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Mulder, Kenneth

Natural Resources

2006

PhD

This dissertation explores the existence and effects of constraints upon the relative flows of resources in living systems of production, both biological and economic. I examine the theoretical and empirical evidence for such constraints as well the effects they have upon system dynamics. I also demonstrate that variation in the stoichiometric quality of a resource-- defined as the relative ratios of its constituent components-- has distinct effects upon system functioning that are missed when resources are viewed as homogenous. An overview of ecological stoichiometry and its economic analog is given in Chapter 1. Chapters 2-4 examine the impact of stoichiometric constraints upon biological production and trophic exchanges. Current models of biological production under stoichiometric constraints, part of the field of ecological stoichiometry, generally assume consumers are composed of fixed ratios of chemical elements. In Chapter 2, I create an alternative model that incorporates an economic production that allows for factor substitution, thereby relaxing the assumption of fixed stoichiometric ratios. I show that such a model is capable of replicating empirical results. Model output also suggests that variable stoichiometric ratios on the part of consumers results in greater stability in consumer-producer systems. I develop this further in Chapter 3 by creating a physiologically-explicit model for the water flea, Daphnia. Allowing for variable consumer stoichiometric ratios, I create an individual model that I calibrate to data for biomass production under a wide range of food qualities. I demonstrate that this model yields a more realistic representation of both individual and population dynamics under nutrient limitation. Finally, Chapter 4 explores some further implications of stoichiometric limitations, showing that adaptations to variable food quality can lead to both interference and facilitation between different consumers.
Chapters 5-7 examine stoichiometric constraints in human welfare production. Here stoichiometry is defined by the relative ratios of four types of capital-- built, human, natural and social. Using a wide variety of data sources, I demonstrate in Chapters 5 and 6 that consumers do have varying preferences for relative amounts of each of the four capitals. In particular, preferences for the four types of capital are correlated with consumer demographics as seen through an analysis of survey data as well as through an econometric analysis of the impact of relative stocks of the four types of capital upon land values. Data collected in Chapter 6 suggest that consumers have an ambivalent relationship to built and human capital stocks. For some demographic groups, these can be disamenities driving consumers to seek locations where built and human capital densities are relatively low, such as the suburbs. On the other hand, there is a consistent correlation between densities of natural and social capital and wealth, suggesting these are consistently viewed as amenities. In Chapter 7, I create a dynamic spatial model of urban development that incorporates demographically-determined preferences for the four types of capital. The model demonstrates the existence of a social trap in which built and human capital are consistently over-supplied while natural and social capital are under-supplied. This is despite the ability of households to differentially invest in the different capitals to correct for such disparities. This has distinct impacts upon consumer welfare.