Geoscience Reference
In-Depth Information
The intimate ties between human and environmental subsystems comprising land
subsequently led to the merger of the IGBP's ecological research with that of LUCC,
as informed by DIVERSITAS (biotic diversity programme), to create the Global
Land Project (GLP, 2005). The GLP, in response to sustainability science, as regis-
tered in the Earth System Science Partnership (ESSP) and related programmes (Kates
et al., 2001), now focuses on land as a coupled human-environment or social-
ecological system and expands base research to various synthesis efforts consistent
with the needs of decision makers, especially vulnerability-resilience and sustain-
ability activities, moving the GLP closer to such concerns as food security and
environmental justice, among others.
Land as a Coupled System
Land systems and their change are product of human-environment interactions and
have been at least since humankind mastered the control of fi re in the hunt, in the
process transforming habitat and fauna (Thomas, 1956; Martin, 2005). These
interactions have intensifi ed globally throughout history (Goudie and Vilas, 1997)
as society attempts to manipulate the productivity of land for resources, or in earth
systems' parlance, ecosystem goods and services (e.g., water, soil nutrients) and to
reduce risks to the vagaries of nature (e.g., drought, pest outbreaks, fl oods). Today,
virtually no part of terrestrial surface of the earth remains unclaimed or lacks some
form of governance, although governing institutions may be ineffective in their
enforcement.
Land systems and their change involve the ambient environmental conditions
(e.g., temperate forest biome); the uses of those conditions (e.g., wheat cultivation,
suburbia, nature reserves); the consequences of the uses, both human and environ-
mental (e.g., arid land degradation; corporate profi ts); and the impacts of those
consequences on the land systems (e.g., loss of biodiversity, shifts in land uses). Thus
land systems are coupled human and environmental subsystems in which both
endogenous (e.g., soil conditions and fertilizer applications) and exogenous subsys-
tem dynamics (e.g., global warming or market failures) affect and even change the
subsystems. Perhaps owing to this complexity or to the aggregation of phenomena
and process required to address land-use/cover change, theory of land system change
per se - coupling the two subsystems - has been diffi cult beyond broad system
concepts (Gunderson and Holling, 2001). Despite this lacuna, research on land
systems and their change moves forward on all fronts - causes, consequences and
system linkages of use and cover change.
Drivers of land use
At the global scale and over the long run, land dynamics appear to track with
the PAT variables - population, affl uence and technology - in the IPAT identity
(Waggoner and Ausubel, 2002; Turner and McCandless, 2004) - as P (population)
and A (affl uence) serve as surrogates for demand for land and land-resources and
T (technology) as the means of fulfi lling that demand. At lower spatio-temporal
resolutions, however, PAT variables give way, at least quantitatively, to a plethora
of political economic and biophysical factors, be they climate change or globalisa-
tion, the last of which leads to the loss of spatial congruency between the source of
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