Land Use And Cover Change Research Paper

1. Land Use And Land Cover

While closely related, the terms land use and land cover refer to quite different dimensions of the earth’s surface that have largely been investigated in distinct scientific traditions. Land cover refers to the biophysical attributes of the earth’s surface and immediate subsurface. This includes vegetative layers (both natural and artificial), exposed soil or rock, and ice, as well as human constructions such as buildings and pavement. While some land covers are considered pristine or at least minimally touched by the human hand (e.g., remote tropical rain forests), others are recognized as transformed or radically altered (e.g., urban areas).

Land use, meanwhile, refers to the human intent to which the land surface is put. While use registers as an imprint on a given location in terms of the change in land cover that would otherwise exist, it also includes the motivations, constraints, and enabling conditions that give rise to the use. Land cover and land use each imply both state and process variables, and have multiple and overlapping properties whose appearance depends to a great degree on the particular ways in which they are observed.

Because of the compound nature of the questions relating human land use practices to land cover states and changes, addressing them involves an amalgam of analytical perspectives spanning, for example, the social and physical sciences, quantitative and qualitative approaches, and academic and policy concerns. Each of the research traditions involved brings its own theoretical perspective and modes of inquiry, and their coupling is not always easy. In particular, the need to merge locally specific explanations of how and why people use land in particular ways, with broader patterns observed at regional or global scales brings into sharp relief a long-standing conundrum of scientific inquiry—scale dependence: the dynamics of land use cover changes vary depending on the spatial and temporal scale at which they are observed. Nevertheless, the enterprise is bound together by the desire to understand how biophysical conditions, particularly ‘initial’ land cover, shapes human activities (opportunities and constraints), and how these activities, or land uses, alter these pre-existing conditions, thereby shaping future livelihood options.

2. Human–Environment Relations In Land Use/Cover Change

The relationship between humans and the natural world appears to be a universal concern of Western thought, occupying a central place in Greco-Roman, Arab, and European mythology and philosophy. Modern attempts to characterize the impact of human activities on the earth include George Perkins Marsh’s seminal work Man and Nature (1864), which has been updated by major multidisciplinary efforts, including Man’s Role in Changing the Face of the Earth (Thomas 1955) and The Earth as Transformed by Human Action (Turner et al. 1990). During the 1990s, the public discussion over the threat of human-induced alterations to the earth’s bio-geochemical cycles (e.g., ‘global warming’) has shifted from speculation to skepticism and finally to widespread acceptance and debate over the details of where, when, and with what consequences such changes may occur.

The bulk of global change science remains dedicated to improving our understanding of the functioning of the earth’s climate system, for example through the modeling of carbon dynamics. However, as the biophysical systems are better understood, greater attention has been focused on the human dimensions, including the major anthropogenic sources of global change, the consequences of that change in terms of the sustainability of livelihood systems, of the vulnerability of particular groups of people and places, and of the societal perceptions of and responses to change (Kasperson et al. 1995; see Human Dimensions of Global Change). These concerns require understanding the human systems— economic, political, cultural, and sociotechnical— associated with human activities at particular places and times (Moran 2000).

Many human activities are known to cause significant disruption of global bio-geochemical cycles, particularly the combustion of fossil fuels. The modification of land cover is also a significant anthropogenic source of bio-geochemical disruption, especially the replacement of forest with grasslands and croplands, and the application of chemical fertilizers and pesticides to croplands. Other important questions driving global change research concern the reduction of biological diversity, both directly through species extinction resulting from human activities, and indirectly through the destruction of habitat. Here again a solid understanding of land use cover dynamics is required.

These concerns are of more than academic interest; policy is actively being crafted to limit human impacts on the environment at both regional and global scales. The effectiveness of environmental laws and agreements depends on sound scientific understanding of the impact of land use practices, in order to target critical areas and to monitor compliance. Accordingly, research programs have been developed at national and international levels, including the Land Use Cover Change (LUCC) Project, under the aegis of the International Geosphere-biosphere Programme and the International Human Dimensions Programme (Lambin et al. 1999). Land use and cover change research constitutes a bridge between the understanding of the biophysical aspects of global change and the human dimensions of sustainability.

Two fundamental, linked, sets of questions underlie land use cover change research: the first concerns the nature, location, and rates of anthropogenic modification of land cover; while the second seeks to understand the reasons behind land-use practices leading to such modifications. The first set of questions is generally examined at relatively broad scales, often using satellite imagery to determine spatial and temporal patterns of change, while the explanation of land use practices requires local-scale research, and often involves interviews with land managers and direct observation of land management practices. As answers to these two sets of questions take shape, it becomes possible to model the trajectories of change that have been observed, and to project future land-cover outcomes.

3. Land Cover Change

Despite having been studied for more than a century, land cover change is still poorly understood, but recent technological and methodological advances show great promise. Two advances in particular bear noting: the ability to observe the current state of the earth’s surface from space, and the ability to reconstruct past land-cover patterns through the techniques of the paleoand historical sciences.

Remote sensing of the earth refers to the use of instruments carried on aircraft and earth-orbiting satellites that detect energy reflected or emitted from the earth’s surface in different portions of the electromagnetic spectrum. The land cover of most inhabited portions of the earth has been periodically recorded through aerial photography since the 1950s, facilitating the production of land-cover maps. Since the 1970s, satellite remote sensing data have provided more frequent views of large areas.

Land-cover research has utilized two sets of satellite imagery, though the distinction between them is disappearing. One set of satellites (e.g., the Landsat, SPOT, and ERS platforms) provides relatively high spatial resolution, sampling the earth’s surface on the order of tens of meters, along swathes of 100–200 km. While such imagery is capable of distinguishing several types of land cover, the satellites take weeks to observe the entire surface of the earth, and views of land cover are often inhibited by cloud cover or other atmospheric conditions, especially in the tropics.

Nevertheless, several efforts have achieved reliable views of land cover from high-resolution imagery at continental, or subcontinental, extents by creating mosaics of images (e.g., North America, Europe, Amazonia, and East Africa). Most of the focus to date has been on those areas where transformation of the earth’s surface has been most dramatic in recent times—the tropics. The clearance of forestlands has garnered special attention, both because of the potential impact on climate change and biodiversity, and because of the relative ease with which this particular form of land-cover conversion can be detected through remote sensing. Estimates of rates of deforestation are becoming more reliable, and researchers have identified so-called hotspots, where habitat destruction— usually deforestation—is most rapid and biodiversity therefore threatened.

Another set of remote sensing systems, primarily intended for the observation of weather, has been acquiring daily views of the earth for over a decade. These images can be compiled to create cloud-free images for ten-day or monthly intervals. These data sources typically suffer from poor spectral and spatial resolution, however advances in processing this rich time series are yielding unique information on seasonal and longer-term climatic patterns, such as El Nino. Separating these natural cycles and rhythms is crucial to the reliable detection of anthropogenic land-cover change. Over the last few years of the twentieth century, significant achievements have been made in the development of global land-cover databases. Global land-cover maps have recently improved in spatial resolution by about an order of magnitude, with reliable databases now produced from data from a single year of observation at a spatial resolution of about 1 km. New satellite systems promise to improve this spatial resolution by a factor of four in the near future, with spectral definition better tuned to land cover change detection. These land-cover data are complemented by similar, related global databases at similar spatial resolutions concerning, for example, human population density and the incidence of fire. (Reviews can be found in special issues of the International Journal of Remote Sensing 21 (2000, no. 6 7) and Photogrammetic Engineering and Remote Sensing 65 (1999, no. 9).)

The detail and reliability of the information provided by both sets of sensors are constantly being enhanced through improvements both in the instruments themselves and in the technology and skill with which the data are processed. As the data from the various satellite systems are better integrated, the gap will close between the global coverage and local case studies using aerial photography and high-resolution imagery. Attempts at such integration have highlighted the disparities between analytical schemes for characterizing land cover, as well as the difficulties of merging information about biophysical and social dimensions of land-use cover dynamics (National Research Council, NRC 1998).

In addition to the very detailed record of land use and related land-cover impacts provided by remote sensing over the second half of the twentieth century, our knowledge of prior land-use impacts is also growing through the analysis of pollen in sediment cores and other paleo-ecological and archaeological techniques. Such techniques have enabled the estimation of the earth’s land cover 6000 years ago (GAIM 2000), and detailed reconstructions are being made for the past three centuries by projecting current land cover back in time using historical agricultural and demographic information. The convergence of remotely-sensed and other historical sources with prehistoric reconstructions will provide a much fuller picture of the earth’s land cover throughout the time of significant human impact, yielding valuable insights on long-term trajectories of change, and of possible path-dependency in the evolution of regional land-cover patterns.

4. Land Use Change

Elements of land-use practices have been a staple topic of investigation for numerous disciplines in the social sciences, including anthropology, archaeology, demography, economics, geography, history, political science, and sociology. Through different lenses, scholars in these fields have sought to explain how and why people in different parts of the world have developed technology and social systems in response to local environmental conditions, how these human actions have in turn shaped the local environment, and how people then respond to these changing conditions (Redman 1999). Thousands of case studies have been undertaken, usually concerning communities or small regions, and some efforts have been made to synthesize these cases in order to extract general principles and to develop a unified theory. While the history of land use in Europe is well documented (e.g., Darby 1956), land-cover transformation has been perceived to be most dramatic in the tropics in recent years, and a great deal of attention has been accorded these regions, with particular attention to agricultural land-use practices (e.g., Ruthenberg 1976).

A broad range of factors has been proffered to explain local land-use practices, with perhaps the greatest effort spent examining agricultural change and the role of population growth. The now-famous work of British economist Thomas Malthus, who predicted famine as an inevitable result of population growth in Europe, has fostered huge debate within the social sciences. Another major landmark was the work of Ester Boserup (1965), who turned the Malthusian thesis on its head, attributing agricultural development in Asia to land pressure driven by population growth. Subsequent refinements have described a range of land use change trajectories that may emerge from land pressure and suggested how the driving forces of change are mediated by social and environmental factors at many levels (Turner and Ali 1996).

In addressing the relationship between population growth and land degradation, political-economic analyses hold external forces responsible when land managers engage in environmentally destructive land use practices. Likewise, cases have been articulated of population growth leading to the rehabilitation of natural resources, including afforestation. A great deal of work has been done to examine the role of demographic factors in land use change, with particular emphasis on government-subsidized settlement programs in Latin America, and rural–urban migration in Africa and Asia. Results suggest complex relationships between land-cover dynamics and the provision of infrastructure (especially roads), family development cycles, urban wage employment, and other factors that vary strongly by region (e.g., Lambin et al. in press; see Property Rights).

In the case of forest cover, global-scale empirical evidence reveals a complex relationship between forest cover and population density, suggesting that as population density rises in newly settled regions, forest cover has often been removed for the purposes of agricultural expansion. Another period ensues during which wood fuel is replaced by other sources (e.g., fossil fuels) and agricultural intensification allows for the production of sufficient food on less land. Eventually affluence rises to the point where attention to environmental rehabilitation becomes feasible and afforestation becomes the dominant trend.

5. Land-Use/Cover Dynamics

Perhaps the main challenge of land use cover change science is to forge robust linkages between the broad views of land cover change provided by remote sensing and other techniques, and the fine-grained understandings of land-use dynamics. In weaving together these diverse strands of inquiry, land use cover change research examines the observed paths, or trajectories, and projects them into the future. While this may not lead to prediction, it will suggest what might happen should present trends continue and, perhaps more importantly, suggest other possible futures. There are significant obstacles to achieving this integration of land-use and land-cover perspectives, but advances in geographic information technologies and new analytical techniques show great promise.

Most early models of land cover change were either empirical (mimicking the observed relationships between variables, such as forest cover and population density), or mechanistic (describing a limited range of landscape processes according to simple equations) (Kaimowitz and Angelsen 1998). While such models have the advantage of requiring minimal, empirical evidence (e.g., maps of forest cover and population density), their utility is limited by the assumption that such relationships will persist and are the main determinants of landscape change (Lambin 1994). In order to incorporate the information gleaned through research on land-use dynamics more realistically, a new generation of dynamic simulation models are being developed that model the behavior and even the learning processes of individual actors in the landscape. Other developments include the generation of land use cover change scenarios and the analysis of syndromes of vulnerability to environmental change.

Bibliography:

1. Boserup E 1965 [1993] The Conditions of Agricultural Growth: The Economics of Agrarian Change under Population Pressure. Earthscan Publications, London
2. Darby H C 1956 The clearing of the woodland in Europe. In: Thomas W (ed.) Man’s Role in Changing the Face of the Earth. University of Chicago Press, Chicago
3. GAIM 2000 Summary report for the GAIM 6000 yr BP experiment and BIOME 6000. Global analysis, integration and modeling. http://gaim.unh.edu/Structure/Key-Issues/Biome6000/index.html
4. Kaimowitz D, Angelsen A 1998 Economic Models of Tropical Deforestation: A Review. Center for International Agroforestry Research, Bogor, Indonesia
5. Kasperson J X, Kasperson R, Turner B L II (eds.) 1995 Regions at Risk: Comparisons of Threatened Environments. United Nations University Press, Tokyo
6. Lambin E F 1994 Modelling Deforestation Processes: A Review. The European Commission, Luxembourg, TREES Series B: Research Report No. 1
7. Lambin E F, Baulies X, Bockstael N, Fischer G, Krug T, Leemans R, Moran E F, Rindfuss R R, Sato Y, Skole D, Turner B L II, Vogel C 1999 Land Use and Cover Change Implementation Strategy. International Geosphere-biosphere Programme Secretariat, Stockholm, IGBP Report No. 48, IHDP Report No. 10
8. Lambin E F, Turner B L II, Geist H, Agbola S, Angelsen A, Bruce J W, Coomes O, Dirzo R, Fischer G, Folke C, George
9. P S, Homewood K, Imbernon J, Leemans R, Li X, Moran E F, Mortimore M, Ramakrishnan P S, Richards J F, Skanes H, Steffen W, Stone G D, Svedin U, Veldkamp T, Vogel C, Xu J in press Our emerging understanding of the causes of landuse and -cover change. Global Environmental Change 4
10. Marsh G P 1864 [1965] Man and Nature: Or, Physical Geography as Modified by Human Action. Belknap Press, Cambridge, MA
11. Moran E 2000 Human Adaptability: An Introduction to Ecological Anthropology. Westview Press, Boulder, CO
12. National Research Council 1998 People and Pixels: Linking Remote Sensing and Social Science. National Academy Press, Washington, DC
13. Redman C L 1999 Human Impact on Ancient Environments. University of Arizona Press, Tucson, AZ
14. Ruthenberg H 1976 Farming Systems in the Tropics. 2nd edn. Oxford University Press, Oxford, UK
15. Thomas W L Jr (ed.) 1956 Man’s Role in Changing the Face of the Earth. University of Chicago Press, Chicago
16. Turner B L II, Clark W C, Kates R W, Richards J F, Matthews
17. J T, Meyer W B (eds.) 1990 The Earth as Transformed by Human Action: Global and Regional Changes in the Biosphere Over the Past 300 Years. Cambridge University Press, Cambridge, UK
18. Turner B L II, Ali A M S 1996 Induced intensification: agricultural change in Bangladesh with implications for Malthus and Boserup. Proceedings of the National Academy of Sciences USA 93: 14984–91