crops – and, worse, the seeds used to plant them – were difficult to keep separate from the weeds that grew in their midst. As early as 1652, settlers in New Haven Colony were debating whether something could be done “to prevent the spreding of sorrill in the corne feilds,” but did so to no avail. Many of these European weeds – to say nothing of grains, vegetables, and orchard trees – would eventually be among the commonest plants of the American landscape, their populations sustained in all places by the habitats human beings and domesticated animals created for them.27
Although the invasion of livestock was sustained by the parallel invasion of edible plants, the two were rarely in perfect balance, at least in the eyes of colonists who for economic reasons sought to raise more animals. Livestock production expanded throughout New England in the eighteenth century and brought with it regular complaints about pasture shortages. By 1748, the Connecticut agricultural writer Jared Eliot was commenting that “the scarcity and high price of hay and corn is so obvious, that there are few or none Ignorant of it.” The shortage of hay, he said, had been “gradually increasing upon us for sundry Years past,” and was the direct result of livestock populations outgrowing available meadowlands. If pastures were inadequate, old and new settlements alike had to follow the process of forest clearing described in the preceding chapter, planting corn and rye before the unplowed soil was finally ready to be seeded with English grasses. During the eighteenth century, the range of grasses which were raised for moving was extended to include such species as timothy, red clover, lucerne (alfalfa), and fowl-meadow grass, all of which rapidly became common throughout the colonies.28
Where mowing was unnecessary and grazing among living trees was possible, settlers saved labor by simply burning the forest undergrowth – much as the Indians had once done – and turning loose their cattle. But because English livestock grazed more closely and were kept in denser concentrations than the animals for whom Indians had burned the woods, English pastoralism had the effect of gradually shifting the species composition of any forest used for pasture. In at least one ill-favored area, the inhabitants of neighboring towns burned so frequently and grazed so intensively that, according to Peter Whitney, the timber “was greatly injured, and the land became hard to subdue. Hurtleberry and whitebush sprung up, together with laurel, sweetfern, and checker-berry, which nothing but the plough will destroy.” In the long run, cattle tended to encourage the growth of woody, thorn-bearing plants which they could not eat, and which, once established, were very difficult to remove. Such plants had to be cleared regularly with a scythe or grub hoe if they were not to take over a pasture entirely. The only other way of dealing with them was to graze sheep heavily in areas which the bushes had taken over; the flocks sometimes succeeded in reclaiming land that had otherwise become useless.29
The tree species of the uplands were also affected by grazing, especially when exhausted fields were allowed to revert to wooded pastures. Hemlocks, whose shallow root systems were very sensitive to fire, tended to disappear from all woods that were burned for pasture. Where they were protected from fire, on the other hand, grazing encouraged their growth by destroying the more edible hardwood species that would otherwise have competed with them, so that hemlocks then became the dominant species of north-facing slopes. When land was initially cleared, whether for crops or pasture, the removal of existing trees had the effect of releasing the dormant seeds of certain species that preferred full sunlight and open growing conditions. Pin cherry was one of these. Timothy Dwight told of a farmer in Vermont in whose fields “there customarily sprung up … an immense multitude of cherry trees,” even though the surrounding forest was composed entirely of beech, hemlock, and maple. Red cedar also often acted as a pioneer on cleared lands.30
Which species invaded which fields depended primarily upon whether or not grazing animals were allowed on the land. The ecological effects of pasturing and clearing on forest composition could become quite complex. In oak and birch forests that were cut for lumber and fuel, for instance, these two tree species were able to regenerate themselves by sprouting from their roots and stumps, and could be cut again in as little as 14 years. Cyclical cutting of this kind – known as a coppice system – was common among colonial farmers, and strongly favored hardwood species, which could sprout, over conifers, which could not. Coppice cutting was a major reason that chestnuts, which were prolific sprouters, increased their relative share of New England forests following European settlement. But if sprout hardwood forests were used for pasture after being cut, the sprouts were destroyed by being grazed, and the less edible white pine often came up instead. Conversely, white pines – which could not sprout but compensated for this by producing enormous quantities of airborne seeds – failed to regenerate themselves unless pasturing took place, because of their need for full sunlight and their inability to compete with hardwood species. The same was true of red cedar. In southern New England, abandoned croplands were more often than not invaded by gray birch; abandoned pastures, on the other hand, were taken over by red cedar and white pine.31
Livestock not only helped shift the species composition of New England forests but made a major contribution to their long-term deterioration as well. If colonial lumberers made sure that woods were stripped of their largest and oldest trees, grazing animals made sure that those trees were rarely replaced. Benjamin Lincoln wrote with some emotion when he argued:
We suffer exceedingly at this day by the ill judged policy of permitting the cattle to run at large in the woods, especially in the full settled towns. Those tracts reserved for building, timber, fence-stuff, and fuel, are constantly thinning, and many of them are ruined as wood land, there are so large a proportion of cattle turned out, compared with the plants which come up in the spring, and the shoots which appear around the stumps of trees fallen the year before.
To Lincoln, allowing animals to graze in the woods was to let trees be “wantonly destroyed,” and he sought to show that doing so was actually “more expensive and injurious to the common interest, than if lands were ploughed, and grain sowed, on which they might feed.”32
Lincoln’s concern was well-founded. Wherever the English animals went, their feet trampled and tore the ground. Because large numbers of them were concentrated on relatively small tracts of land, their weight had the effect of compacting soil particles so as to harden the soil and reduce the amount of oxygen it contained. This in turn curtailed the root growth of higher plants, lowered their ability to absorb nutrients and water, and encouraged the formation of toxic chemical compounds. Soil compaction, in other words, created conditions that were less hospitable to plant life and eventually lowered the soil’s carrying capacity for water. (One of the things that distinguished European clover and timothy grass from other plants was precisely their ability to live on severely compacted soils containing little oxygen.) Ironically, then, an additional effect of woodland grazing was to kill many of the plants on which livestock depended for food, so that animals ran out of browse before their grazing season was over. Their survival in these circumstances depended on the colonists’ efforts to open new pastures, create additional hay meadows, or cultivate more grain crops. Pasture deterioration was thus an incentive for still more intensive colonial deforestation.33
But the greatest effect of domesticated animals on New England soils came in the one area from which they were systematically excluded during most seasons of the year: croplands. Precolonial Indian women had had only their hoes and their own hands to turn the soil; the colonists, on the other hand, could use their oxen and horses to pull plows, which stirred the soil much more deeply. Plowing destroyed all native plant species to create an entirely new habitat populated mainly by domesticated species, and so in some sense represented the most complete ecological transformation of a New England landscape. Animals made it possible for a single colonial family to farm much larger areas than their Indian predecessors had done. Moreover, colonial farmers, because of their fixed notions of property ownership, continued to plow the same fields years after Indians would have abandoned them. The intimate connection between grazing animals, plows, and fixed property lay at the heart of European agriculture, with far-reaching ecological consequences.34
Whatever the causes that reduced the ground cover of New England soils, the long-term effect was to put those soils in jeopardy. The removal of the forest, the increase in destructive floods, the soil compaction and close-cropping