Life on the edge: a look at ports of trade and other ecotones.

Author:Gallaway, Terrel

Conjunctures create opportunity. This paper examines both natural and institutional conjunctures that provide unique and valuable opportunities whose beneficiaries range from bugs to businesses. Thorstein Veblen, for example, argued that with the rise of the machine age businessmen sought gain by controlling industrial conjunctures rather than relying on unmanageable ones found in nature (1904, 17). The paper shows that ecotones are conjunctures that have been studied by ecologists, anthropologists, and economists such as Karl Polanyi. Moreover, the examination of ecotones may prove valuable to subjects as varied as economic geography, environmental economics, and economic anthropology.

Ecotones and edge effects are concepts borrowed from ecology and are useful tools for analyzing a wide range of economic phenomena. Ecotones are commonly defined as the transition zone between adjacent ecosystems (Holland 1988; Gosz 1991; Bowersox and Brown 2001). (1) Wetlands, tree lines, and the meeting of savanna and desert are all examples of ecotones. Ecotones, sometimes called edges, frequently support comparatively large amounts of diversity, activity, and biomass--a phenomenon known as edge effect. (2) Part of this edge effect is accounted for by the simple fact that the ecotone supports many of the species from each of the overlapping communities. In addition, there are species "which are characteristic of and often restricted to the ecotone" (Odum 1971, 157). This paper examines the economic analog of ecological ecotones and demonstrates the usefulness of the concept in explaining the locus of economic activity as well as causes and consequences of this activity. Some of these ecotones are the same biophysically defined ecotones studied by ecologists; others are more of an analog or extension. They are shaped by social and institutional systems not emphasized by ecologists.

The history of the ecotone concept illustrates its use as a tool for understanding issues of location, composition, and dynamics. The etymology of ecotone suggests a tension (tonos) between households (oikos). This tension refers to "limit conditions that prevail at the extremes of the tolerance spectrum of populations, species, and communities (conditions between sub-optimal and lethal values)" (Lachavanne 1997, 12). Early use of this term, such as by Frederic Clements ([1905] 1977), focused on intersections between plant communities (Hansen, di Castri, and Naiman 1988, 11). The emphasis was primarily on how such transitions affect diversity and species distribution (Gosz 1991, 10). A more modern approach focuses on a wide variety of boundaries and emphasizes boundary dynamics, or "how boundaries influence ecological processes within patches and over the larger landscape; how boundaries affect the exchanges or redistribution of materials, energy, and organisms between landscape elements; and how these transfers can, in turn, act to change the location and nature of boundaries" (Gosz 1991, 10). This broader, more dynamic emphasis grew out of recognition that, while many ecological studies focused on relatively homogenous landscape units, landscapes themselves are a complex and diverse mosaic. Accordingly, boundaries needed to be studied because "abiotic and biotic components must move across heterogeneous landscapes" and ecotones serve important filtering and control functions between landscape components (Holland and Risser 1991, 1).

Collisions between systems studied by economists also create ecotones. For the purposes of this paper, we can define an economic ecotone as an opportune conjuncture between multiple interacting systems. These ecotones are an important locus of economic activity because they create unique opportunities. Studying the interstices between systems is important to understanding where and why such edge-specific phenomena take place. The conjunctures between market power and competition or between private property and common property help spur economic activity best understood by studying the edge between systems rather than each homogenous system individually. Additionally, ecotones are important to understanding intersystem dynamics. If one wants to understand the long-run viability of a system, he or she must examine the interactions between that system and others--studying the flow of materials, income, and power. Focusing on competitive markets, for example, is insufficient for understanding the viability of the competitive sector. One must also examine the collision between competition and market power. The following is a survey of a variety of economic ecotones; it is meant to better illustrate the usefulness of the concept.

Historical Ecotones--A Locus of Economic Activity

Ecotones frequently cradle economic activity. Sometimes these ecotones are defined in principally ecological and geographical terms; other times they are defined in principally cultural and institutional terms. In the former cases, these economic ecotones are precisely the ones studied by ecologists; in the later cases, their composition, if not their consequence, exists outside the purview of ecology.

Humans, like other occupants of the upper levels of the trophic pyramid, are often attracted to ecotones by an abundant and diverse food supply. "Throughout their history, human populations have actively positioned their communities to take advantage of animal and plant populations on either side of and within ecotones" (Crumley 1993, 379). Consider, for example, the Native Americans indigenous to the southeastern part of what is now the United States. Traditionally, many of these peoples lived along the coastal plain, concentrated especially near the coastline--itself an ecotone between land and sea.

The second important region for the Southeastern Indians was the piedmont, a band of hilly uplands between the Appalachian Mountains on the one side and the coastal plain on the other. The piedmont is separated from the coastal plain by the "fall line," an imaginary line drawn through the shoals and rapids of the rivers as they fall abruptly from the uplands to the flat coastal plain. The territory lying immediately to either side of the fall line was an important region in itself. Some of the most populous societies in the prehistoric Southeast lay along this line, the reason being that from this vantage point the Indians could exploit the natural resources of the coastal plain, the piedmont, and the fall line itself. The best freshwater fishing in the Southeast was at the fall line, where in certain seasons fish could be taken in vast numbers as they swam upstream to spawn. (Hudson 1976, 19) The fall line illustrates the way ecotones create unique opportunities for taking advantage of the adjoining regions as well as the idiosyncratic characteristics of the ecotone itself. In a very real sense, these Native Americans enjoyed the best of three worlds, while avoiding many of the constraints of each.

Ecotones also provide good locations for centers of trade because they allow access to different types of food and other goods, as well as different cultures. (3) The most obvious example is the seaport. In the case of seaports, the meeting of land and sea provides the above benefits plus combining the living space of the land with the facilitated transportation of the sea. Polanyi, while never mentioning the word "ecotone," was clearly aware of their anthropological significance with regard to trade. "Thus," he explained, "we find the port of trade as a universal institution of overseas trade preceding the establishment of international markets. It was, as a rule, situated on coastal or riverain sites, where inlets and extensive lagoons eased transportation by land. A related institution, however, might also be found far inland, on the border of two ecological regions, such as a highland and a plain, but particularly on the border of the desert, that alter ego of the sea" (1968, 239).

The port of trade concept was introduced by the Interdisciplinary Project at Columbia University in the book Trade and Market in the Early Empires; Polanyi is only one of the contributing authors who discussed it (1957, 263). (4) Anne C. Chapman likewise emphasized the port need not be on the sea. "Transshipments naturally develop from the earliest times on the borders of ecological regions, such as highland and plain, desert and jungle, forest and savannah" (1957, 116). Chapman went on to explain the role of such enclaves in Aztec-Maya trade. Francisco Benet mentioned the importance of ecological borders in the location of a class of Berber suqs that served as large regional markets (1957, 197). Others examined ports of trade on the Guinea coast and in the ancient eastern Mediterranean. (5)

Clearly, ecological ecotones have long shaped human society, and they still help shape local culture and politics (see, for example, Crumley 1993, 379). Indeed, the connection between human activity and ecotones is so strong that the historical and anthropological record has been used as a tool for tracking ecotonal shifts that resulted from long-term swings in global temperatures (1993). However, the economy is shaped by more than ecological and physiographical boundaries. Institutional boundaries, in particular, are very important in shaping modern economies. These institutional ecotones also create unique opportunities and allow people to take simultaneous advantage of multiple systems.

Nonecological Ecotones: The Geography of Human Institutions

The ecologist Paul Risser (1995) has argued that ecotones exist in a wide variety of scales that "can be defined by the question being asked or the problem being addressed" (319). The flexibility and generality of the ecotone concept is likewise captured in a definition of ecotones offered by a 1987 working group. They defined an ecotone as a "zone of transition between adjacent ecological systems, having a set of characteristics...

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