Browsing by Author "Dr. Frederick W. Cubbage, Committee Chair"

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Landscape characteristics and North Carolina stream life: A multiple-scale ecological risk assessment of nonpoint source pollution
(2002-10-16) Potter, Kevin Mark; Dr. George R. Hess, Committee Member; Dr. Frederick W. Cubbage, Committee Chair; Dr. Gary B. Blank, Committee Member
Nonpoint sources of pollution may be responsible for as much as 50 percent of current water quality degradation in the United States, and as much as 70 percent in the Southeast. In this study, I used an ecological risk assessment methodology, at the watershed scale and riparian scales (zones 300, 100, and 50 feet on either side of streams), to analyze and quantify the impact of nonpoint pollution on the ecological integrity and water quality of North Carolina streams. Specifically, I determined how land-use patterns relate to aquatic ecological integrity, including the extent to which one of the most widely promoted best management practices (BMPs) – the preservation of riparian vegetated buffers – correlates with better ecological integrity. The central goal of this project was the creation of a set of empirical models that describe the vulnerability of North Carolina aquatic ecological integrity – as measured by benthic macroinvertebrate community structure - to changes in the landscape-scale sources of nonpoint pollution. The models, the result of multiple regression analysis of Geographic Information System (GIS)-derived data, take into account watershed eight land form characteristics, and three land cover types derived from 1992 Multi-Resolution Land Characterization (MRLC) Consortium raster data: forest, urban, and agriculture. The land form characteristics considered in this analysis are topographic complexity, mean elevation, watershed slope/relief ratio, watershed area, watershed shape, rainfall, soil clay content, and ecoregion. The regression equation models created by this process can be used by managers and policymakers to weigh the risks of management and policy decisions for a given watershed or set of watersheds, including whether vegetated riparian buffers are ecologically effective and economically efficient in achieving water quality standards. The coefficient of multiple determination (R²) for each equation indicates the proportion of variability in the invertebrate tolerance indices attributable to the landscape variables included in the model. The unstandardized regression coefficients for each landscape variable represent that variable's weight and direction in the vulnerability index equation. The standardized (beta weight) regression coefficients indicate the relative importance of the landscape characteristic relative to the other landscape variables in the model equation. The results of this study indicate that (1) landscape characteristics at the watershed scale predict variability in benthic macroinvertebrate community structure better than characteristics at the riparian scale; (2) land cover variables are of secondary importance to certain land form features, but are still significant predictors of macroinvertebrate community structure; (3) developed land use is the most important land cover variable at the watershed scale, while forested land cover is the most important at the riparian scale; (4) wider riparian buffer zones yield only minor differences in invertebrate community structure; and (5) more research is needed on how these interactions vary by the size of a watershed and the ecoregion in which it is located. Based on these findings, it appears that water quality and stream ecological integrity may be most at risk in North Carolina watersheds where a higher amount of urban development is occurring at the watershed scale, where a lower percentage of forest cover exists in riparian corridors, and where the topography is generally flatter. The ecological risk assessment process that produced these results was relatively simple and inexpensive. The results are straightforward and generally easy to interpret. The vulnerability model equations that resulted from this assessment process can provide a basis for quantitatively comparing, ranking, and prioritizing risks, which can be useful in cost-benefit and cost-effectiveness analyses of alternative management options. Specifically, they offer a useful approach for characterizing the risk of potential land management options through the simulation of land use change, such as conversion of land cover or implementation of best management practices.
Nonindustrial private forestland owners: Estimating responses to economic and demographic changes
(2002-12-02) Snider, Anthony Glenn; Dr. Jon Stucky, Committee Member; Dr. Elizabethann O'Sullivan, Committee Member; Dr. Frederick W. Cubbage, Committee Chair; Dr. George Hess, Committee Member
This research endeavor consisted of two distinct efforts. First, following a literature review of the characteristics, objectives, and incentive programs available to nonindustrial private forest (NIPF) landowners, the potential effects of wood chip mill harvests on forest management practices of these landowners in North Carolina were analyzed. The study estimated NIPF pulpwood harvest volumes and the impacts of changes in timber market returns to NIPF owners. Economic welfare effects of producer and consumer surpluses attributable to market adjustments were also calculated. Potential savings from reduced site preparation costs from cleaner harvests associated with chip mill markets were estimated. Additionally, the potential changes in financial returns to growing timber with wood chip markets were estimated using discounted cash flow analyses of typical forest management returns. Given the existing market structure and price elasticities for timber, increased timber demand and better markets would consistently increase economic returns for both timber buyers and sellers. In absolute terms, forest industry (buyers) had higher benefits while NIPF owners (sellers) had higher percentage benefits. Based on 1990 trends in timber production and prices, some NIPF owners have experienced decreased returns from softwood stumpage sales. Increasing hardwood pulpwood timber production and prices have yielded average statewide incremental returns of $595,000 per year for NIPF owners. Approximately 80% of the total value accrued to owners in the coastal plain, but the largest average annual percentage increase per year (9.9%) was received for NIPF hardwood pulpwood harvests in the mountains. Higher timber prices and shorter rotations for growing softwood timber led to sawtimber production with a chip component having the greatest returns for NIPF owners, followed by chipping the stand entirely at a shorter rotation, and last, production of sawtimber alone. These alternatives generated internal rates of return (IRRs) of about 6% to 13%. The lower timber prices and long rotations for hardwoods generally yielded lower investment returns, ranging from about 3% to 7% IRRs depending on the forest type and management regime. The addition of a wood chip component did little to increase these returns. These economic analyses suggest that better markets will benefit both NIPF landowners and timber buyers, thus prompting increased harvests for chip wood. The second component of this research involved the analysis of archival tax data on the North Carolina Use-Value Property Tax Program. Following a review of rural land preservation tools, an analysis of the effects of property values, property taxes and population density on landowner decisions to sell, subdivide, or withdraw their properties from the use-value program in North Carolina was conducted. Parcel level tax data from nine counties representing the three geophysical regions and urban levels of North Carolina for the period 1987 through 1999 were collected using a disproportionate stratified systematic sample. Data were analyzed using logistic regression. The odds of landowners subdividing increased with tract size, population density, and acreage value of the tract. Increases in population density, acreage value, and taxes paid, raised the odds of landowners selling their properties. Sales were less likely to occur in urban counties. The odds of landowners deciding to withdraw from the use-value program increased with higher population density, but declined with increases in property taxes. Additionally, withdrawal was less likely in the piedmont and among the largest parcels. The effect of population growth outweighed the effects of other continuous variables on all three landowner decisions and was the only significant variable in regressions on parcel sales, subdivision, and withdrawal from the use-value program.