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Analysis of Land Use Change: Theoretical and Modeling Approaches
Helen Briassoulis, Ph.D.

1.1. Overview of Issues Related to Land Use Change

Land is the stage on which all human activity is being conducted and the source of the materials needed for this conduct. Human use of land resources gives rise to "land use" which varies with the purposes it serves, whether they be food production, provision of shelter, recreation, extraction and processing of materials, and so on, as well as the bio-physical characteristics of land itself. Hence, land use is being shaped under the influence of two broad sets of forces – human needs and environmental features and processes. Neither one of these forces stays still; they are in a constant state of flux as change is the quintessence of life. Changes in the uses of land occurring at various spatial levels and within various time periods are the material expressions, among others, of environmental and human dynamics and of their interactions which are mediated by land. These changes have at times beneficial, at times detrimental impacts and effects, the latter being the chief causes of concern as they impinge variously on human well-being and welfare. Lay and scientific interest on land use change has a long history as there have been no instances in which people used land and its resources without causing any harm. Ancient writers, philosophers, scientists and the like but also lay people have left records of the unwanted consequences of changes in the uses of land in the form of pieces of literature, philosophy, science and folklore.

The magnitude of land use change varies with the time period being examined as well as with the geographical area. Moreover, assessments of these changes depend on the source, the definitions of land use types, the spatial groupings, and the data sets used. A few indicative figures are given here to show salient changes in major uses of land. Table 1.1a contains data on global and regional land use and population change in the last 300 years for three main land use types. Figures 1.1a, 1.1b, 1.1c, 1.1d, 1.1e, 1.1f and 1.1g depict these changes. Table 1.1b presents the magnitude of change in each of the three major land use types distinguished in Table 1.1a as percent of total 1980 land area of each regional grouping and for the world as a whole. What is important to note in these Tables and the associated Figures is the variability of changes among the major land use types as well as the geographical variability of land use changes within and between land use types. Population change is used as a proxy measure of changes in the area of human settlements especially in urban areas. These latter changes are difficult to assess unambiguously as they are haunted by definitional and data problems (Douglas 1994). Changes in the uses of land which cause major concern are associated with conversion to and from cropland as well as with forest clearance. Tables 1.1c and 1.1d present data on global land areas converted to regular cropping and global areas of different ecosystems converted to cropping, respectively. Table 1.1e presents data on estimated area cleared over time. Conversion of cropland and forest land to urban uses is another important type of land use change because of its serious socio-economic and environmental implications. The interested reader may find additional material on estimates of land use changes in, among others, Turner et al. (1990), Meyer and Turner (1994), Brouwer et al. (1991), various editions of the FAO Production Yearbook, the United Nations Statistical Yearbooks, the World Bank’s World Development Reports, EUROSTAT’s yearbooks.

In the last 300 years the impacts of land use change have increasingly assumed from significant to threatening proportions. What is most important, however, is that, with few exceptions, it is human and not nature’s agency which brings about these changes and which is responsible for their magnitude and severity. Simply consider these major environmental problems: desertification , eutrophication , acidification , climate change, eustatic sea-level rise , greenhouse effect, biodiversity loss. In all of them and in myriad other less publicized and less visible, land use change caused by human activities is implicated to a greater or lesser extent. The impacts of these environmental problems are serious both in the short and in the long term. In the short term, food security, human vulnerability, health and safety are at stake; in the longer term, the viability of earth is being threatened. Hence, the impetus to study global environmental change in general and land use change in particular. As regards the former, the International Geosphere-Biosphere Programme (IGBP) and the International Human Dimensions Programme (IHDP) are the main scientific initiatives undertaken at the international level. Under the auspices of these two programmes and following a period of deliberations, the Land Use and Cover Change (LUCC) Core Project/Research Programme came into life in 1993 (for more information the reader is referred to Turner et al. 1995 and LUCC’s web site listed in Appendix 1.B).

The scientific study of the determinants and impacts of land use change is not confined, however, to the international level. The subject has engaged scientists in most countries of the world as, in almost all cases, the control of land use and the directing of its change towards particular types were of immediate concern to public authorities and individuals on such matters as quality of drinking water, availability of water for agriculture, flood and other natural hazards, fresh and sea water pollution, atmospheric pollution. This diversity of concerns is associated inevitably with a diversity of disciplines being involved in these studies. But the earth and life sciences are not the only and exclusive territories of scientific activity on land use change. The social sciences and the humanities have long explored various facets of the nature-society interactions from the level of the individual to the level of social groups, particular societies, and "society" as a whole (to whatever the latter may refer). While such a diversity of perspectives and disciplinary "encounters" on particular subjects are always welcome, the general impression a student of land use change gets is that of a polyphony of meanings and of approaches which express particular points of view, definitions of the issue of land use change, and, consequently, proposed solutions. The gap between the life/earth sciences, on the one hand, and the humanities/social sciences, on the other, is particularly visible, intense, and frustrating. Despite mutual acknowledgment of the close interconnections between the bio-physical and socio-economic dimensions of land use change, there is still considerable lack of communication between them and, hence, limited opportunities for essential integration of their different worlds. Researchers working on related subjects seem to have limited, inadequate, or no knowledge and awareness of what each other are doing and how they are studying particular aspects of the same indivisible entity; land, its uses and their changes.

There would be no immediate concern and urgency for such an integration was it not for the critical need to address the issues associated with land use change comprehensively and holistically; i.e. in an interdisciplinary or, better, in a transdisciplinary way – a term of a rather recent usage, a successor of the terms multi- and interdisciplinary. Bridging the natural and the social sciences worlds is expected to provide those necessary theoretical and modeling frameworks and tools which will assist in the comprehensive conceptualization and operationalization of the broad repertoire of land use change issues. A prerequisite to this quest for integration and synthesis of the various theoretical and modeling approaches to land use change is a thorough stock-taking of all attempts to date towards this purpose originating in diverse areas of the terrain of scientific knowledge. The present is a modest attempt to present systematically and evaluate critically representative approaches to land use change. It builds on several noteworthy past attempts as well as on the more recent activities undertaken in the context of the LUCC research program. It is intended to provide, on the one hand, the ground for a more comprehensive and in-depth account of extant and evolving approaches and, on the other, the ground for the much desired synthesis into useful spatial (land use) decision support systems. Given the present high interest on the subject and the continuous (and speedy) accumulation of knowledge in terms of both theories and models, this is an open-ended endeavor. Several of the issues which are presented and discussed in this first attempt at compilation are awaiting for further analysis and enrichment in the course of time.

Reviewing and presenting systematically the extant literature on the subject was not an easy task for a variety of reasons the most important of which are mentioned here only. The first is, as usual, conceptual/definitional and a matter of nomenclature. The same concept is defined differently not only in different but, sometimes, in the same discipline or in its fields and, usually, is given different names. Or, the same word is used with differing meanings in the same or in different contexts. Both conceptualizations and definitions may overlap also making analysis even more troublesome. An example which is further analyzed in this chapter is the definition of "land use" which sometimes is used synonymously with that of "land cover" especially on aggregate spatial levels. Similarly, the term "spatial change" is used frequently to denote land use change although spatial change has a much broader meaning as its use in a variety of other contexts reveals. This example brings us to the second reason why this review was not easy which is the fact that land use change is studied explicitly or implicitly in broader contexts dealing with spatial change and, more frequently, with environmental change. In these contexts, theorizing on and modeling of land use change was not always straightforward or did not constitute the principal object (or, purposes) of study although land use was and always is the inevitable intermediary in the nature-economy-society (or, any pair of them) interactions. Hence, the study of land use change is masked by the study of other types of changes in which land use is unavoidably implicated. The third reason, which draws from the previous one, is that theories of land use change may appear as derivatives of theories of broader socio-economic and environmental changes. Similarly, models of land use change may be either simplistic or land use change is modeled "residually" in the context of larger models; i.e. the emphasis is on modeling of micro- or macro- socio-economic or environmental change and land use change is simply assessed as a consequence of these changes by using simple proportionality coefficients. Lastly, a considerable number of important theories and models are essentially aspatial, i.e. they take no account of the material and geographic surroundings and constituents of human activities or they reduce them to certain uniform, geometric characteristics that bear a remote or no relationship to the physical characteristics of land. In this case, there is no direct way to study land use and its changes.

For these reasons, certain decisions were made about what to include and what not to include in this study from the broad spectrum of theoretical and modeling approaches which relate, in one way or another, to land use and its change. The general rule applied was that priority is given to those theories and models which treat land use and, more importantly, its change explicitly. The exact meaning of "explicitly" is clarified in chapters 3 and 4. Secondarily, theories and models which have an easy identifiable link to land use change were included. Certain theories and models – of the aspatial variety – which bear importantly on land use change, as they concern its determinants (or, drivers as they are called in the pertinent literature), are briefly mentioned. Finally, although several of the theoretical and modeling approaches which are included here are used (or, originate) in planning – especially, physical, land use and spatial planning, in general – a host of other theories and models which are relevant in the context of planning are not included explicitly. With this, a last, important point is made. Land use change is driven by a variety of forces which relate differently to one another in different spatial and temporal settings. Holistic theories of land use change need to draw on a variety of theories relating to the drivers of this change, first, to offer realistic and meaningful accounts of land use change, second, to provide rigorous theoretical bases for modeling this change, and, third, to guide action in problem solving (i.e. planning) situations. More importantly, however, this blending and synthesis of theories – if it is ever achieved - may dissolve the present thematic boundaries (industrial change, spatial change, institutional change, etc.) and reveal a unified theory, a meta-theory of change.

The present work is organized in five chapters. This first chapter, the Introduction, discusses alternative purposes for which analysis of land use change is undertaken, defines the terms land, land cover, land use, land cover change and land use change, introduces briefly the bio-physical and socio-economic drivers of land use change as well as its environmental and socio-economic impacts, and closes with a presentation of selected land use and land cover classification systems. The second chapter is devoted to a brief historical overview of the study of land use change over time and in various quarters. It draws parallels to changes or differences in socio-cultural values, technology, economic organization, magnitude of environmental problems associated with land use change, as well as changes in the theorizing and modeling traditions of the disciplines of the natural and the social sciences that engage in the study of land use change. The third chapter presents and evaluates selected theories of land use change classified according to the main theorization traditions to which they belong. The fourth chapter presents and evaluates a selection of models of land use change classified according to the modeling tradition to which they belong. An understanding of the majority of models presented is facilitated by solid knowledge of statistics, calculus, and operations research methods. Lastly, the fifth chapter summarizes the main issues pertaining to theories and models of land use change, discusses selected issues in of a more general concern in the context of the analysis of land use change and outlines future research directions.

1.2. The Purpose of the Analysis of Land Use Change

The approaches taken for the analysis of land use change are determined critically by the analyst’s objectives. The definitions and land use classification systems used, the theoretical schemata adopted and the models employed all depend on the main questions and the user needs the analysis seeks to address; i.e. on its purpose. Characteristic purposes of analysis are briefly discussed in this section grouped into six main categories: description, explanation, prediction, impact assessment, prescription and evaluation.

Descriptive studies of land use change are almost indispensable in any analytical endeavor as a first step towards more refined analyses. Description of land use change documents changes from one type of land use to another over a given time period and within a given spatial entity. Changes in both the qualitative as well as the quantitative characteristics of land use are described, the level of detail conditioned by the spatial level of analysis and the availability of requisite data. Descriptive studies of land use change have provided the impetus for more thorough investigations of the "why" of these changes as well as for taking actions (policies) to counteract the negative impacts of the changes identified.

Description alone, however detailed and thorough it may be, is not enough to provide the basis for understanding the observed land use changes or to guide policy and decision making towards effective ways to cope with the adverse implications of these changes. Explanatory analyses attempt to fill this gap. Explanation attempts to address the question of "why" these changes have occurred (or, are occurring) and to uncover the factors or forces that bring about these changes directly or indirectly, in the short or the longer run. The level of explanation offered by any study is a matter of the chosen spatial and temporal level of analysis. Macro-analyses necessarily refer to global changes and take into account global explanatory factors or determinants of land use change. As the analysis moves towards lower spatial levels, explanation moves deeper into the social and psychological dynamics that underlie observed human behavior and, consequently, land use change. Similarly, explanatory analyses over long time periods attempt to reveal the macro-forces that induce land use changes such as social, cultural and technological change. On the contrary, short-term explanatory analyses necessarily seek for more immediate factors affecting human behavior that leads to land use change although the influence of the larger macro-forces can be taken into account as conditioning the shorter-term phenomena. Explanatory studies employ more or less specific theoretical schemata that account for the main determinants of land use change and their intricate interrelationships.

In addition to describing and explaining land use change, an important purpose for conducting such analyses is to predict future changes in land use. Predictions may be unconditional or conditional. Unconditional predictions, also called trend extrapolations, provide future images of the land use patterns in an area that will exist if past trends continue into the future. Unconditional predictions may be mechanistic extrapolations of past land use change or, if they are informed by theory, they may be more thorough projections of past trends in the determinants and the resulting land use change into the future. Conditional predictions of land use change produce alternative land use futures of an area under hypothetical conditions or scenarios. Some analyses are conducted with the purpose of predicting land use changes caused by climatic change or by changes in future population, food and other habits and so on. Conditional predictions, based usually on scenario analysis, are frequently used in the context of policy making on issues of global change (e.g. climate change, biodiversity loss, desertification ). In both unconditional and conditional predictions, the critical issues are again the spatial and temporal level of analysis.

Another important purpose of the analysis of land use change is impact assessment. The contemporary interest is not so much on land use change itself as is on its various environmental and socio-economic impacts at all spatial levels. In addition, as policies are designed to address several of the environmental and socio-economic problems in which land use change contributes in one way or another, policy impact assessment has emerged as a significant scientific activity. The recent policy interest, specifically, is on the broader issue of sustainability of development as it is impacted by land use change triggered by proposed or implemented policies. Land use changes with adverse impacts – such as land degradation, desertification , depopulation, etc. – contribute negatively to the achievement of long term sustainability as they reduce the natural, economic, human, and social capital available to future generations.

In a normative perspective, the analysis of land use change may seek to address the question of "what should be"; in other words, the purpose is to prescribe land use configurations that ensure the achievement of particular goals. Presently, these goals come under the broad search for "sustainable land use solutions". The purpose of this type of analysis is to indicate those patterns of land use (and, consequently, to prescribe the necessary change from past patterns) which are associated with environmental preservation, economic prosperity and welfare and social equity (that hopefully ensures their acceptability).

Finally, analysis of land use change may be undertaken for evaluating either past, present or future (policy-driven) changes in patterns of land use in terms of certain criteria such as environmental deterioration (or improvement), economic decline (or growth), or social impoverishment; or, more generally, against the criterion of sustainability . The results of these evaluations may be used to suggest land use alternatives (i.e. changes over those on which the evaluation was based) that would contribute to the attainment of these goals. Prescriptive and evaluative analyses of land use change are not discussed – except in particular instances – in the present study as they are beyond its scope.

Regardless of its purpose, a reliable and consistent analysis of land use change requires that certain prerequisites are satisfied; namely, that the basic terms used in the analysis are clearly defined, land use classification systems compatible with the purpose of the analysis are used, valid theories frame the analysis, and the analytical techniques used can represent realistically the particular land use change issues under consideration. The rest of this chapter first clarifies the terms "land", "land cover", "land use", "land cover change" and "land use change"; then, it discusses the drivers and impacts of land use change; and, finally, it presents selected available land use classification systems used in related analyses.

1.3. Defining Land, Land Cover, Land Use, Land Cover Change and Land Use Change

Studies of land use change do not always employ similar definitions of the principal terms land, land use and land use change. Definitions and descriptions of these terms vary with the purpose of the application and the context of their use. It is, thus, necessary to look at alternative definitions and descriptions of these terms that are more frequently used in these studies, especially those offered by official sources of land and land use data.

1.3.1. Land

The Food and Agriculture Organization (FAO) defines land as an area of the Earth’s surface (FAO 1996). However, FAO (1995) gives a more refined and holistic definition which was used also in the documentation for the Convention to Combat Desertification (FAO 1995, 6 citing UN 1994):

"Land is a delineable area of the earth’s terrestrial surface, encompassing all attributes of the biosphere immediately above or below this surface, including those of the near-surface climate, the soil and terrain forms, the surface hydrology (including shallow lakes, rivers, marshes, and swamps), the near-surface sedimentary layers and associated groundwater reserve, the plant and animal populations, the human settlement pattern and physical results of past and present human activity (terracing, water storage or drainage structures, roads, buildings, etc.)". (FAO 1995, 6).

Wolman (1987) cites Stewart’s (1968) definition of land: "the term land is used in a comprehensive, integrating sense…..to refer to a wide array of natural resource attributes in a profile from the atmosphere above the surface down to some meters below the land surface. The main natural resource attributes are climate, land form, soil, vegetation, fauna and water" (Wolman 1987, 646).

Hoover and Giarratani (1984, 1999) state that land "first and foremost denotes space….. The qualities of land include, in addition, such attributes as the topographic, structural, agricultural and mineral properties of the site; the climate; the availability of clean air and water; and finally, a host of immediate environmental characteristics such as quiet, privacy, aesthetic appearance, and so on" (Hoover and Giarratani 1984, 131).

FAO (1995) cites Chapter 10 of Agenda 21 (UNCED 1993) which states that "the definition of land used to be "a physical entity in terms of its topography and spatial nature; this is often associated with an economic value, expressed in price per hectare at ownership transfer" (FAO 1995, 6).

It is worth noting that all definitions of land, although in general similar, differ as to the priority given to the attributes that characterize land. The natural sciences (FAO 1995, Wolman 1987) start from and detail the natural characteristics of land while the social sciences, more specifically economics (Hoover and Giarratani 1984, 1999), start from the mere element of space and refer more abstractly to the natural features of a segment of space. These differences in the definition of land show up in the next chapters of this study in the ways different disciplines theorize on and model land use change.

1.3.2. Land Use and Land Cover

The terms land use and land cover are not synonymous and the literature draws attention to their differences so that they are used properly in studies of land use and land cover change.

"Land cover is the biophysical state of the earth’s surface and immediate subsurface" (Turner et al. 1995, 20). In other words, land cover "describes the physical state of the land surface: as in cropland, mountains, or forests" (Meyer 1995, 25 cited in Moser 1996, 247). Meyer and Turner (1994) add: "it embraces, for example, the quantity and type of surface vegetation, water, and earth materials (Meyer and Turner 1994, 5). Moser (1996) notes that: "The term originally referred to the type of vegetation that covered the land surface, but has broadened subsequently to include human structures, such as buildings or pavement, and other aspects of the physical environment, such as soils, biodiversity, and surfaces and groundwater" (Moser 1996, 247).

"Land use involves both the manner in which the biophysical attributes of the land are manipulated and the intent underlying that manipulation – the purpose for which the land is used" (Turner et al. 1995, 20). In a similar vein, Meyer (1995) states that "land use is the way in which, and the purpose for which, human beings employ the land and its resources (Meyer 1995, 25 cited in Moser 1996, 247). Briefly, land use "denotes the human employment of land" (Turner and Meyer 1994, 5). Skole (1994) expands further and states that "Land use itself is the human employment of a land-cover type, the means by which human activity appropriates the results of net primary production (NPP) as determined by a complex of socio-economic factors" (Skole 1994, 438). Finally, FAO (1995) states that "land use concerns the function or purpose for which the land is used by the local human population and can be defined as the human activities which are directly related to land, making use of its resources or having an impact on them" (FAO 1995, 21).

While the above definitions of land use refer mostly to larger, territorial scales, at the urban scale, interest focuses on other aspects of the term. In the words of Chapin and Kaiser (1979): "At territorial scales involving large land areas, there is a strong predisposition to think of land in terms of yields of raw materials required to sustain people and their activities. At these scales, ‘land’ is a resource and ‘land use’ means ‘resource use’. In contrast, at the urban scale, instead of characterizing land in terms of the production potential of its soils and its submineral content, the emphasis is more on the use potential of the land’s surface for the location of various activities" (Chapin and Kaiser 1979, 4). This connotation of the term "land use" is implicit in several other texts dealing with land use in the context of urban and regional analysis and planning (see, for example, Hoover and Giarratani 1984, 1999, Ch. 6).

As it was the case with the definition of the term "land" above, different definitions of "land use" are employed at various levels of analysis and, most of the time, by different disciplines, a fact that inhibits more holistic and integrated approaches to the analysis of land use and its change in general. Wolman (1987) cites Clawson (1982, 111) noting "… the difference in the perception the city planners and the agricultural experts have of land use" (Wolman 1987, 647).

The description of land use, at a given spatial level and for a given area, usually involves specifying the mix of land use types, the particular pattern of these land use types, the areal extent and intensity of use associated with each type, the land tenure status (Bourne 1982, Skole 1994). More detailed natural and physical characteristics are recorded for each land use type for a complete description of land use (see, for example, Chapin and Kaiser 1979 for the case of urban land use studies; Meyer and Turner 1994 for regional and higher level studies).

It will have become apparent by now from the above discussion that land use and land cover are not equivalent although they may overlap. The distinction is schematically depicted in Table 1.2. Meyer and Turner (1994) state that "By land cover is meant the physical, chemical, or biological categorization of the terrestrial surface, e.g. grassland, forest, or concrete, whereas land use refers to the human purposes that are associated with that cover, e.g. raising cattle, recreation, or urban living" (Meyer and Turner 1994, x). Land use relates to land cover in various ways and affects it with various implications. As Turner and Meyer (1994) state: "A single land use may correspond fairly well to a single land cover: pastoralism to unimproved grassland, for example. On the other hand, a single class of cover may support multiple uses (forest used for combinations of timbering, slash-and-burn agriculture, hunting/gathering, fuelwood collection, recreation, wildlife preserve, and watershed and soil protection), and a single system of use may involve the maintenance of several distinct covers (as certain farming systems combine cultivate land, woodlots, improved pasture, and settlements). Land use change is likely to cause land cover change, but land cover may change even if the land use remains unaltered" (Turner and Meyer 1994, 5). Meyer (1995) adds the important point that "changes in land cover by land use do not necessarily imply a degradation of the land" (Meyer 1995, 25 cited in Moser 1996, 247).

The importance and the necessity of distinguishing between land use and land cover is most evident in analyses of the environmental impacts of land cover changes. In the study of the interaction of grasslands with the physical processes of global change, for example, Graetz (1994) emphasizes the need "to retain the definition of grassland by ecological attributes (vegetation structure and composition) rather than by its principal use, livestock production. ….. it is not possible directly to relate land use as such to the major physical processes of global environmental change. Land use cannot be directly related to these forms of global change because it is a qualitative descriptor. Land use categories are abstract typologies that, although useful, cannot be meaningfully included in process models seeking to forecast the time and space patterns of global change. It is land cover, rather than land use, that has the mechanistic meaning in the processes of global environmental change" (Graetz 1994, 127).

However, the distinction between land use and land cover, although relatively easy to make at a conceptual level, is not so straightforward in practice as available data do not make this distinction clearly all the time, a fact that complicates the analysis of either one of them. At the global level, "key sources of global data do not distinguish clearly between cover and use" (Meyer and Turner 1994, 95). Skole (1994) provides more insights into these data problems. The links between land use and land cover are elaborated further in the next section.

1.3.3. Land Use Change and Land Cover Change

In the analysis of land use and land cover change, it is first necessary to conceptualize the meaning of change to detect it in real world situations. At a very elementary level, land use and land cover change means (quantitative) changes in the areal extent (increases or decreases) of a given type of land use or land cover, respectively. It is important to note that, even at this level, the detection and measurement of change depends on the spatial scale; the higher the spatial level of detail, the larger the changes in the areal extent of land use and land cover which can be detected and recorded.

However, both in the case of land cover as well as of land use, the meaning and conceptualization of change is much broader. In the case of land cover change, the relevant literature distinguishes between two types of change: conversion and modification (Turner et al. 1995, 22; Skole 1994, 438). Land cover conversion involves a change from one cover type to another. Land cover modification involves alterations of structure or function without a wholesale change from one type to another; it could involve changes in productivity, biomass, or phenology (Skole 1994, 438). Land cover changes are the results of natural processes such as climatic variations, volcanic eruptions, changes in river channels or the sea level, etc. However, most of the land cover changes of the present and the recent past are due to human actions – i.e. to uses of land for production or settlement (Turner et al. 1995, 27). More specifically, Meyer and Turner (1996) suggest that "Land use (both deliberately and inadvertently) alters land cover in three ways: converting the land cover, or changing it to a qualitatively different state; modifying it, or quantitatively changing its condition without full conversion; and maintaining it in its condition against natural agents of change" (Meyer and Turner 1996, 238).

In a similar vein, land use change may involve either (a) conversion from one type of use to another – i.e. changes in the mix and pattern of land uses in an area or (b) modification of a certain type of land use. Modification of a particular land use may involve changes in the intensity of this use as well as alterations of its characteristic qualities/attributes – such as changes from low-income to high-income residential areas (the buildings remaining physically and quantitatively unaltered), changes of suburban forests from their natural state to recreation uses (the area of land staying unchanged), and so on. In the case of agricultural land use, Jones and Clark (1997) provide a qualitative typology of land use changes: intensification , extensification , marginalization and abandonment (Jones and Clark 1997, 26-27).

The reason why the linkage between land use and land cover change is emphasized is that the environmental impacts of land use change and their contribution to global change are mediated, to a considerable extent, by land cover changes. Thus, their analysis necessitates the examination of the ways in which land use relates to land cover change at various levels of spatial and temporal detail. The specification of the spatial and temporal levels of detail is of crucial importance for the analysis of both changes as: (a) it guides the selection of the types of land use and land cover that will be analyzed, (b) it determines the drivers and processes of change that can be detected and, thus, (c) it affects the identification and explanation of the linkages between land use and land cover within particular spatio-temporal frames. As regards the latter, the point is that local level land use changes may not produce significant local land cover change (and, consequently, significant environmental impacts). However, they may accumulate across space and/or over space and produce significant land cover changes at higher (e.g. regional or national) levels. This is the case, for example, of agricultural land conversion to urban uses that results from the decision of the individual land owners to convert their farmland to non-farm uses. Similarly, land use changes may be more qualitative rather than quantitative at lower levels of spatial and temporal detail but they show up as quantitative changes at higher levels and in the longer run. For example, gradual and incremental changes in the types of crops grown at the farm scale or in the quality of land management may result in the long run in abandoned agricultural land or seriously degraded farmland (in other words a change in category from productive to nonproductive land).

1.4. Land Use Change: Bio-Physical and Socio-Economic Drivers

The analysis of land use change revolves around two central and interrelated questions: "what drives/causes land use change" and "what are the (environmental and socio-economic) impacts of land use change". This section addresses the first of these questions. The precise meaning of the "drivers" or "determinants" or "driving forces" of land use change is not always clear, commonly accepted and understood by all those who engage in studies of land use change. Frequently, certain driving forces are emphasized over some others and there is confusion as to the semantic categories to which these causes of land use change belong. Two principal distinctions are made in the following. The first regards the origins of the drivers of land use-cover change. It is almost unanimously accepted that there are two main categories: bio-physical and socio-economic drivers. The bio-physical drivers include characteristics and processes of the natural environment such as: weather and climate variations, landform, topography, and geomorphic processes, volcanic eruptions, plant succession, soil types and processes, drainage patterns, availability of natural resources. The socio-economic drivers comprise demographic, social, economic, political and institutional factors and processes such as population and population change, industrial structure and change, technology and technological change, the family, the market, various public sector bodies and the related policies and rules, values, community organization and norms, property regime. The relationship between bio-physical and socio-economic drivers and other components of the land use-cover system are depicted in Figure 1.3a. It should be noted that the bio-physical drivers usually do not cause land use change directly. Mostly, they do cause land-cover change (or changes) which, in turn, may influence the land use decisions of land owners/managers (e.g. no farming on marginal lands). In addition, land use changes may result in land cover changes which, then, feedback on land use decisions causing perhaps new rounds of land use change (or changes).

The second distinction is semantic and concerns a categorization of the various factors and processes that contribute, in one way or another, to land use change and, through certain human actions, cause land cover and environmental change. In this context, human driving forces, human mitigating forces and proximate driving forces are distinguished mainly (Turner et al. 1995, Moser 1996, Kates et al. 1990, Turner and Meyer 1994). Human driving forces, "or macroforces are those fundamental societal forces that in a causal sense link humans to nature and which bring about global environmental changes" (Moser 1996, 244). Examples of those forces include: population change, technological change, sociocultural/socioeconomic organization (economic institutions and the market, political economy, ecology, political institutions). Human mitigating forces "are those forces that impede, alter or counteract human driving forces" (Moser 1996, 244). Examples of these forces are local to international regulation, market adjustments, technological innovations, and informal social regulation through norms and values. Proximate driving sources "are the aggregate final activities that result from the interplay of human driving and mitigating forces to directly cause environmental transformations, either through the use of natural resources (e.g. as input to agriculture, mining activities, or as raw materials for industrial production), through the use of space, through the output of waste (solid waste, emissions, pollution, etc.) or though the output of products that in themselves affect the environment (e.g. cars, plastic bags)" (Moser 1996, 244-245). Many more examples of proximate sources of change can be added: biomass burning, fertilizer application, species transfer, plowing, irrigation, drainage, livestock pasturing, pasture improvement (Turner and Meyer 1994, 5), deforestation and site abandonment (Skole 1994, 438), breaking up of large tracts of grassland, expansion of cultures which promote erosion (e.g. maize, sugarbeet), farming of fields in the fall line (Lehmann and Reetz, 1994), urbanization, suburbanization, urban fringe development, fire. The relationships among those forces as well as among them and the other components of the land use-cover system are depicted in Figures 1.3b and 1.3c. Land use and land cover are connected through the proximate causes of change which translate the human goals of land use into changed physical states of land cover. Land use change that drives land cover change is shaped by human driving forces that determine the direction and intensity of land use (Turner and Meyer 1994).

1.5. Land Use Change: Environmental and Socio-Economic Impacts

The second central question with which the analysis of land use change is concerned is: "the (environmental and socio-economic) impacts of land use change". In fact, it was the negative impacts that stimulated the scientific and policy interest on land use change. As Kates et al. (1990) put it, "The lands of the earth bear the most visible if not necessarily the most profound imprints of humankind’s actions" (Kates et al. 1990, 6).

The impacts of land use change are broadly categorized into environmental and socio-economic, the former having received more attention and publicity than the latter. One of the reasons for this imbalance in attention may be that the latter are more subtle, longer-term and subject to the influence of many more complex, and less visible and verifiable, factors than the former. But, it should be noted that the environmental and the socio-economic impacts are closely interrelated; the former causing the latter which then feedback to the former again, potentially causing successive rounds of land use change. A widely publicized case of a chain of environmental and socio-economic impacts of land use change is that of shifting cultivators in Latin America and other parts of the world. The sequence of land use change starts with forest clearance; cultivation follows, then heavy grazing, and, ultimately, land abandonment and movement to another location (along newly built highways which serve oil drilling sites) where the sequence is repeated (Blaikie and Brookfield 1987).

The impacts of land use change are usually distinguished according to the spatial level on which they manifest themselves into global, regional and local impacts. Note that the terms global, regional and local do not have a precise physical meaning in studies of land use change especially as regards the regional and local levels. For example, a region may be a subdivision of the world (e.g. Latin America, China, the Sahel, large world biomes , etc.) or a subdivision of a large nation (e.g. a state or a group of states of the USA) or, even a subregional subdivision of a nation’s region. From another viewpoint, for the purposes of the analysis of the impacts of land use change, a region may be defined on the basis of geographic and environmental characteristics like the Mediterranean region, the Baltic Region, etc. Similar comments apply to the delineation of local areas especially where the local is used as the opposite of the global.

As regards the global environmental impacts of land use and cover change, Meyer and Turner (1996) note that "Land use and land cover is a relatively new addition to the core concerns of global environmental change research. Its full incorporation was delayed by a narrow view of what could be considered global change, restricting it to those processes that occur in fluid global change systems: the atmosphere, the oceans, the climate. Human impacts in this realm have been referred to as systemic forms of global change (Turner et al. 1990); they are incontestably global in the sense that intervention at one point can affect the entire system, having direct physical repercussions on the other side of the globe. The classic examples are stratospheric ozone depletion , global climate change, through an intensified greenhouse effect, and eustatic sea-level rise as a consequence of climate change" (Meyer and Turner 1996, 237). These authors continue to point out that, even in the narrow, systemic meaning of global change, land use change impacts can be global in nature as: (1) many land uses (e.g. agriculture, grazing and forestry) release substantial amounts of trace gases that may produce global climate change and (2) a thorough understanding of the land-use/cover systems that are affected is required to assess the environmental and other impacts of many global phenomena like sea-level rise or stratospheric ozone depletion (Meyer and Turner 1996).

In addition, Meyer and Turner (1996) emphasize that land use-cover change impacts "are basic to another class of environmental changes that can be regarded as global in reach, the ones that Turner et al. (1990) call globally cumulative. Though not physically connected through a globally operating system, these changes can reach a global scale and status when their occurrence in many places adds up. Deforestation, wetland drainage, and grassland degradation have all amounted to a globally significant alteration of the land cover class involved" (Meyer and Turner 1996, 237-238). Large scale environmental phenomena like land degradation and desertification , biodiversity loss, habitat destruction and species transfer (Meyer and Turner 1996) fall in the same category as all of them are caused by land use changes. A comprehensive review of global environmental transformations associated with land use changes can be found in Kates et al. (1990).

At subglobal scales, what is broadly referred to as the regional level, the environmental impacts of land use change are equally significant and widely known. Eutrophication of water bodies, acidification of aquatic and terrestrial ecosystems, floods, soil nitrate pollution , land degradation and desertification , groundwater pollution, marine and coastal pollution and many more are environmental alterations that follow either directly or indirectly from land use changes (see, for example, Briassoulis 1994, Brouwer et al. 1991, Blaikie and Brookfield 1987, Jongman 1995, Laws 1983, Ortolano 1984) . The sources of these regional impacts may not be located in the receptor region but they may be located in more than one (frequently distant) regions. The prominent example in this case is acidification that involves long-distance transport of acidifying gases and substances. In addition, several of the regional impacts of land use change take a long time to show up as it is the case of chemical soil pollution and the phenomenon of the so- called "chemical time bombs". These are defined as possible chains of events responding to slow environmental alterations, resulting in the delayed and sudden occurrence of harmful effects due to the mobilization of chemicals stored in soils and sediments (Hesterberg et al. 1992, Stigliani 1991).

Finally, land use change causes a multitude of environmental impacts at the lower spatial levels in urban, suburban, rural and open space areas which have been extensively documented. Especially important are the land use changes (land conversion) that occur in the periphery of large urban concentrations that are subject to urbanization and industrialization pressures and frequently result in losses of prime agricultural lands and tree cover. Their environmental impacts include changes in the hydrological balance of the area, increase in the risk of floods and landslides, air pollution, water pollution, etc. Other local impacts of land use change include soil erosion, sedimentation, soil and groundwater contamination and salinization , extinction of indigenous species, marine and aquatic pollution of local water bodies, coastal erosion and pollution. The importance of these impacts is not restricted to the local area of interest as they are frequently cumulative arising out of the decisions of many individual land and property owner to act in their narrow self-interest. In addition, land use changes in one area may have environmental repercussions in other distant areas. For example, urbanization or tourism development in an area increases the demand for water which, however, is provided by another area. Excess water abstraction reduces the water available for agriculture and plant growth in the latter area and may induce saltwater intrusion in coastal areas.

In addition to the environmental, the socio-economic impacts of land use change are equally significant and give rise to serious concerns at all spatial levels. Global level socio-economic impacts concern issues of food security, water scarcity, population displacement and, more generally, the issue of human security and vulnerability to natural and technological hazards. International and non-governmental organizations such as the FAO, the World Bank, the IHDP Programme, etc. undertake systematic assessments to support policy and decision making at all spatial levels on the above issues (Alexandratos 1988, Liverman 1989, Lonergan 1998).

The food security and the water scarcity issues may arise out of reductions in the area of agricultural land and decreases in available water supplies that result from soil erosion, land degradation, desertification , industrialization, urbanization, suburbanization, and above all, poor management of environmental resources. In all these instances, unsuitable uses of land play an important role. These issues concern the fundamental question of whether there is enough food to feed the growing population of the earth and enough water to cover present and future demands of an increasingly industrializing and urbanizing world. In parallel, they concern the question of whether the distribution of the food and water resources is even throughout the globe. Population displacement is another issue that is being investigated to identify the potential role played by environmental degradation to population movements away from localities experiencing environmental stress. Finally, human security and vulnerability is a collective term used to denote all those factors that may pose threats to human health, welfare and well-being in a given geographic area. A proposed measure is the "Index of Vulnerability" comprising 12 indicators – food import dependency ratio, water scarcity, energy imports as a percentage of consumption, access to safe water, expenditures on defense vs. health and education, indicator of human freedoms, urban population growth, child mortality, maternal mortality, income per capita, degree of democratization and fertility rates (Lonergan 1998, 27).

Regional level socio-economic impacts of land use change are more variegated reflecting the variety of regional settings where these changes occur. These, too, however, arise out of the same processes discussed above and evolve around such issues as availability of land for regional food production, changes (reduction) in land productivity and, consequently, (lower) profitability and changes in industrial structure, employment/ unemployment, poverty, population change and migration, and quality of life issues such as health and amenity.

Finally, local level socio-economic impacts of land use change comprise similar concerns but they are restricted to the particular localities where these changes occur. The issue of farmland conversion to urban and other uses (e.g. tourism) has received special publicity and concern has been expressed as, in addition to the environmental impacts mentioned before, it causes also serious socio-economic impacts (see, for example, International Regional Science Review 1982; Gray 1981). In the case of tourism development on previously agricultural land, a less visible but extremely important socio-economic impact is the increased dependency of the tourist region on not locally produced farm products and the increased pressures for agricultural output grown in and bought from other areas. Local level socio-economic, like the environmental impacts, may act cumulatively and cause larger than local impacts in the longer term.

A point that needs to be stressed is that usually all impacts of land use change are assumed to be negative. This is not always true for two reasons. First, whether an impact is positive or negative depends on the spatial and temporal scale concerned. Second, human mitigating forces mentioned above, such as environmental and social regulation and policies, land restoration projects and similar actions may impede the negative influences of human driving forces and, thus, mitigate if not eliminate, the unwanted consequences of land use change.

The larger question, however, that relates to the impacts of land use change is that of the sustainability of development at all spatial levels. Conceptualizing sustainability as the achievement of a balance between social, economic and environmental goals, the role of land use and its change is of central importance. The negative environmental and socio-economic impacts of land use change detract from the achievement of these go as they erode both the environmental and the socio-economic resource base of an area and, thus, reduce its ability to support equitably the needs of its population both in the short and in the longer term. In this perspective, land use planning and management become imperative. The broad goal of managing land use and its change is to develop the land resources in ways that capitalize on their local potential and suitability, avoid negative impacts and respond to present and future societal demand within the limits of the carrying capacity of the local environment (see, among others, FAO 1995).

1.6. Land Use and Land Cover Classification Systems

The analysis of land use change depends critically on the chosen system of land use and land cover classification. The magnitude and quality of land use change is expressed in terms of specific land use or land use/cover types. The assessment of the environmental and socio-economic impacts of land use change is possible only when the particular environmental and socio-economic features of the chosen land use/cover types are specified. If this requirement is not met, then, the analysis will be of limited value in guiding policy and decision making especially at lower scales. Hence, the need to discuss available land use and land cover classification systems and consider their suitability for the analysis of land use change at various spatial and temporal levels.

In developing any land classification system, a central dilemma concerns the choice between representing "what is" and "what should be". The "what is" encompasses the land available on earth and its characteristics as described by a given technology at a given point in time while the "what should be" relates to values placed on the land and its characteristics and the resulting choices made by people about uses for land (Wolman 1987, 655).

Before considering alternative land classification systems it is worth noting that all of them are distinguished in terms of the spatial scale of analysis for which they are developed and the purpose of their development. The spatial scale determines the level of environmental and socio-economic detail contained in the classification system while the purpose of the study determines the particular attributes of the land use types that will be considered. In addition, available technology for data collection is a significant determinant of their structure and content. The following presentation will attempt to focus on land use as opposed to land cover classification systems although the two are often interrelated (as land use and land cover are interrelated) and the existing systems do not always distinguish clearly between land use and land cover.

The development of land classification systems has a long history in various countries of the world. Soil classification systems were the first to be produced by both national (e.g. the U.S. Soil Conservation Service, Canada’s Soils Directorate) and international (the FAO) organizations to serve the needs of producing soil maps and provide a basis for determining land capability and suitability for growing various types of crops (see, for example, Marsh 1991). The need for developing land use and land cover classification systems ensued first focusing, as it was natural, on agriculture and forestry – uses of land occupying large tracts of land and playing important environmental and economic roles. After the 1960s and 1970s, efforts to develop land use and cover classification systems for other types of land use proliferated, a response to growing urban and industrial pressures on land and the need to provide a basis for rational land use planning and management (see, for example, Kleckner 1981, Gray 1981, Pierce and Thie 1981). In the following, examples of land use and cover classification systems at various spatial scales and for various purposes are offered.

At the world scale, the first land use classification systems produced concerned the major land uses of the world. The FAO produces land use statistics, starting in the 1950s, using a 4-category classification of land use: arable land (or, cropland), grass land (or permanent pasture), forest land (or, forest and woodland), other land (which includes urban areas, unmanaged rangelands, land in polar regions, desert land, tundra, stony and rocky land in mountains and all other classified land) (Wolman 1987, 647; Beale 1997). Wolman (1987), however, cites another FAO publication describing world land use in terms of five categories: arable or cropped, meadow and permanent pasture, forest and woodland, unused but potentially productive, and built-over, wasteland and other. The relevant data are collected annually by means of questionnaires from national governments. Since the mid-1990s, the FAO is in the process of developing a more elaborate international framework for classification of land uses using a 3-level hierarchical system to develop classes of land use (see Appendix 1.A and FAO 1995).

At the subglobal level, mostly the national level, several land use classification systems are in use. In the U.S.A., the U. S. Geological Survey has developed the Land Use and Cover Classification System for use with remotely sensed data (Anderson et al. 1976). This system, like the FAO system, uses a 2-level hierarchy to define classes of land use and it is suitable up to the substate regional level (see Appendix 1.A). In Canada, the Lands Directorate of Environment Canada initiated the Canada Land Inventory in 1963 (Pierce and Thie 1981). An elaborate land use classification system has been set up which is being continuously improved to meet the variegated needs of users and uses. In Europe, several land use classification systems appeared especially after the 1980s. Two of them are mentioned here (the reader can find more information about other systems and related projects in Beale 1997). The CORINE system (Coordinated Information on the European Environment) was set up in 1985 in the European Community with the objective, among others, to improve data availability and compatibility across the European Community and within the member states. Its final product is a digital land cover data base made up of 44 classes with mapping units based on a tiered hierarchical classification scheme (NUTS) used in the European Community for statistical purposes. Another project, CLUSTERS (Classification for Land Use Statistics: Eurostat Remote Sensing Programme), is being developed in coordination with the EUROSTAT (the European Union Agency for statistical information). This system is also based on a hierarchical scheme of developing land use types that attempts to provide a standard system for studying land use applicable throughout the European territory whilst taking into account official classifications of land use at European level (see Appendix 1.A and Beale 1997).

Land use classification systems vary with the purpose and context of their use also. Classification systems for special types of land use usually employ more detailed and elaborate criteria that reflect the particularities of the land use type of concern as well as the intended use(s) of the classification system. In particular, emphasis is given on those characteristics of the land resources that determine the suitability of land for a given use or may constrain its development. Land use classification systems for agriculture are the most widely developed both by international (the FAO) and national organizations. The FAO has produced several documents describing procedures for land evaluation in agriculture in which criteria to classify agricultural land are described and detailed definitions of land use types and their subdivisions and other features are offered (FAO 1976, 1978, 1996; Alexandratos 1988). For example, in developing the Agro-Ecological Zoning (AEZ) methodology – a procedure for small scale land suitability assessment, land was described on the basis of the 15,000,000 Soil Map of the World and an inventory of climatic data. Land use requirements are de facto climate-related and soil-related crop requirements. Land use alternatives were restricted to those involving the world’s major (annual) food and fibre crops, selected on the basis of the area occupied, the total production and the financial value they represent. Eleven major crops were selected: wheat, paddy rice, maize, pearl millet, sorghum, cotton, phaseolus bean, white potato, sweet potato and cassava (FAO 1996). Land use was classified into Land Utilization Types (LUT) defined as "a use of land defined in terms of a product, or products, the inputs and operations required to produce these products, and the socio-economic setting in which production is carried out" (FAO 1996, 72). Note that in a previous publication, FAO defined a major kind of land use as "a major subdivision of rural land, such as rainfed agriculture, irrigated agriculture, grassland, forestry or recreation" (FAO 1976). The AEZ typology presented above has been used in several studies of land use change and land use planning at various spatial levels (see, for example, Jansen and Schipper 1995, FAO/IIASA 1993, Fischer et al. 1996b).

Typologies for agricultural land use classification are developed also by competent national bodies such as the USDA, the USGS, the BLM in the USA, the Lands Directorate in Canada, various agencies in the European Union and its member states and other countries internationally. A very thorough analysis of past and contemporary efforts towards developing an agricultural typology is found in Kostrowicki (1991).

Land use-cover classification systems for forest and woodland are equally well developed despite the wide differences found among countries as regards applicable definitions and typologies (Moser 1996). FAO, the U.N. ECE, the World Resources Institute, the USGS, the USFS, the BLM, the Joint Research Centre (JRC) of the European Union at Ispra (Italy) and many other agencies worldwide provide systems of forest land classification that are instrumental in recording quantitative and qualitative changes in the status of forests in individual countries, large world regions and internationally. Classification systems for parks and parkland also exist given their important role in nature preservation and various types of recreation (Wolman 1987).

Finally, classification systems for the built environment (urban land use and transportation systems) are increasingly being developed the historical origin for their necessity being identified with McHarg’s (1969) plea for designing the built environment within the limits set by nature. Given the variety of types of built-up land and the contexts within which it occurs, selected ways to classify urban land use are presented here based on Chapin and Kaiser (1979). These authors define classification as "a systematic means of grouping similar categories of land use in the pursuit of some predetermined goals" (Chapin and Kaiser 1979, 239). Many of the available systems have been influenced by the SIC (Standard Industrial Classification) system that is used for the classification of industrial activities (Chapin and Kaiser 1979, 240). This is a hierarchical system of classification, the lower level codes giving more detail on the characteristics of the industrial establishment(s) and products involved – and the associated space requirements for the present purposes. Appendix 1.A presents a selection of classification systems of urban land use categories.

Two things must be noted as regards the development of land use classification systems in general. Firstly, the context of development and use of these systems determines critically their structure and content. In several countries, particular land use types exist which are absent or negligible in other countries (e.g. informal settlements, desert). Secondly, the development of land classification systems is increasingly being influenced by the availability and use of satellite data and remote sensing techniques. These changes in technology facilitate the direct use of available data in conjunction with available techniques of analysis and models. Cowen and Jensen (1998) discuss the capability of remote sensing technology to measure key attributes of urban and suburban environments accurately at the requisite levels of spatial, temporal, and spectral resolution. They present a Table which depicts the relationships between selected urban/suburban attributes and the remote sensing resolutions required to provide such information (Cowen and Jensen 1998, 166).

To close this section, a brief discussion of the problems encountered in the development and use of land use/cover classification systems for the analysis of land use change is deemed necessary. Firstly, these systems have undergone several changes over time reflected in changes in definitions of the land use/cover types. These changes are due to changes in the qualitative characteristics of the uses of land itself (and the corresponding land cover), the needs of various types of users, the methods of analysis, and the technology used to collect and record the related data. Wolman (1987) notes that "the recent use of remote sensing techniques can introduce changes in classification as mapping units are defined by distinctive signatures of the many sensors used" (Wolman 1987, 647). Turner et al. (1995) observe that, originally, data collection was based on field surveys. After the 1960s, new survey techniques based on computer processing of aerial photographs and satellite images are being used. "These techniques directed classifications towards the land cover attributes captured in such imagery. Many existing land use classifications are based on the vegetational and artificial cover of the land surface: the World Land Use Classification, the Canada Land Inventory and Land Use Classification, the Second Land Use Survey of Britain Classification, the Canadian Land Use Classification, and the World Map of Present-Day Landscapes (Moscow State University-UNEP 1993, Rjabehakovnd.) to name a few" (Turner et al. 1995, 49).

The result of these changes is that "Not all classifications of land are semantically consistent and the typologies become even more complex as the scale is enlarged, covering smaller and smaller areas, and as the focus of interest shifts" (Wolman 1987, 647). A review of land use classification systems by Mucher et al. (1993) indicates that none of them is acceptable in a global change context (cited in Turner et al. 1995, 49). The drawbacks they note include: (a) lack of a sound definition of the units of analysis, ranging from field to farm to region (confused with mapping units); (b) overlapping of land use classes (because of the lack of clearly defined criteria; most hierarchical classifications are only comprehensive at the first level, and are far from comprehensive at lower levels); (c) near-total absence of quantitative class boundaries (critical or threshold values of the criteria), adding a significant subjective element to land-use assignments; (d) combination of land use with other dimensions, such as climate characteristics, that may influence land use but are not inherent features of it; (e) multiplicity of land use classification objectives, often closely tied to regional or disciplinary foci (Turner et al. 1995, 49-50). Turner et al. (1995, 50) observe that existing classifications do not use common classificatory principles and often conflate use and cover. Similar problems exist for classification systems of particular land use types (see, for example, Moser 1996).

Appendix 1.B contains addresses of web sites of organizations which provide information on classification systems for land use and land use change.