Local Optimisation

In a balanced ecosystem, every variable is at its optimum. Attempts to maximise any of these variables will lead to an unbalanced system, even to the point of irreversible damage or self-destruction. However, it could be argued that this kind of suboptimisation is exactly what has occurred in the agro-ecosystem and, at this point, it is necessary to distinguish between suboptimisation and local optimisation.

Local optimisation means that a variable is changed to suit new circumstances resulting from the fact that the system itself has been changed. An obvious example is the yield and quality of a domesticated crop species, compared with its wild progenitors. The domesticated species is a component of an agro-ecosystem, not a wild ecosystem. The chief requirement of a wild ecosystem is survival in the face of ecological and evolutionary competition. In the agro-ecosystem, this competition has been largely eliminated. The survival of the cultivar depends on entirely new criteria, such as its yield and the quality of its product. The increase in these properties is local optimisation. This increase would be suboptimisation in a wild ecosystem, but the agro-ecosystem is a different system, with different requirements.

If all people disappeared, and all agriculture stopped, the agricultural lands of our planet would quickly revert to being wild ecosystems, and our domesticated species would soon disappear. Typically, the most highly domesticated lines would disappear first, and the least domesticated lines would survive the longest.

In a later section of this book (see 11.10), the domestication of horizontal resistance to crop parasites is discussed. This quantitative resistance occurs in every plant and against every parasite of that plant. Its natural optimum is sufficient to ensure that the parasites of a wild host plant do not impair its competitive ability. However, this kind of resistance is at a low level in most modern cultivars. Indeed, it is often at a level considerably lower than that of the optimum in wild plants. We should now domesticate it to a considerably higher level than the optimum of wild plants, if we want to reduce the use of crop protection chemicals to the minimum. This domestication of horizontal resistance would constitute local optimisation.

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