This study intends to explore the effects of two drying schedules with options of conditioning and post-drying storage on the drying speed and quality of western hemlock timbers. Western hemlock (Tsuga heterophylla), the species of interest in this study, is one of British Columbia's most abundant tree species that accounts for 75 to 80% of British Columbia's exports to Japan. It is usually combined with amabilis fir (Abies amabilis) for processing and economical purposes. Hemlock is difficult to dry due to its compression wood, wetpockets and large spread of initial moisture content and basic density. Consequently, it seems practical to dry hemlock by itself. In this study, hemlock was dried using two different schedules with optional conditioning and optional seven day post-drying storage in a covered and climatized space. These eight experimental runs were compared to a control run, which utilized an established drying schedule. To assess the kiln dried timber quality, twist, diamonding, and checks were evaluated using pre-drying and post-drying and/or post-storage measurements. Drying times and casehardening were also considered. Data analysis and evaluation illustrated that conditioning and the harsher schedule reduced casehardening, while the milder schedule developed less twist and diamonding. Even though it appears that the control run developed less shape distortions than the treatment runs, the control run required longer drying times. When using the harsher schedule the kiln was immediately available for the next run, and the dried timber could be stored in a covered area in order to level out the moisture gradients and alleviate casehardening. As a subsequent step, the timber could be planed to reduce twist, diamonding and superficial checks. / Forestry, Faculty of / Graduate

Five plant associations and one Alluvial Complex are recognized for the Dry Subzone of the Interior Western Hemlock Zone of British Columbia. These include 22 phytocoenoses, here described as biogeocoenoses or forest types. Additionally 3 intrazonal Pinus ponderosa plant associations and 2 interzonal ecotones are discussed. In phytosociological analysis modified Zurich-Montpellier techniques are employed. For tree studies, dominance/ frequency/density (DFD) indices and standard forestry methods are applied. Phytocoenose descriptions are based on synthesis tables which include plant lists (total 538 species), habitat descriptions and tree growth data from 15.5 one-fifth acre plots. Forest types comprise: 1) Lichen association (Cladonietum) - open stands with Pseudotsuga menziesii as the edaphic climax dominant, occurring on xeric rock outcrops; 2) Moss association (Pachistimeto-Callier gonelletum) - closed stands with Tsuga heterophylla as the climatic climax dominant, occuring on me sic sites; this includes 6 forest types; 3) Aralia Oakfern association (Aralieto-Gymnocarpietum) - closed stands with Tsuga heterophylla, Thuja plicata as the edaphic climax codominants, occuring on moist sites; this includes 7 forest types; 4) Devil's Club association (Oplopanacetum) - closed stands with Thuja plicata as the edaphic climax dominant, occurring on wet sites; this includes 4 forest types; 5) Skunk Cabbage association (Lysichitetum) - open stands with Thuja plicata as the edaphic climax dominant, occurring on water-saturated ground; this includes 2 forest types; 6) Alluvial Complex - unstable riverside vegetation dominated by Populus trichocarpa. The Lichen, Skunk Cabbage and Alluvial Complex communities are floristically the most clearly defined, and are readily recognizable on the basis of lesser vegetation dominants alone. Recognition of mesic communities relies on a characteristic combination of species. The zonal (climatic climax) biogeocoenose is the Slope Normal Moss forest type of the Moss Association. The dynamic relationships of forest types are discussed. Secondary succession may go from the deforested stage directly to the climax, if edaphotope disturbance is minimal, but normally a pioneer-tree stage intervenes. This Subzone is unique in that, the pioneer stage of the zonal community may differ substantially from the climatic climax if humus is removed by fire. On mesic sites, proceeding from pioneer-conifer to climax stages, crown cover decreases and lesser vegetation increases. Tsuga heterophylla is the exclusive dominant of the climax forest„ In decreasing order of importance, as determined by DFD indices, Subzone trees are Tsuga heterophylla, Thuja plicata. Pinus monticola, Pseudotsuga menziesii, Betula papyrifera, Picea engelmannii, Larix occidentalis, Populus tremuloides, Pinus contorta, Populus trichocarpa. Abies lasiocarpa and Abies grandis. Most rapid tree height growth of Thuja plicata, Pseudotsuga menziesii, Pinus monticola and Picea engel-mannii occurs in Devil's Club communities; of Tsuga heterophylla, Larix occidentalis, Pinus contorta, Betula papyrifera, Populus tremuloides in Aralia Oakfern communities; and of Populus trichocarpa in Alluvial Complexes. Forest types are more productive in pioneer than in climax stages. Estimates of net primary productivity and standing crop of forest types for tree trunks of all tree species summed as one, showed that the greatest pioneer- conifer stand productivity (1251 kilogram/ hectare/year) and climax stand standing crop (180 x 10³ kg/ha) belong to the Devil's Club association, and the least productive (126 kg/ha/yr) and lowest standing crop (15 x 10³ kg/ha) to the Lichen association. It is concluded that biogeocoenotic classification provides a sound basis for land use planning in this region, and should be applicable to other areas. / Science, Faculty of / Botany, Department of / Graduate

Quantitative measures of stand density and stocking are very important because only with full knowledge of the growing stock can a forest be managed efficiently. Stocking is concerned with fraction of area occupied with trees. Density is related to the degree of crowding within the area occupied. These quantitative values are determined by parameters that could be measured on the ground and on aerial photographs. The methods used to estimate height, crown width, and crown closure from aerial photographs are thoroughly described. The writer also describes the stocking and density conditions under which trees grow, with illustrations by both theoretical models and actual sample plot crown models. Forty-seven sets of ground and photo-measurements were taken and analysed by simple and multiple regression methods. A comparison of photo and ground values was then made to evaluate the usefulness of aerial photographs for density and stocking measurements. The correlation of the ratio of height (Ht) to crown width (CW) from the ground and photo data to age, site index, crown closure, basal area, adjusted basal area, crowding factor and adjusted crowding factor were also studied. Eight assumptions regarding normality of density and full stocking were made so that the interrelationship between the individual density and stocking measurements could be studied more effectively. It is concluded that Ht/CW ratios are measurable from aerial photographs and shown that they are useful as a measure of stand density and stocking. / Forestry, Faculty of / Graduate

This thesis is concerned with plant associations within the Subalpine Mountain Hemlock Zone as indicators of recreational land use capability. With the field recognition of approximately twenty plants (trees, tall shrubs, low shrubs, and ground plants) all the plant associations within this zone can be identified. Knowing the biogeoclimatic characteristics of the plant associations and the limitations of land for recreation, land use decisions concerning summer recreation can be made. The objectives are to develop criteria for rating the limitation of land for selected recreational activities; to summarize information about the plant associations and biogeoclimatic conditions found within the Subalpine Mountain Hemlock Zone of southwestern British Columbia for planning purposes; to assign capability ratings to land based on the biogeoclimatic characteristics of the plant associations and on the criteria for rating the limitation of land for recreational activities; and to illustrate how the capability ratings of plant associations for recreation can be used in recreation planning. This study is a response to the need for a simple, rapid, accurate, inexpensive, site specific approach to land use planning based on readily recognizable indicators. By identifying and mapping plant associations, a recreational land use capability distribution is made apparent. With such detailed site specificity, planners and natural resource managers can make rational decisions about land use based on the biogeoclimatic characteristics of plant associations and on the limitations of land for recreational activities. It is suggested that the land use planning approach presented in this thesis can be extended not only to other biogeoclimatic zones besides the Subalpine Mountain Hemlock Zone but also to other activities besides recreation. / Applied Science, Faculty of / Community and Regional Planning (SCARP), School of / Graduate

The hemlock woolly adelgid (HWA) Adelges tsugae (Annand) (Hemiptera: Adelgidae), has spread throughout most of the range of eastern hemlocks, Tsuga canadensis (L.) and the entire range of Carolina hemlocks, Tsuga caroliniana (Engelman) in eastern North America. Forest managers often implement an integrated pest management (IPM) strategy that combines chemical, silvicultural, and biological control tactics to create a more sustainable and effective approach for managing HWA. Laricobius spp. (Coleoptera: Derodontidae) are the primary biological control agents within IPM scenarios for HWA. Imidacloprid (IMI), the most widely used insecticide for HWA management, is typically applied to the soil below HWA infested trees and breaks down into several metabolites, including two with insecticidal properties; 5-hydroxy imidacloprid (5H-IMI) and imidacloprid-olefin (IMI-OLE). Imidacloprid-olefin is known to be up to 14 times as lethal to HWA as IMI and is produced as imidacloprid is first hydroxylated into 5H-IMI and further metabolized into IMI-OLE. Because Laricobius spp. spends half of its life in aestival diapause in soil below HWA infested trees, there is the potential for these biological control agents to encounter toxic residues within an IPM setting. Imidacloprid and its metabolites are known to cause mortality in Laricobius spp. feeding on HWA from previously treated trees, but the impact of soil applied imidacloprid on their subterranean survivorship has not been studied. Furthermore, there is limited knowledge on the subterranean portion of Laricobius spp. life cycle. The first study determined the depth to which Laricobius spp. burrowed during their subterranean life phase using 3D X-ray microscopy. When held in containers with two differing soil compaction intensities, 0.2 kg/cm2 and 0.5 kg/cm2, Laricobius spp. were found to burrow an average (± SE) of 2.7 ± 1.5 cm and 1.4 ± 1.3 cm deep, respectively. The second study assessed the effect of three different imidacloprid soil treatments; soil injection, soil drench and CoreTect tablets, on the subterranean survivorshiop of Laricobius spp. The soil drench application technique applied in fall 2020 consistently resulted in significantly higher IMI, 5H-IMI, and IMI-OLE residues than the other two treatments over both years of this study (2021 and 2022). The soil injection treatments from both 2020 and 2017 resulted in above average field emergence of beetles in 2021 and 2022, with relatively insignificant residue quantities present. This study suggests that the soil injection treatment method provides a lower level risk of metabolite exposure to Laricobius spp. compared to soil drench and CoreTect tablet imidacloprid application methods. / Master of Science in Life Sciences / In eastern North America, there are two species of hemlock trees whose longevity and unique shade tolerant adaptations are important to the ecosystems within which they are found. Eastern hemlocks range from southeastern Canada to the southern Appalachian Mountains, while Carolina hemlocks are restricted to the southern Appalachians from northern Georgia to Virginia. Since its first formal identification in Richmond, VA in 1951, the hemlock woolly adelgid (HWA) has caused widespread damage and mortality throughout much of the range of eastern hemlocks and the entire range of Carolina hemlocks. HWA consumes nutrients and restricts water flow within the tree, eventually leading to tree mortality. Forest managers typically rely on an integrated approach, that combines chemical applications with the simultaneous release of insects that naturally attack HWA on untreated trees within the same forest setting. Imidacloprid is the most widely used insecticide for HWA management and is typically applied to the soil below HWA infested trees. This insecticide is absorbed through the roots and travels through the tree where HWA feed and die as a result. Laricobius spp., the primary insect consuming HWA on infested trees, spends part of their life in a below ground summer dormancy. Imidacloprid and its secondary compounds are known to cause mortality in Laricobius spp. feeding on HWA from treated trees, but the impact of soil applied imidacloprid on their below ground survivorship has not been studied to date. Furthermore, while extensive studies have taken place to understand the biology of Laricobius spp., there is limited knowledge about their dormant state. In one study, the depth to which Laricobius spp. burrowed during their below ground life phase was determined using 3D X-ray microscopy. In a second study, the effect of three common imidacloprid treatments; soil injection, soil drench, and CoreTect tablets, on below ground survivorship was examined. Laricobius spp. were found to burrow an average (± S.E.) of 2.7 ± 1.5 cm and 1.4 ± 1.3 cm deep in soil compacted at 0.2 kg/cm2 and 0.5 kg/cm2, respectively. Chemical residue quantities were greatest in soil treated with soil drench in fall 2020, and were found to significantly impact Laricobius spp. survival. Overall, survival was the lowest from the soil treated with CoreTect tablets in 2020. Surival was the greatest from soil that received soil injection treatments in both 2020 and 2017 and had relatively insignificant imidacloprid residues present where the insects typically occur in the soil. Findings from this study suggest that imidacloprid application using the soil injection method is a less risky technique for chemical control in an IPM setting when compared to soil drench and CoreTect methods.

The hemlock woolly adelgid (HWA), Adelges tsugae Annand (Hemiptera: Adelgidae) is a small, non-native insect that feeds on hemlock (Tsuga spp.) species native to the eastern United States. One biological control agent, Laricobius osakensis, shows promise due to its voracious feeding on and synchronous life cycle with HWA. This beetle species is originally from Japan and has undergone all the necessary testing while in quarantine, gaining permission for field release in 2010. Field releases began in the fall of 2012 and continued the following fall. Reproduction occurred at the first year's field sites with beetles recovered at both sites the following fall. During the second year of field work, beetle recovery was low due to winter temperatures that caused high HWA mortality. All of the L. osakensis beetles released in the field are first reared in an Insectary on Virginia Tech's campus. To improve health of these beetles during rearing, a series of chemical amendments were added to the water baths where HWA infested cut hemlock branches were placed. HWA samples were taken from each treatment and analyzed for carbon, nitrogen and total carbohydrates and beetles emergence was recorded in relation to prescribed treatment. None of the treatments appeared as the best for improving HWA health, but there were differences between the sampling months within the two years. These differences in month correlate with the biological processes occurring within HWA at these times such as reproduction and preparation for aestivation. No treatment helped increase beetle emergence. / Master of Science in Life Sciences

Thesis (M.S.)--West Virginia University, 2007. / Title from document title page. Document formatted into pages; contains vii, 55 p. : ill., maps. Includes abstract. Includes bibliographical references (p. 47-50).

Thesis (M.S.) -- University of Tennessee, Knoxville, 2006. / Title from title page screen (viewed on Feb. 5, 2007). Thesis advisor: Paris Lambdin. Vita. Includes bibliographical references.

Where timber production is the primary management objective, knowledge of the relationship between the potential productivity of candidate tree species and levels of light, heat, nutrient, moisture and aeration is necessary for species- and site-specific decision making. For example, foresters need to decide which tree species to regenerate on a particular harvested area to obtain maximum sustainable productivity. Similarily, when considering the application of silvicultural treatments such as spacing or fertilizing, foresters need to determine whether the potential productivity of a particular site warrants the cost of the treatment. We used the site index (height of dominant trees at breast height age) of western redcedar (Thuja plicata Donn. ex D. Don.) as a measure of productivity, and described the pattern of mean site index in relation to field identified soil moisure and soil nutrient regimes.

An invasive insect, hemlock woolly adelgid (HWA), has initiated widespread hemlock decline and mortality in the Great Smoky Mountains National Park (GSMNP). Riparian hemlock mortality impacts on vegetative and aquatic systems of first-order, headwater streams were evaluated. Reference sites for this study were representative of the best available conditions within the GSMNP, with initial stages of HWA presence. Impacted sites were defined as areas with over 90 percent hemlock mortality. Impacted streams had decreased canopy coverage and increased light availability. Residual red maple, yellow birch, and sweet birch capitalized on the loss of hemlock, with increases in relative basal area and species importance values. Rosebay rhododendron responded with increased density and height at impacted sites, thereby preventing woody regeneration. Since long-term regeneration and post-mortality canopy recruitment are limited, alterations of vegetative composition and structure in the stream riparian zone are expected. A seasonal assessment (Sept. 2009 – March 2010) of aquatic impacts revealed increased diurnal variation in stream temperature and exhibited cooler temperatures during the colder months than reference streams. Impacted streams exhibited greater amounts and larger size classes of large woody debris (LWD). Higher concentrations for several nutrients, including silicon, sodium, potassium, magnesium, chlorine, and copper were detected in impacted streams than detected in reference streams. Impacted streams were characterized by higher pH and increased acid neutralization capacity, while reference streams exhibited nitrate concentrations three times higher than impacted stream concentrations. Reference streams were experiencing the initial stage of HWA-induced defoliations, increasing stream nitrate concentrations, while impacted sites had levels suggesting nitrate concentrations have returned to pre-infestation levels. A seasonal assessment of macroinvertebrates found species diversity, abundance, and taxa richness were not affected by hemlock mortality. Impacted streams had a lower density of Chironomidae and Ephemeroptera when compared to reference streams, while Pleuroceridae snails were virtually eliminated at impacted stream sites. Reference streams were dominated by the collector/filter functional feeding group (FFG), while impacted streams were dominated by the scraper FFG. Hemlock mortality induced by the presence of HWA has resulted in short-term impacts to vegetative and aquatic dynamics in stream riparian areas of the Great Smoky Mountain National Park.