• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 597
  • 168
  • 80
  • 31
  • 26
  • 23
  • 13
  • 7
  • 7
  • 7
  • 6
  • 6
  • 6
  • 6
  • 6
  • Tagged with
  • 1268
  • 248
  • 180
  • 126
  • 116
  • 110
  • 93
  • 90
  • 88
  • 85
  • 84
  • 84
  • 83
  • 81
  • 77
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
251

Localization of Expansin Expression During Adventitious and Lateral Rooting in Response to Auxin in Loblolly Pine

Xu, Fuyu January 2002 (has links) (PDF)
No description available.
252

Effect of Stand Density on Behavior of Leaf Area Prediction Models for Eastern White Pine (Pinus strobus L.) in Maine

Pace, Micah D. January 2003 (has links) (PDF)
No description available.
253

Soil and plant response to slash pile burning in a ponderosa pine forest

Meyer, Natalie Jo. January 2009 (has links) (PDF)
Thesis (MS)--Montana State University--Bozeman, 2009. / Typescript. Chairperson, Graduate Committee: Catherine A. Zabinski. Includes bibliographical references (leaves 77-86).
254

Swelling, cell wall porosity and chemical modification of wood

Papadopoulos, Antonios N. January 2001 (has links)
Kinetic profiles were investigated for the pyridine catalysed reaction of Corsican (CP) and Scots pine (SP) sapwood with a homologous series of linear chain carboxylic anhydrides namely, acetic (AA), propionic (PA), butyric, valeric and hexanoic (HA). With AA. it has been found that the reaction profiles are described by a model where diffusion dominates the reaction process, that is to say that reaction of the reagent molecules with a specific reaction site is rapid compared with diffusion. With longer chain anhydrides, the rate of chemical reaction and diffusion both contributed to the reaction kinetics. The reaction activation energies (Ea) were detennined for the catalysed reaction of pyridine swollen pine sapwood samples and phenolic model compounds (in solution) with the series of anhydrides, using the methods of initial rates and rate constants. Both methods resulted in comparable values. The wood species did not influence the Ea. With wood samples, the Ea was largest for the reaction of AA, and decreased as the molecular weight of the anhydride increased. When the reactions were performed in homogeneous solutions, there was no correlation molecular weight of anhydride and Ea. It is suggested that the lower values obtained for the Ea for reaction with wood are related to the restricted space surrounding the accessible hydroxyl groups (OH). The cell wall micropore network of oven-dried (OD) CP and SP sapwood was investigated by reaction with AA and PA in a non-swelling solvent (xylene) and with swollen wood. Significant differences in reactivity were found between species. The volumetric changes in CP and SP sapwood due to modification with the series of anhydrides were studied. Again significant differences in the response of the wood cell wall were found between species. A comprehensive investigation into the water sorptive properties and into the effect of molecular size of the substituent group upon the sorption of water vapour of softwood modified with the series of anhydrides was perfonned. The sorption isotherms for untreated and chemically modified wood were analysed using the Hailwood-Horrobin model. The results are interpreted by consideration of both the number of OH groups reacted and the volume occupied by adduct in the cell wall. It is considered that the latter effect is more important. In the final part of this study, an approach was made to investigate the cell wall porosity of unmodified and modified wood, using the nitrogen adsorption technique. Results indicated that the true porosity of the cell wall was not determined by this technique.
255

Soil texture of Pinus ponderosa plant communities in British Columbia

Ogilvie, Robert Townley January 1955 (has links)
The field, work for this investigation was carried out in the summer of 1952, during this time soil samples and field notes were made. Further soil samples were secured in the summer of 1953, The area in which the yellow pine communities were studied was in the Okanagan, Similkameen, Nicola and South Thompson valleys as well as the southern Cariboo in the vicinity of Clinton, The soil samples were air-dried, weighed and the gravel fraction ( particles greater than 2 mm. in diameter) separated by sieve. The gravel fraction was weighed and the percentage determined for each sample. The mechanical analysis was done by means of the Bouyoueos hydrometer Method, following the removal of organic matter by hydrogen peroxide, and carbonates by treatment with hydrochloric acid. The results of the mechanical analysis were expressed in terms of percentages, by weight, of sand, silt and clay on the basis of the soil sample with the gravel removed. Using the textural classification of the United States Department of Agriculture the results were expressed In terms of sandy loam, loam, etc. for each plant community. The ranges in soil texture for each plant community are: Agropyron association - sandy loam to clay loam with extremes of sand and clay. Stipa subassociation - sandy loam. Artemisia subassociation - clay loam. Purshia association – generally sand, occasionally sandy loam. Aristida subassociation- sand to sandy loam. Rhus association - loamy sand with high percentage of gravel. Arctostaphylos association - sandy loam or loamy sand to sand. Arctostaphylos - Calamagrostis association - sand to sandy Calamagrostis association - sandy clay loam to sandy loam. Symphoricarpos association - sandy loam and sandy clay loam. / Science, Faculty of / Botany, Department of / Zoology, Department of / Graduate
256

Analysis of biomass, biomass sampling methods, and weight scaling of lodgepole pine

Johnstone, W. D. (Wayne David) January 1967 (has links)
Tree and tree component weights of 63 forest-grown lodgepole pine trees were investigated. Data were collected from one tenth-acre plot located in south western Alberta. Both graphical and multiple regression techniques were used. Of the independent variables tested, tree basal area was most closely related to the component weights, with the exceptions of bole bark weight and total stem dry weight. The fresh and dry weights of bole bark were most closely associated with tree height, and total stem dry weight was most closely associated with dbh. Very reliable estimates of tree and tree component weights were obtained using regression techniques and the independent variables previously mentioned. The proportions of the component weights of the total tree weights were determined. The proportions were highly variable and widely dispersed about the mean. The tree characteristic most closely associated with the various proportions varied for the component being analysed. The proportion of the total tree weight contained in the stem, slash, bark and bole wood decreased with increasing tree size. The proportion represented by the needles, branches, merchantable stem, and crown increased with tree size. The crown and needle characteristics of lodgepole pine were investigated. Tree size, whether measured as stem weight in pounds or cubic foot stem volume (ob), was most closely correlated with dry needle weight (in pounds). The number of needles per cubic foot of stem volume increased with increasing tree size. The needle characteristics of lodgepole pine are highly variable. Needle length was significantly related to needle width. Needle length was not significantly related to any tree characteristics. The need to develop reliable sampling methods for biomass and fire control studies was discussed. Double sampling with regression appeared to offer accurate estimates with a minimum of weight measurement. The number of trees required to obtain a sample mean within plus or minus 10 per cent of the population mean at the 95 per cent confidence level is too large to be practical for most biomass and fire control studies. A higher standard error of estimate is probably more desirable, thus allowing a greater number of conditions to be sampled in order to increase the representativeness of the study. The mutual relationship between tree weight and tree volume was investigated. Tree volume was highly correlated with tree weight. Reliable estimates of tree weight were obtained from tree volume. Variation in moisture content and specific gravity, within and between trees was analyzed. These variables were surprisingly uniform and appear to pose only minor problems in weight scaling, for lodgepole pine. / Forestry, Faculty of / Graduate
257

Nitrogen availability and soil microclimate after clearcutting lodgepole pine

Haskin, Catherine Marie January 1985 (has links)
Long term management of lodgepole pine depends, in part, on the nutrient capital of the site. Harvesting has been shown to increase the availability of nitrogen and other nutrients for a limited period of time. This increase, or nutrient flush, following cutting has been attributed to several factors including changes in organic matter quantity and quality, soil moisture and temperature regimes, and competition for nutrients. Knowledge of the duration and the magnitude of the nutrient flush would be valuable for management decisions. A consequence of lodgepole pine clearcuts was studied for soil nitrogen availability and microclimate. Mineral soil and forest floor samples were anaerobically incubated and analyzed for ammonium-nitrogen (ppm). The mineral soil showed a flush lasting about 12 years, peaking by year 8, while the forest floor material showed no trend. The size of the increase from year 2 to year 8 was about 52%. Temperature (air and soil), soil moisture, solar radiation, and precipitation data were collected, and a soil water budget was calculated using a simple water balance model. The average calculated soil water deficit was 119 mm, but this may have been an over-estimate. Windrowing following cutting may have depleted the site nitrogen reserve which in turn reduced the amount that was mineralized during incubation. The interaction between the soil temperature and moisture may have further limited nitrogen availability to the lodgepole pine trees. It is concluded that the dynamics of nitrogen availability following clearcutting are important for the establishment and growth of lodgepole pine. The summer moisture deficit appears to limit the nitrogen mineralization rate as well as seedling growth. / Forestry, Faculty of / Graduate
258

Repellent effects of pineoil on the Sitka spruce weevil, Pissodes strobi (Peck), and an evaluation of large scale aerial photographs for detecting weevil damage

Carlson, Jerry A. January 1987 (has links)
This study was designed to investigate the repellent effects of pineoil on the Sitka spruce weevil (=white pine weevil), Pissodes strobi Peck, and to evaluate the utility of large scale color aerial photography for detecting weevil attacked Sitka spruce, Picea sitchensis (Bong.) Carr.. Two formulations of pineoil, BBR1 and BBR2, were field tested for their effect in protecting immature Sitka spruce from weevil attack in 36 twenty meter square plots at two locations on Vancouver Island. The pineoil formulations were applied both topically to the terminal leaders and in slow release devices hung at the apical whorl of Sitka spruce trees. The topical application of BBR1 to the leaders of all trees in the plots reduced the number of new weevil attacks to two trees compared with 24 new attacks in the control plots. None of the other pineoil treatments were found to differ significantly from the controls. An examination of the weevil attack history in the study plots showed that the average number of new weevil attacks in the pineoil treated plots were proportionately lower than the number of new attacks in the control plots. These findings suggest that applications of BBR1 to the terminal leaders of Sitka spruce trees will protect them from attack by P. strobi. Large scale color infra-red (CIR) and normal color (NC) aerial photograph stereo transparencies were evaluated for their utility in detecting weevil attacks in immature Sitka spruce stands. Four independent interpreters correctly identified an average of 38% more weeviled trees on CIR film than on NC film during a 1 minute test period. More errors were made by the interpreters with CIR film than with NC film. Interpreter errors made with CIR film were mainly due to a lack of ability to discriminate between new weevil attacks and attacks made the previous year. Errors made with NC film were due mainly to misidentifying healthy trees as new weevil attacks. These findings suggest that for the purpose of detecting weevil attacked Sitka spruce trees, CIR aerial photographs would be both faster and more accurate than NC photographs. / Forestry, Faculty of / Graduate
259

Jiggs

Sosa, Mario 05 1900 (has links)
Jiggs is a documentary that explores how Jiggs Gaffney serves despite his mental disability. By observing Jiggs’ involvement at Pine Cove Christian Camps, and revealing his past, the documentary shows how anyone can be used for a greater good, and reveals how God can be served and glorified by anyone, no matter the individual circumstances.
260

Assessment of early successional arthropod and breeding bird response to intercropping switchgrass within an intensively managed loblolly pine forest

Marshall, Craig Daniel 07 May 2016 (has links)
Loblolly pine (Pinus taeda) plantations are a common land use of the southeastern United States that have the potential to function as a source of cellulosic biomass for biofuel production. A novel land use practice of intercropping switchgrass (Panicum virgatum) between planted loblolly pines has been developed as a potential method of cellulosic biomass production. I evaluated response of arthropods and breeding birds to intercropping switchgrass within loblolly pine plantations compared to typically managed pine plantations. I detected 13 arthropod orders and 44 breeding bird species during 2014 – 2015. Intercropping switchgrass reduced arthropod diversity and evenness, with richness not affected. Arthropod abundance response to intercropping switchgrass varied among orders. Breeding bird species did not respond differently to intercropping switchgrass compared to typically managed pine. Continued assessment is needed to provide greater insight regarding potential effects of this land use practice throughout a rotational period.

Page generated in 0.0655 seconds