Today, the presence of us human beings has become pervasive in all ecosystems. As discussed earlier, man can be either seen as part and parcel of
‘nature’ or as an agent acting on ‘nature’. It is questionable whether we can find any landscape still in its pristine natural form, without the influence of man, apart from the icy continent of Antarctica. Man has inhabited, altered and engineered most other landscapes. Accordingly, many branches of human knowledge have tried to address the various issues involved:
Where human beings are active agents in ecosystems, then the field of study is sometimes called human ecology and the resulting systems have been given a variety of labels such as anthroposystems, socionatural systems and, in a more specialized case, agroecosystems. (Simmons, 1996: 11).
The concept followed is that of a man-nature duality, which, Simmons points out, forms the very basis of Western scientific tradition (Ibid: 11). Such a dualistic vision necessitates the separation of an ecosystem and its human components in order to measure the degree of human impact upon the ecosystem:
To help our discussions of the impact of the human societies upon nature, we need to be able to characterize an area of natural landscape and its processes, and then within the same conceptual frame detail the impact upon it of human activities and how our societies have continued to live within the new system thus created. (Ibid: 12)
The man-nature duality is a convenient tool for measuring the impact our species has had upon the earth that is much older than we are. In other words, take any landscape, and it has many components which were formed long before man appeared on the evolutionary scene, and may even house living components who arrived on earth much earlier than Homo sapiens. However, the state the landscape is in today, and the state that its other living components find themselves to be in, are all more or less shaped by the activities of one species, man. Simmons describes it in the following manner:
While it is convenient to think of humans as components of ecosystems, there can be no doubt that they differ from other organisms in their power to manipulate many of the other components of the system. For a start, human activity has created genotypes in both plants and animals
by the processes substituting human for natural selection, and we have created new ecosystems by a variety of processes. (Ibid: 30)
Human impact on landscapes, then, has given rise to new landscape forms, and altered the conditions for the abiotic and biotic components. Some of the changes came about as a result of human interaction with nature where the outcomes were not foreseen by the agents, while some other changes were deliberate, designed by man to engineer specific outcomes.
We have established beyond doubt that human societies have altered their biophysical environments since very early times, even if we cannot assign a precise beginning to the process. From the start, the metamorphoses were of tow kinds: those which were deliberate and those which were accidental. Sometimes, no doubt, the two have been virtually indistinguishable…. (Ibid: 403)
However, the decoupling of man and nature scarcely reduces the enormous complexities inherent in the system. We can say that the landscape is the visual manifestation of a complex web of interactions between ecosystemic components, many of which are invisible to the human eye, and many of which are still unknown to the human mind. Nevertheless, human beings have a decisive impact upon the landscape in the sense that they alter many of its components and physical characteristics. What human induced changes can do, in effect, transcends the limitations set by human agents, for many parts of the complex
web of interactions and dynamic synergies between physical, biotic and other components of a given landscape are poorly understood. Thus, human activities upon the face of the earth give rise to an enormously complex process, which can affect the system in a manner that is still not properly understood. The complexity of the system and its evolution as a result of the impact of man can be seen as akin to Lovelock’s (1979) ideas about natural systems housing living beings, i.e.
these systems evolve with, by, and for their inhabitants. However, this evolution happens in a manner that it cannot be analyzed neatly. As Simmons argues:
Possibly the greatest worry about many of the possible synergisms is what is usually called the ‘jump effect.’ This encapsulates the idea that the interaction of a number of variables (which can be both natural and cultural) does not proceed by a simple linear fashion from A to B, but rather changes little for a long time and then suddenly jumps from A to B at an unpredictable time and with an amplitude of fluctuation that is unforeseen except in the broadest of terms. (Simmons, 1996: 416).
And
…no system is safe from unpredictable change from chaotic and synergistic interactions. (Ibid: 422)
With these many components involved, and these many interpretations of the interaction between man and nature and the evolution of the whole system, it is useful to ask, what is the nature of this interaction, what effect does this have on the other component and features of a given landscape? There is no simple
answer to this question. In many instances, human alteration of landscapes has created verdant green patches in arid zones and allowed crop varieties to flourish, while in some other instances it has led to the disappearance of exotic animals and plants from the face of the earth, as discussed earlier. The nature of human interaction with physical and biotic systems can best be summarized as dual in nature, as having both a benevolent and a malevolent side.
After all, transformation of the earth’s surface seems to be one of the inevitable concomitants of human societies down the millennia….we should therefore be concerned that such metamorphoses ought to be creative rather than destructive. Yet there seems a persuasive case that no alterations ought to be total. (Ibid: 425)
As the landscape is taken as the visual manifestation of the complex web of existences and processes that goes by the name of an ecosystem, it can be observed that such effects bear upon the ecosystem as well, thereby altering it and making it evolve in ways that are poorly understood, even at present.