Download 2009Spring-SABM-Lecture4-Models

Agrarian models, frontier models, markets,
“Spatial Agent-based Models of Humanenvironment Interactions”
Feb 18, 2009
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
Plan for today
• MR POTATOHEAD
• Land-use change in frontier regions
• MP/OWL illustration
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
“Frontier”
• “We define “frontier” as an area of changing
resource use, such as might occur with changing
technology, transportation, or economic relations”
• May or may not involve immigration (but usually
does), location on the periphery
• “A frontier is a place of land-use change and part
of a continuing advance of that change across
space “
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
Goal of effort
• Theoretical meta-model of LUCC in frontier
regions
• Understand what is important to model and
whether or not we are modeling it
• Understand what might happen in other
cases in future
• Draw extrapolations beyond case studies
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
What is the land-use change process?
• New population with new tools, resources,
tastes, cultures
• Perceived greater opportunities/relative
resource abundance
• Populations often maintain links to home
• Transition through time from subsistence to
market-oriented prodcution -> increasing
integration
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
More process
• Various and changing risks (subsistence
vs.market)
• Household is often unit of analysis and
demographics are important
• Land holding consolidation triggered by
outmigraion, economic integration,
speculative land uses, shifts in ag strategies
• Fragmentation can occur through inheritance
• Outmigration also important
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
Summary of key complex processes/drivers
ｷ
In-migration of a distinctly new set of agent types, possessing different
technology, cultural preferences, and connections to external regions;
ｷ
A gradual process of market integration, potentially driven by increases
in accessibility through improvements in transportation infrastructure, through
the connection of the new agent populations with external regions, or both;
ｷ
A variety of land fragmentation vs. land consolidation outcomes in
terms of both land ownership/management and land cover, potentially driven by
relative changes in mortality and fertility, in-migrants’ rates of success and
failure and resulting out-migration rates, the degree of land vs. labor scarcity
resulting from these processes, the levels of and variability in biophysical
suitability of the area, and the particular land tenure and land transfer institutions
present in each location;
ｷ
A variety of land tenure and land transfer institutions, whose
development may be influenced by the degrees of land scarcity and market
integration present in each location;
ｷ
Outcomes that may depend on individual heterogeneity (such as risk
management strategies, risk preferences, knowledge, and resources);
ｷ
Outcomes that depend on biophysical heterogeneity (soil quality,
topography, and climate).
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
Key questions:
• What processes should be included, and why
are they important?
• What conclusions follow from models that
have these processes?
• Can we draw any generalizations?
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
Comparison points from MP model:
1. Spatial data structure. (I.1) How do the agent-parcel relationships and the
decision making units in the model allow representation of processes of changes
in household density, land consolidation, and diversification in response to risk?
What are the outcomes of these processes?
2. Non-spatial social networks. (I.3) What social networks are important in each
study site, and how might inclusion of these networks in models change
outcomes? How do social networks influence information flow, mutual aid, land
transfers (inheritance through kinship networks as well as markets), migration
into and out of the area, and flows of remittances?
3. Land suitability and resulting potential land uses. (I.6) How have
biophysical conditions in each site influenced evolution of land use in the region,
including the potential success of subsistence crops, opportunities for resource
extraction, and development of ties with external markets?
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
More comparison points:
1. The varied land-use knowledge, cultural preferences, and capital of
indigenous vs. in-migrant land users. (III.1) How do variations in land-use
knowledge, cultural preferences, and capital affect land productivity (I.7)?
What new land uses have in-migrant populations brought, and how have these
affected the differential success of each population in local and market
contexts?
2. Land exchange. (V) How have the institutions shaping land exchange/use
influenced patterns of resource use, distributions of land holdings, and the
relationship between household size and land holding size? How have these
patterns evolved as land exchange institutions have changed?
3. Internal and external economic and institutional drivers. (I4 & I5) How do
internal markets exacerbate or mitigate relative resource scarcity? How have
external drivers influenced rates of market integration, differential success rates
between agent types, and ultimately, land-use and land-cover consolidation?
Spatial ABM H-E Interactions, Lecture 4
Dawn Parker, George Mason University
General conclusions and future directions:
• Need to better model land consolidation and land
fragmentation (Land markets?)
• Non-spatial social networks important, need to
improve multiple social relations, position in
networks,
• Land suitability/transitions well modeled
• Need better modeling of interactions between inmigrants and indigenous pops
• Need to model local markets with endogenous
Spatial
ABM H-E markets
Interactions, Lecture 4
prices, including
land
Dawn Parker, George Mason University