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In this chapter we present our current understanding of the dynamics and controls for important avenues of land cover change in the region including fire, insect disturbance, human land use, vegetation dynamics, and changes in the area of surface waters. We extend our discussion of controls to evaluate how land cover change might respond to possible future changes in the region. We then discuss the implications of future changes for major feedbacks to the climate system. Finally, we discuss the future challenges to understanding the patterns, controls, and consequences of land cover change in Canada and Alaska. [ABSTRACT FROM AUTHOR]

One of the conclusions from the previous chapters in this volume is that enormous progress has been made over the past decade in land-cover and land-use change research. The community has made great strides in implementing the original research agendas that have been described in international, national, and agency plans (Liverman et al., 1993; Turner et al., 1993; Turner et al., 1995; Janetos et al., 1996; IGBP 1999; Lambin et al., 1999). But one could also conclude that the original motivations for the rapid development of research into land-cover and land-use change have yet to be fully realized. The original vision was to understand the end-to-end sequence of land cover and land use changes, integrating changes that are driven by natural variability with those driven by human decisions, measuring the actual changes on the landscape, and evaluating both the ecological and socioeconomic consequences for humans (Janetos et al., 1996). Moreover, the international and national programs have emphasized the need to develop models of the various processes involved, with the ultimate goal of developing integrated models that can simulate the important processes and consequences for particular landscapes or societies (Liverman et al., 1993; Turner et al., 1993; Turner et al., 1995; Janetos et al., 1996; IGBP 1999; Lambin et al., 1999). The goal of this chapter is to present the major research challenges that have not yet been met, but that still will be required to achieve the ultimate goals. The chapter will address both theoretical and empirical issues, and will further address some of the methodological needs that future studies will have. [ABSTRACT FROM AUTHOR]

What is and ought to be humankind's relationship with nature?This question has stood the test of time as an overarching intellectual and moral query confronting society and to which much research and pedagogy has been directed. The question can be traced to antiquity in western society (Glacken 1967), and has had no less profound thinkers in eastern societies. It has been recrafted in many forms following the Enlightenment, traced through such landmark concepts as noösphere and biosphere (Vernadsky 1945; Lapenis 2002), human modification of the earth (Thomas 1956; Marsh 1965), and ecosystem and biosphere function (Worster 1977; Lovelock 1988; Moran 2000; Golley 1992). These questions moved to the forefront of public concern in the 1960's American environmental movement, inspired in no small part by Rachel Carson's Silent Spring (1962), and led such initiatives as the International Biological Programme (IBP), which took advantage of the growing capabilities of computing to carry out large-scale ecosystem studies, including a "human adaptability" component examining the genetic, physiological, and behavioral adaptations that made it possible for human populations to thrive in environments considered to be extreme (Baker and Weiner, 1966; Odumi and Pigeon, 1970; Odum 1971; Baker and Little, 1976; Jamison et al., 1978). UNESCO's Man and the Biosphere Programme gave an even stronger role to the human dimensions of environmental concerns, especially as it has evolved today towards themes of sustainable development (www.unesco.org/mab). [ABSTRACT FROM AUTHOR]

Of the challenges facing the Earth over the next century, land use and land cover changes are likely to be the most significant. This anthropogenic process affects many parts of the earth's system (e.g., climate, hydrology), global biodiversity, and the fundamental sustainability of lands. Various estimates indicate that 50 percent of the ice-free land surface has been affected or modified in some way by human activity (Vitousek et al., 1997), while 10 to 55 percent of the net primary productivity has been captured by human land use activities (Rojstaczer et al., 2001). Over the next century, global population is projected to increase by 50-100% and it is likely that there will also be an increase in the global standard of living. Thus pressures to further convert or manage "natural" ecosystems for human needs as well as capturing more of the global net primary productivity are also likely to increase. Understanding of the patterns of land use and land cover change has increased significantly over the last decade (e.g., Turner 2002a). This has been facilitated in part by increased awareness of the issues and by the large number of focused studies directed to understanding the nature of land-cover and land-use change (LCLUC). These studies have made significant advances in furthering our understanding of the socio-economic drivers of LCLUC, the impacts on natural and human systems, as well as feedbacks between natural and human systems. Given the large number of case studies that have been performed, we now have the opportunity to look broadly at the results of these studies to assess if there are fundamental patterns of land-use and land-cover change that consistently appear regardless of global location, social organization, economic state, etc. Furthermore, we can now assess whether there are persistent impacts of LCLUC that can be identified and related to the overall patterns. [ABSTRACT FROM AUTHOR]

Models are used in a variety of fields, including land change science, to better understand the dynamics of systems, to develop hypotheses that can be tested empirically, and to make predictions and/or evaluate scenarios for use in assessment activities. Modeling is an important component of each of the three foci outlined in the science plan of the Land use and cover change (LUCC) project (Turner et al., 1995) of the International Geosphere-Biosphere Program (IGBP) and the International Human Dimensions Program (IHDP). In Focus 1, on comparative land use dynamics, models are used to help improve our understanding of the dynamics of land use that arise from human decision-making at all levels, households to nations. These models are supported by surveys and interviews of decision makers. Focus 2 emphasizes development of empirical diagnostic models based on aerial and satellite observations of spatial and temporal land cover dynamics. Finally, Focus 3 focuses specifically on the development of models of land use and cover change (LUCC) that can be used for prediction and scenario generation in the context of integrative assessments of global change. Given space limitations, we focus on spatially explicit models of LUCC. Because the majority of models of this sort are implemented at relatively local scales - sometimes called landscape scales (e.g., 1-100,000km2), we focus on these scales. These models, therefore, may not be appropriate for scaling up to continental and global scales. However, we discuss needs and prospects for models coupling crossscale dynamics towards the end of the chapter. [ABSTRACT FROM AUTHOR]

This chapter reviews some of the issues that arise when joining remotely sensed and social science data. The focus is methodological, not substantive. The goal is to identify, describe, and review methodological challenges, recognizing that the solutions will be driven to a large extent by a researcher's substantive questions and scientific goals. As noted, the history of joining data on pixels and people is short. Hence it is highly likely that some key questions have not even surfaced, a point to which we return in the conclusion of the chapter. Also, we do not address potential ethical issues that might arise when joining remotely sensed and social science data except to note here that ethical issues definitely do arise and researchers need to be careful about them (see discussion by Rindfuss and Stern 1998). Readers must remember that the assessment offered here is a start and not a finish. The chapter opens with perhaps the most fundamental question that researchers interested in joining people and pixels must face: where to begin? There is no necessary parallel between social units and land units. Moreover, coverage of one does not necessarily guarantee coverage of the other. The first section discusses the implications of the starting point, land or people. Then, linking relations (e.g., ownership, use, or access) are addressed. The need for temporal depth presents challenges on both sides of the landpeople equation, and these are discussed next. We then turn to challenges associated with the joining of diverse disciplines, which is often a necessary part of joining people and pixels. The chapter concludes with an overview of new topics and challenges that will need to be addressed as the field develops. To date, researchers linking people and pixels at finer scales have tended to focus on land use in rural areas, especially in frontier environments; there is a need to encompass urban areas as well. [ABSTRACT FROM AUTHOR]

It is an interesting time for mapping and monitoring of land cover using remote sensing. There are exciting new kinds of maps derived from remote sensing at a variety of spatial scales. For example, there are a number of new kinds of maps of land cover becoming available globally. Following in the footsteps of the global land cover products derived from the 1992 1km AVHRR time series (the IGBP Discover Map (Loveland et al., 2000) and the University of Maryland Land Cover Map (Hansen et al., 2000)), two new products have been developed. One is the GLC2000 Land Cover Map (Bartalev et al., 2003) made using data from the SPOT4-VEGETATION sensor. Another is the MODIS land cover map, made using a time series of data from the MODIS sensor (Friedl et al., 2002). All of these maps are categorical in nature and include classes roughly at the level of biomes. There are differences between the legends of these maps, but their basic nature is similar. A somewhat different set of products are based on the idea of continuous fields, with a good example being percent forest cover (Hansen et al., 2002). These maps are also global and provide a different perspective on land cover. At the same time that these global maps were being produced using coarse resolution imagery (meaning imagery of approximately 1km or coarser), new maps at high spatial resolution over large areas were made. The best example in this regard is the use of Landsat imagery to produce a 30m land cover map of the United States, referred to as the MRLC land cover map (Vogelman et al., 2001). For the first time it is now feasible to acquire and process the large amounts of high resolution data necessary to map large areas in great spatial detail. [ABSTRACT FROM AUTHOR]

Land use change is important from a variety of perspectives. It is of interest in its own right. Processes like urbanization, the expansion of a frontier, land degradation, or recreational uses of land have long been of theoretical and research interest. Population growth, and the pressure it puts on land use and agricultural practices, has been an issue since Malthus' classic essay and has been central to the thinking of such 20th century scholars as Hawley (1950), Davis (1963) and Boserup (1965, 1981). More recently, however, it has been global change issues that have driven interest in land use change (Lambin et al., 1999; de Sherbinin 2002). As the relationships between land use change and climate change are better understood, it has become self-evident to broader scientific constituencies that population processes influence land use change, and that land use change can, in turn, influence population processes. [ABSTRACT FROM AUTHOR]

Research on fire is often of an applied nature, addressing questions of how to manage landscapes for fire, how to determine fire danger, how to model fire behavior, fire impacts and post-fire succession (Martell 2001; Chuvieco 2003). This in part reflects the desire of the funding agencies to maximize the benefits from the large amounts of public money spent each year on fire management. There is an increasing body of fire research in the area of global change, for example studying the potential impacts of climate change altering fire regimes, the impact on the atmosphere in terms of emissions, radiative forcing and chemical composition and feedbacks to the surface (Scholes et al., 1996; Stocks et al., 1998; Govaerts et al., 2002). In this chapter we examine fire as a component of the land use and land cover change research, the satellite systems at our disposal to study fire and summarize case studies on fire and land use, from three different regions. [ABSTRACT FROM AUTHOR]

Urban places may be broadly defined as the settlements where most people live and work. Human beings worldwide tend to cluster in spatially limited habitats occupying less than 5% of the world's land area. Urbanization may be defined as those environment altering activities that create and maintain urban places. This includes the processes of construction, habitation, transportation, energy and water use, communication, industrialization, commercial and manufacturing services, plus civic activities associated with education and governance. The physical patterns of urban areas produce distinctive spatial and spectral signatures that are recorded by many types of remotely sensed data. The seven thousand year old history of urbanization can be seen as a consequence of evolving technological capabilities to harness resources to support greater and greater human populations and enhanced occupational specialization and diversification. Today more than half of the world's population lives in urban areas, with the most rapid increases occurring in the developing countries of Latin America, Asia, and Africa. In Europe, North America, and Japan 80% or more of the population already lives in urban areas. [ABSTRACT FROM AUTHOR]

Terrestrial ecosystems affect climate through exchanges of energy, water, momentum, mineral aerosols, CO2, and other atmospheric gases. Changes in community composition and ecosystem structure alter these exchanges and in doing so alter surface energy fluxes, the hydrologic cycle, and biogeochemical cycles. As a result, changes in land cover through natural vegetation dynamics or human uses of land can alter climate. Much of our knowledge of the influence of vegetation on global and regional climate comes from climate models. In these models, the absorption of radiation at the surface, the exchanges of sensible and latent heat between land and atmosphere, storage of heat in soil, and the frictional drag of the surface on wind influence climate. Important surface properties that determine these exchanges include: albedo, which determines the absorption of solar radiation at the surface; surface roughness, which affects turbulence and the turbulent fluxes of sensible heat, latent heat, and momentum; soil water, which affects the partitioning of net radiation into sensible and latent heat; vegetation, which alters the hydrologic cycle and also affects albedo, surface roughness, canopy physiology, and the leaf area from which heat and moisture are exchanged with the atmosphere; and soil texture, which affects infiltration, runoff, and soil water. The first generation of land models coupled to atmospheric models parameterized these processes using simple aerodynamic bulk transfer equations and simple prescriptions of albedo, surface roughness, and soil water (Sellers et al., 1997). These models evolved into a second generation of models such as the Biosphere-Atmosphere Transfer Scheme (BATS, Dickinson et al., 1993) or Simple Biosphere Model (SiB, Sellers et al., 1986) that include the full hydrologic cycle and vegetation effects on energy and water fluxes. [ABSTRACT FROM AUTHOR]

The expansion and intensification of human land use in recent decades is resulting in major changes in biodiversity. Biodiversity, a term that has entered into common usage only in the last twenty years, refers to the diversity of life at all levels of organization, from genetic to species to ecosystem (Levin 2000). Although we refer throughout this chapter most commonly to species diversity, land use change alters biodiversity at all of these levels. For example, reduced habitat from land use change decreases population sizes and reduces genetic diversity within a species. At the other extreme, land use change commonly leads to more homogenous landscapes reducing ecosystem diversity (Flather et al., 1998). The advent of remotely sensed data from satellites has provided a basis for quantifying rates of land use change around the world and consequences on biodiversity. Global satellite-based data sets, useful for analyses of rates of land use change since the 1970s, are now becoming available. These analyses reveal that in these recent decades, land use continues to intensify in formerly occupied areas and expand into what were formerly natural habitats. This paper aims to summarize what we have learned about interactions between land use and biodiversity, especially during the period of satellite data availability. The goal of this chapter is to synthesize current knowledge on the influences of recent land use change on biodiversity. We first review the ways by which land use change affects biodiversity. We then summarize the use of remote sensing for studying land use change and its influence on biodiversity. Then, drawing heavily on NASA LCLUC case studies, we examine the consequences of land use change for biodiversity. Finally, we highlight promising conservation and management efforts aimed at better sustaining biodiversity and human communities undergoing land use change. [ABSTRACT FROM AUTHOR]

Water quality and quantity are widely recognized as important environmental resources for society (Arnell et al., 2001). Quantity refers to the presence of a sufficient supply of fresh water to support the human and natural systems dependent on it, while quality refers to the suitability of the supply for its intended use (e.g. agricultural, domestic, industrial, or natural). Water is a dynamic substance, however, and the water cycle is a series of fluxes between reservoirs of varying size, residence time, and state. This interconnected property means that there are important consequences of the life history of water on a landscape, from its first appearance in precipitation to its exit to the ocean. The water carries a signature of its history (i.e., nutrient and pollutant loads) that has impacts and consequences on the reservoirs through which it passes. Climate change will almost certainly impact the water cycle. These effects have been studied in some detail, although largely at global/regional scales; details are presented elsewhere in this book (Bonan et al., Chapter 17). For example, precipitation has increased 0.5-1% per decade in the 20th century in the mid-high latitudes of the northern hemisphere, with a greater frequency of heavy precipitation events, and these trends are likely to continue (IPCC Reports, 2001). This establishes the essential parameters of the water fluxes, but how that water is transported, allocated, and modified during residency on the land is an important research area for Land Cover and Land Use Change (LCLUC). Land cover and land use are important determinates of the water supply on its transit through a landscape. Climate broadly establishes the upstream supply term of the water budget, and the effects of land cover and land use on water quality and quantity at the local level have been well established through numerous studies. For example, it is well documented that deforestation increases stream flow through decreased evapotranspiration (Bosch and Hewlett, 1982). Urban- and suburbanization also increase stream flow through increased runoff, but also decrease water quality when the amount of impervious surface in a watershed exceeds 10-15%of the total land cover (Schueler, 1994). The demand for water in all regions, but particularly in arid and semi-arid environments, for domestic, industrial, and agricultural uses has led to water engineering projects on all scales (Rosenberg et al., 2000). The net result is that demand often exceeds supply in these systems, resulting in some of the 20th century's largest land transformations with consequent impacts on aquatic systems. [ABSTRACT FROM AUTHOR]

Major uncertainties in the global carbon (C) balance and in projections of atmospheric CO2 include the magnitude of the net flux of C between the atmosphere and land and the mechanisms responsible for that flux. A number of approaches, both top-down and bottom-up, have been used to estimate the net terrestrial C flux, but they generally fail to distinguish possible mechanisms. In contrast, calculations of C-fluxes based on landuse statistics yield both an estimate of flux and its attribution, that is, land-use change. A comparison of the flux calculated from land-use change with estimates of the changes in terrestrial C storage defines a residual terrestrial C sink flux of up to 3 PgC yr-1, usually attributed to the enhancement of growth through environmental changes (for example, CO2 fertilization, increased availability of N, climatic change). We explore whether management (generally not considered in analyses of land-use change), instead of environmental changes, might account for the residual sink flux. We are unable to answer the question definitively. Large uncertainties in estimates of terrestrial C fluxes from top-down analyses and land-use statistics prevent any firm conclusion for the tropics. Changes in land use alone might explain the entire terrestrial sink if changes in management practices, not considered in analyses of land-use change, have created a sink in the northern mid-latitudes. [ABSTRACT FROM AUTHOR]

Over the last two decades, land-use changes in China have been dominated by an urban transformation unprecedented in human history. The Chinese landscape, which for thousands of years was mainly rural, is becoming increasingly urban. Natural ecosystems, farms, rangelands, towns, and villages are being converted into, or enveloped by, extended metropolitan regions. This urban revolution has profound environmental impacts, including local and regional climate change, loss of wildlife habitat and biodiversity, stress on food production systems, and pressure on water resources. Urbanization can also lead to poor housing conditions, inadequate waste disposal, and rapid spread of infectious diseases. Every aspect of the urbanization process, ranging from the provision of social welfare programs to the construction of transportation infrastructure, presents huge environmental and socioeconomic challenges. However, urbanization does not have only negative impacts. Urban development can offer opportunities for concentrated and efficient land use, progress in environmental quality, and resources for solid and waste water treatment. From a socioeconomic perspective, urbanization can also lead to better living conditions and improvements in well-being through wider availability of health care, better education services, access to reliable energy supplies, and advances in sanitation. The dramatic urban land-use changes in China have been fueled by economic reforms that lead to impressive economic growth through the 1980s and 1990s. During these two decades, global average annual rates of growth ranged between 2 and 3 percent, respectively, while the Chinese economy grew at breathtaking rates of 10 percent and greater (World Bank 2000). The overwhelming success of the reforms has led to urban changes unparalleled anywhere on Earth. According to recent figures, of the 488 major urban areas in the world, nearly one-quarter are located in China. Furthermore, China's urban population is predicted to increase by more than the total population of the United States in the next 25 years (United Nations 2001). [ABSTRACT FROM AUTHOR]

Land use in the Khabur River drainage of northeastern Syria has changed from open rangeland to an intensely cultivated landscape in less than 100 years. In this semi-arid zone successful agriculture usually requires either supplemental or full irrigation. The drivers of the changes have included settlement of refugees, rapid population growth, ambitious plans to develop the water resources for summer cropping, decisions by individual farmers to install wells, and competing needs and programs in the river's headwaters in Turkey. Collectively these have led to fundamental alteration of the natural drainage in favor of ground water extraction, storage reservoirs and irrigation canals. We have monitored the magnitude of recent changes through satellite imagery. The sustainability of the system under current practices is in doubt. [ABSTRACT FROM AUTHOR]

While the environmental impacts of tropical deforestation have received considerable attention, reductions in biomass are in stark contrast to significant increases in woody plant abundance in many grasslands worldwide. Though not well quantified on a global scale, this vegetation change has been widely reported in tropical, temperate and high-latitude rangelands worldwide (Archer 1994; Archer et al., 2001). Land-cover change of this type and magnitude is likely to affect key ecosystem processes in grasslands, and may significantly alter carbon cycling and feedbacks to climate change. Moreover, the proliferation of woody vegetation at the expense of grasses threatens to render substantial portions of these areas incapable of supporting pastoral, subsistence, or commercial livestock grazing, thus adversely affecting ≈20% of the world's population inhabiting these lands (Turner et al., 1990; Campbell and Stafford Smith, 2000). While interannual climate variability, atmospheric CO2 enrichment, and nitrogen deposition are also likely contributing factors (Archer et al., 1995; Kochy and Wilson, 2001), land use practices associated with livestock grazing and reductions in fire frequency have been implicated as proximate causes for this widespread land cover change (Archer 1995; Caspersen et al., 2000; Van Auken 2000). [ABSTRACT FROM AUTHOR]

Land degradation over vast areas in tropical semi-arid regions, as a result of persistent drought and inappropriate land management, was brought to international public attention in the early 1980s following two catastrophic droughts in the African Sahel within a 10 year period. It was ultimately concluded that an interaction between climate and human land use was occurring at a sub-continental scale and that new techniques were needed to monitor and explain these processes. Similar situations have been recognized throughout the world, some in quite different climates (e.g., Mabbutt and Floret, 1980). While there has been significant progress in the study of the landatmosphere interactions involved in desertification (Xue and Fennessy, 2002), studies of the ecological components of the process of desertification have mainly been at the local scale related to, for example, wind, gully and sheet erosion, bush encroachment, and salinization. The land surface processes of desertification also operate over large areas and long time scales (Prince 2002), and these have not received much attention. This is mainly because of the difficulty in obtaining appropriate data, although unfamiliarity with these time and space scales may also have contributed to the lack of progress. Studies of the anthropogenic component of desertification have largely assumed the biophysical nature of desertification, and have dealt with socioeconomic (Vogel and Smith, 2002), governmental and political perspectives (Chasek and Corell, 2002) assuming that desertified areas have the same properties as arid ecosystems. Following a discussion of the significance of time and space scales in the definition of desertification, this chapter explores the potential of remote sensing of annual primary production to detect desertification. The concept of reduction in mean, interannual, potential production is applied to the country of Zimbabwe, which has several features that make it suitable for the assessment of the extent of actual desertification as defined here. Finally the results are discussed in the context of global monitoring of desertification. [ABSTRACT FROM AUTHOR]

Boreal forest is the major type of land cover in Northern Eurasia. It forms one of the world's largest forest tracts and amounts to some 25% of the world's forest cover. Boreal forest ecosystems developed under the influence of an active natural disturbance regime that created a complex and dynamic pattern of land cover. Species mix, patterns of succession, and the role of specific disturbance factors vary from region to region. Fire and insect damage represent two major natural disturbance factors, although the extent and patterns of these disturbances may partly reflect human influences. Human impact on boreal forests is expanding throughout Northern Eurasia and includes timber harvest, fire control, drainage of peat lands, urban, agricultural and infrastructure development, industrial pollution, forestation and conservation measures. The impact of projected climate change and potential feedbacks from boreal forest ecosystems are expected to be strong making it very important to understand the current patterns of forest cover, its attributes, and change over time. Case studies within the boreal forest of Eurasia focus on regions that vary greatly in the extent of human impact on forest ecosystems. In the heavily populated west (St. Petersburg region) few primary forests remain and repeated logging is the major disturbance factor while urban expansion and agricultural change (including abandonment of agricultural lands) also plays a role. In Central Siberia, timber harvest is expanding into previously unexploited forests while fire and insects continue to play a major role as some abandonment of agricultural lands adds to forest cover. Finally, in Northeast China fire control is taking effect while intensive use of forests is maintained and localized land clearing for agriculture continues. Remote sensing was used in all three study regions as a basis for the analysis of forest cover and disturbance patterns. [ABSTRACT FROM AUTHOR]

Characterizing and mapping land cover and land use change in the rain forests of Central African is a complex process. This complexity is marked by the diversity of land use practices across six different countries (Cameroon, Central African Republic, Democratic Republic of Congo, Equatorial Guinea, Gabon, and Republic of Congo), the lack of full and continuous cloud-free coverage by any single optical remote sensing instrument, and the limited institutional capacity to implement mapping and monitoring activities. As part of the NASA Land Cover Land Use Change Program (LCLUC) and the Central Africa Regional Program for the Environment (CARPE), an "Integrated Forest Monitoring System" (NASA-INFORMS project; http://www.whrc.org/africa) was established in close collaboration with national forest services, private logging companies, and conservation organizations. This project has been focused on developing remote sensing products for the needs of forest conservation and management, insuring that research findings are incorporated in the forest management plans at the national level. In this chapter, we will describe how multi-temporal and multi-sensor remote sensing observations and techniques have been integrated with in-situ data for habitat mapping, logging monitoring, and biomass estimation. Using time-series of Landsat imagery, for example, we have mapped the expansion of logging activities in the northern Republic of Congo, providing a new monitoring tool for the national forest service. Indices for estimating the intensity of timber harvesting are also in development. Maps of forest types, as well as deforestation assessment around population centers, have been produced in collaboration with different stakeholders in order to promote better forest management practices in the region. [ABSTRACT FROM AUTHOR]

Southeast Asia is a culturally, environmentally, and geographically rich, diverse, and dynamic region. Comprised of eleven countries, it spans the Indochina and Malay peninsulas and the Malay Archipelago. Five nations, Cambodia, Laos, Myanmar, Thailand, and Vietnam, are entirely on the mainland. The remaining six, Brunei, East Timor, Indonesia, Malaysia, Philippines, and Singapore, are spread across thousands of islands. Coastal zones and river deltas, piedmont zones and mountain chains, with peaks reaching heights greater than 19,000 feet, characterize the region. The land cover and land use change patterns evident in Southeast Asia are as diverse and dynamic as the political, economic, and demographic spheres in these eleven nations. [ABSTRACT FROM AUTHOR]

Human beings are altering land cover at rates and scales that are unprecedented in human history (NRC 2002), rivaling glacial/interglacial transitions in magnitude (NAS 2000). Nowhere are human-mediated changes in land cover affecting global processes more than in the tropics. Understanding the causes and effects of regional land cover and land use change (LCLUC) is one of the grand challenges in the environmental sciences (NAS 2000). Further refinement in the estimates of tropical forest conversion will also be important for balancing the global carbon budget, and reconciling flux estimates from models (Houghton et al., 2000) and atmospheric measurements (Ciais et al., 1995a, 1995b). Land cover and land use change are important drivers of ecological change in Amazonia. Conversion to agricultural and urban land creates widespread ecological disturbance, even at some distance from the zone of direct encroachment (Walker and Solecki, 1999). Land cover change in this region is globally significant, having a large influence on hydrology, climate, and global biogeochemical cycles (Crutzen and Andreae, 1990; Houghton and Skole, 1990; Salati and Vose, 1984; Shukla et al., 1990; Houghton 1991). Despite the recognized importance of tropical LCLUC, which affects everything from aerosols and biodiversity to the global carbon and hydrologic cycles, hard data on LCLUC in these regions have been sparse or nonexistent. Consequently, global change scientists have had to rely on frequently inaccurate FAO estimates of forest loss (Kaiser 2002). This has forced the Intergovernmental Panel on Climate Change (IPCC) to emphasize that deforestation estimates in tropical countries may be in error by +/-50%. Past FAO estimates have suffered from a strong reliance of secondary sources, or very sparse sampling; the comprehensive use of remote sensing data has been heretofore absent in the implementation of the observation and measurement efforts, and only recently considered for future assessments. In recent years, several important LCLUC studies of tropical forest loss or degradation have been published in the scientific literature, some utilizing remote sensing observations (cf. Nepstad et al., 1999; Achard et al., 2002; DeFries et al., 2002;), however, these studies, when taken together as a whole, contain considerable uncertainty and broad differences in our current understanding of rates of deforestation and degradation. Indeed, all of these studies have had to rely on indirect estimation techniques, or imperfect sampling schemes to make large-area or global estimates. [ABSTRACT FROM AUTHOR]

Three research projects, supported by the NASA Land Cover and Land Use Change (LCLUC) Science Program have been conducted in the Central America and Mexico (Mesoamerica) region. The first two projects were conducted in Northern Guatemala (Maya Biosphere Reserve) and the Southern Yucatan Peninsular Region (SYPR) of Mexico. The third project, focused on the Mesoamerican Biological Corridor, had broader coverage over the entire Central American region under a cooperative research memorandum of understanding between NASA and the environmental ministers of the seven Central American countries. This chapter will begin with an overview of the Mesoamerican Biological Corridor concept and the status of forest protection and forest changes using data analyzed for sample sites distributed throughout the region. Given the importance of protected areas in the region and the threats facing them, the bulk of the chapter will address the Northern Guatemala and SYPR sites located in and around two major Biosphere Reserves. Both of these case studies utilized time-series Landsat imagery combined with socio-economic household surveys and landscape level analysis to examine human driving forces that influenced forest and land cover/use changes. This research demonstrates that medium spatial resolution satellite imagery is well suited for monitoring tropical forests and remote biological reserves (Sader et al., 2001a; Turner et al., 2001). [ABSTRACT FROM AUTHOR]

To ensure systematic long-term observations of the environment several efforts have been made in recent years to provide international coordination of observational systems working within the framework of various overarching international organizations. One such effort is known as Global Observations of Forest Cover/Global Observations of Land Cover Dynamics (GOFC/GOLD). Originally it was set up to consider the monitoring of forests and hence the original name of Global Observations of Forest Cover (GOFC) but has been extended to all land cover types (see section 4.3). GOFC/GOLD is one of the Panels of the Global Terrestrial Observing System, an organization sponsored by four UN bodies, namely the Food and Agricultural Organization (FAO), the United Nations Educational Scientific and Cultural Organization (UNESCO), the United Nations Environmental Programme (UNEP), the World Meteorological Organization (WMO) and the International Council for Science (ICSU). GOFC as an organization was originally set up by the Committee for Earth Observing Satellites (CEOS) and it retains close links with that organization because of the importance of spaceborne remotely sensed observations to the goals of GOFC/GOLD. In this chapter we review the goals of the organization and make an assessment of progress made in realizing the plans formulated in the later part of the 1990's. In doing the latter we propose a new template which is used to assess objectively how close we are to achieving the goals of long term operational systematic observations of land cover for the whole globe. [ABSTRACT FROM AUTHOR]