Browsing by Author "Dr. George Hess, Committee Member"

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Green Weight, Volume and Taper Equations for Virginia pine (Pinus virginiana) in the Piedmont Region of North Carolina.
(2005-09-29) Adams, John William; Dr. George Hess, Committee Member; Dr. Robert Abt, Committee Member; Dr. Bronson Bullock, Committee Chair
Virginia pine (Pinus virginiana) is a prolific pioneer tree species in the Piedmont region of North Carolina that has the potential to be a commercially important tree species. Reliable estimates of weight, stem volume and taper are needed for proper management of approximately 405,000 acres of Virginia pine presently located in the North Carolina Piedmont region. A study was conducted to derive merchantable green weight and merchantable volume equations to any upper stem diameter or height for Virginia pine (Pinus virginiana) across the Piedmont region of North Carolina. Models were derived from data collected at the North Carolina State University?s Hill Demonstration Forest. For total and merchantable green weight models, 100 Virginia pine trees were destructively sampled and weighed. Fixed and mixed effects models were fit and prediction equations were developed for total green weight, green weight to any merchantable outside bark or inside bark diameters, and green weight to any upper merchantable height. Combined variable equations, nonlinear ratio equations and nonlinear exponential ratio equations were fit to these data. Using AIC and minus two log likelihood as the criterion for model fit, the mixed effects ratio model proved superior for predicting green weight to any upper merchantable height, while the mixed effects exponential ratio model was superior for predicting green weight to any upper diameter (outside or inside bark). For merchantable volume, 105 Virginia pine trees were sampled to obtain outside and inside bark diameters to estimate stem volume. A combined variable equation was used to determine both inside and outside bark total volume. Fixed and mixed effects models were fit and prediction equations were developed for merchantable volume outside bark to any upper merchantable diameter outside bark and inside bark volume to any upper merchantable diameter inside bark. Equations to predict merchantable outside and inside bark volume to any upper merchantable stem height were also derived. Nonlinear ratio equations and nonlinear exponential ratio equations were fit to these data. Using AIC and minus two log likelihood as the criterion for model fit, the mixed effects ratio model proved superior for predicting merchantable outside bark volume and merchantable inside bark volume to any upper stem height, while the mixed effects exponential ratio model was superior for predicting merchantable outside bark volume to any upper stem diameter outside bark. A mixed effects exponential ratio model was also superior for predicting merchantable inside bark volume to any upper stem diameter inside bark. Taper equations were derived for the fixed effects models to predict diameter at any given height and to predict height at any given diameter for Virginia pine trees. The results of this research should be of interest to forest managers and private landowners in the Piedmont physiographic province of North Carolina and will enable foresters to develop more accurate estimates of weight or volume to any specified merchantable diameter or height limit for Virginia pine trees.
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.
Relationship of Headwater Stream Geomorphology to Catchment Geomorphology in the Piedmont of North Carolina
(2007-11-04) Howard, Susan Marie; Dr. George Hess, Committee Member; Dr. James Gregory, Committee Chair; Dr. Stacy Nelson, Committee Member
Headwater streams serve as the connection between land and rivers. They are the places in the landscape where water first begins to accumulate into a flowing stream. These headwater streams directly drain more than half of the landscape, creating water flow and possibly pollution pathways to larger river systems. Ongoing studies in North Carolina of the characteristics of headwaters streams to support field identification and digital mapping initiatives have raised many questions about the relationships of catchment and stream geomorphology. The objectives of this research were to 1) determine the differences among catchment geomorphologic parameters at the intermittent and perennial stream origins, 2) to describe the stream geomorphology as the headwater streams transition from intermittent to perennial and 3) to determine if significant relationships exist between stream geomorphology and the associated catchment geomorphology in the headwater stream reaches. Large variation was found in drainage area, valley slope and catchment shape values at both the intermittent and perennial origins. Drainage area threshold has been proposed as an indicator of intermittent or perennial stream origin and the ArcHydro extension of ArcGIS uses a drainage area threshold value set by the user to begin modeling of the stream network. However, with catchment size at the intermittent origins ranging from 2.4 to 15.6 acres and at the perennial origins ranging from 10.1 to 25.8 acres among the 8 highly similar catchments, drainage area does not appear to be a simple predictor of stream origin location. Horton?s form factor and valley slope at the intermittent and perennial origins also varied greatly from stream to stream and are not simple threshold indicators of stream origin. Stream geomorphology measures also varied greatly in their progression downstream. Sinuosity, which is a measure of stream pattern, increased in the downstream progression as a general trend. Within-reach channel slope, a measure of stream profile, decreased as the channels progressed from intermittent to perennial also with some minor variation. However, cross-sectional area, a measure of stream channel dimension, was highly variable throughout the headwater stream reaches. Channel cross sections varied from deeply entrenched, with relatively high cross-sectional area, to depositional fans having very little stream channel at all (very low cross-sectional area). This wide variation in channel cross-sectional area occurred not only among the 8 studied stream channels but within the same stream at different locations along a study reach. Possible relationships found were between stream sinuosity and catchment drainage area, between Horton's form factor and catchment drainage area, between valley slope and catchment drainage area and channel slope and catchment drainage area. Relationships were not found in other comparisons, most notably in the cross-sectional area to catchment drainage area relationship and in the channel slope to cross-sectional area relationship. Further research is needed to quantify possible relationships found in this study. Research in this area is complicated by the lack of undisturbed watersheds in the region. Variation in location, geology, soil characteristics, and land use complicates efforts to find comparable study sites. Highly detailed studies such as this involve a large time investment in data collection.