Environmental Conservation Masters Theses Collection Copyright (c) 2013 University of Massachusetts - Amherst All rights reserved. http://scholarworks.umass.edu/eco_theses Recent documents in Environmental Conservation Masters Theses Collection en-us Fri, 25 Jan 2013 20:28:16 PST 3600 Torsional Shear Strength and Size Effect in Structural Composite Lumber http://scholarworks.umass.edu/theses/964 http://scholarworks.umass.edu/theses/964 Fri, 23 Nov 2012 07:56:35 PST The natural variation of strength properties within brittle materials leads to size effect, a well-known phenomenon whereby the mean strength of a material is observed to decrease as the stressed volume increases. An important implication of size effect is that size adjustment parameters must be incorporated into multi-axial constitutive and failure models used in numerical simulations to predict material response to loading. This experimental study seeks to verify and quantify the presence of depth effect under shear failure in the orthotropic principal material directions of parallel strand lumber (PSL) and laminated veneer lumber (LVL). Torsion tests have been performed on specimens of fixed length and differing cross section to get a pure shear failure, by using a Universal Test Machine. The experimental results indicate that there is no depth effect for LVL from torsional shear stresses. PSL testing was limited to one size, and depth effect was not evaluated. A finite element model was built to simulate the torsional test for the 44x140mm LVL specimen. Comparing the experimental test results and the simulation results, the model provided an accurate prediction of the torsional test for Structural Composite Lumber.

]]> Yang, Zhuo Investigation of Compliance with the ANSI Z133.1 - 2006 Safety Standard in the New England Tree Care Industry http://scholarworks.umass.edu/theses/915 http://scholarworks.umass.edu/theses/915 Fri, 23 Nov 2012 07:23:35 PST Arborists are exposed to many occupational hazards and experience more than three times the overall fatality rate of all U.S. workers. Investigations into fatal incidents lead to a better understanding of industry dangers. However, this knowledge does not extend to how tree workers operate when an injury or fatality does not occur. Current research regarding fatal and nonfatal injuries does not include the accreditation status of the company at which the worker was employed, nor whether certified arborists were on staff. Given the highly skilled nature of the work involved, certification and accreditation might ensure a minimum level of demonstrated safety practices. This study aimed to 1. Determine whether certification and accreditation in the tree care industry are associated with safer workplace behavior, and 2. Identify safety practices that tree workers commonly violate. Tree care companies in southern New England were divided into three categories: accredited, non-accredited with certified arborists on staff, and non-accredited with no certified arborists on staff. A stratified random sample of 63 companies was evaluated in the field by direct observation, assessing workers’ adherence to the industry’s safety standard, the American National Standards for Arboricultural Operations (ANSI Z133.1-2006). Analysis indicated that, overall, accredited companies and those with certified arborists on staff complied with the Z133.1 Standard more than those without. Although these companies were more compliant, few significant differences emerged, and low overall compliance was found for personal protective equipment and chainsaw and chipper safety. There were low levels of compliance across all types of companies with the basic aspects of safety, including feeding the chipper from the curbside, not drop-starting a chainsaw, and using head, eye, and hearing protection. Implications of findings include possible considerations for improvements on accreditation and certification processes. Further findings address aspects of the Z133.1 Safety Standard that are currently unclear.

]]> Julius, Alexandra K. Factors Influencing Increased Sustainable Harvesting and Primary Processing of Massachusetts Native Woods http://scholarworks.umass.edu/theses/815 http://scholarworks.umass.edu/theses/815 Thu, 23 Aug 2012 05:44:32 PDT Forest-related practitioner’s harvest/business expansion decisions are important in that these decisions, although individually made, have a cumulative influence on the overall prosperity of the forest products industry and forest coverage in Massachusetts. This paper explored the decision making process of five stakeholder groups in Massachusetts’ forest products production and distribution chain - landowners, foresters, loggers, sawmills, and wholesalers - aiming to find out what factors or specific possible reasons influence each stakeholder’s harvest/business expansion decisions.

In recent years, Massachusetts has had a shrinking forest products industry despite a healthy forest with growing tree volumes. This has led to a dependence on imports for its local forest products consumption. To solve this problem, Damery, Yadav, & Zhao (2008) surveyed landowners, foresters, loggers, sawmills and wholesalers to identify barriers to expansion of the local forest products industry. This paper takes advantage of the data gathered and conducts further analysis to answer the question: despite the barriers, why do some practitioners still choose to make harvest/business expansion decisions while others do not?

For landowners, foresters, and loggers who have sufficient useful responses, quantitative analysis was conducted through statistical hypothesis testing and econometric modeling to identify causal factors that may lead to the differences. Factors of significance were: 1) years of forestland ownership, 2) Chapter 61 enrollment, and 3) willingness to harvest with neighbors for landowners; 1) practicing years, 2) previous assisted harvest volumes, 3) workmen’s compensation concern, and 4) small-diameter log markets emphasis for foresters; and 1) nature of logging operation (hobby/part-time/full-time), and 2) competition concern for loggers. Due to the small sample size for sawmills and wholesalers, qualitative analysis was conducted through anecdotal analysis to reveal specific possible reasons, rather than generalizable factors, that may explain different choices.

Among all nine factors identified, five of them concerning stakeholder’s attitudes and choices have the potential to be influenced by policy. Programs that can: increase landowner enrollment in Chapter 61, promote cooperation with neighboring landowners, mitigate forester concern with workmen’s compensation, improve markets for small-diameter logs, or improve the competitive landscape for loggers, have the potential to increase production of Massachusetts native woods.

]]> Zhao, Yuxi Population Size, Habitat Use and Diet of Kittlitz's Murrelets in Prince William Sound, Alaska http://scholarworks.umass.edu/theses/749 http://scholarworks.umass.edu/theses/749 Thu, 12 Apr 2012 01:10:17 PDT During the summer of 2008 and 2009, we studied the ecology of the Kittlitz’s Murrelet (Brachyramphus brevirostris), a small diving seabird and candidate for the U.S. Endangered Species List, in Prince William Sound (PWS), Alaska. At-sea survey data suggests that the population significantly increased from 2001 to 2009, however there is limited evidence of reproductive success. Habitat use models showed individuals were observed in shallower waters, closer to glaciers, the shoreline, and further from moraines than the available habitat during the daytime. Finer extent sampling from 2008 suggests temperature-depth profiles also influence Kittlitz’s Murrelet daytime habitat use. The associations between Kittlitz’s Murrelets and water column characteristics are likely an effect of prey availability. Stable isotope work in 2009 suggests birds were generalist foragers prior to the breeding season, becoming more specialized following the breeding season. This specialization may have been a response to strict foraging constraints during the flightless fall molt. Time budgets of radio-tagged individuals suggest birds may have been responding to ephemeral prey concentrations, and working near their maximum energetic limits. Remote monitoring of radio-tagged individuals showed birds left the glacial fjord system during the nighttime, possibly spending these hours near gillnet fishing areas, suggesting a new possible area of concern in evaluating potential threats to Kittlitz’s Murrelet populations.

]]> Allyn, Andrew J. Building Integrated Aquaculture http://scholarworks.umass.edu/theses/741 http://scholarworks.umass.edu/theses/741 Mon, 21 Nov 2011 09:43:42 PST Exploratory research into a fresh concept, building integrated aquaculture, has found new information on the topic. Motives indicating building integrated aquaculture is important for sustainable development were identified. A review of the literature found relatively little in the way of experiments, aquaculture operations, and case studies which documented or demonstrated a deep understanding of the interactions between building and aquaculture systems. A simple experiment was conducted observing thermal energy and moisture interactions in simulated aquaculture facilities, some with tank covers and insulation. Two different retrofit programs were developed in a case study of building integrated aquaculture for an existing structure on the campus of the University of Massachusetts.

]]> Woodin, Erik A. Evaluating the Influence of Disturbance and Climate on Red Spruce (Picea rubens Sarg.) Community Dynamics at its Southern Range Margin http://scholarworks.umass.edu/theses/710 http://scholarworks.umass.edu/theses/710 Mon, 21 Nov 2011 09:34:12 PST Picea rubens(red spruce) populations experienced a synchronous rangewide decline in growth and vigor starting in the 1960’s, which was likely caused by climate change or environmental disturbances (e.g., acid deposition); However, it is yet unknown if populations continue to decline or have recovered. In the context of global warming, red spruce is a species of concern because it is at its southern continuous range margin in Massachusetts. This study uses tree-ring data coupled with population data from permanent plots to quantify the status of red spruce in Massachusetts. Tree cores were extracted from red spruce and used to examine radial growth rates, determine a growth-climate relationship, and document disturbance events. Red spruce at these plots ranged from 90 to 184 years old, and comprised 15 to 29 m2/ha-1 basal area. Over the past 50 years, red spruce has decreased in density, basal area, and relative importance while red maple, yellow birch, and American beech have increased. Red spruce saplings persisted in some plots, but the sapling layer was comprised mostly of American beech or red maple. However, red spruce seedlings were common at red spruce dominant plots indicating that if favorable conditions occur, it could return to its more dominant position in the canopy.

Dendroclimatological analyses show that red spruce is sensitive to both temperature and precipitation. Most sites are correlated with temperature, while only twoforests were correlated to precipitation. The general temperature response of the red spruce studied was positively correlated with winter temperatures while the general precipitation response was negatively correlated with precipitation. Temporal analysis of the climate-growth response indicates that red spruce here have not had a temporally-stable, climate-growth relationship. Prior to 1960, radial growth was positively correlated with temperatures from November of the previous growing season to January of the current year. After 1960, all sites showed a shift in growth responses consistent with increased summer temperature stress; narrowed tree rings were formed during warm temperatures in July and August. Precipitation remained relatively constant over the past century, while temperatures have increased up to 2˚C across the study area. Of the two precipitation-sensitive forests, one forest shifted from being positively correlated with current January precipitation to negatively correlated with previous October precipitation while the second forest showed a strong positive relationship with August precipitation.

Because the radial growth of red spruce here are mostly constrained by temperatures, there has been negative growth response to regional warming and precipitation has been stable, I suggest the change in climate response is potentially due to warming and a physiological threshold response to increasing temperatures. Interestingly, disturbance frequency and intensity have increased over the same time period, which could be either a trigger or a response to the shift in the growth-climate relationship.

]]> Ribbons, Relena R.