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Chapter 1: Background and principles

Nature of sustainable land management (SLM)
Aspects of sustainability
Principles of sustainability evaluation

Nature of sustainable land management (SLM)

Many definitions have been proposed to describe aspects of 'sustainable development'. Their variety reflects the complexity of relationships involved. Environmental characteristics, market forces, social ambitions, development objectives and conservation aims are but examples of the forces and factors that interact to determine sustainability. Definitions of sustainable management differ because observers place differing importance on these various factors.

Recognizing that a clear objective is essential to successful evaluation, the FESLM Working Party, in Nairobi (1991), laid a foundation for the following definition of SLM:

"Sustainable land management combines technologies, policies and activities aimed at integrating socio-economic principles with environmental concerns so as to simultaneously:

- maintain or enhance production/services (Productivity)
- reduce the level of production risk (Security)
- protect the potential of natural resources and prevent degradation of soil and water quality (Protection)
- be economically viable (Viability)
- and socially acceptable (Acceptability)."

These five objectives of Productivity; Security; Protection; Viability and Acceptability are seen to be the basic 'pillars' on which the SLM edifice must be constructed and against which its findings must be tested and monitored1. Each objective is complex, and requires further brief examination:

Productivity: the return from SLM may extend beyond material yields from agricultural and non-agricultural uses to include benefits from protective and aesthetic aims of land use.

Security: management methods that promote balance between a land use and prevailing environmental conditions, reduce the risks of production; conversely, methods that destabilize local relationships increase that risk.

Protection: the quantity and quality of soil and water resources must be safeguarded, in equity for future generations. Locally, there may be additional conservation priorities such as the need to maintain genetic diversity or preserve individual plant or animal species.

Viability: if the land uses being considered are locally not viable, the use will not survive.

Acceptability: land use methods can be expected to fail, in time, if their social impact is unacceptable. The populations most directly affected by social and economic impact are not necessarily the same.

The objectives of the FESLM intentionally embrace the totality of on-going experience on Earth. They allow for consideration of the effects of everything on any activity. It is right that they should do so, for it is not possible, in a global context, to exclude as irrelevant any influence on the future development of any activity. This is true in principle. In practice, if the size of the task is to remain within acceptable limits, it is obviously necessary to restrict the investigation of sustainability to those interacting influences that appear most significant to the directions of development of the land use in question. Conscious limitations have to be placed on the range of investigation and, in reporting the findings of evaluations achieved using the FESLM, these limitations must be stated.

One consequence of this complexity is that evaluation of sustainability can scarcely be contemplated in terms even approaching the complexity of the real world on areas larger than a small field - an area small enough to ensure that, within it, physical, biological, economic and social influences operate almost uniformly. Planners, however, will require estimates of sustainability relating to larger areas, but it must be made clear that these will be based on selected, simplified concepts of the more complex reality. The FESLM is designed on this understanding.

These primary requirements of sustainability must be viewed in a positive light. Some 'trade-off' between objectives may be unavoidable-for example, lower productivity and profit may be accepted if this is necessary to achieve the required level of environmental protection-but all five 'pillars' must be soundly developed if the SLM itself is to be sound.

Aspects of sustainability

Sustainability and suitability
Sustainability and stability
Classifying sustainability - Stability and confidence
Sustainability and scale
'Detailed' and 'generalized' forms of sustainability evaluation

'Sustainability', within the context of the FESLM, is a measure of the extent to which the overall objective of SLM (as defined above) can be met by a defined land use on a specific area of land over a stated period of time.

Definition of the land use and specification of the relevant area serve to define a unique evaluation exercise. It is important to emphasize that the primary objective of the FESLM is evaluation. It may be that sustained production could be most easily achieved by doing something else, perhaps elsewhere, but uncovering planning solutions of this kind is not the immediate object of evaluation. It is also true that the route to sustained production may involve adaptation of the form of use with time. Progressive change of this kind can be built into the description of the use for evaluation - but, obviously, only to the extent that the need can be foreseen. Evaluation is not planning; but, as discussed later, the FESLM is designed to directly assist planning by assisting comparison of alternative forms of use.

The phrase 'over a stated period' is also important. It introduces a controlled variable into the process of evaluation. It recognizes that indefinite sustainability is unreal and that such concepts as "sustainable into the foreseeable future" are almost meaningless. By assigning a fixed period of time to an evaluation, the evaluator provides a measure of the confidence with which sustainability has been assessed-a measure of the apparent stability of the system. As discussed later, these measures could provide a basis for classifying differing degrees of sustainability.

Recognizing a time period over which sustainability is evaluated permits some flexibility in achieving the 'pillar' requirements-so long as these requirements are met over the period as a whole. Patterns of productivity, in particular, must be flexible. In an agricultural context the time scale might include regular regenerative fallows leading to cyclical changes in productivity, fertility etc. Short term climatic variation might give rise to similar year on year differences but, provided there is no progressive decline over the stipulated period, sustainability may be unimpaired. This degree of flexibility is essential if SLM overall is to be a realistic objective.

The initial definition of the land use should not be so tightly drawn as to preclude minor flexibility in the nature and volume of inputs as needs arise (of fertilizers, herbicides, farm equipment, for example, in the case of agriculture); provided always that such introductions do not change the basic nature or objective of the use and are both economically and socially acceptable within the system.

Sustainability and suitability

'Land suitability' has been defined as the fitness of a given type of land for a specified kind of land use (FAO, 1976). The authors might helpfully have added 'or vice versa'.

The interactions between environmental factors which determine 'suitability" at a given moment are largely the same as those which decide whether the same land use is 'sustainable' through a period of future time on the plot in question. Whilst suitability evaluation calls for observation and measurement of these factors in the present, sustainability evaluation requires that the future, possibly changed, states of these factors are predicted.

A form of land use may be regarded as 'sustainable' if no permanent or progressive deterioration of its 'fitness' (i.e. its 'suitability') to the land in question is foreseen over a reasonably lengthy period of future time. In other words, sustainability can be considered to be an extension in time of the concept of suitability.

The Framework for Land Evaluation, published by FAO in 1976 and still widely used in various forms, established a set of procedures for determining land suitability. Because these procedures take account of economic and other rapidly changing factors, the validity of suitability assessments is recognized to be short lived. Even with this understanding, the authors recognized that it was not sensible to declare a particular use 'suitable' if it was known that, in time, this use would degrade the quality of the land. Uses that were not sustainable were specifically excluded from consideration. This view is enshrined in one of the six 'Principles' that govern the FAO Framework; this states that ''suitability refers to use on a sustained basis".

The Land Evaluation Framework fails to explain in any depth how the sustainability of a proposed land use is to be assessed, but the procedures developed by FAO for analysing suitability provide a good starting point for sustainability evaluation - before embarking on the more demanding task it makes sense to ensure the current fitness of the use in question! Characterization of the site and other basic data collection required to determine suitability provide a sound foundation for evaluating sustainability.

Sustainability and stability

Environmental factors differ greatly in 'stability'; that is to say in the likelihood and rapidity of their expected change with time. In the context of the FESLM, the time scale is that of the evaluation.

Some factors, such as topographic form or geology, are very stable-unlikely to change significantly, even over periods that are long in human terms. Others, notably economic factors, such as profit margins, but also events like the incidence of pests or disease, are very unstable-likely to change frequently and rapidly. Between these extremes there are many factors in which change is either uncertain, as with climate; or gradual, as with population growth or genetic crop improvement.

Of course, change is not necessarily undesirable in relation to the requirements of sustainability. The effects of change in one unstable factor may be more than offset, in a positive or negative sense, by change in some other factor. Herein lies the difference between stability (concerned only with the likelihood of change) and sustainability (concerned with the balance between positive and negative change in relation to a particular system).

Changes in a land use system with time reflect instability in one or more individual factors. An understanding of the likely direction and nature of such instability provides a basis for evaluating sustainability. As discussed in more detail in a later section, factors which are relevant to the continued success of a land use and which respond to environmental stress in a predictably unstable manner are called 'Indicators' of sustainability. Certain critical levels (expressions) of these indicators are called 'Thresholds' since their prediction provides direct guidance in evaluating sustainability.

It may be possible to compile the interacting stabilities of individual factors to assess the 'stability' of an entire land use/environment system; but it is usually more helpful, in the context of the FESLM, to think in terms of the stability of individual factors. A measure of the reliability of each evaluation may be obtained by combining our understanding of the stability of the various factors and of their individual importance in achieving the pillars of sustainability. This measure-one of confidence-could provide a basis for classifying sustainability.

Classifying sustainability - Stability and confidence

We have defined 'sustainability' as a measure of the extent to which a form of land use is expected to meet the 'pillar' requirements of Productivity, Security, Protection, Viability and Acceptability into the future. Sustainability is a dynamic concept; for it can be assumed that the determinative factors and their interactions, will change with the passage of time. Only if there is a continuing positive balance of effect of these interactions with respect to the requirements will the land use remain sustainable.

It can be argued that a land use is either sustainable or it is not - that recognition of shades of sustainability is not meaningful. Literal interpretation of the word 'sustainable' suggests this. Yet it is apparent that on different lands some forms of land use call for more effort, more inputs, to sustain than do others. Generally speaking the more productive the land use (the more that is taken out of the land as 'product') the more difficult it is to achieve sustainability.

Failure to meet any one of the 'pillars' renders a land use unsustainable, but the ease with which the different "pillars' are achieved will certainly differ from one use to another. In this sense, some forms of land use can be considered more 'sustainable' than others.

In planning land use in the future, as pressure on available land increases, great human and financial importance will be attached to decisions on whether or not a particular land use system is sustainable. In marginal situations, of which there will be many, planners will require more guidance than can be expressed by a Yes/No decision. They will need guidance on the relative sustainability of alternative uses.

Equally, those undertaking sustainability analysis may feel themselves unequal to the responsibility of presenting Yes/No advice, especially if the range and reliability of diagnostic data at their disposal are less than optimal.

Regrettably, in many parts of the world, the land use options available to planners may all be unsustainable - often clearly so, certainly in the long term as human population increases. The planners' need will then be for comparisons of relative unsustainability.

Procedures are required, therefore, for classifying both sustainability and unsustainability. A different approach to the two circumstances may assist definition of class limits. In neither case will this be easy. Both approaches depend, directly or indirectly, upon the stability of the factors which determine the status of sustainability in each situation.

The following class distinctions are proposed for discussion and investigation:


Confidence limits


1. Sustainable in the long term

25 years +

2. Sustainable in the medium term

15 - 25 years

3. Sustainable in the short term

7 - 15 years


4. Slightly unstable

5 - 7 years

5. Moderately unstable

- 5 years

6. Highly unstable

less than 2 yrs.

The time periods listed against each class under 'Confidence limits' require explanation. They are intended to illustrate the length of time expected to elapse before continued use of a system would become unacceptable. They may be interpreted as a measure of the evaluator's confidence in the stability of factors affecting the system.

In the case of 'sustainable' classes, the initial balance of instability effects is positive in relation to each of the required pillars of sustainability. In contrast, in the unsustainable classes, this initial balance is negative in respect to one or more pillars.

In the classification proposed, systems with a 'life' of 7 years or more are classified 'sustainable'; those with less are 'unsustainable'. The choice of 7 years is arbitrary and could be adjusted to meet local circumstances.

Some may protest that even 25 years is too short for a satisfactory measure of sustainability. A much longer period, a 100 years or even 'in perpetuity', may be a more desirable goal. Some threats to sustainability, such as diminishing soil fertility or slow erosion, may be predictable over such time scales. There is no reason why such predictions might not be reported as a qualification of the classification. But there will always be unforeseeable threats that will limit the value of forecasts over these longer periods - human unrest or warfare being, perhaps, the most probable.

It will be apparent also that, in many parts of the world, there are active land use systems which should be placed in Class 6 - 'Highly unstable', since they palpably fail to meet some or all of the 'pillar' requirements (eg. they generate an economic loss or a conservation disaster) but which, for a variety of reasons, not all bad, are expected to continue for far more than 2 years. Whether continuation reflects artificial subsidy, irresponsibility, indifference or a lack of any identified alternative, classification as 'Highly unstable' should draw desirable attention to a serious situation.

In fact, all of the time values shown as confidence limits are intended to be indicative only. These or other values would be considered and adopted locally; the choice being guided by the need to pass on the most pertinent information from local evaluation findings. Clearly, class limits would be standardized within a single evaluation study but, with present knowledge, attempts to correlate sustainability classes recognized in different studies is likely to prove more hazardous than fruitful.

As a footnote to this section, it should be said that some may suggest a distinction between classes of sustainability based on foreseen differences in future economic, social, or 'productivity' parameters - eg. Use 'A' is more sustainable than Use 'B' because, in future, it will yield a more desirable return. But these are distinctions of future suitability, not of sustainability.

Sustainability and scale

The immense range and complexity of diagnostic data associated with sustainability evaluation increases with the size of the study area (see Footnote 1, p. 7). Therefore, if the study area is enlarged, it becomes increasingly necessary to select and generalize the data used. This is true of all kinds of spatially arranged resource analyses, but it is made much more difficult in the context of sustainability by the complexity of factors involved and their anticipated change with time.

Values of 'scale' (eg. 1:5000 or 1:100 000), reflecting that of the land resource maps on which the evaluation is based, should be used to denote the level of detail of a particular local sustainability evaluation. Because of great differences in the nature and the spatial basis of the data used (physical, economic, social etc.), the scale 'value' will be seen only as a crude measure of the relative detail of separate evaluations.

Particular problems relating to 'location' arise in attempting to evaluate sustainability over an area larger than a small field. The characteristic of 'location' itself is of particular importance to sustainability. Location has a direct bearing, for example, on the distance (and difficulties of access) to markets and sources of supply. If a large area is evaluated the sites of specific evaluation interest (those with the specified form of land use) may be found in a number of different places each with different location characteristics.

Other related problems can all be described as "off-site" effects since they depend, not on characteristics within the area(s) examined but on the positioning of these area(s) within the surrounding region and on characteristics of this surrounding countryside. Factors in this category, which are discussed separately in chapter 4, include pollution hazards (to or from the site), flood hazard, and problems of population movement. Such factors can be assessed directly in respect of a small field. Within a larger region, in which the land use to be evaluated may occupy several areas, they have to be conceptualized and averaged in some potentially complex manner.

'Detailed' and 'generalized' forms of sustainability evaluation

Closely related to 'scale, are the considerations which distinguish detailed sustainability evaluation (based on the whole pathway of the FESLM) from more generalized evaluations of large areas, in which FESLM procedures may be short cut.

In a detailed study, at a 'scale' of 1/10 000 or less and relating to no more than a few hectares of land, most factors that are diagnostic of sustainability can be expected to act uniformly on the land use in question-which is assumed to occupy most if not all of the land. Moving into the future, the factors continue to act uniformly over the land, although their status may change and new factors may become important. What is crucial in this context is that the situation being evaluated approximates closely to reality. The evaluator is not free to choose the environmental factors which he/she evaluates; these, in all their complexity, are intrinsic to the specific site. He/she is free to select the factors he/she thinks are most significant and does so by working through the whole pathway of the FESLM.

In contrast, when the sustainability of a specific land use is studied within a large area it is likely that the use occupies only parts of the area as a whole and that there will be minor differences, at least, between these parts. With the passage of time the use may be extended to new, presumably similar, sites within the area and will cease to occupy others. In these circumstances it is apparent that sustainability can only be evaluated in terms of conceptual 'average' values of the environmental characteristics and that factors relating to 'location' must be averaged also.

The larger is the area studied, the more difficult it is to ascribe representative "average' values to environmental characteristics and the greater are the uncertainties of change within the area with time. Differences in the influence of separate factors on sustainability are themselves likely to differ within a large area. Faced with these uncertainties, it is pointless to pursue subtleties of evaluation or to apply diagnostic criteria to possibly unrepresentative data. Instead the evaluation must focus on broad 'indicator, attributes and 'thresholds", all expressed in rather generalized terms as discussed further in chapter 4.

Clearly 'detailed' and 'generalized" sustainability studies differ in kind. If the latter can be supported by the former on representative sites, so much the better.

Principles of sustainability evaluation

The procedures advanced in the FESLM are intended for practical application and it is hoped to provide maximum flexibility in their application to meet local circumstances. Nevertheless, certain principles are considered fundamental to the approach and methods employed. These Principles are intended to govern the further development and use of the FESLM in all circumstances. Some of these principles (Nos. i, iii, iv) are shared, in essence, with the Framework for Land Evaluation (FAO, 1976). The Principles are:

i. Sustainability is evaluated for defined kinds of land use: minor change in the objective of a land use, or in the means employed in achieving this objective, can alter the sustainability of the use. A sustainability evaluation is meaningless unless both aspects of land use are adequately defined and remain substantially unchanged or are the subject only of foreseen and defined modifications.

ii. Sustainability Evaluation relates to specific land sites: the character of the land is no less fundamental than that of the land use in deciding sustainability. Given the importance of economic and social factors in sustainability evaluation the precise location of the site may be crucial.

iii. Sustainability Evaluation is a multi-disciplinary activity: all aspects of the human environment-physical, biological, economic and social-may bear upon sustainability and so may require specialized investigation. All parties with a legitimate interest in an evaluation need to be identified and involved as early and as thoroughly as possible to ensure cooperation and achieve a widely acceptable solution.

iv. Evaluation is made in terms relevant to the physical, economic and social context of the areas concerned: It is not realistic to recognize as sustainable forms of land use which, although successful elsewhere, depend for success on factors such as available manpower, marketing infrastructure, or transport which are lacking in the area concerned. In presenting an evaluation it will usually be desirable to state what local constraints on land use choice have been taken into account.

v. Sustainability relates to a defined timeframe: to attempt to predict sustainability over indefinite periods would be unrealistic.

vi. The processes and practices of any existing present land use should be fully understood and its present suitability established before change based on sustainability evaluation is recommended: to do otherwise is to risk costly waste of time in evaluation and unreliable recommendations.

vii. Evaluation is based on scientifically valid procedures and data and on a choice of criteria and indicators of sustainability which reflect understanding of causes as well as of symptoms: only on this basis is evaluation likely to lead to prevention and cure of degradation and instil confidence.

One further principle governing the implementation of evaluation findings is desirable to ensure that the work consistently achieves positive results. This is:

viii. Introduction of new or modified practices will be made initially on an experimental scale and its subsequent progress carefully monitored: field validation is necessary to avoid costly mistakes.


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