RELATING LAND USE & GLOBAL LAND-COVER CHANGE

Understanding the significance of land-cover changes for climate, biogeochemistry, or ecological complexity is not possible, however, without additional information on land use. This is because most land-cover change is now driven by human use and because land-use practices themselves also have major direct effects on environmental processes and systems.

Land-use is obviously determined by environmental factors such as soil characteristics, climate, topography, and vegetation, but it also reflects land's importance as a fundamental factor of production. Thus understanding past changes in land use and projecting future land-use trajectories requires understanding the interactions of the basic human forces that motivate production and consumption. High population growth or increasing consumer demand combine with varied land-tenure arrangements, degrees of access to financial capital, shifts in international trading patterns, and local inheritance laws and customs to produce unique land uses in different places and times. Research on how such human factors interact in driving land use will improve projections of land use and our comprehension of human responses to environmental changes. For the economic, social, and behavioral sciences, it will also provide an opportunity for basic research into the factors that shape individual and group behaviour.

Evaluating the causes and the consequences of changes in land use and land cover is becoming an urgent need for more than the academic research community. At the 1992 UN Conference on Environment and Development, a framework convention on climate change and a convention on biodiversity were signed, as was a declaration of principles on forests; while no formal action was taken on desertification, a broad agreement was reached to work toward a conference and a convention in the near future. Changes in land use and land cover are significant components of all the problems addressed by these agreements, yet we do not have enough knowledge about such phenomena to decide how these conventions should best be structured and which of their proposed elements are likely to be effective. At present, we are unable to answer even the most basic questions. For example: are the world's deserts really spreading, and if so, why? Are population pressures extending land uses, such as agriculture or settlement, to areas that cannot sustain these uses? How are deforested areas of land used, and what are the implications of these different uses for the net emission of greenhouse gases?

Recognizing the importance of studies of changes in land use and land cover in developing our understanding of global environmental change, the International Geosphere-Biosphere Programme (IGBP) and the Human Dimensions of Global Environmental Change Programme (HDP) formed an ad hoc working group in early 1991 to investigate the possibilities of a joint effort by natural and social scientists to study the issue. The members of the working group were:

Billie Lee Turner II - USA, cultural-ecologist and geographer, Chair Lourdes Arizpe - Mexico, social anthropologist Paul Cheung - Singapore, demographer Dean Graetz - Australia, grassland ecologist Pablo Gutman - Argentina, resource economist Dennis Ojima - USA, ecologist with interest in trace gas emissions William Reiners - USA, plant ecologist David Skole - USA, modeller with interest in remote sensing.

The group met in New York City with the assistance of the Social Science Research Council in May 1991 and in Dalaro, Sweden in October 1991, with support from the Swedish Council for Planning and Coordination of Research (FRN). Carolyn Malmstrom represented the IGBP Seaetariat at the New York meeting. Several additional individuals took part in the working group's second meeting: Vladimir Annenkov (Russia, geographer), Olga Bykova (Russia, geographer), Exequiel Ezcurra (Mexico, ecologist), Richard Moss (USA, political scientist, Programme Officer of the IGBP and HDP), Ing-Marie Andreasson Gren (Sweden, economist), Steven Sanderson (USA, political scientist), and Uno Svedin (Sweden, FRN).

The working group recommended that a joint IGBP-HDP Core Project Planning Committee be established to develop an interdisciplinary research programme involving social and natural scientists to project future states of land cover. This recommendation was based on the following conclusions of the working group:

• Understanding the past and future impacts of changes in land cover is central to the study of global environmental change and its human driving forces and impacts, including hydrology, the climate system, biogeochemical cycling, ecological complexity, and land degradation and its impacts for agriculture and human settlement.

• Land-cover modelling requires improved knowledge of land use; it is not possible to make projections of future states of land cover without knowledge of the factors that determine land use and land-use change.

• The major determinants of land use are demographic factors such as population size and density; technology; level of affluence; political structures; economic factors, such as systems of exchange or ownership; and attitudes and values.

• Additional basic research is required to understand how these factors interact to drive land cover change or how projections about them could be used to project future patterns of land use, future rates of land-cover change, and future states of land-cover.

• Categorization of land-cover changes and associated socio-political-economic conditions must be carried out in conjunction with coordinated case studies to further our understanding of changes in land use and their implications for the functioning of the Earth system.

• The knowledge gained through this categorization and the case studies will be crucial to developing regional and global models of land-use/land-cover change.

In light of the recommendation of the working group and the importance of the subject, the Scientific Committee of the IGBP and the Standing Committee of the HDP decided to establish a joint Core Project Planning Committee (CPPC), under the joint chairmanship of B L Turner and D L Skole, with responsibility to develop a detailed scientific plan for an IGBP-HDP project on changes in land use and land cover. The CPPC terms of reference are given on pages 62-63 of this report. It was further decided to hold an open scientific meeting to review the scientific plan that will be proposed by the CPPC. Assuming the subsequent establishment of the project, a Joint Scientific Steering Committee would then be formed to coordinate its implementation.

This report presents the main findings of the working group. It describes the research questions defined by the working group and identifies the next steps needed to address the human causes of global land-cover change and to understand its overall importance. The plan outlined by the working group calls for the development of a system to classify land-cover changes according to their socio-economic driving forces. Selected case studies will be carried out according to a common protocol and will provide detailed settings in which to refine the classification of socio-economic situations and land-cover changes. In the final step of the plan, the knowledge gained regarding the human determinants of land use and the driving forces of land-cover change will be used to develop a global land use and land-cover change model. The model will be designed to link to other global environmental models. In all of it activities, the CPPC will pay special attention to defining the data needed to support research on human forcing of land-cover change.

4. Human Causes of Land-Use Change