Identifying the causes of land-use change requires understanding both how people make land-use decisions (decision-making processes) and how specific environmental and social factors interact to influence these decisions (decision-making context). It is also critical to understand that land use decisions are made and influenced by environmental and social factors across a wide range of spatial scales, from household level decisions that influence local land use practices, to policies and economic forces that can alter land use regionally and even globally.
Proximate versus Underlying Causes
The causes of land-use change can be divided into two categories: proximate (direct, or local) and underlying (indirect or root). The proximate causes of land-use change explain how and why local land cover and ecosystem processes are modified directly by humans, while underlying causes explain the broader context and fundamental forces underpinning these local actions. In general, proximate causes operate at the local level (individual farms, households, or communities) and underlying causes originate from regional (districts, provinces, or country) or even global levels, though complex interplays between these levels of organization are common. As a result, underlying causes also tend to be complex, formed by interactions of social, political, economic, demographic, technological, cultural, and biophysical variables. Some local-scale factors are endogenous to decision makers and are therefore under local control. However, underlying causes are usually exogenous (originate externally) to the local communities managing land and are thus uncontrollable by these communities. In general, underlying causes tend to operate more diffusely (i.e., from a distance), often by altering one or more proximate causes.
Interaction of Causes
Land-use change is always caused by multiple interacting factors. The mix of driving forces of land-use change varies in time and space according to specific human-environment conditions. Biophysical drivers of land use change, such as droughts induced by climate change or loss of soil fertility by erosion may be as important as human drivers, which include economics and policy. As a result, biophysical factors, both abiotic (climate, terrain) and biotic (native and introduced species, primary productivity, etc.), tend to define the natural capacity or predisposing conditions for land-use change among localities and regions. Trigger events, whether biophysical (a drought or hurricane) or socioeconomic (a war or economic crisis), also drive land-use changes. Therefore, land-use changes tend to be driven by a combination of factors that work gradually and factors that happen intermittently.
Major Causes of Land-Use Change
Natural Variability. Natural environmental changes interact with the human decision making processes that cause land-use change. Highly variable ecosystem conditions driven by climatic variations amplify the pressures arising from high demands on land resources, especially under resource-limiting condtions, such as dry to sub-humid climatic conditions. Though natural and socioeconomic changes may operate independently, natural variability may also lead to socioeconomic unsustainability, for example when unusually wet conditions alter the perception of drought risks and generate overstocking on rangelands. When drier conditions return, the livestock management practices are ill adapted and cause land degradation. Land-use change, such as cropland expansion in drylands, may also increase the vulnerability of human-environment systems to climatic fluctuations and thereby trigger land degradation.
Economic and Technological Factors. Economic factors and policies influence land use decision making by altering prices, taxes, and subsidies on land use inputs and products, changing the costs of production and transportation, and by altering capital flows and investments, credit access, trade, and technology. The unequal distribution of wealth between households, countries, and regions also determines who is able to develop, use, and profit from new technologies that increase profits from land management, such as the adoption of mechanized large scale agriculture. Economic changes are increasingly mediated by institutional factors, markets and policies, such as agricultural subsidies, that are influenced by global factors driving a trend toward intensive commercial agriculture and away from subsistence croplands. For example, giving farmers better access to credit and markets (by road building and other infrastructure changes), combined with improved agricultural technology and secure land tenure can encourage forest converstion to cropland, depending on how the new technologies affect labor markets and migration, whether the crops are sold locally or globally, how profitable farming is at the forest frontier, and the capital and labor intensity of the new technologies.
Demographic Factors. Both increases and decreases in local populations have large impacts on land use. Demographic changes include not only shifts in fertility and mortality (e.g. the demographic transition), but also changes in household structure and dynamics, including labor availability, migration, urbanization, and the breakdown of extended families into multiple nuclear families. Migration is the single most important demographic factor causing rapid land-use changes, and interacts with government policies, changes in consumption patterns, economic integration, and globalization. The growth of urban aspirations, urban-rural population distribution, and rapid urban expansion are increasingly important factors in regional land-use change, within major urban centers, in peri-urban areas, and even in remote hinterland areas. Many new urban dwellers in developing countries still own rural landholdings so that growth of urban areas not only creates new local and regional markets for livestock, timber, and agricultural products, it also increases urban remittances to the countryside.
Institutional Factors. Land-use changes are influenced directly by political, legal, economic, and traditional institutions and by their interactions with individual decision making. Access to land, labor, capital, technology, and information are structured by local and national policies and institutions, including: property-rights; environmental policies; decision-making systems for resource management (e.g., decentralized, democratized, state-controlled, local communal, legal) and social networks concerning distribution and access to resources. Land managers differ in their ability to participate in and to define these institutions. Moreover, institutional controls on land use are increasingly shifting from local to regional and global levels as a result of the increasing interconnectedness of markets, the rise of international environmental conventions, the consolidation of small landholdings, and the shift from communal, traditional systems to formal, state-sanctioned land ownership. Land degradation and other negative environmental consequences of land-use changes are often the result of ill-defined policies and weak institutional enforcement that undermine local adaptation strategies, such as subsidies for road construction, agricultural production, and forestry, and widespread illegal logging in Indonesia and other nations. On the other hand, the recovery or restoration of land is also possible with appropriate land-use policies. It is therefore critical that institutions that influence land management decisions are built around participation by local land managers and concern for the environment.
Cultural Factors. The motivations, collective memories, personal histories, attitudes, values, beliefs, and individual perceptions of land managers influence land-use decisions, sometimes profoundly. The intended and unintended ecological consequences of land-use decisions all depend on the knowledge, information, and management skills available to land managers, and these in turn are often linked to political and economic conditions, e.g., the status of women or ethnic minorities. The cultural models of land managers and other agents of land use change thus help explain management of resources, adaptive strategies, compliance or resistance to policies, social learning, and social resilience in the face of land-use change.
Globalization. Globalization processes can amplify or attenuate existing driving forces for land use change by removing regional barriers to change, weakening national connections, and increasing the interdependency among people and between nations. Globalization as such is not itself a driver of land-use change but acts as an underlying process for other driving forces. Although the environmental effects of macroeconomic policies and trade liberalization are particularly important in countries with fragile ecosystems (e.g., semiarid lands and mangrove forests), international trade and other forms of globalization can also improve environmental conditions through green certification and eco-labeling, wider and more rapid spread of technologies, better media coverage allowing international pressure on states that degrade their resources, and free circulation of people, which provides better educational and employment opportunities. International institutions (including organizations within the United Nations (UN) system and non-governmental organizations) can be instrumental in setting political agendas, building consensus, and promoting and funding policies aimed at sustainable land management.
Pathways of Land-Use Change
Land-use change processes occur at the interface between human and environmental systems, interacting with both of these systems and with each other by feedbacks, synergistic effects and other system processes. Moreover, land managers constantly make trade-offs between different land-use opportunities and the constraints imposed by a variety of external factors.
This apparent complexity in land-use change processes can be reduced greatly by recognizing that there are a limited number of ways in which these causes interact. In other words, a limited number of syndromes of land use-change processes are observed repeatedly around the world.
- Loss of land productivity on sensitive areas following inappropriate use.
- Deforestation on forest frontiers by weak state economies, for geopolitical reasons or to promote interest groups.
- The transition from communal to private land ownership in developing regions.
- Ecological marginalization of the poor by land expropriation for large-scale agriculture, dams, forestry projects, tourism, and wildlife conservation.
- The "tragedy of enclosure": decreased land availability by land zoning for forest reserves, wilderness areas or agro-industrial plantations.
- Land use intensification in peri-urban and market-accessible areas of developing regions.
- Urbanization-driven changes in regional consumption patterns and income distribution with impacts on rural land use.
- New economic opportunities linked to new market outlets, changes in economic policies, or capital investments.
- Policy interventions that drive modifications of landscapes and ecosystems.
- The breakdown of traditional extended families and its impacts on resource use efficiency.
- Macroeconomic shocks and structural adjustment policies with undesirable consequences on natural resources.
- Delayed and ineffective social responses to deteriorating environmental situations, combined with absence of political will to mitigate damage and to alter the trajectory of change.
In summary, despite the diversity of causes of land-use change, there are some generalizable patterns of change that result from recurrent interactions between driving forces. Even though these sequences may play out differently in specific situations, their identification may confer some predictive power by analogy with similar pathways in comparable regional and historical contexts.
- Angelsen A., Kaimowitz D. 2001. Agricultural Technologies and Tropical Deforestation. Wallingford, UK: CABI Publishing. 440 pp. ISBN: 0851994512
- Angelsen A., Kaimowitz D. 1999. Rethinking the causes of deforestation: lessons from economic models. World Bank Research Observer, 14(1):73-98.
- Contreras-Hermosilla A. 2000. The underlying causes of forest decline. CIFOR Occasional Paper 30, Center for International Forestry Research, Bogor, Indonesia.
- Geist H. J., Lambin E. F. 2002. Proximate causes and underlying driving forces of tropical deforestation. BioScience, 52(2):143-50.
- Geist H. J., Lambin E. F. 2004. Dynamic causal patterns of desertification. BioScience, 54(9):817-829.
- Kates R. W., Haarmann V. 1992. Where the poor live: Are the assumptions correct? Environment, 34(4):4-28.
- Lambin E. F., Turner B. L., Geist H., Agbola S., Angelsen A., et al. 2001. The causes of land-use and land-cover change: moving beyond the myths. Global Environmental Change, 11(4):261-69.
- Lambin E. F., Geist H., Lepers E. 2003. Dynamics of land use and cover change in tropical regions. Annual Review of Environment and Resources, 28:205-241.
- Leemans R., Lambin E. F., McCalla A., Nelson J., Pingali P., Watson B. 2003. Drivers of change in ecosystems and their services. In Ecosystems and Human Well-Being: A Framework for Assessment, ed. H. Mooney, A. Cropper, W. Reid. Washington, DC: Island Press. ISBN: 1559634030
- McConnell W., Keys E. 2003. Meta-analysis of agricultural change. In Seeing the Forest and the Trees: Human-Environment Interactions in Forest Ecosystems, ed. E. Moran, Bloomington, IN: Center for the Study of Institutions, Population, and Environmental Change. ISBN: 0262134535
- Ostrom E., Burger J., Field C. B., Noorgaard R. B., Policansky D. 1999. Sustainability—revisiting the commons: local lessons, global challenges. Science, 284:278-82.
- Redman C. L. 1999. Human Impact on Ancient Environments. Tucson: Arizona University Press. 288 pp. ISBN: 0816519633
- Stafford Smith D. M., Reynolds J. F. 2002. Desertification: a new paradigm for an old problem. In Global Desertification: Do Humans Cause Deserts?, ed. J. F. Reynolds, M. Stafford Smith, 403-24. Berlin: Dahlem University Press.