Time, space set limits to sustainable planning

OVEREXPLOITATION of the planet's resources is causing environmental damage worldwide. An alternative is sustainable development, defined as a pattern of resource use that satisfies current needs without compromising the future. But it raises as many questions as it answers: Sustainable development for whom, in what context and with what objectives?

Resource use means different things to different people in different areas. In the developing world, use of natural resources has been geared largely towards meeting basic needs, such as food, fodder and fuel of a large population struggling below subsistence level. In the developed world, on the other hand, resource use is largely geared to maintaining -- if not accelerating -- the high levels of consumption of a much smaller population.

The guiding principles of sustainability traverse ecological, economic, social and cultural dimensions. Because these have to be reconciled with each other, the wide variation in strategies that result should hardly be surprising. An example would be nomads practising animal husbandry for a living, who may require as a short-term strategy a development plan rooted in their accustomed value system; tribal farmers practising jhum (slash-and-burn) cultivation in the northeastern hills, may consider instead a forest-based, plantation economy as the best long-term bet.

Thus the question is then of a scaling of temporal and spatial senses. In case of the temporal senses, is the objective infinite sustainability -- a pattern of resource use that does not lead to appreciable change in either quality or quantity of capital? If not, should one's sights be set on a more easily foreseeable 50-100 years? Would this scale be in conflict during the typical planning framework in local settings of 10-5 years?

Sustainability's temporal dimension becomes even clearer when related to attributes that characterise different ecosystems. A miniature ecosystem of microorganisms created in a culture flask may have a very brief turnover period; a village pond ecosystem may have to be viewed in terms of a few decades; grassland ecosystems may have a much longer turnover period, and a forest ecosystem has to be viewed in terms of at least a century. The time frame becomes even longer if one considers a "landscape" -- a combination of contiguous ecosystem types.

Finally, the temporal scale has to be based on pragmatism. While sustainability implies a period that is infinite, this is clearly not practical. A short time frame may have value as a short-term strategy that is ideal but necessitated by ecological, economic, social and/or cultural constraints. A time frame of 50 to 100 years may be practical as a long-term strategy.

The spatial scale must be addressed as well for sustainable development. For instance, in a rural landscape, complex types of ecosystems -- humanmade as well as natural -- exist. Agriculture in a limited sense and a village unit in a broader sense can be viewed as ecosystem types created and maintained through human inputs; a village pond and a patch of pasture are natural ecosystem types. In practical terms, a particular ecosystem type is too small a unit and the planet, too large, one may prefer instead to settle for a "landscape" -- a closely-knit combination of contiguous ecosystem types -- as an appropriate spatial scale for sustainable development, which, after all, involves a series of compromises, balancing the twin objectives of a better life for humans and the preservation of the natural resource base. Through such compromises, short-term strategy can be reconciled with long-term perceptions, and local or national objectives united with regional or global goals.

---P S Ramakrishna is professor of ecology at the School of Environmental Sciences, Jawaharlal University.