Bird poop is the critical link in a very complex system of land use and ecology. When the settlers move from the Blue Ridge into the Tennessee and Ohio valleys they found an extensive forest which they began to cut. They cleared this forest to supply a growing national timber industry, and they cleared the forest to open fields to grow their grains and graze their livestock. Some of the trees they felled they notched and used for their first houses, the log cabins of the frontier. Other trees were split with ax and wedge or maul and the "rails" from the length-wise splitting of the trees were stacked and made into frontier fences. The fences kept the cattle in the now new pasture. The first season or so the native grasses of the forest and the heavy mast of the oaks and chestnuts supplied the livestock. Soon, however, the shade tolerant original grasses died out and there appeared a new order of weeds and grasses whose lineage could be traced in manure-borne seeds dropped along the frontier roads leading west. Some of these seeds were of European origin and had come to America in the holds of the first ships.
Once the forest was cleared, fences built, and a new regime of sunlight began to play upon the land, a new avian order began to emerge. Small birds--not the eagles, hawks, turkeys and passenger pigeons of the old forest--began to appear in greater numbers. A few species, like the weeds they followed, were of European origin and they multiplied rapidly in the new ecosystems of North America. Several complexly related things began to happen: in the field, the cattle grazed and dropped their rich manure into the pasture. They grazed up to the fence but could not reach very far under it or beyond it. Weeds grew thickly in the fencerow. These weeds and other grasses helped to protect the field against erosion by trapping the loose soil carried off by rain. The fence weeds also trapped some of the excess nutrient load of the manure being washed off by the rain. The weeds, the accumulating soil, and the fertilizer enhanced the weed growth under the fence. The root mound of the weeds expanded and toughened. Insects and grubs bored the loose roots and soil and mice, voles, shrews, and moles followed the insects under the fence.
The omnivorous birds followed the insects and perched upon the fence to find them. The fences provided stalking platforms for the birds. The birds also fed on the berries and fruits of some of the forest trees such as the cherries, cedars, hackberries, and serviceberries. While the perched birds waited for insects to appear in the weeds of the fence, they dropped their seed laden poop into the fence row. The fence and the weeds now protected the seeds within a nutrient rich mound. Soon the fencerow was asprout in cedars and cherry trees. Now the birds did not have to make two trips, one to the row and one to the forest. As the cedars or other trees matured and fruited, the birds could perch on the fence and eat either insects or tree fruits depending upon what was available. And their poop still fell into the fencerow.
Now the foundations of an artificial, but extremely interesting ecosystem are in place. The original fence, the weeds, and the new trees begin to interact. A complex mat of roots begins to lock the mounding soil structure into place protecting the fence row and the field against even violent erosion. The maturing trees protect the fence and vines and briars add strength and protection as well. By now the same process is in place on the opposite side of the road from this fence: two thickening fence rows are emerging. The birds still come and do their work of feed and poop. The birds also build their nests in the trees. The prickly leaves of the young cedars offer good protection to small species such as tits, wrens, and warblers. Other trees begin to appear: sassafras, dogwood, sourwood, persimmon. As the original trees grow, they provide shelter not only for birds but for squirrels as well. Chipmunks, rabbits, and groundhogs work the thick grass of the base and use the shelter defense of the weeds and briars. The squirrels venture along the fence into the forest and bring back varieties of nuts. Hickories and oaks appear in the fence row.
At this point the fencerow is perhaps twenty-five years old, and the tallest trees are about thirty feet. The old rail fence is rotted, but the growth of weeds, saplings, vines, and briars is so dense that it is hard to repair the fence. But this density itself serves as a fence securely restraining the cattle in the field. In the summer the leaves of the trees are thick and provide a band of shade in the road and for a few feet into the field. In fall and winter, the bare branches of the trees provide perches for other birds--the predatory hawks and owls who work the rich fence row and feed on the small mammals there. The fence row is beginning to function not only to protect the field but to affect the micro climate of weather around the field. The dense shade of the row holds moisture while the thickening band of trees alters the wind patterns. Winds blowing across the field are filtered by these trees and wind-borne seeds such as those of the maple, tulip poplar, and box elder are trapped in the fence row.
Now there may be nearly two dozen species of trees in the fence row and perhaps thirty species of birds using the site throughout the year. The trees are older now and taller. Decades ago, the tops of the trees on either side of the road joined and the squirrels had a treetop bridge across the road. The two fence rows have become a country lane. Some of the older trees die and begin a double service to the fence row. The decaying trees provide shelter to new birds--the woodpeckers--and their nest cavities provide shelter in turn to other birds. Other animals have followed the mice, rabbits, and squirrels. The snakes have been there for a long time. Already the early fence row attracted the insectivorous reptiles like the garter snakes. As the bird population of the row increased, the bird and egg eating snakes like the black racer frequented the fencerow. As the small mammal population increased, the copperheads and timber rattlers would occasionally hunt the row. The predatory hawks now found competition from the bobcat and fox while the skunk would appear from time to time to raid the hornet nests in the rotting wood of the dead trees or to dig out the yellowjacket nests from the soft undersoil of the fencerow.
At maturity, the double fencerow country lane has become a critical ecological element in the totality of the settled rural landscape. Although entirely artificial in origin, beginning in the aftermath of the clearing of the forest, the lane and any single fencerow now serves to stabilize the open land and to offer prime habitat for dozens of animals from the invertebrates up the food chain to the large predators. The structure of such lanes and fencerows is horizontally and vertically complex. A minutely adjusted interaction of weather, soils, seeds, plants, and animals develops and is sustained in the fencerows. Much of the health of the farmland is stored in the fencerows and in the twentieth century, the fencerows and lanes are the prime zones of biodiversity in the agricultural landscape. No other portion of the fields or forest support the sheer numbers of plants and animals in such close interaction as do these rows and lanes.
Perhaps no better protection against field erosion and no better containment barrier to agricultural runoff can be found than these fencerows and lanes. Yet today, across Franklin County and throughout the region, the lanes and fencerows are being destroyed at an alarming rate. A massive technology of assault in the form of hydraulically articulated bush hogs not only groom the understory of the fencerow but can reach twenty feet into the air and mulch the treetops into a feathered hedge. As suburban development reaches further into the country side, suburban expectations follow. Suburbanites want their roads paved and pretty. County road departments pave roads using standard machinery and now well-established specifications for road building. No lane is wide enough to allow for a modern crowned, graded road. The "law" of paving is inevitable: the fencerow or lane must be bulldozed to make way for the widening of the road.
The same technology that widens the road clears the seaming fencerows between the fields. In 1990, miles and miles of fencerows across the county were bulldozed in the late summer and early fall. The fields once enclosed by these rows eroded severely in the great winter solstice storm that year. Fortunately this process has not proceeded very far although many fencerows have been lost and several old lanes have been destroyed. The general impression, however, when one observes Franklin County from a vantage point like Keith Springs Mountain or one of the Sewanee views is of a landscape intricately seamed by miles upon miles of fence rows. The health of our farmland and the critical biodiversity of our environment is enfolded in these fencerows and lanes. We might even surmise that our land is held together by bird poop and tree roots.
Sampler of Edges, Fencerows, Lanes
