How far could a squirrel travel in the treetops? A prehistory of the southern forest
Paul B. Hamel, and Edward R. Buckner 1998. How far could a squirrel travel in the treetops? A prehistory of the southern forest. Transactions of the 63rd North American Wildlife and Natural Resources conference; 1998 March 20-25; Orlando, FL. Washington, DC: Wildlife Management Institute: 309-315.
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Introduction
Conservation activities aimed at protecting old-growth forests; at maintaining populations of desired species groups, such as oaks (Quercus sp.), wild turkeys (Meleagris gallopavo), other game species or Neotropical migratory birds; and at increasing populations of endangered species, such as red-cockaded woodpeckers (Picoides borealis), Bachman’s warblers (Vermivora bachmanii), Louisiana black bears (Ursus americanus luteolus) and Tennessee coneflowers (Echinaea tennesseensis), require a target environment. This target, often viewed as the environment at some specified past time, becomes the desired future condition. If the target can be considered a stable ecosystem that is self-perpetuating under control of natural processes, the envisioned environment is a defendable “natural” target for land-use planning. If the target is not easily regarded as “natural,” but must involve cultural intervention for its appearance or persistence, the planning process must derive a target environment by some other method, one more clearly reflective of the values of the planners themselves.
Our purpose in this paper is to suggest time periods as potential candidates for the “original” or “natural”condition of the southern forest and to evaluate the forest conditions at those times in light of knowledge of past geological and cultural conditions.
The “Original” Southern Forest in 1607
A most useful starting point for characterizing the prehistory of the southern forest is the establishment of permanent English colonies in 1607. We begin there. A frequent vision of the forest, shared by authors too numerous to mention (e.g., Alverson et al. 1994) depicts relatively complete coverage of closed-canopy forest from the Atlantic Coast to the Great Plains. In this view, a squirrel, presumably a gray squirrel (Sciurus carolinensis), would have been able to move almost in a straight line from treetop to treetop across the Carolinas and Tennessee to the Mississippi River.
This view of the southern forest assumes that natural processes, beginning with glacial retreat and continuing to the arrival of European/African colonists, maintained an extensive, relatively unbroken forest canopy over the South. Several distinct implications for forest conservation and management are apparent. First, a preponderance of climax forest cover would be the historically stable, long-existing condition. Second, wildlife species adapted to later successional conditions, such as pine (Dendroica pinus) and cerulean warblers (D. cerulea), were very numerous and at carrying capacity in stable and extensive habitats. Third, early successional species, such as prairie (D. pensylvanica) and Bachman’s warblers, were less abundant, occupied habitats ephemeral in time and space, and were selected for dispersal ability and high reproductive rates. This forest is an obvious candidate for the desired future condition (i.e., target) in the conservation planning of the southern landscape.
In reality, the 1607 forest was probably very extensive, as popular writers suggest. However, this view conceals a myth (Denevan 1992b). The myth, that long-continuing natural forces were responsible for that extensive forest, is exposed by the history of the southern forest (Williams 1989, Denevan 1992b). The southern forest was perhaps at its greatest extent in 1607, a result of changing human activity, not continuous forest development. We briefly document forest conditions at the time humans entered the South 12,000 to 15,000 Years Before Present (YBP); in 1492, at the time of contact between southern Europeans and Native Americans; and return later to 1607.
The “Original” Southern Forest in Late Glacial Times During glacial times, the southern forest ecosystem included boreal species in communities resembling to those recognized as the Canadian spruce-fir (Picea-Abies) forests of today (Delcourt and Delcourt 1991). …
The transience of forest communities in geologic time is the first factor creating uncertainty in setting the 1607 forest as a desired future condition.
A second factor that has received intense attention in the literature is the use of fire by people to control and modify vegetation. Records are scanty and interpretations disparate, so our conclusions will not be agreeable to all. Many writers (e.g., Day 1953) conclude that fire was used by Native Americans as a primary management tool for vegetation manipulation (cf. Van Lear and Waldrop 1989). …
The final ingredient that shaped the prehistory of the southern forest was the isolation of the Americas from Europe, Africa and Asia. That isolation created a “virgin soil” condition, not of extensive undisturbed forest, but of human populations isolated from disease pathogens (Whitmore 1991). Contact in 1492 between the Old and New Worlds injected diseases endemic in the Old World (e.g., smallpox, measles, typhus and malaria) as epidemics into the New World. The result was horrific loss of human life. …
Human population collapse following epidemic disease outbreaks led to abandonment of Native American agricultural fields no longer needed to produce food crops and reduction of fires set to maintain those fields. Huge, open agricultural areas, measured in thousands of acres, were noted by earliest Spanish explorers, particularly the members of DeSoto’s expedition in 1540 (Dobyns 1983, Cowan 1985, Doolittle 1992). Even then, depopulated villages were described. Probably they were colonized first by the cane that the people maintained for use as a construction material (Platt and Brantley 1997). Subsequently, these cane patches were colonized by other woody species, which in time shaded out the canebrakes. The range of Native American peoples who maintained canebrakes as sources of construction materials is a close approximation of the distribution of Bachman’s warbler.
Woody encroachment onto Native American old fields may reflect the initiation of some of the old-growth bottomland forests of today. …
Conclusion
We conclude that no specific past time can be said to represent the true “original” condition of the southern forest, that human activity has shaped that forest for millennia and that the desired future condition of the southern forest has more to do with societal values than with some ideal past condition. We did not arrive at this conclusion easily. Our examination of the historical record of human inhabitation and forest development does provide an indication of the resilience of southern biota and offers hope to conservation planners and policy makers that desired future conditions can in fact be specified and achieved.
Probably, a squirrel could no more have traveled through unbroken forest from Norfolk, Virginia to Greenville, Mississippi in 1492 than it can in 1998.
