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<p> Sap flow measurements scaled to represent canopy transpiration (Ec) and eddy covariance measurements of total forest water vapour flux (E) were compared with soil water, meteorological measurements and modelled interception estimates to quantify the above canopy flux of water to the atmosphere from a temperate White pine ecosystem located on the Norfolk sand plain at Turkey Point, Ontario, for the growing season of 2006. Hydraulic redistribution (HR) was found to have occurred at the site on 26 days during the study (growing season of 2006). During a drought period in June, the nightly increases in stored water (up to 0.50 mm) provided by HR reduced drought intensity in the root zone by maintaining soil water contents ( 0) at levels above the water content associated with the approximate wilting point(() of 0.07). Daily forest water fluxes (E) averaged 2.4 mm d-1 and reached maximums of 4 mm d-1 regularly. Canopy transpiration (Ec) averaged 1.2 mm d-1• Modelled interception accounted for 18% of gross precipitation over the study period. Ec and interception loss (EI) contribute the majority (81%) of the water vapour exchanged between the forest and the atmosphere. E1 accounted for 34% of E and Ec accounted for 47%. Ec was controlled linearly by atmospheric demand (VPD) until a variable transition point was reached, after which mid-day Ec rates remained relatively constant. Ec rates were limited to approximately 0.10 mm hh-1 through the study period. This limitation was sensitive to early morning VPD and soil water deficit. Increases in early morning VPD caused maximum Ec rates to arrive earlier in the day and to be reduced in magnitude. This shift in the timing and magnitude of Ec rates masked a relationship between Ec and soil water content that caused Ec to be strictly limited once root zone soil water content (Bo-25cm) reduced to ~0.07. This study illustrates that the water storage capacities of different site characteristics (particularly the canopy and soil) are an important factor to consider when investigating how changing precipitation characteristics might affect the hydrology of an ecosystem, and discusses the interrelationship between transpiration, soil water supply and atmospheric demand. </p> / Thesis / Master of Science (MSc)

For operational forest management, a forest inventory is commonly conducted to determine the timber stocking and the value of standing trees in a stand. With time and costs constraints, appropriate sampling designs and models are required to perform the inventory efficiently, as well as to obtain reliable estimates for the variables needed to make projections. In this dissertation research, a simulation study was conducted to extensively explore four important topics in forest inventories: selection of measurement trees in point samples, projection from plot- and stand-level aggregations, subsampling height for volume estimation, and updating stand projections using periodic inventories. A series of simulated loblolly pine plantations with varying degrees of spatial heterogeneity were generated at different stages in stand development. Repeated sampling was used to examine various sampling schemes and growth projection methods. Highlights for the four topics follow: 1. Stand total volume can be reliably estimated using measurement trees tallied by Big BAF, point-double sampling, or random selection of a specified number of trees. However, number of trees per unit area in small-size classes were overestimated across the three tree-selection methods when sample data were aggregated into diameter classes. 2. Plot-level and stand-level projections produced similar estimates for dominant height, basal area, and stems per unit area. As spatial heterogeneity increased, stand-level projections indicated a significant bias of predicted total volume compared with the plot-level projections. 3. Sampling intensity, stand age and spatial heterogeneity have greater influence on the reliability for total volume estimation compared to subsampling intensity and measurement error for height measurements. 4.The variability of total volume estimates increases with increasing projection length (i.e., longer time intervals between inventory entry points). However, the estimates of stand total volume can be greatly improved by updating the models with information obtained in periodic forest inventories, especially when the original models are not well calibrated. The results of this study provide useful guidance and insights for forest practitioners to design forest inventories and improve growth projection systems in operational forest management. / Doctor of Philosophy / For operational forest management, a forest inventory is commonly conducted to determine the timber stocking and the value of standing trees in a stand for management decisions, financial planning and fiduciary reporting requirements. With time and costs constraints, appropriate sampling designs and models are required to perform the inventory efficiently, as well as to obtain reliable estimates for the variables needed to make stand projections. Loblolly pine (Pinus taeda L.) is the primary commercial species in the southeastern United States. In this dissertation research, a simulation study was conducted to extensively explore several important topics in forest inventories, including selection of measurement trees in point samples, projection from plot- and stand-level aggregations, subsampling height for volume estimation, and updating stand projections using periodic inventories. A series of simulated loblolly pine plantations with varying degrees of spatial heterogeneity were generated at different stages in stand development. Repeated sampling was used to examine various sampling schemes and growth projection methods. The results of this study provide useful guidance and insights for forest practitioners to design forest inventories and improve growth projection systems in operational forest management.

Modeling growth dynamics of juvenile loblolly pine plantations can help to address important management decisions that have to be made in young stands. The present study addressed diameter and height prediction as well as crown development analysis as functions of independent variables such as site index, relative spacing and age for trees younger than ten years old. It was found that height prediction for trees one and two years old was a function of the products of the variables site index and age (or square root of age) and relative spacing and age (or square root of age). For trees three years old and older these were also the independent variables used to explain height prediction but in this case age (or square root of age) was another significant independent variable. In regard to diameter prediction it was observed that groundline diameter was a function of age for trees one and two years old; while this variable was also a function of site index and relative spacing for trees three, four and five years old. For trees older than five years old diameter at breast height was a function of age, site index and relative spacing. The analysis of crown development showed that for trees five years old and older variables like diameter at breast height, total height, age, site index and relative spacing were significant when crown ratio was the dependent variable. For trees younger than five years old, groundline diameter and the other same independent variables (i.e. total height, age, index and relative spacing) were again found significant when crown ratio was the dependent variable. / Ph. D.

This study tests the hypothesis: Bark beetles initially locate their host trees in a non-random manner. The association of the southern pine beetle (<u>Dendroctonus frontalis</u> Zimm.) and associated Coleoptera with stressed trees suggested the direction for this study. Loblolly pine trees, <u>Pinus taeda</u> L., were stressed by severing and girdling. The bark beetle population trapped at stressed trees was then compared to the bark beetles trapped at unstressed control trees. The experiments were conducted in an apparently normal, old-field mixed pine-hardwood forest located in Nottoway County, Virginia, during 1975 through 1977. The girdling technique consisted of three circumferential chain saw cuts 5 cm deep at approximately 1 m above the ground. The severing technique was accomplished by guying the trees with 3.2 mm wire rope to maintain the trees' normal vertical position. The bole was then severed with a chain saw. The control trees were not treated in any manner. The insects associated with the treated and control trees were trapped with a four-way glass baffle placed over an aluminum funnel attached to a 1 liter jar containing 2.5 cm of water. The traps were placed at mid-bole and collected weekly during the growing season. The bark beetle complex studied in this experiment consisted of the following species: <u>Dendroctonus frontalis</u> Zimm, <u>D. terebrans</u> Oliv., <u>Ips avulsus</u> Eichh., <u>I. grandicollis</u> Eichh., <u>I. calligraphus</u> Germ., <u>Hylastes</u> spp., <u>Cossonus</u> spp., and <u>Pityophthorus</u> spp. The bark beetles were not trapped at the treated trees until the trees' foliage had begun to fade. The time period varied from two weeks to two years and also with the month of treatment. The number of bark beetles trapped at trees with faded needles was 40.06/trap-week for the first week the bark beetles were trapped at the tree. Control trees trapped the same number of bark beetles per trap-week as treated trees with green needles, .06 bark beetles per trap-week. The southern pine beetle and associated Coleoptera during endemic population levels exhibit a non-random directed attraction to the treated trees after they died, as evidenced by the fading of the trees' foliage. The conclusion is reached that these insects have the ecological role of scavengers in pine forests. / Ph. D.

The pales weevil, Hylobius pales (Herbst), and the deodar weevil, Piss odes nemorensis Germar, are regeneration pests of pine plantations in the eastern United States. Attempts to sample regeneration weevils in Virginia have met with little success. Two trap types were field tested to determine their effectiveness in sampling H. pales and P. nemorensis populations in Virginia Christmas tree plantations. Labor intensive pit traps, using natural host materials and synthetic volatiles, caught significantly more weevils than PVC pitfall traps baited with synthetic volatiles alone. No differences in trap catches were observed between stationary and rotated traps. Vegetation management had no effect on trap catch. However, it was observed that newly planted white pine seedlings (Pinus strobus L.) were fed upon by H. pales at Significantly higher rates in plots not managed for competing vegetation than in herbicide treated plots. Feeding activity in mowed plots was intermediate. Trap catch did not correlate with seedling damage within or among sampling periods, or between years. The seasonal activity of both species is reviewed in detail. Mark-and-recapture techniques used to assess trap efficacy showed traps baited with pine material were most effective, irrespective of trap type. The response of H. pales adults to different ethanol-and-turpentine ratios in a laboratory bioassay did not vary with respect to gender or age. No gender differences in response to treatments were observed in these studies. / Master of Science

Clean laboratory technology and pure culture techniques were combined to determine the effect of ectomycorrhizae on the uptake of lead by Pinus sylvestris L. seedlings. By culturing the ectomycorrhizal fungus, Pisolithus tinctorius (Pers.) Coker and Couch, in liquid Hagem's medium with different concentrations of lead (0, 50, 250 and 500 ng/g sol), it was determined that the fungus readily takes up lead from such and aqueous medium. It was also determined that the pH of the medium controls the amount of lead in solution that can be taken up by the fungus. A series of growth studies where Pisolithus was cultured on Hagem's agar indicated that the growth of the fungus is reduced when the lead concentration in the medium is approximately 25 ug/g sol. It was estimated that a lead concentration of approximately 1,000 ug/g sol may completely inhibit the growth of the fungus. Furthermore, it was determined that the acetate ion is inhibitory to the growth of Pisolithus. By culturing mycorrhizal and non-mycorrhizal seedlings of P. sylvestris and analyzing the seedlings' roots, stems and leaves for their lead concentrations, it was determined that ectomycorrhizae facilitate the uptake of lead. Ectomycorrhizal roots can take up more lead from a vermiculite/hydroponic solution mixture because of their greater surface area and exploration of vermiculite surfaces as well as their increased production of lead solubilizing acids. This additional lead found in mycorrhizal roots, however, does not appear to be translocated to the above ground portions of the seedlings. This increased uptake of lead by mycorrhizal roots is expected to take place in natural soil systems as well. / Master of Science

M. S.

An earlier publication presented evidence for enhancement of isocitrate lyase (threo-L_S isocitrate glyoxylate lyase, EC 4.1.3.1) activity by a factor that diffuses into the megagametopnyte from the embryo of stratified germinating Pinus ponderosa seeds. In contrast, the data reported here indicate the rate of increase in specific activity of embryoless seeds was greater during the first four days than in seeds with embryos left in situ. A similar pattern of activity was observed in seeds which retained their embryos for two days to allow germination to occur prior to excision, but the peak activity was slightly nigher. The highest enzyme activity was achieved in seeds which retained their embryos the longest. A model is included to resolve these apparently diverging effects of the embryo on isocitrate lyase activity. A diffusate prepared from two day germinated embryos had no significant influence on the enzyme activity of embryoless seeds. The phenomena reported here were not dependent on stratification. Imbibition was the only prerequisite for germination and develooment of enzyme activity to occur. / Master of Science

Site index curves for natural stands and plantation stands of loblolly pine in the Southeast were constructed from temporary age height data by an anamorphic technique and two polymorphic techniques. These different systems of site index curves were evaluated using sectioned tree data. Evaluation results showed the anamorphic site index curves were best for the plantation stands, and the polymorphic curves constructed using a data stratification method were best for the natural stands. / Master of Science