The Forest Unseen: A Year's Watch in Nature by DavidGeorge Haskell Read Free Book Online Page A

arrival of humans on this continent. Temperate forest has been growing in eastern North America for the last fifty million years. In those ancient times, the forest grew in a thick band across Asia, North America, and Europe. This swath was cut into fragments by the cooling of the earth’s climate, especially by the periodic ice ages that pushed temperate forests southward, then drew them northward as the ice retreated. Now, the remnants of this forest grow in widely separated patches in eastern China, Japan, Europe, the Mexican highlands, and eastern North America. The temperate forest’s dance across the continents has one unvarying theme: the presence of mammalian browsers, often in large numbers.
    The deer that walked across the mandala is one of the last representatives of a much larger plant-trimming bestiary. Giant ground sloths hulked their rhino-sized bodies around the forest, browsing vegetation. They were accompanied by woodland musk oxen, giant herbivorous bears, long-nosed tapirs, peccaries, woodland bison, several species of extinct deer and antelope, and, most dramatic of all, the mastodons. The mastodons were relatives of the modern elephant, with tusks and a broad, low head. They stood three meters tall at the shoulder and browsed through the northern edge of the eastern forest. They, like many other large herbivores, went extinct at the end of the last ice age, about eleven thousand years ago. The ice ages had come and gone before, but this thaw brought with it a new predator, humans. Shortly after the arrival of humans, most of the large herbivores were gone. The smaller mammals were minimally affected by this extirpation; only large, meaty creatures disappeared.
    Fossil evidence of these large herbivores abounds in caves and swamps across the eastern United States. These fossils provided fuel for the nineteenth-century debate about evolution. Darwin thought these animals were further evidence for the idea that the natural world is always in flux. He commented, “It is impossible to reflect on the state of the American continent without astonishment. Formerly it must have swarmed with great monsters; now we find mere pygmies comparedto the antecedent, allied races.” Thomas Jefferson disagreed, believing that giant sloths and other creatures must still be alive. After all, why would God create them, then kill them off? Creation reflected God’s perfect handiwork, therefore nature would unravel if pieces were allowed to fall away. Jefferson instructed the explorers Lewis and Clark to bring back reports of these creatures from their trek to the Pacific coast. The expedition found no evidence of living mastodons, sloths, or any other extinct creatures. Darwin was right; pieces of creation can be destroyed.
    Like the footprints left by the deer’s visit to the mandala, the passing herbivores have left signs in the architecture of some of our native plants. Honey locust and holly trees have thorny stems and leaves. These thorns are deployed only to three meters’ height, twice as high as any living herbivore can reach but exactly the right height to deter the extinct mega-browsers. The honey locust is doubly lost because its seedpods, which are two feet long, are too large for any living native species to consume whole and thus disperse the seeds, although they are perfectly sized for large extinct herbivores such as mastodons and ground sloths. Osage orange’s milky softball is another fruit whose seed-dispersing partner has died. Similar fruits on other continents are eaten by elephants, tapirs, and other large herbivores of the kind that exist only as fossils in North America. These widowed plants wear history on their sleeves, giving us a glimpse into the bereavement of the whole forest.
    The structure of ancient forests is forever hidden from us, but the bones of extinct browsers and the stories of the first Americans suggest that this was not an easy place for shrubs and saplings to thrive. North