- Email: [email protected]
Land Change Science
Land Change Science B. L. Turner II, Arizona State University, Tempe, AZ, USA & 2009 Elsevier Ltd. All rights reserved.
Glossary Biosphere It is the intersection zone of the Earth’s land, ocean, and atmosphere systems that support life. Coupled Human–Environment System It is a bounded unit comprising a set of human and environmental relationships. Ecosystem Services These are resources and processes of ecosystems that benefit humankind. Spatial Econometrics It is the incorporation of spatial effects in quantitative and statistical methods addressing economic principles. Sustainable Land Architecture The pattern of land uses and covers that provision human uses and maintains a full range of ecosystem services. Sustainability It is provisioning humankind without threatening the functioning of the biosphere. Vulnerability It is the degree to which a system is likely to experience harm due to the exposure to a hazard.
Land-change science (LCS) is a transdisciplinary field of study that seeks to observe and monitor land-cover and land-use changes and explain and model these changes as a coupled human–environment (or social–ecological) system. Land cover refers to the biophysical condition (e.g., forest, grassland, and paved surface) of some portion of the terrestrial surface of the Earth, and land use is the human intent or activity associated with that condition (e.g., reserve, pasture, and settlement). In addition to detecting and monitoring changes in land cover, largely from satellite information, LCS examines societal structures and individual behavior that determine land uses, the impacts of those uses on the structure and function of the biophysical subsystem, and the environment feedbacks, foremost ecosystem (environmental) services, from that subsystem to land uses and the human subsystem. Understanding the coupled system through the medium of land cover and use not only provides insights about outcomes and processes in both subsystems, but also informs synthesis questions about the vulnerability and sustainability of human–environment relationships.
Development of LCS The question of global warming stimulated various science agendas to improve understanding of the Earth system and the human impacts on it. The resulting
research efforts quickly realized that understanding the processes linking the terrestrial surface of the Earth, often addressed in terms of ecosystems, to the Earth system at large was incomplete without understanding the human-induced changes on that surface (i.e., as they affect, for example, albedo and sources and sinks of carbon, or methane emissions), including the rates and trajectory of those changes. This need, in turn, required improved understanding of the human drivers (e.g., population or policy change) of land use. This use, however, is also affected by changes in the biophysical subsystem, either directly through land-cover changes in the ecosystem services or indirectly through land-cover impacts on the Earth system at large, such as global climate change. The importance of these dynamics increased as concerns about global environmental changes enlarged from climate change to loss of biodiversity and ecosystems, land degradation, and ultimately, sustainability. Land changes are critical to a range of issues that culminate in the maintenance of the biosphere (that portion of the Earth system sustaining life) and human well-being.
Land Change in Global Environmental Change Given that humankind evolved as a land-based species, it is not surprising that human impacts on the terrestrial surface of the Earth are ancient, traced back to the control of fire and perhaps the extinction of Late Pleistocene and early Holocene megafauna. With each major technological epoch (stone tools fire, domestication, fossil fuels, etc.), the number, magnitude, spatial reach, and pace of land changes wrought by humankind enlarged. Estimates of human-induced transformation (radical change) in land-cover range as high as 50% of land surface of the Earth. If coadapted landscapes and indirect impacts through climate change are considered, virtually the entire land surface has been affected by human activity. Much of this impact has changed the states of the Earth system, as in the 40% of the land surface in which forest, grasslands, and wetlands have been converted to agriculture. These and other land changes are the second-largest source (to fossil-fuel burning) of human-induced carbon dioxide, and the significant source of methane, to the atmosphere. Land practices, through the use of fertilizers, make humankind the largest contributor to the global nitrogen cycle, surpassing nature. In addition, about 85% of annual water withdrawals globally are
107
108
Land Change Science
taken for agriculture, with important consequences for the water cycle. Clearly, land change is the principal factor to date in changing the land states of the Earth system and, in doing so, has played an important role in changing the biogeochemical cycles that permit that system to function and sustain the biosphere. The magnitude and spatial reach of these changes raises serious questions about the sustainability of human uses of ecosystems, landscapes, and the Earth system.
Observation/Monitoring Satellite- and air-based sensors observing the Earth have proliferated over the last quarter-century, providing a wealth of new and novel information about the changes in the land surface of the Earth. Improved seamless coverage of global land covers (e.g., forest cover) and high spatiotemporal resolution data on specific locales have helped to document such attributes of the terrestrial surface as increases and losses in the area of temperate and tropical forests, respectively, changes in aboveground carbon sources and sinks, losses of ecosystems and biomes of high biotic diversity, urban expansion into agricultural lands, and changing phenology (e.g., timing of the flowering of vegetation) and primary productivity (e.g., photosynthesis). Refocusing on regions and locales, major advances in the development of land-cover classification provide increasing detail of the land surface, capable of differentiating among forest types and phases of their successional growth as well as detecting invasive species, selective logging, and the buildup of fuel loads in fire-prone forests, among other examples. It is precisely such detail that permits tests of various theories and concepts emanating in the social sciences relevant to understanding the human causes and consequences of land change. For example, smallholders throughout the tropical world employ slash-and-burn cultivation practices where land-use decisions are affected by the stage of vegetative regrowth in crop–fallow cycles. Distinguishing these stages via remote sensing facilitates tests of theories of agricultural change, a major component of improving understanding of land dynamics in that part of the world.
Drivers/Causes of Land Change In global environmental change, the term driver denotes a forcing function on some part of the Earth system. Drivers can be both biophysical factors that change land cover (e.g., long-term declines in rainfall) and human factors that change land use (e.g., population or policy change). Much social science work, however, treats drivers as causes of land use and addresses them through theoretical and empirical assessments. The human
drivers or causes vary by the scale of analysis employed, and at lower spatial scales, by the context of the case examined. Over the long term and at the global scale, the PAT variables of the IPAT identity [I (environmental impact) ¼ P (population) x A (affluence or per capita consumption) x T (technology; efficiency of resource use and disposal)] are the only factors to track consistently with land change, perhaps because P and A serve as coarse indicators of the demand for ecosystem goods and services. Below the continental scale or for pan-global land covers of specific types (e.g., tropical deforestation), the PAT variables need not capture demand, in part because economic globalization often disassociates the sources of demand from the extraction or production of resources to fulfill them. In such cases, the PAT factors may be operating, but they are not necessarily the most important for land change. The variance in drivers/ causes acting on specific types or cases of land-cover change and the variance in land outcomes owing to the synergy of different drivers/causes may be so large that generalizations prove difficult. For specific areas of land change, however, a variety of research has demonstrated the roles of markets, policy, transportation and roads (infrastructure), nongovernmental market interventions, household life cycles, and resource governance, among other causes. Increasingly, attention is paid to nested or linked causes, hierarchically arrayed. For example, international policy affects national and local policies and programs, which, in turn, change resource governance and thus access to land or the income that can be generated from it, concomitantly changing land use and cover. Causes combined in explanations that consider both structural (i.e., sociopolitical organization) and behavioral (i.e., individual decision making) factors prove difficult to test, owing to data limitations, but, when possible, provide improved explanation of land changes.
Land–Cover Consequences LCS pays special attention to ecosystem goods and services (e.g., water filtration, pollination, and food and fiber production) in their roles as resources traded in the market place and thus having a classical economic value (i.e., provisioning services as in food and fiber production) and as factors maintaining the functioning of the biosphere and nature’s condition (e.g., regulating and supporting services, such as climate controls and nutrient cycling). The wide range of these goods and services (which also include cultural and preserving services as in, respectively, sacred places and maintenance of biotic diversity) has been examined at different scales of analysis, demonstrating their importance to the maintenance of the biosphere, from ecosystem to landscapes to the Earth system, and the consequences on these
Land Change Science
functions as the goods and services are drawn down by human activity and consumption. The interconnections between human-driven changes in land cover and environmental dynamics have drawn considerable attention, demonstrating their implications for such far-flung phenomenon and processes as the frequency and magnitude of forest fires, regional-scale precipitation changes, and exposing human populations to new disease vectors.
Modeling Global environmental change and sustainability science are found on experiments, tests, and the need to address the future through quantitative-based forecasts. Modeling is essential in either case. Land-change modeling has been served by advances in the geographical information sciences (GIScs) and its grounding in the use of and methods for spatially explicit data and products. For many, if not most of the questions addressed by LCS, knowing or forecasting the kind, magnitude, and pace of land change is insufficient; the location of the change is essential as well. The spatial arrangement of ecosystems and landscapes matters in regard to environmental functions, and hence the delivery of ecosystem goods and services that society expects. Likewise, the spatial arrangement of the human uses of the same ecosystems and landscapes determine the consequences for goods and services and their feedbacks on land use. Given the prevalent use of remotely sensed data (Observation/ Monitoring above), the pixel in the imagery commonly marks the level of spatial explicitness that the models may take (e.g., about 30 m2, the most-prevalent used imagery in LCS). A large range of models are employed, especially as they have emerged from spatial econometrics and spatial analysis. Major advancements have been made in agent-based, integrative assessment models – those that attempt to model agents’ (individuals’) land-use decisions in the face of knowledge about changes in environment and institutions (rules of governance). The performance of these models in explaining and projecting the magnitude and location of different land types of change continues to improve, although the uncertainty in projections beyond a decade enlarges substantially.
Synthesis LCS attempts to integrate the knowledge gained from the various components of its study (Figure 1) to inform synthesis issues that typically carry both research and outreach-application implications. Examples include various attempts to understand and identify areas vulnerable to or resilient in the face of environmental
109
change (e.g., climate change) and ‘natural’ hazards (e.g., hurricanes) or sustainable in the face of increasing human uses. Drawing from risk-hazard research and critiques of it, both of which focus on the vulnerability of people, and from ecological research focused on the resilience of ecosystem, LCS has developed an emphasis on the vulnerability–sustainability of the coupled human– environment system. This vision recognizes that hazards simultaneously affect both the human and environmental subsystems and that the synergy of the two subsystems determines the total system response to the hazard. The coupled-system approach to vulnerability are illustrated by the recent hazard of Hurricane Katrina, the 2005 tropical storm that devastated coastal Mississippi (state) and the city of New Orleans, Louisiana. The exposure and sensitivity of New Orleans and the wetland habitats between the city and Gulf of Mexico have been altered by hydraulic works designed to facilitate waterborne traffic, permitting housing development in lowlying terrain, and by constructing access canals to gas and oil pumps distributed across the Mississippi delta. The overall effect of canal and levee construction reduces the buildup of sediments that maintain wetlands in the delta, especially the cypress swamps. These losses reduce the barriers to storm surges surrounding New Orleans, and the canals serve to funnel storm waters into the city, stressing the levees intended to protect the metropolitan area. The vulnerability of New Orleans, therefore, was and remains the product of human–environment interactions, and Katrina’s impact on both the city and ecosystems of the delta was profound. LCS has addressed an array of other synthesis issues and questions. For example, increasing attention is paid to the efficacy of the boundaries of nature reserves and parks, especially in cases where significant land use surrounds or people have the right to cultivate or collect resources within the reserves. In some cases, land changes outside the park, even at considerable distances from the park boundaries, affect biotic diversity within the park, especially where migratory animals are involved, raising the need for and design of biological corridors to facilitate the movement of biota. In other cases, the delimitations of the reserve boundaries and the rules of land and resource uses within the reserve to serve both human and environmental concerns have proven beneficial to the success of the reserve. In another example, LCS addresses the political–economic conditions that facilitate a forest transition – or cases in which economic modernization leads to a return of forest cover on lands once taken from forest. Drawing from lessons in environment development, LCS has also entertained real-world application, addressing the co-production of knowledge and participatory programs for land management. The resulting approaches can be found in formulizations such as the Drylands Development Paradigm.
110
Land Change Science Ear th system
T1.1
T2.1
T1.3
Land systems
T1.2
Land use and management
sys Eco tem services
Political/institutional regimes
T2.2 isio Dec n making
Population Social/economic structure
Ecological Dist u systems Biogeochemistry Biodiversity Water Air
T2.4
Culture Technology
ce an rb
Social systems
Soil
T2.3
T3.1 Critical pathways of change T3.2 Vulnerability and resilience of land systems T3.3 Effective governance for sustainability
T1. Dynamics of land systems T2. Consequences of land system change T3. Integrating analysis and modeling for land sustainability
Figure 1 Thematic concerns of land change science Global Land Project (2005). Science Plan and Implementation Strategy. Stockholm: International Geosphere-Biosphere Programme Secretariat.
These and other synthesis activities raise concerns about sustainable land architectures. The entire terrestrial surface of the Earth will soon be governed, leading to de facto or de jure designs of land uses and covers. These designs, commonly undertaken at the local or region level, invariably seek to provide a wide range of human uses and ecosystem services. The consequences of these designs for ecosystem services and human well-being at ascending spatial scales of concern are largely unknown. The aggregation of local to regional designs to the continental and global scales may well produce negative consequences for people and the environment processes operating at the large scales. Understanding the societal and environmental implications of the patterns of land use and land cover at different spatial scales thus beckons as a grand challenge for LCS.
LCS in Geographic Context Geography has a long tradition of human–environment studies focused on land and landscape, the modern origins of which are registered by the nineteenth-century German geographic traditions of landschaft (landscape), which can be linked to the search for ‘the unity in nature’ as articulated by Alexander von Humboldt and other students of natural history. The legacies of this vision,
some taken to detrimental extremes, range in orientation from the sciences to the humanities as exemplified by the nineteenth-century French geography of Vidal de la Blache, and the twentieth-century ‘geographic factor’ of Ellen Churchill Semple and Ellsworth Huntington, the cultural landscape of Carl Sauer, and the human ecology and natural hazards of Harlan Barrows and Gilbert White. Perhaps the most direct links in contemporary human–environment geography to LCS reside in cultural and political ecology. Indeed, former cultural ecologists from geography and anthropology, steeped in systemsbased approaches to human–environment problems, helped to spawn LCS as a formal international research program linking with GISc and ecology and environmental science to address land change in its own right as part of global environmental change and sustainability concerns. With interests in the politics and power relations of problem framing and answers, political ecology (PE) shares many of the same topical themes with LCS (e.g., causes of land change and vulnerability), but has entertained them foremost through the concerns about environment and development. Global change and sustainability, and environment development are, of course, intimately intertwined, and the potential for LCS and PE to inform one another is large, as in case of vulnerability research themes, and is beginning to take place across a
Land Change Science
large spectrum of shared topical interests. Indeed, in an increasing number of cases it is difficult to distinguish the methods used in and the outcomes of land-based research themes carried out in either subfield. Examples include the complex connections between international policies, land uses, and drought as they affect desertification in the Sahel of West Africa; Brazilian policy shifts, market vagaries, and largeholder–smallholder dynamics affecting the kind, amount, and pace of deforestation in the Brazilian Amazon; and human–environment relationships that need to be considered in order to establish effective biosphere reserves. Perhaps the main distinction between the two, serving as a modest impediment to more fruitful exchanges, resides in their explanatory foci: LCS anchored in post-positive science and PE in structural and constructivist explanatory visions. Regardless of the distinctions among different interests in geography, LCS addressed through the coupled human–environment systems appears to be at the vanguard of an emerging human–environment science that transcends traditional disciplines. The union of human, environmental, and geographical information/remote sensing research expertise is taking place in different programmatic ways that hold long-term consequences for the human–environment traditions in geography. This union has begun to be matched by the newly minted schools and degree programs, especially in North America, that hold the human–environment conditions and the coupled system dynamics that create them, as the objects of their study. This development may be seen as reinventions, with a decidedly science orientation, of the human–environment intellectual traditions championed by Humboldt and of its LCS component as linked to landschaft. See also: Environmental Studies and Human Geography; Physical Geography and Human Geography; Political Ecology; Remote Sensing; Resource and Environmental Economics; Simulation; Vulnerability.
111
Further Reading Global Land Project (2005). Science Plan and Implementation Strategy. Stockholm: International Geosphere-Biosphere Programme Secretariat. Gutman, G., Janetos, A., Justice, C. et al. (eds.) (2004). Land Change Science: Observing, Monitoring, and Understanding Trajectories of Change on the Earth’s Surface. New York: Kluwer Academic. Kates, R. W., Clark, W. C., Corell, R. et al. (2001). Sustainability science. Science 292, 641--642. Lambin, E. and Geist, H. (eds.) (2006). Land-Use and Land-Cover Change: Local Processes to Global Impacts. Berlin: Springer. Liverman, D., Moran, E. F., Rindfuss, R. R. and Stern, P. C. (1998). People and Pixels: Linking Remote Sensing and Social Science. Washington, DC: National Academy Press. Millennium Ecosystem Assessment (2005). Ecosystems and Human Well-Being: Synthesis. Washington, DC: Island Press. Reynolds, J. F., Stafford Smith, M., Lambin, E. F. et al. (2007). Global desertification: Building a science for dryland development. Science 316, 847--851. Turner, B. L. II. (2003). Contested identities: Human-environment geography and disciplinary implications in a restructuring academy. Annals of the Association of American Geographers 92, 52--74. Turner, B. L. II, Lambin, E. F. and Reenberg, A. (2008). The emergence of land change science for global environmental change and sustainability. Proceedings of the National Academy of Sciences 104, 20666--20671. Turner, B. L. II, and Robbins, P. (2008). Land change science and political ecology: Similarities, differences, and implications for sustainability science. Annual Review of Environment and Resources 33, 295–316. Veldkamp, T. and Lambin, E. F. (eds.) (2001). Predicting land-use change. Special issue. Agriculture, Ecosystems, and Environment 85(1–3), 1--6. Wu, J. (2006). Landscape ecology, cross-disciplinarity, and sustainability science. Landscape Ecology 21, 1--4.
Relevant Websites http://www.globallandproject.org/ Global Land Project. http://www.igbp.kva.se/ International Geosphere-Biosphere Programme. http://www.ihdp.unu.edu/ International Human Dimensions Programme on Global Environmental Change. http://lcluc.umd.edu/ NASA Land-Cover and Land-Use Change Program.
Glossary Biosphere It is the intersection zone of the Earth’s land, ocean, and atmosphere systems that support life. Coupled Human–Environment System It is a bounded unit comprising a set of human and environmental relationships. Ecosystem Services These are resources and processes of ecosystems that benefit humankind. Spatial Econometrics It is the incorporation of spatial effects in quantitative and statistical methods addressing economic principles. Sustainable Land Architecture The pattern of land uses and covers that provision human uses and maintains a full range of ecosystem services. Sustainability It is provisioning humankind without threatening the functioning of the biosphere. Vulnerability It is the degree to which a system is likely to experience harm due to the exposure to a hazard.
Land-change science (LCS) is a transdisciplinary field of study that seeks to observe and monitor land-cover and land-use changes and explain and model these changes as a coupled human–environment (or social–ecological) system. Land cover refers to the biophysical condition (e.g., forest, grassland, and paved surface) of some portion of the terrestrial surface of the Earth, and land use is the human intent or activity associated with that condition (e.g., reserve, pasture, and settlement). In addition to detecting and monitoring changes in land cover, largely from satellite information, LCS examines societal structures and individual behavior that determine land uses, the impacts of those uses on the structure and function of the biophysical subsystem, and the environment feedbacks, foremost ecosystem (environmental) services, from that subsystem to land uses and the human subsystem. Understanding the coupled system through the medium of land cover and use not only provides insights about outcomes and processes in both subsystems, but also informs synthesis questions about the vulnerability and sustainability of human–environment relationships.
Development of LCS The question of global warming stimulated various science agendas to improve understanding of the Earth system and the human impacts on it. The resulting
research efforts quickly realized that understanding the processes linking the terrestrial surface of the Earth, often addressed in terms of ecosystems, to the Earth system at large was incomplete without understanding the human-induced changes on that surface (i.e., as they affect, for example, albedo and sources and sinks of carbon, or methane emissions), including the rates and trajectory of those changes. This need, in turn, required improved understanding of the human drivers (e.g., population or policy change) of land use. This use, however, is also affected by changes in the biophysical subsystem, either directly through land-cover changes in the ecosystem services or indirectly through land-cover impacts on the Earth system at large, such as global climate change. The importance of these dynamics increased as concerns about global environmental changes enlarged from climate change to loss of biodiversity and ecosystems, land degradation, and ultimately, sustainability. Land changes are critical to a range of issues that culminate in the maintenance of the biosphere (that portion of the Earth system sustaining life) and human well-being.
Land Change in Global Environmental Change Given that humankind evolved as a land-based species, it is not surprising that human impacts on the terrestrial surface of the Earth are ancient, traced back to the control of fire and perhaps the extinction of Late Pleistocene and early Holocene megafauna. With each major technological epoch (stone tools fire, domestication, fossil fuels, etc.), the number, magnitude, spatial reach, and pace of land changes wrought by humankind enlarged. Estimates of human-induced transformation (radical change) in land-cover range as high as 50% of land surface of the Earth. If coadapted landscapes and indirect impacts through climate change are considered, virtually the entire land surface has been affected by human activity. Much of this impact has changed the states of the Earth system, as in the 40% of the land surface in which forest, grasslands, and wetlands have been converted to agriculture. These and other land changes are the second-largest source (to fossil-fuel burning) of human-induced carbon dioxide, and the significant source of methane, to the atmosphere. Land practices, through the use of fertilizers, make humankind the largest contributor to the global nitrogen cycle, surpassing nature. In addition, about 85% of annual water withdrawals globally are
107
108
Land Change Science
taken for agriculture, with important consequences for the water cycle. Clearly, land change is the principal factor to date in changing the land states of the Earth system and, in doing so, has played an important role in changing the biogeochemical cycles that permit that system to function and sustain the biosphere. The magnitude and spatial reach of these changes raises serious questions about the sustainability of human uses of ecosystems, landscapes, and the Earth system.
Observation/Monitoring Satellite- and air-based sensors observing the Earth have proliferated over the last quarter-century, providing a wealth of new and novel information about the changes in the land surface of the Earth. Improved seamless coverage of global land covers (e.g., forest cover) and high spatiotemporal resolution data on specific locales have helped to document such attributes of the terrestrial surface as increases and losses in the area of temperate and tropical forests, respectively, changes in aboveground carbon sources and sinks, losses of ecosystems and biomes of high biotic diversity, urban expansion into agricultural lands, and changing phenology (e.g., timing of the flowering of vegetation) and primary productivity (e.g., photosynthesis). Refocusing on regions and locales, major advances in the development of land-cover classification provide increasing detail of the land surface, capable of differentiating among forest types and phases of their successional growth as well as detecting invasive species, selective logging, and the buildup of fuel loads in fire-prone forests, among other examples. It is precisely such detail that permits tests of various theories and concepts emanating in the social sciences relevant to understanding the human causes and consequences of land change. For example, smallholders throughout the tropical world employ slash-and-burn cultivation practices where land-use decisions are affected by the stage of vegetative regrowth in crop–fallow cycles. Distinguishing these stages via remote sensing facilitates tests of theories of agricultural change, a major component of improving understanding of land dynamics in that part of the world.
Drivers/Causes of Land Change In global environmental change, the term driver denotes a forcing function on some part of the Earth system. Drivers can be both biophysical factors that change land cover (e.g., long-term declines in rainfall) and human factors that change land use (e.g., population or policy change). Much social science work, however, treats drivers as causes of land use and addresses them through theoretical and empirical assessments. The human
drivers or causes vary by the scale of analysis employed, and at lower spatial scales, by the context of the case examined. Over the long term and at the global scale, the PAT variables of the IPAT identity [I (environmental impact) ¼ P (population) x A (affluence or per capita consumption) x T (technology; efficiency of resource use and disposal)] are the only factors to track consistently with land change, perhaps because P and A serve as coarse indicators of the demand for ecosystem goods and services. Below the continental scale or for pan-global land covers of specific types (e.g., tropical deforestation), the PAT variables need not capture demand, in part because economic globalization often disassociates the sources of demand from the extraction or production of resources to fulfill them. In such cases, the PAT factors may be operating, but they are not necessarily the most important for land change. The variance in drivers/ causes acting on specific types or cases of land-cover change and the variance in land outcomes owing to the synergy of different drivers/causes may be so large that generalizations prove difficult. For specific areas of land change, however, a variety of research has demonstrated the roles of markets, policy, transportation and roads (infrastructure), nongovernmental market interventions, household life cycles, and resource governance, among other causes. Increasingly, attention is paid to nested or linked causes, hierarchically arrayed. For example, international policy affects national and local policies and programs, which, in turn, change resource governance and thus access to land or the income that can be generated from it, concomitantly changing land use and cover. Causes combined in explanations that consider both structural (i.e., sociopolitical organization) and behavioral (i.e., individual decision making) factors prove difficult to test, owing to data limitations, but, when possible, provide improved explanation of land changes.
Land–Cover Consequences LCS pays special attention to ecosystem goods and services (e.g., water filtration, pollination, and food and fiber production) in their roles as resources traded in the market place and thus having a classical economic value (i.e., provisioning services as in food and fiber production) and as factors maintaining the functioning of the biosphere and nature’s condition (e.g., regulating and supporting services, such as climate controls and nutrient cycling). The wide range of these goods and services (which also include cultural and preserving services as in, respectively, sacred places and maintenance of biotic diversity) has been examined at different scales of analysis, demonstrating their importance to the maintenance of the biosphere, from ecosystem to landscapes to the Earth system, and the consequences on these
Land Change Science
functions as the goods and services are drawn down by human activity and consumption. The interconnections between human-driven changes in land cover and environmental dynamics have drawn considerable attention, demonstrating their implications for such far-flung phenomenon and processes as the frequency and magnitude of forest fires, regional-scale precipitation changes, and exposing human populations to new disease vectors.
Modeling Global environmental change and sustainability science are found on experiments, tests, and the need to address the future through quantitative-based forecasts. Modeling is essential in either case. Land-change modeling has been served by advances in the geographical information sciences (GIScs) and its grounding in the use of and methods for spatially explicit data and products. For many, if not most of the questions addressed by LCS, knowing or forecasting the kind, magnitude, and pace of land change is insufficient; the location of the change is essential as well. The spatial arrangement of ecosystems and landscapes matters in regard to environmental functions, and hence the delivery of ecosystem goods and services that society expects. Likewise, the spatial arrangement of the human uses of the same ecosystems and landscapes determine the consequences for goods and services and their feedbacks on land use. Given the prevalent use of remotely sensed data (Observation/ Monitoring above), the pixel in the imagery commonly marks the level of spatial explicitness that the models may take (e.g., about 30 m2, the most-prevalent used imagery in LCS). A large range of models are employed, especially as they have emerged from spatial econometrics and spatial analysis. Major advancements have been made in agent-based, integrative assessment models – those that attempt to model agents’ (individuals’) land-use decisions in the face of knowledge about changes in environment and institutions (rules of governance). The performance of these models in explaining and projecting the magnitude and location of different land types of change continues to improve, although the uncertainty in projections beyond a decade enlarges substantially.
Synthesis LCS attempts to integrate the knowledge gained from the various components of its study (Figure 1) to inform synthesis issues that typically carry both research and outreach-application implications. Examples include various attempts to understand and identify areas vulnerable to or resilient in the face of environmental
109
change (e.g., climate change) and ‘natural’ hazards (e.g., hurricanes) or sustainable in the face of increasing human uses. Drawing from risk-hazard research and critiques of it, both of which focus on the vulnerability of people, and from ecological research focused on the resilience of ecosystem, LCS has developed an emphasis on the vulnerability–sustainability of the coupled human– environment system. This vision recognizes that hazards simultaneously affect both the human and environmental subsystems and that the synergy of the two subsystems determines the total system response to the hazard. The coupled-system approach to vulnerability are illustrated by the recent hazard of Hurricane Katrina, the 2005 tropical storm that devastated coastal Mississippi (state) and the city of New Orleans, Louisiana. The exposure and sensitivity of New Orleans and the wetland habitats between the city and Gulf of Mexico have been altered by hydraulic works designed to facilitate waterborne traffic, permitting housing development in lowlying terrain, and by constructing access canals to gas and oil pumps distributed across the Mississippi delta. The overall effect of canal and levee construction reduces the buildup of sediments that maintain wetlands in the delta, especially the cypress swamps. These losses reduce the barriers to storm surges surrounding New Orleans, and the canals serve to funnel storm waters into the city, stressing the levees intended to protect the metropolitan area. The vulnerability of New Orleans, therefore, was and remains the product of human–environment interactions, and Katrina’s impact on both the city and ecosystems of the delta was profound. LCS has addressed an array of other synthesis issues and questions. For example, increasing attention is paid to the efficacy of the boundaries of nature reserves and parks, especially in cases where significant land use surrounds or people have the right to cultivate or collect resources within the reserves. In some cases, land changes outside the park, even at considerable distances from the park boundaries, affect biotic diversity within the park, especially where migratory animals are involved, raising the need for and design of biological corridors to facilitate the movement of biota. In other cases, the delimitations of the reserve boundaries and the rules of land and resource uses within the reserve to serve both human and environmental concerns have proven beneficial to the success of the reserve. In another example, LCS addresses the political–economic conditions that facilitate a forest transition – or cases in which economic modernization leads to a return of forest cover on lands once taken from forest. Drawing from lessons in environment development, LCS has also entertained real-world application, addressing the co-production of knowledge and participatory programs for land management. The resulting approaches can be found in formulizations such as the Drylands Development Paradigm.
110
Land Change Science Ear th system
T1.1
T2.1
T1.3
Land systems
T1.2
Land use and management
sys Eco tem services
Political/institutional regimes
T2.2 isio Dec n making
Population Social/economic structure
Ecological Dist u systems Biogeochemistry Biodiversity Water Air
T2.4
Culture Technology
ce an rb
Social systems
Soil
T2.3
T3.1 Critical pathways of change T3.2 Vulnerability and resilience of land systems T3.3 Effective governance for sustainability
T1. Dynamics of land systems T2. Consequences of land system change T3. Integrating analysis and modeling for land sustainability
Figure 1 Thematic concerns of land change science Global Land Project (2005). Science Plan and Implementation Strategy. Stockholm: International Geosphere-Biosphere Programme Secretariat.
These and other synthesis activities raise concerns about sustainable land architectures. The entire terrestrial surface of the Earth will soon be governed, leading to de facto or de jure designs of land uses and covers. These designs, commonly undertaken at the local or region level, invariably seek to provide a wide range of human uses and ecosystem services. The consequences of these designs for ecosystem services and human well-being at ascending spatial scales of concern are largely unknown. The aggregation of local to regional designs to the continental and global scales may well produce negative consequences for people and the environment processes operating at the large scales. Understanding the societal and environmental implications of the patterns of land use and land cover at different spatial scales thus beckons as a grand challenge for LCS.
LCS in Geographic Context Geography has a long tradition of human–environment studies focused on land and landscape, the modern origins of which are registered by the nineteenth-century German geographic traditions of landschaft (landscape), which can be linked to the search for ‘the unity in nature’ as articulated by Alexander von Humboldt and other students of natural history. The legacies of this vision,
some taken to detrimental extremes, range in orientation from the sciences to the humanities as exemplified by the nineteenth-century French geography of Vidal de la Blache, and the twentieth-century ‘geographic factor’ of Ellen Churchill Semple and Ellsworth Huntington, the cultural landscape of Carl Sauer, and the human ecology and natural hazards of Harlan Barrows and Gilbert White. Perhaps the most direct links in contemporary human–environment geography to LCS reside in cultural and political ecology. Indeed, former cultural ecologists from geography and anthropology, steeped in systemsbased approaches to human–environment problems, helped to spawn LCS as a formal international research program linking with GISc and ecology and environmental science to address land change in its own right as part of global environmental change and sustainability concerns. With interests in the politics and power relations of problem framing and answers, political ecology (PE) shares many of the same topical themes with LCS (e.g., causes of land change and vulnerability), but has entertained them foremost through the concerns about environment and development. Global change and sustainability, and environment development are, of course, intimately intertwined, and the potential for LCS and PE to inform one another is large, as in case of vulnerability research themes, and is beginning to take place across a
Land Change Science
large spectrum of shared topical interests. Indeed, in an increasing number of cases it is difficult to distinguish the methods used in and the outcomes of land-based research themes carried out in either subfield. Examples include the complex connections between international policies, land uses, and drought as they affect desertification in the Sahel of West Africa; Brazilian policy shifts, market vagaries, and largeholder–smallholder dynamics affecting the kind, amount, and pace of deforestation in the Brazilian Amazon; and human–environment relationships that need to be considered in order to establish effective biosphere reserves. Perhaps the main distinction between the two, serving as a modest impediment to more fruitful exchanges, resides in their explanatory foci: LCS anchored in post-positive science and PE in structural and constructivist explanatory visions. Regardless of the distinctions among different interests in geography, LCS addressed through the coupled human–environment systems appears to be at the vanguard of an emerging human–environment science that transcends traditional disciplines. The union of human, environmental, and geographical information/remote sensing research expertise is taking place in different programmatic ways that hold long-term consequences for the human–environment traditions in geography. This union has begun to be matched by the newly minted schools and degree programs, especially in North America, that hold the human–environment conditions and the coupled system dynamics that create them, as the objects of their study. This development may be seen as reinventions, with a decidedly science orientation, of the human–environment intellectual traditions championed by Humboldt and of its LCS component as linked to landschaft. See also: Environmental Studies and Human Geography; Physical Geography and Human Geography; Political Ecology; Remote Sensing; Resource and Environmental Economics; Simulation; Vulnerability.
111
Further Reading Global Land Project (2005). Science Plan and Implementation Strategy. Stockholm: International Geosphere-Biosphere Programme Secretariat. Gutman, G., Janetos, A., Justice, C. et al. (eds.) (2004). Land Change Science: Observing, Monitoring, and Understanding Trajectories of Change on the Earth’s Surface. New York: Kluwer Academic. Kates, R. W., Clark, W. C., Corell, R. et al. (2001). Sustainability science. Science 292, 641--642. Lambin, E. and Geist, H. (eds.) (2006). Land-Use and Land-Cover Change: Local Processes to Global Impacts. Berlin: Springer. Liverman, D., Moran, E. F., Rindfuss, R. R. and Stern, P. C. (1998). People and Pixels: Linking Remote Sensing and Social Science. Washington, DC: National Academy Press. Millennium Ecosystem Assessment (2005). Ecosystems and Human Well-Being: Synthesis. Washington, DC: Island Press. Reynolds, J. F., Stafford Smith, M., Lambin, E. F. et al. (2007). Global desertification: Building a science for dryland development. Science 316, 847--851. Turner, B. L. II. (2003). Contested identities: Human-environment geography and disciplinary implications in a restructuring academy. Annals of the Association of American Geographers 92, 52--74. Turner, B. L. II, Lambin, E. F. and Reenberg, A. (2008). The emergence of land change science for global environmental change and sustainability. Proceedings of the National Academy of Sciences 104, 20666--20671. Turner, B. L. II, and Robbins, P. (2008). Land change science and political ecology: Similarities, differences, and implications for sustainability science. Annual Review of Environment and Resources 33, 295–316. Veldkamp, T. and Lambin, E. F. (eds.) (2001). Predicting land-use change. Special issue. Agriculture, Ecosystems, and Environment 85(1–3), 1--6. Wu, J. (2006). Landscape ecology, cross-disciplinarity, and sustainability science. Landscape Ecology 21, 1--4.
Relevant Websites http://www.globallandproject.org/ Global Land Project. http://www.igbp.kva.se/ International Geosphere-Biosphere Programme. http://www.ihdp.unu.edu/ International Human Dimensions Programme on Global Environmental Change. http://lcluc.umd.edu/ NASA Land-Cover and Land-Use Change Program.