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A flexible method to approximate diameter distributions in forest stands was developed. Different functions, each in the form of a modified Weibull cumulative distribution function (cdf), were joined together to form a segmented cdf. Five percentile points (the 0th, 25th, 50th, 75th, and l00th percentiles) were used to determine a segmented cdf. Based on the one-sample KolmogorovSmirnov goodness-of-fit statistic, the segmented cdf was found to perform almost as well as the Weibull distribution for unthinned data and to be superior in case of thinned stands, especially when the data were irregular. A growth and yield model for thinned loblolly pine plantations was developed based on data from 128 0.2-acre permanent plots in the Virginia Piedmont and Coastal Plain. The segmented cdf which characterized the diameter distribution of a stand was searched for such that the resulting total basal area and average dbh estimates were identical to those predicted from stand variables using regression equations. Program THINNED was written in standard FORTRAN to provide stand and stock tables for thinned old-field loblolly pine plantations. Trials with several thinning intensities at ages 15, 20, and 25 and a final harvest at age 30 showed that, for average sites (site index 60 feet at base age 25 years), residual basal areas of 95 square feet per acre resulted in approximately the same total volume (volume removed in thinnings plus final harvest volume) production as unthinned stands. Heavier thinnings (i.e. residual basal areas of less than 95 square feet) resulted in a slight decrease in total volume production, whereas residual basal areas of more than 95 square feet showed a slight increase in total volume production. Estimates from the new model was compared with those from Coile and Schumacher (1964). Total volume production predicted by program THINNED was little affected by thinning, as confirmed by many researchers. The Coile and Schumacher model, however, predicts higher stand response to thinning and consequently its predicted total volumes were consistently higher than those from program THINNED. On the other hand, total volumes resulting from periodic thinnings predicted from the new model agreed closely with observed yields reported by Goebel et al. (1974). / Ph. D.

During the third growing season after thinning, eight-year-old loblolly pine gas exchange parameters were measured. Full sunlight and stand light conditions for upper (sun) and lower (shade) crown foliage were examined. Xylem water potential, litterfall dynamics and tree growth were monitored. Nutrient availability, chlorophyll content and chlorophyll a/b ratio were assessed. At the end of the third post-thinning growing season (eleventh season since planting), thinned trees had larger stem and crown diameters, and live crown ratios. Thinned trees grew 11 cm more in height, and approximately 35% more in diameter, basal area and volume. Only crown diameter differences were statistically significant at p=0.05. Upper crown foliage was found to have somewhat higher net photosynthesis, stomatal conductance and transpiration when measured under saturating light conditions. Lower crown needles displayed features usually associated with shade foliage: lower photosynthetic capacity, lower light compensation point and dark respiration rates. Observed physiological differences were not related to plant water status, chlorophyll content or chlorophyll a/b ratio. The higher light saturated gas exchange rates for upper crown foliage were paralleled by lower stomatal limitations to photosynthesis, possibly the effect of better potassium supply facilitating more efficient stomatal function. Light conditions in thinned stands did not differ significantly between the upper and lower crowns, even though light levels in the lower crowns of unthinned stands were nearly a third of that in the upper crowns. This had an effect on in situ photosynthetic rates, which were similar in the upper and lower crowns of thinned trees. In situ photosynthetic rates in thinned stands were also similar to those measured under saturating light. In the unthinned stands, because of light differences, gas exchange rates were significantly reduced in the lower crowns, with only upper crown foliage fully utilizing its potential for photosynthesis. The physiological activity in the upper crowns of unthinned trees tended to be even higher than in the upper crowns of thinned trees. Litterfall timing did not differ between the thinned and unthinned stands. Litterfall per hectare was higher in unthinned stands, but when expressed on a per tree or unit basal area basis it averaged higher in thinned stands. A larger photosynthetic apparatus together with full utilization of photosynthetic potential in both crown positions are likely the major reasons for better growth of thinned trees. / Master of Science

I Sverige finns ca 1,2 miljoner hektar skog som bedöms ha omedelbart röjningsbehov. Skog där röjningen uteblir eller är svag kan komma att klassas som konfliktbestånd. I konfliktbestånd är stammarna många och diameterspridningen stor och dessa kan då behövas underröjas innan gallring. I denna studie jämfördes produktionen, kostnaderna och intäkterna från fyra olika underröjningsbehandlingar, oröjd, siktröjt, röjt allt upp till 5 cm i brösthöjd och röjt allt upp till 7 cm i brösthöjd. Behandlingen oröjd gav det bästa nettot och sämst hade upp till 5 cm efter gallring och uttransport av virke. En anpassad eller svag röjning gav lägre totalkostnader jämfört med ingen eller hårdare röjning. / In Sweden there are about 1,2 million hectares of forest with immediate need of pre-commercial thinning. Stands, where conducted pre-commercial thinning are light or even absent, become tight with thin stems. In such stands pre-commercial thinning before first thinning may be required, due to operational advantages such as increased visibility. This study compared production, cost and revenues from four different pre-commercial thinning treatments: no pre-commercial thinning, sight pre-commercial thinning, cleared everything up to 5 cm diameter at breast height and cleared everything up to 7 cm diameter at breast height. The treatments whit no pre-commercial thinning had best net value and worst had up to 5 cm. A custom or weak pre-commercial thinning give a lower total cost compared to no or harder pre-commercial thinning.

To ensure that thinning is done properly and correct due to instruction, regularly manual monitoring of the stand is done by the harvester operator after thinning. The aim of this study is to investigate the reliability of a newly developed program, that is using harvester data to automaticly calculate stand variables after thinning. A manual forest inventory was carried out in ten differens stands i south west of Sweden, where basal area, stem density, volume and species mix were estimated and compared to the automatically calculated data. The results shows that volume and stem density were estimated with high precision while the systematic deviation for basal area was 10 %, which is a significant differens.

Fumed silica filler has long been used to structurally reinforce silicone elastomers. Unfortunately, the combination of as little as a few weight percent of untreated fumed silica nanoparticles [uFSN] with a siloxane polymer, such as PDMS, forms a difficult to process waxy solid admixture that even long periods of high shear mixing will not thin. In the course of the current work it was noted that after a period of storage certain solid admixtures would become viscous liquids when subjected to additional high shear mixing. It was further found that the required aging period could be decreased if the admixture storage temperature were increased. The only known interaction of PDMS and uFSN at moderate conditions is the adsorption of polymer on filler, and this interaction is also known to occur more quickly at higher temperature. This study examines the relationship between polymer adsorption and admixture liquefaction. Further, the mechanical properties of cured elastomers containing liquefied admixtures are examined to assess the degree of reinforcement that these materials afford.

Individuals with intellectual and developmental disabilities, such as Autism Spectrum Disorder, often engage in challenging behavior that severely limits positive outcomes. Although treatment packages comprising functional communication training and multiple schedules of reinforcement have demonstrated great promise to both increase appropriate, socially acceptable communication responses for preferred items and decrease challenging behavior associated with not having access to preferred items, resurgence of challenging behavior has been reported to occur during lengthy periods when preferred items are not available (i.e., extinction). This study evaluated whether noncontingent access to an alternative item during an abrupt shift to a lengthy period of extinction would reduce the extent of challenging behavior. Two children with Autism Spectrum Disorder participated. The results of this study indicated that (a) functional communication training successfully reduced challenging behavior and increased the rate of functional communication responses (FCR) for both participants, (b) multiple schedules of reinforcement (i.e., signaled periods of reinforcement and extinction for FCRs) successfully produced discriminated FCRs, and (c) no major differences in challenging behavior were observed when alternative items were presented during the abrupt shift to a terminal period of extinction versus when alternative items were not presented. Limitations and future directions of research are discussed.

Thesis (M.S.)--Oregon State University, 1984. / Typescript (photocopy). Includes bibliographical references (leaves 104-107). Also available on the World Wide Web.

The spatial distribution and monthly fluctuation of beetle species were studied in the experimental forests of Liu-Kuei Station, Taiwan Forestry Research Institute, Taiwan. Beetles were surveyed using pitfall traps from January to December, 2004. Our result showed that species richness, abundance and Shannon diversity of beetles were significant higher in Natural Forest than those of the others, and species richness and abundance were lowest in Taiwania Plantation. The composition and trophic structure of beetle community in the Thinning Plantation resulting from thinning were compared with that in the Taiwania Plantation and natural forest. Beetles communities of Natural Forest, Taiwania Plantation and Thinning Plantation were separated from each other by ordination (PCA), meaning three forest stands have distinct species assemblages. The three group assemblages were also revealed by cluster analysis. The ground-surface air humidity, litter litter depth and herbs cover were major environment factors influencing the beetle distribution. The relative size of trophic guilds in the Thinning Plantation has changed compared to Taiwania Plantation. Detritivores increased significantly in the Thinning Plantation, suggested an increase of nutrient-cycle in the Plantation. Eight dominant beetle families that were Carabidae, Scarabaeidae, Curculionidae, Staphylinidae, Scydmaenidae, Erotylidae, Nitidulidae and Biphyllidae showed different pattern of population fluctuation. The peak mainly from March to June, and Curculionidae, Scarabaeidae, Nitidulidae also show a moderate peak in August and September. In the two plantation areas, most dominant taxa showed a similarly fluctuation patterns, which are slightly different to those of Natural Forest.

Diss. (sammanfattning) Umeå : Sveriges lantbruksuniv., 2009. / Härtill 4 uppsatser.