prehistory. The pines occur today where there has been clearing followed by regular burning and the same is likely in the past. The Nicaraguan pines are fire tolerant once mature, and large numbers of seedlings survive to maturity if they can escape fire during their first three to seven years (Denevan 1961, 280). Where settlement has been abandoned and fire ceases, mixed hardwoods gradually replace pines. This succession is likely similar where pines occur else-where at low elevations in tropical Central America, the Caribbean, and Mexico.
Midwest Prairies and Tropical Savannas
Sauer (1950, 1958, 1975) argued early and often that the great grass-lands and savannas of the New World were of anthropogenic rather than climatic origin, that rainfall was generally sufficient to support trees. Even nonagricultural Indians expanded what may have been pockets of natural, edaphic grasslands at the expense of forest. A fire burning to the edge of a grass/forest boundary will penetrate the drier forest margin and push back the edge, even if the forest itself is not consumed (Mueller-Dombois 1981, 164). Grassland can therefore advance significantly in the wake of hundreds of years of annual fires. Lightning-set fires can have a similar impact, but more slowly if less frequent than human fires, as in the wet tropics.
… Most ecologists now believe that the eastern prairies “would have mostly disappeared if it had not been for the nearly annual burning of these grasslands by the North American Indians,” during the last 5,000 years. A case in point is the nineteenth-century invasion of many grasslands by forests after fire had been suppressed in Wisconsin, Illinois, Kansas, Nebraska, and elsewhere (M. Williams 1989a, 46).
The large savannas of South America are also controversial as to origin. Much, if not most of the open vegetation of the Orinoco Llanos, the Llanos de Mojos of Bolivia, the Pantanal of Mato Grosso, the Bolívar savannas of Colombia, the Guayas savannas of coastal Ecuador, the campo cerrado of central Brazil, and the coastal savannas north of the Amazon, is of natural origin. The vast campos cerrados occupy extremely senile, often toxic oxisols. The seasonally inundated savannas of Bolivia, Brazil, Guayas, and the Orinoco owe their existence to the intolerance of woody species to the extreme alternation of lengthy flooding or water-logging and severe desiccation during a long dry season. These savannas, however, were and are burned by Indians and ranchers, and such fires have expanded the savannas into the forests to an unknown extent. It is now very difficult to determine where a natural forest/savanna boundary once was located (Hills and Randall 1968; Medina 1980).
Other small savannas have been cut out of the rainforest by Indian farmers and then maintained by burning. An example is the Gran Pajonal in the Andean foothills in east-central Peru, where dozens of small grasslands (pajonales) have been created by Campa Indians – a process clearly documented by air photos (Scott 1978). Pajonales were in existence when the region was first penetrated by Franciscan missionary explorers in 1733.
The impact of human activity is nicely illustrated by vegetational changes in the basins of the San Jorge, Cauca, and Sinú rivers of northern Colombia. The southern sector, which was mainly savanna when first observed in the sixteenth century, had reverted to rainforest by about 1750 following Indian decline, and had been reconverted to savanna for pasture by 1950 (Gordon 1957, map p. 69). Sauer (1966, 285–88; 1975, 8) and Bennett (1968, 53–55) cite early descriptions of numerous savannas in Panama in the sixteenth century. Balboa’s first view of the Pacific was from a “treeless ridge,” now probably forested. Indian settlement and agricultural fields were common at the time, and with their decline the rainforest returned.
Anthropogenic Tropical Rain Forest
The tropical rain forest has long had a reputation for being pristine, whether in 1492 or 1992. There is, however, increasing evidence that the forests of Amazonia and elsewhere are largely anthropogenic in form and composition. Sauer (1958, 105) said as much at the Ninth Pacific Science Congress in 1957 when he challenged the statement of tropical botanist Paul Richards that, until recently, the tropical forests have been largely uninhabited, and that prehistoric people had “no more influence on the vegetation than any of the other animal inhabitants.” Sauer countered that Indian burning, swiddens, and manipulation of composition had extensively modified the tropical forest.
“Indeed, in much of Amazonia, it is difficult to find soils that are not studded with charcoal” (Uhl et al. 1990, 30)….
The Amazon forest is a mosaic of different ages, structure, and composition resulting from local habitat conditions and disturbance dynamics (Haffer 1991). Natural disturbances (tree falls, landslides, river activity) have been considerably augmented by human activity, particularly by shifting cultivation. Even a small number of swidden farmers can have a widespread impact in a relatively short period of time....
Indian modification of tropical forests is not limited to clearing and burning. Large expanses of Latin American forests are humanized forests in which the kinds, numbers, and distributions of useful species are managed by human populations.
…There are no virgin tropical forests today, nor were there in 1492.
Wildlife
The indigenous impact on wildlife is equivocal. The thesis that “over-kill” hunting caused the extinction of some large mammals in North America during the late Pleistocene, as well as subsequent local and regional depletions (Martin 1978, 167–72), remains controversial. By the time of the arrival of Cortéz in 1519, the dense populations of Central Mexico apparently had greatly reduced the number of large game, given reports that “they eat any living thing” (Cook and Borah 1971–79, (3) 135, 140). In Amazonia, local game depletion apparently increases with village size and duration (Good 1987). Hunting procedures in many regions seem, however, to have allowed for recovery because of the “resting” of hunting zones intentionally or as a result of shifting of village sites.
On the other hand, forest disturbance increased herbaceous forage and edge effect, and hence the numbers of some animals (Thompson and Smith 1970, 261–64). “Indians created ideal habitats for a host of wildlife species … exactly those species whose abundance so impressed English colonists: elk, deer, beaver, hare, porcupine, turkey, quail, ruffed grouse, and so on” (Cronon 1983, 51). White-tailed deer, peccary, birds, and other game increases in swiddens and fallows in Yucatán and Panama (Bennett 1968; Gordon 1982, 96–112; Greenberg 1991). Rostlund (1960, 407) believed that the creation of grassy openings east of the Mississippi extended the range of the bison, whose numbers increased with Indian depopulation and reduced hunting pressure between 1540 and 1700, and subsequently declined under White pressure.
Agriculture
Fields and Associated Features
To observers in the sixteenth century, the most visible manifestation of the Native American landscape must have been the cultivated fields, which were concentrated around villages and houses. Most fields are ephemeral, their presence quickly erased when farmers migrate or die, but there are many eye-witness accounts of the great extent of Indian fields. On Hispaniola, Las Casas and Oviedo reported individual fields with thousands of montones (Sturtevant 1961, 73). These were manioc and sweet potato mounds 3–4 m in circumference, of which apparently none have survived. In the Llanos de Mojos in Bolivia, the first explorers mentioned percheles, or corn cribs on pilings, numbering up to 700 in a single field, each holding 30–45 bushels of food (Denevan 1966, 98). In northern Florida in 1539, Hernando de Soto’s army passed through numerous fields of maize, beans, and squash, their main source of provisions; in one sector, “great fields … were spread out as far as the eye could see across two leagues of the plain” (Garcilaso de la Vega 1980, (2) 182; also see Dobyns 1983, 135–46).
It
