252)

      Our species has evolved to become the planet’s dominant heterotroph in what has been (when measured on the biospheric time scale of more than three billion years) a very brief period of time. Less than 2.5 million years have elapsed since the emergence of our genus (withHomo habilis), our species became identifiable about 200,000 years ago, and shortly after the end of the last glaciation (less than 10,000 years ago) various societies began to move from subsistence foraging to settled existence energized by harvesting cultivated plants and domesticating animals. Afterward our capacities for expansion, extraction, production, and destruction began...

  7. Scientific Units and Prefixes
    (pp. 253-254)
  8. References
    (pp. 255-296)
  9. Subject Index
    (pp. 297-304)
  10. Species Index
    (pp. 305-308)