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CHAPTER II. LITERATURE REVIEW
Forest Ownership
Fragmentation is the process of subdivision of bigger forestland tracts into smaller portions with different owners and managers. First noted in the 1980s on forestlands across the Northeastern U.S. (Harper et al., 1990), fragmentation is an issue of increasing concern in Virginia, a state with over 5.3 million hectares of forestland and nearly 470,000 forest landowners. Nonindustrial private forest (NIPF) owners, i.e., those individuals who own forestland but do not own the facilities to process trees harvested on their land, control 58% of the total commercial forestland in the U.S. (Egan and Jones, 1997). In 1992, NIPF lands accounted for 75% of the forest base in the state of Virginia (Hodge and Southard, 1992). In five years that figure has increased slightly, to just over 77% (Shaffer and Meade, 1997). Fifty-one percent of all Virginia NIPFs are less than 100 acres in size, a percentage that has been slowly increasing this decade (Thompson and Johnson, 1996). These factors seem to indicate that the forested land base of Virginia is subject to increasing fragmentation.NIPF owners often make management decisions that affect the condition of their forestland, and one of the most important considerations is whether and in what manner they are going to harvest timber (Egan and Jones, 1997). This fact, along with the continuous loss and degradation of large amounts of forest land, leads to the conclusion that timber production has been concentrated on a smaller and smaller forested land base (Fox, 2000). Timber supply, therefore, has become more and more dependent on NIPF owners and their views and attitudes. Egan et al. (1997) reported survey results that indicated the reluctance of NIPF owners to clearcut, and 55% of the respondents even stated that this practice should be banned. An ongoing international trend in forestry practices is the shifting towards more “close-to-nature silviculture” in stand-level management (O’Hara, 2001). The same author also stated that “although a considerable amount of forest land will continue to be managed in intensive, even-aged plantations, the trend toward alternative silviculture will likely affect many areas.” In order to meet the forest management objectives of the landowners and satisfy the timber demand of the society, specific silvicultural regimes become crucial (Helms, 1998).
Regeneration Alternatives
Pine-hardwood mixtures are a natural component of forested ecosystems in the Southeastern U.S. The hardwood component of these mixed stands varies from region to region, but some of the dominant hardwood species of the Virginia Piedmont are typically oak species (Quercus spp.), blackgum (Nyssa sylvatica Marsh.), red maple (Acer rubrum L.), sweetgum (Liquidambar styraciflua L.), sourwood (Oxydendron arboreum (L.) DC.), hickory species (Carya spp.), and yellow-poplar (Liriodendron tulipifera L.) (Sheffield et al., 1989). The softwood component of pine-hardwood stands in the South is comprised mainly of yellow pines (Pinus spp.), the loblolly-shortleaf group, and Virginia and pitch (P. rigida Mill.) pines (Sheffield et al., 1989). Wood production potential in many of these forests is severely restricted by the dominance of low-quality stems and undesirable species (Knight and McClure, 1978). Many of the lands owned by NIPF landowners are producing at 50% or less of their productivity potential (Webb, 1990). Poor stand conditions are mainly due to abusive agricultural practices prior to reforestation, continuous detrimental high-grading, and wildfire in the region (Smith and Linnartz, 1980).Although timber production as a source of income has always been an objective of NIPF landowners (Egan et. al, 1997), lower productivity in this region is due in part to the reluctance these landowners have towards site preparation (Moorehead and Dangerfield, 1990). The unwillingness to spend the $70 to $120 per hectare required for conversion to pine plantation makes most NIPF landowners choose to leave their poorly stocked stands of low quality hardwood forests unmanaged (Waldrop, 1997). Improving productivity on these NIPF lands in the Southeast, though, is very important in order to meet future timber demands (Waldrop, 1997). Approximately 50% of the Virginia forest resource is located in the Piedmont physiographic province, totaling almost 2.5 million hectares of commercial timberland (Brown, 1986). Just about two million hectares, or nearly 72%, are composed of mixed pine-hardwood forest types (Brown 1985, 1986). Regeneration methods have been developed for much of the central and southern hardwood regions of the United States (Merritt, 1980; Smith and Linnartz, 1980; Smith, 1994). The majority of this work involved guidelines for even-aged silviculture and stocking guides.
ABSTRACT
ACKNOWLEDGMENTS
LIST OF TABLES
LIST OF FIGURES
CHAPTER I. Introduction and Justification
CHAPTER II. Literature Review
Forest Ownership
Regeneration Alternatives
Productivity and Sustainability of Plantation Systems
Site Preparation
Competition
Herbicide Application
Fertilization
Planting Stock and Tree Improvement
Pine Species Alternatives
CHAPTER III. Impact of Weed Control and Fertilization on Growth of Eastern White, Loblolly, Shortleaf, and Virginia Pine Plantations in the Virginia Piedmont
Abstract
Introduction
Methods and Materials
Study Site Description
Study Design
Soil Sampling and Analysis
Foliage Sampling and Analysis
Survival and Growth Data Collection
Data Analysis
Results
Pine Survival
Height Growth
Pine DBH
Pine GLD
Pine Stem Volume
Seedling Sources
Hardwood Competition
Soil Analysis
Foliar Analysis
Discussion
Conclusions
Literature Cited
CUMULATIVE LITERATURE CITED
APPENDIX A: Plot Level Survival and Height Data for the Four Pine Species and the Four Silvicultural Treatments
APPENDIX B: Plot Level Survival And Growth Data for the Four Loblolly Pine Seedling Sources and the Four Silvicultural Treatments
APPENDIX C: Plot Level Survival, Dbh, Gld, And Stem Volume Data for the Four Pine Species and the Four Silvicultural Treatments at Age 5
APPENDIX D: Plot Level Foliar Nutrient Data for the Four Pine Species and the Four Silvicultural Treatments at Age 5
APPENDIX E: Plot Level Soil Nutrient Data for the Four Pine Species and the Four
Silvicultural Treatments at Age 5
APPENDIX F: Plot Level Hardwood Competition Data for the Four Pine Species and two Silvicultural Treatments at Age 5
APPENDIX G: Pine Stands in Replication 1 (Block 1) Pictures at Age 5
APPENDIX H: Plot Level Natural Regeneration Data at Age 5
APPENDIX I: Plotting Hardwood Competition Measure (Sum of Hardwood Heights) Against Pine Volume (Cm3), Absolute Volume Change (Cm3), and Relative Volume Change (%) as Compared to Weed Control Treatment Plots
VITA
