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General
Active off-site effects
Passive off-site effects
Allowing for off-site effects
Some issues that do not relate directly to characteristics of the investigated site and do not fit comfortably, therefore, within the framework procedures of the FESLM, may be important in decision making on sustainability. These issues may be distinguished as 'active' or 'passive' depending on whether the causal agent is within or outside the evaluated area:
• Active Off-site Issues: Effects which arise away from the site but are caused by on-site activities (eg. pollution of groundwater).
• Passive Off-site Issues: Effects which are felt upon the site and which alter sustainability but which are caused by change in conditions or activities away from the site itself.
It is apparent that conditions at the site must always be evaluated within the context of the surrounding environment (eg. the climate, the road network, the economic and the social scene). Normally this environmental envelope is assumed to be stable, but here we are concerned with anticipating and evaluating the effects of change outside the site.
A form of land use which is profitable and stable but which damages the surrounding land is clearly unacceptable to the community at large. A system of sustainability evaluation which lacks the capacity to consider this possibility is inadequate. Equally inadequate, would be a system of evaluation that accepts as sustainable a form of land use uniquely adapted to present surroundings when all around is about to change.
The basic procedures of FESLM are
focussed on the site itself (including those attributes which form part of the
environmental envelope). These procedures need to be extended to include examination of
the possibilities of 'active' or 'passive' change in the surrounding area. If change is
anticipated, the effects of such change have to be fed back into the FESLM procedures. How
far afield these additional investigations should range, and the detail in which they
should be carried out, is a matter for judgement based on local circumstances.
In developed countries, nitrate pollution of rivers, lakes and groundwater caused by excessive use of fertilizers or intensive animal production is a well publicized off-site, ill effect of agriculture. Other forms of toxic pollution may also need to be monitored. Civic pressure may prevent continuation of such land use through legislation, or impose changes in management that make the use unsustainable.
In developing countries the most serious off-site effects relate to poorly designed irrigation and drainage systems that lead to salinization, alkalinization and/or waterlogging of surrounding land.
Wherever the proposed land use involves intensive production with fertilizers and/or irrigation and drainage' the possibilities of off-site effects need to be specifically investigated.
Forms of land use that create problems of large volume waste disposal (wood processing, intensive animal husbandry etc.) threaten surrounding land in a variety of ways which also need consideration.
More subtle are possible economic
and social effects of new production on local markets, labour availability, and so forth.
The prevailing surrounding situation in these contexts will be examined, of course, within
the FESLM but if production and employment on the site itself will be large this may
create local imbalances which need to be projected and fed back into the analysis.
Population growth, climate change and pandemic disease are examples of predicted change on a global scale that may affect the investigated site and its surrounding areas. The prospect of such change promotes active concern for sustainability but current knowledge leaves us incompetent to predict what the changes will be. As suggested in discussing the final stages of analysis, these current uncertainties may require separate consideration of alternative future scenarios; "informed guestimates" of the pattern of future change.
At a regional level, political upheaval, wars and 'acts of God' in the area surrounding the site may be even more difficult to predict. However, not all regional changes that could significantly affect performance on the site are so obscure.
Examples of impending change that might reasonably be foreseen include:
• Changes in the Regional hydrology: Many human activities (such as dam building, deforestation, town and road building) affect the hydrology of a region. The effects may not be predictable exactly, but trends in change important to sustainability on a particular site may be identifiable - such as the level and frequency of floods or the level of groundwater.
• Changes in pest or disease incidence: Historical evidence in particular, coupled with knowledge of impending regional control measures, may guide understanding of the development and movement of centres of infection/infestation.
• Changes in regional infrastructure: Development of new roads, railways, storage facilities, markets etc. may affect prospects not only on the investigated site but also in areas with a competitive product.
• Changes in human population: Absolute numbers, age distribution, urban migration etc. will assuredly affect markets, labour availability and the sustainability of some forms of land use.
Passive off-site effects, those which originate at a distance but may effect the site itself, need to be considered very early in the evaluation, since they might influence a wide range of the indicators on which the evaluation will rely.
Little can be said about the precautions to be taken, since the range of possibilities in any one site is so large, but, before embarking on a detailed study of the site itself, a rapid overview of the surrounding country for evidence of impending change could be very worthwhile. If change is foreseen, the implications of such change on the environmental indicators of the site will have to be introduced into the evaluation.
In contrast, the implications of active off-site effects, arising from the planned activities on the site, cannot be fully assessed until a late stage in the evaluation when all the foreseeable interactions of land and land use have been projected.
Again, it is not possible to enlarge
on the form the assessment should take, beyond the indications of the most obvious risks
given above. There may be local, legal constraints to guide a judgement on sustainability
if the possibility of harmful effects on the surrounding countryside, or population, is
foreseen. More often, the evaluator will be required to judge whether continued
development of foreseen effects can be regarded as acceptable.