r ...A'" I V

Prehistoryof the Southern ForestBY EDWARD BUCKNER

Individual tree species are the "personalities" of the forest.Most that we see today have been around for a long time,having evolved during the Tertiary Period 35 million

years ago. Throughout the geological millennia speciesmigrated individually over the landscape, largely in responseto climate changes. While the species composing todal'sforests have remained relatively constant in recent geologicaltime, their groupings into "forest associations" have shiftedas species responded individually to changing environments.The forest associations making up the southern forest regionhave become, by far, the most complex of these regions.

Over the past 2 million years there have been radical cli-matic changes in eastern North America. During the Pleisto-cene Epoch there were at least twenty major glaciations.Each glaciation lasted approximately 90 thousand years andwas followed by an interglacial period lasting approximately10 thousand years. These shifting climates drove trees northand south across the North American landscape many times.Since each tree species responds differently to these changes,forest associations have always been "in flux," thus the needto reevaluate them periodically

.The most recent glaciation, the Wisconsin, peaked 18thousand to 20 thousand years ago. Early in the warmingperiod that followed, while ocean levels were still low due towater locked in the ice fields, man entered the NorthAmerican landscape via Berengia-the land bridge betweenpresent-day Siberia and Alaska. These earliest residents dis-persed quickly throughout the Americas. Although anatom-ically they were "modern humans," their Stone Age culturerelied on hunting-gathering as the means of subsistence.Their primary food was large animals-"megafauna" such aswooly mammoth, mastodons, and elk.

These grazing animals thrived on grasslands or openforests. But by the beginning of the Holocene Epoch (the last10 thousand years) most megafauna were extinct due likelyto a combination of factors such as hunting pressures, cli-mate changes, and habitat losses. As the megafauna disap-peared other grazing animals such as bison, deer, and elkbecame the primary food source for early Indian cultures.During this time, early inhabitants used fire to keep the land-scape open, favoring the grasses and shrubs that supportedthe animals on which they depended.

38 ForestHistoryToday

Also during this warming period the glaciers began theirretreat from the Missouri and Ohio River valleys. The borealforests, having extended as far south as Atlanta, Georgia,migrated to Canada. Temperate species moved out of GulfCoast refuges to form the forests that now cover much ofeastern North America. Thus after the last ice age, the treesmigrated into regions that had already been subjected tohuman influences for thousands of years.

In contrast to the tundra and boreal forests they replaced,ifleft undisturbed, temperate forests tend to "close," formingtwo or three canopy layers that shade the ground anddeposit a litter layer the combination of which precludes thedevelopment of grasses. The increasing tendency of theforests to close as temperate forest species became morefirmly entrenched had to be countered by frequent burning.Had they been aware of the consequences, the native peoplewould have seen the encroachment of the temperate forest asa serious threat to their subsistence. Closed forests providelittle toward basic human needs, regardless of the period,especially as human population increases. This is especiallytrue of the late-successional, climax forests in which bothplant and animal production is relatively low-generallyonly replacing mortality

At the peak of the warming period (HypsithermalInterval-6 thousand to 8 thousand years ago) rudimentaryagriculture began to be practiced. By the time of Columbusapproximately half of the food supply for native Americanscame from agriculture that was practiced on the rich, moiststream bottoms where competition from native vegetationwas most intense. To accomplish this, hot fires had to beused during dry weather when the surrounding uplandswere highly flammable, provided there was sufficient fuelbuildup since previous fires.

This regular use of fire, along with such uses as warfareand hunting, improved grazing, berry production, and nutgathering, and maintained pines over broad areas that wouldotherwise have supported hardwoods. Without disturbanceconifers would have essentially disappeared from the south-ern forest; except for hemlock in the mountains, varioushardwoods are the climax species throughout the region.

Testifyingto the widespread occurrence of even-aged, pio-neer (early successional) forests were the thousands of miles

of palisades documented in both thearchaeological records and the earlyEuroAmerican historical accounts.

This construction required a nearbysource of straight, small-diameteredtrees that would not have been foundin late-successional forests. An obvi-

ous source would have been young,even-aged forests that are characteris-tically found on abandoned agricul-tural fields and after hot fires.

Due to highly variable fire ratesand intensities, there resulted adiversity in fire effects that main-tained landscape conditions rangingfrom closed, multilayered forests to"park-like" woodlands to openprairies. Factors contributing to thevaried fires included: fuel buildup,fuel moisture, relative humidity,wind speed and direction, slope "N t al" t d if th .

a ur s an 0 sou ern pIne.angle and position, aspect (directionthe slope faces), temperature, anddays-since-last-rain. Ecologists haveargued that, were it not for Indianfires and buffalo grazing, the bound-ary between the tall grass prairie andeastern forests would have been

much furtherwest in 1492,possiblyeven eliminating the tall grass sec-tion of the western prairie.

Landscape diversity was the great-est in the undulating, hilly, moun-tainous sections of the South. Aspectand slope position strongly influ-enced both soil and surface moisture

conditions and, in turn, firebehavior.Upper slopes and those facing south-to-west dry more rapidly and burnwith greater frequency and intensity,which maintained disturbance-

dependent species such as the yellowpines. Later successional types, possi-bly climax, were common on lowernorth-to-east slopes where fires wereboth less frequent and less intense.These diverse landscape conditionsprovided both the plant and animalneeds of the native people.

Trees adapted to these conditionswhere they survived long enough. Inthe South there are three serotinous-cone pines (the pond,table mountain, and sand pines) whose copes remain closeduntil fire opens them and prepares the site' for the successfulestablishment of these light-demanding trees. Another fire-adapted species is longleaf pine. This stately flagship of thesouthern pinery once occupied approximately 90 millionacres in the southern coastal plain. Today it is relegated to

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roughly 4 million acres, its demise due largely to effective fireprevention and protection.

There can be little question that the southern forest of

1492 contained a strong cultural imprint. People were here,altering the landscape, before the trees that compose today'sforests arrived. While the landscape was likely a mosaic ofcover types and successional stages, changes in its prehis-

ForestHistoryToday 39

toric character did not endat this time.

Records of the southern

interior landscape did notbegin until the sixteenthcentury. Around 1540 De-Soto's chroniclers providedsketchy descriptions allud-ing to open landscape con-ditions and evidence of

recently abandoned agricul-tural fields. However, de-tailed characterizations werenot available until aroundthe time of the Revol-

utionary War when botanistWilliam Bartram traveled

through the region.Events occurred between

the years of DeSoto and therevolution that had pro-found effects on the south-

ern forest. Early explorerswere highly resistant to, yetcarriers of, European dis-eases such as smallpox, in-fluenza, malaria, and ty-phoid fever. However, theAmerican Indians, havinghad no previous exposure,caught the extremely viru-lent diseasesquickly Archae-ological and historical evi-dence attests to the occur-

rence of pandemics duringthe sixteenth and early sev-enteenth centuries that rav-

aged the native populationwith mortality estimated ashigh as 90 percent. Sincerecent estimates of the

native American populationin 1492 go as high as 100million, mortality was likelymore than 50 million. This

freed much of the land from cultural pressures allowingforests to close-a condition that, over broad areas, had neverbefore been the case. These 1O0-to-200-year-old forests werethe wildernesses described in many early historical accountsof the southern forest region. Their fate over the next twocenturies is a matter of the historical record.

Man has been a dominant factor in the evolution of North

American landscapes since we first arrived over 12 thousandyears ago. Not only have we altered the landscape, we haveimparted "genetic fixes" in species that influence their abili-

40 ForestHistoryToday

Indians raised abundant cropsof corn, as well as sunflower and squash, in their North Carolinavillage of Secoton.Library of Congress.

ty to compete in these culturally altered ecosystems. As inthe past, the character of tomorrow's forests will be depen-dent on our action or inaction. Knowledge and understand-ing of past conditions and plans to identify desired futureconditions are essential if we are to steer our forests toward

ecological, economic, and aesthetic health.

Reprintedfrom Forest Farmer, vol.54, no. 4, july/August 1995.