The present study was undertaken to examine the litter decay fungi of red cedar (Thuja piicata Donn). The fungi involved in conifer litter decay have not been examined intensively and there has been no study of red cedar litter decay. Since Thuja is often found in wet, poorly drained areas, it provided an opportunity to observe occurrence of litter decay fungi relative to slight differences in distance from a stream margin. This was determined by observing changes in the frequency of the fungi at various distances from the margin of a stream and also by observing seasonal changes in fungal populations. An ordination of the data was performed to determine if there were species associations which would characterize the relatively minor horizontal and vertical spatial changes in the sites. The sites were divided into subsites (high, middle and low with respect to the stream) and samples were taken at each subsite. Red cedar branchlets from the L and F litter layers were washed and plated on a selective medium or placed in moist chambers; all observed species were isolated and identified. Most of these were members of the Fungi Imperfecti. The frequency of occurrence of the more commonly isolated species was utilized in a Principal Components Analysis (PCA) to determine associations of subsites, layers or species. There was little distinction between the three subsites, but there was a general separation of the high subsite from the low subsite, the middle subsite showing affinities to both. The L and F layers represented a division of the litter layer which formed more distinct clusters in the ordination, especially in the Site B data. Seasonal distinction among the samples seemed to reflect the extremes of the seasons. The spring and summer samples generally grouped together, as did the fall and winter samples. Species associations reflected various combinations of the above groupings, depending on the species groups involved. Again the most distinct groups represented extremes, e.g., species prominent in dry samples, especially in the high subsite, or species prominent in moist conditions, especially in the low subsite. No single variable provided clear distinction among the various subsites, layers, seasons or species. However, the combination of all of these gave general indications as to probable fungal associations. / Science, Faculty of / Botany, Department of / Graduate

No description available.

Master of Science / Department of Horticulture, Forestry, and Recreation Resources / Cheryl Boyer / The nursery industry in the United States, particularly in the Great Plains region is growing; however, materials used in creation of artificial substrates used to grow ornamental nursery crops continue to increase in price. Eastern Redcedar (Juniperus virginiana L.) is an indigenous plant throughout much of the United States and, in the Great Plains, it has become a pest. Use of wood-based substrates (primarily composed of pine trees) has been proven effective in both nursery and greenhouse production. Eastern Redcedar chips (JVC) could become a local and sustainable resource for the horticulture industry throughout the Midwest. Experiments were conducted to determine if JVC could be used as a substrate to replace or supplement three major substrate components; pine bark (PB), perlite, or peat moss. Four studies evaluated ornamental crop growth: two focused on comparing nursery crop production in PB and JVC, one focused on greenhouse production in peat moss, and the last on plant propagation in perlite. The first experiment (Chapter 2) involved combining ratios of JVC and PB with two fertilizer rates to grow woody plants. It was shown that while higher levels of fertilizer produced larger plants, that plants grown at either rate of fertilizer showed the same growth trends. As JVC content increased more than 20%, growth measurements such as shoot dry weight and plant height decreased. This decrease in growth can be attributed to the physical properties of JVC, which showed that as JVC content increased so did airspace with a corresponding decrease in container capacity. A follow-up experiment (Chapter 4) evaluated several different particle sizes of JVC and a PB control. It showed that despite the different particle sizes JVC substrate produced less growth than plants grown in PB though plants grown in JVC were all similar to each other. Another experiment (Chapter 3) was conducted to evaluate if JVC as a replacement for peat moss in producing greenhouse-grown annual crops. JVC’s low container capacity hindered plant growth with each increase in JVC content associated with a decrease in growth. Finally a propagation experiment (Chapter 5) used a combination of finely-ground JVC and perlite to grow cuttings of woody and herbaceous plants. It was shown that, in most cases, JVC and perlite were equivocal rooting cuttings. This work demonstrates that JVC can be used as a PB and peat moss supplement, but not a replacement nursery and greenhouse crop production. Use of JVC as a perlite replacement for plant propagation is recommended.

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.

Thesis (M.S.)--University of North Texas, Dec., 2009. / Title from title page display. Includes bibliographical references.

Thesis (Ph. D.)--Oregon State University, 1994. / Typescript (photocopy). Includes bibliographical references (leaves 109-125). Also available on the World Wide Web.

Doctor of Philosophy / Department of Horticulture, Forestry, and Recreation Resources / Charles J. Barden / Recurrent, landscape-level fires played an integral part in the development and persistence of eastern oak (Quercus spp.) forests of the United States. These periodic surface fires helped secure a competitive position for oaks in the regeneration pool by maintaining a desirable species composition and forest structure. This historical fire regime was altered with the European settlement of North America, and fire suppression within forestlands became a standard practice since 1930s. With decades of fire suppression, mature oak-dominated woodlands have widely converted to shade-tolerant tree species. Prescribed fire has successfully been used to enhance oak regeneration in eastern forests. However, oak woodland restoration within the forest-prairie ecotone of the Central plains has not been systematically studied. Fuel beds under shade-tolerant species are often less conducive to fire. Therefore, monitoring fuel loading (FL) and its changes are essential to inform management decisions in an oak regeneration project. Rapid expansion of eastern redcedar (Juniperus virginiana/ERC) is another ecological issue faced by land managers throughout North America’s midcontinent forest-prairie ecotone. Hence, it is worthy to monitor ERC expansion and effects on deciduous forests, to inform oak ecosystem restoration interventions within this region. Therefore, the main objectives of this dissertation were three-fold: (1) understand the effects of prescribed burning and mechanical thinning to encourage oak regeneration; (2) investigate the initial effects of an oak regeneration effort with prescribed fire and mechanical thinning on FL; and (3) monitor the spatio-temporal dynamics of ERC expansion in the forest-prairie ecotone of Kansas, and understand its effects on deciduous forests. The first two studies were conducted on a 90-acre oak dominated woodland, north of Manhattan, Kansas. The experimental design was a 2 (burn) x 2 (thin) factorial in a repeated measures design. The design structure allowed four treatment combinations: burn only (B), thin only (T), burn and thin combined (BT), and a control (C). Burning and thinning treatments were administered in spring 2015. Changes in the FL estimates after the burn treatment revealed that the BT treatment combination consumed more fuel and burned more intensely compared to the B treatment. This observation was reflected in vegetation responses. The thinning reduced the canopy cover significantly, but under enhanced light environments, both oaks and competitive species thrived when no burn was incorporated. In contrast, burn treatments controlled the competitive vegetation. Hence, the most promising results were obtained when both fire and thinning were utilized. The remote sensing study documented the expansion of ERC in three areas of eastern Kansas over 30 years. The use of multi-seasonal layer-stacks with a Support Vector Machines (SVM) supervised classification was found to be the most effective approach to map ERC distribution. Total ERC cover increased by more than 6000 acres in all three study areas investigated in this study between 1986 and 2017. Much of the ERC expansion was into deciduous woodlands. Therefore, ERC control measures should be incorporated into oak woodland restoration efforts within the forest-prairie ecotone of Kansas.

Doctor of Philosophy / Department of Biology / John M. Blair / Juniperus virginiana, an important woody plant invader in the U.S. Central Plains, has increased considerably in density and cover in large areas previously dominated by tallgrass prairie. Change in the phenology and nitrogen use efficiency of the dominant plant communities as J. virginiana replaces native prairies may lead to increased plant productivity and biomass accumulation, but may also alter the microclimate and litter quality that affect soil microbial communities responsible for key soil processes. I have focused my investigations on changes in key soil processes that could lead to differences in soil N availability, as well as changes in ecosystem C and N pools and fluxes as J. virginiana expands into native grasslands. Juniperus virginiana forest soils exhibit greater cumulative annual net N mineralization (11.52 ± 0.38 µg N g¯1 soil y¯1) compared to prairie soils (7.90 ± 0.26 µg N g¯1 soil y¯1) (F = 60.67, P = 0.016), yet slightly reduced potential soil C flux. Examination of internal soil N cycling revealed that both J. virginiana and prairie soils minimize potential soil N losses, by rapid microbial immobilization of inorganic N, and constraining nitrification via substrate limitation or environmental constraints. Leaf-level photosynthetic nitrogen use efficiency (NUE) was over a magnitude higher in the dominant grass, Andropogon gerardii, but high annual ecosystem-level NUE and greater soil N availability may contribute to the higher productivity and rapid accrual of C in newly established J. virginiana forests. Increased plant productivity and elimination of fire in J. virginiana forests have allowed at least 80,000 kg ha-1 increase in ecosystem C storage in about half a century. Soil organic C, an important long-term sink, has also increased significantly in J. virginiana forests, with approximately 34% replacement of C4 grass-derived soil C with new C from trees in the A-horizon. The observed high productivity of J. virginiana and increased N availability necessary to support continued plant biomass accumulation are possible because of substantial (~ 44%) increase in ecosystem N in measured pools, which is a likely a result of reduced volatilization of N from biomass burning, possible increased exogenous N inputs, and/or N translocation from deeper soil horizons. Reduced fire return intervals in prairie provide an opportunity for J. virginiana to establish and facilitate N accrual, which may allow this species to accelerate is own establishment through creating conditions of increased N availability and efficient utilization of N.

Breast height radial growth of 165 western red cedar (Thuja plicata Donn), 14.5 western hemlock (Tsuga heterophylla (Raf.) Sarg.) and 33 Douglas fir trees (Pseudotsuga menziesii (Mirb.) Franco), in young natural stands on the eastern side of the University of British Columbia Research Forest near Haney, B.C. was analysed. Individual tree parameters measured included breast height diameter, total height, age at breast height, radial growth over last five and ten years, crown width, live crown length, tree class, live crown ratio, height/age ratio, crown width/breast height diameter ratio, and height/ crown width. Stand parameters measured were number of trees per plot, average breast height diameter of plot, and basal area per acre of plot. Plots were of variable radius as determined in prism cruising. Growth was investigated from results of simple correlation coefficients and several multiple regression analyses computed on an IBM 7040. Causes of variation in growth were assessed by studying interaction of variables affecting growth patterns. Individual species have distinctly different modes of growth. Species react differently to changes in stand density. Radial growth can be determined from measurements of tree crowns; and crown development reflects changes in stand density. Difference between species are found as crown development varies with stand density changes. Crown dimensions of western hemlock are least sensitive to changes in stand density as measured by basal area per acre, crown width/breast height diameter, live crown ratio, or height/crown width. An understanding of how crown dimensions change with variation in stand density can be used to refine predictions of tree radial growth derived from crown measurements. / Forestry, Faculty of / Graduate

Growth release of trees following canopy disturbances is of interest to ecological scientists and forest managers. Using dendroecological techniques, I examined growth release of canopy and subcanopy trees following the formation of natural, fine-scale canopy gaps in old-growth, western red cedar-western hemlock forests of coastal British Columbia. I aimed to quantify detailed information on release of the three shade-tolerant tree species that constitute these stands: western red cedar (Thuja plicata), western hemlock (Tsuga heterophylla), and Pacific silver fir (Abies amabilis). As a first step, I calibrated the radial-growth averaging method to account for regional-scale variability and capture a more complete range of growth releases that may occur following the formation of fine-scale gaps in the study stands. A 25% threshold, 5-year moving average, and 10-year window emerged as appropriate parameters for detecting releases using radial-growth averaging. Basal area increment was also the most appropriate growth index for detecting releases. Establishing these empirically-based criteria was important for quantifying the magnitude and duration of releases. Tree diameter and growth rate prior to release were the most important predictors of the magnitude and duration of releases, but identity of the tree species and distance from the gap center were also important predictors. Western hemlock and Pacific silver fir were often growing slowly both in the canopy and subcanopy, giving them tremendous potential to release. For these species, releases were generally intensive and persistent. In contrast, western red cedar were often growing quickly both in the canopy and subcanopy, giving them less potential to release. Compared to western hemlock and Pacific silver fir, western red cedar releases were less intensive and persistent. Patterns related to distance from the gap center emerged for trees growing along the north-south axis of gaps. Regardless of species, increasing distance from the gap center resulted in decreasing magnitude and duration of releases. However, patterns for duration were complex, as the distance effect was greater for trees north of the gap center. Information on growth release of trees is useful for reconstructing the history of past canopy disturbances, elucidating mechanisms of tree species coexistence, and assessing and predicting stand changes due to forest management in coastal British Columbia.