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  • 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.
331

Influence of site factors and climate on timber properties of Sitka spruce (Picea sitchensis (Bong.) Carr.)

Vihermaa, Leena January 2010 (has links)
In plantation grown Sitka spruce, timber density is an important quality concern. Currently Sitka spruce timber meets the requirements for C16 strength grading which is the minimum requirement for construction uses. However, the margin is not exceeded by much and a small reduction in density could lower the log grading. Therefore it is essential to understand how timber density is impacted by site factors and climate in order to predict the potential effects of climate change on timber quality in Sitka spruce in the future. This has important economic implications for UK forestry. To assess the influence of site factors and climate on growth and resulting timber properties in Sitka spruce, three experiments were established; a large scale wood quality survey (“The Benchmarking experiment”), a detailed inter-site density study (“The Level II experiment”) and a continuous growth monitoring experiment (Dendrometer experiment). In the ‘Benchmarking’ experiment, increment cores were collected from 68 sites over a geographically wide area in Scotland and Northern England in order to quantify the effect of selected site factors on density. These samples were not suited for climate analysis at annual ring level and therefore disks that allowed reliable dating of the tree rings were collected from three Level II sites. The Level II samples were also used in an acoustic velocity study and an assessment of the within-tree patterns in density. Material from both Benchmarking and Level II sites was used for modelling radial density. In addition to this the Level II data functioned as a test dataset for the different density models that were developed on the Benchmarking data. Density and other tree ring variables were measured with an ITRAX X-ray densitometer and WinDENDRO software. Some acoustic measurements were also carried out with a purpose built ultrasonic scanner to allow calculation of radial variation in stiffness. A dendrometer experiment was established to monitor short term growth variation in Sitka spruce in real time. The aim was also to use the growth data to date density profiles and hence identify causes for the density differences. Data analysis was carried out in R mainly using linear and non-linear mixed effects models, the dendrochronology software package dplR and methods of time series analysis. It was found that the largest part of the variation in density was between trees within each site. Both density and stiffness were mostly influenced by the growth rate or by another variable describing the tree vigour. Fast growth decreased density both by increasing earlywood proportion as well as decreasing the density of both earlywood and latewood. Models for the radial behaviour of density and stiffness could be fitted to the data, but random tree effects remained large. This limits the applicability of these models to new sites as reparameterisation would be required, which requires data from time consuming density and acoustic velocity measurements. The possibility of modelling the model coefficients from easily measurable stand and tree variables was investigated but the results were not promising. The Dendrometer experiment indicated that annual growth in Sitka spruce was initiated in late May and terminated by mid September. Ring widths detected by the dendrometers, micro core measurements and X-ray density based tree ring analysis differed, which caused difficulties in dating the density profile. To decrease these problems in the future the microcore sample storage protocol was revised. The dendrometer data indicated that the growing season was divided into several sections between which the growth rate differed. Latewood density and maximum density had the strongest correlations with the climatic variables. At one site the correlations included temperature and rainfall in April whereas at the other precipitation throughout the growing season or during the May-August period were important. Temperature was correlated positively with density variables and rainfall negatively.
332

Notes on the Technique of Tree-Ring Analysis, I

Douglass, A. E. 07 1900 (has links)
No description available.
333

The Application of Tree-Ring Dates to Arctic Sites

Giddings, J. L., Jr. 10 1900 (has links)
No description available.
334

Notes on the Technique of Tree-Ring Analysis, III

Douglass, A. E. 10 1900 (has links)
No description available.
335

Notes on the Technique of Tree-Ring Analysis, II

Douglass, A. E. 04 1900 (has links)
No description available.
336

Contextual fit of residential structures in forested landscapes

Tibbels, Stephen Brett, 1960- January 1990 (has links)
Contextual fit relationships have been examined in many different man-made environments. To date, however, investigation of contextual fit relationships between manmade structures and natural settings has been minimal. The present research examines contextual fit of residential structures to their forested settings. Structure color contrast to setting was found to be inversely related to both perceived fittingness and aesthetic appeal. A positive relationship between fittingness and aesthetic appeal was uncovered. The bearing that these findings can have on visual quality, preservation of forest setting sense of place, and quality of life, is discussed.
337

Habitat use and life history of the Mount Graham red squirrel

Froehlich, Genice Frances, 1953- January 1990 (has links)
I studied habitat use by 9 radio-collared Mt. Graham red squirrels (Tamiasciurus hudsonicus grahamensis) during the summers of 1988 and 1989 in the Pinaleno Mountains, Arizona. My 2 study areas represented an Engelmann spruce (Picea engelmannii)/corkbark fir (Abies lasiocarpa) association on High Peak and a Douglas-fir (Pseudotsuga menziesii) association on Merrill Peak. I trapped 9 squirrels in 33,400 trap hours, and calculated the seasonal home range for 4 animals, 2 in each study area. Hidden density was 0.54 and 0.2 middens/ha, respectively, but seasonal home range size (x = 3.62 ha) did not vary between habitats. Squirrel numbers decreased on both study areas between 1988 and 1989. I concluded that preference for habitat characteristics in midden areas explained lower densities in the mixed conifer vegetation. Squirrels fed mainly on cones and mushrooms, depending on season and availability. Mt. Graham red squirrels may breed twice/year.
338

Fences as barriers to desert mule deer along canals in central Arizona

Carmichael, Gregory Bruce, 1965- January 1991 (has links)
Water associated with the Central Arizona Project (CAP) and its delivery systems attract wildlife. Crossing structures, alternate water sources, and fences have been built to reduce wildlife mortality associated with canals. Their effectiveness, however, has not been evaluated. I assessed the effectiveness of a woven wire and an electric fence located on the CAP and Tonopah Canals, respectively. The purpose of these fences was to prevent desert mule deer (Odocoileus hemionus crooki) from entering canals. I established track plots to quantify differences in deer use between areas separated by the canals. I used line intercept transects to examine differences in the vegetation between the north and south sides of the CAP. Both types of fences were effective in keeping deer out of the canal. The north side of the CAP had more deer use and more ground cover than the south side. If future offshoot canals are small, they may be left unfenced, if follow-up studies reveal no significant wildlife mortality.
339

Habitat selection by mountain sheep in Mojave Desert scrub

Berner, Louis Robert, 1963- January 1992 (has links)
I identified habitat use by 12-18 mountain sheep (Ovis canadensis nelsoni) in a 320-ha enclosure between June 1990 and June 1991 on the Desert National Wildlife Refuge, Nevada. The enclosure included 9 vegetation associations and 5 slope classes. I used a non-mapping technique and line transects to determine availability of vegetation associations and slope classes, and species composition, respectively. I determined use of habitats by mountain sheep with instantaneous sampling. Mountain sheep used midslopes and draw associations on the west side of the study area, and slope classes of 36-80% more than expected based on availability. I tested Hansen's (1980) habitat evaluation model on the study area. The model was >98% accurate in predicting mountain sheep use of habitat. Habitat use by mountain sheep in the enclosure was similar to habitat use of free-ranging mountain sheep.
340

Fawning habitat of desert mule deer in the Belmont and Bighorn mountains, Arizona

Fox, Kevin Bryant, 1964- January 1992 (has links)
I monitored female desert mule deer (Odocoileus hemionus crooki) (n = 7) with radio telemetry in the Belmont and Bighorn mountains, Arizona, 1991. I examined habitat use, size of seasonal ranges, predation by coyotes, and behavior, and I identified fawning and fawn rearing habitat. Female desert mule deer preferred the montane vegetation associations and avoided creosote flats (Larrea tridentata) during fawning. Size of seasonal ranges were smaller in the 2 weeks postpartum (X = 3.75 km2 than in the 2 weeks prior to fawning (X = 6.71 km2 Activity during the first or last 4 hours of daylight differed 2 weeks postpartum and the remainder of the year (P = 0.034). Female desert mule deer were less active during daylight 2 weeks postpartum. Females during fawning were not any closer to water than the remainder of the year.

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