Snow Avalanche Disturbance in Intermountain Spruce-Fir Forests and Implications for the Spruce Bark Beetle (Coleoptera: Scolytidae)

Spruce beetle outbreaks are the primary biotic disturbance affecting forests in the Intermountain spruce-fir zone. Major snow avalanches can produce large quantities of host material for spruce beetle colonization; however, few studies have examined the influence of avalanche disturbance on outbreak initiation. The purpose of my research was to investigate potential relationships between these two disturbance agents. In the first study, I used dendro-ecological analyses to date major avalanche years on the Wasatch Plateau in south-central Utah, and then determined what climate factors were associated with avalanche occurrence. The results indicated that mean January snowfall was significantly related to the probability of major avalanche years, although model correlations were extremely low. Potential dating errors, the lack of complete historical climate data, and the absence of snow pack information may have prohibited obtaining higher model correlations. In the second study, I investigated how the seasonal availability of host material al influenced spruce beetle brood production. I found that significantly fewer mean numbers of spruce beetles were produced in downed spruce felled during August 1997 than from trees felled in April of 1998. More brood adults also were present in, or emerged from the bottom surfaces of sample trees than either unexposed (North, East) or exposed (South, West) bole aspects. These results provided evidence that with greater potential for spruce beetle populations to build in host material produced in the spring, snow avalanche disturbance could contribute to the risk of outbreaks. I constructed snow avalanche and spruce beetle outbreak chronologies from historic documents in the third study, and used classification tree analysis to predict historic spruce beetle outbreaks from major avalanche years and historic climate data. Major snow avalanche years were not identified in this analysis as important for the occurrence of spruce beetle outbreaks. Historic spruce beetle outbreaks, however, were significantly related to generally warm fall and winter temperatures and to drought. These results indicate that climate and other factor not considered in this analysis have a greater influence on spruce beetle epidemiology than the production of host material by snow avalanches

Associations of Armillaria Root Disease in Jack Pine with \u3ci\u3eArceuthobium Americanum\u3c/i\u3e

Relationships between jack pine dwarf mistletoe (Arceuthobium americanum Nutt. ex Engelm.) and Armillaria root disease (Armillaria ostoyae (Romagn.) Herink) were examined to determine how these two disease agents contribute to jack pine (Pinus banksiana Lamb.) decline and mortality in the Belair Provincial Forest, Manitoba, Canada. The incidence and extent of Armillaria root disease was strongly related to tree vigor. Dwarf mistletoe infection did not affect either the incidence of Armillaria or the mean percentage of root system colonization within vigorous, declining, and dead classes of trees. However, field observations and other analyses indicate that dwarf mistletoe was primary responsible for jack pine decline and mortality. In dwarf mistletoe mortality centers, Armillaria appeared to act opportunistically, extensively colonizing only the stressed trees. Analysis of distributions of percent Armillaria colonization revealed that rapid root system colonization occurred just prior to, or at the time of tree death

Influence of Fallen Tree Timing on Spruce Beetle Brood Production

This study compared brood production of the spruce beetle (Dendroctonus rufipennis Kirby [Coleoptera: Curculionidae, Scolytinae]) in downed host material felled during summer and spring seasons on the Wasatch Plateau in south central Utah. Thirty-three matched pairs of Engelmann spruce (Picea engelmannii Parry ex Engelm.) trees were selected for study in spring 1996. One tree of each pair was cut during August 1996 (summer-felled), and the other tree was cut in early April 1997 (spring-felled), so that trees would be colonized by spruce beetles of the same flight period. Brood adults were collected and counted from bark samples, which were removed from the top, bottom, and sides of all sample trees in October 1998. The number of emergent adults produced in June 1999 was determined from exit holes counted in bark samples removed from these same locations. Mixed-model procedures were used to compare differences in the mean number of adults produced in summer-felled versus spring-felled trees in each year. The results indicated that significantly fewer spruce beetles were produced in summer-felled trees than in spring-felled trees. More brood adults were also present in, or emerged from, unexposed bole aspects (bottom, north, and east) of sample trees than exposed aspects (top, south, and west). These findings suggest that disturbances providing spruce beetles with an abundance of fresh host material in the spring result in the greatest potential for spruce beetle production, particularly beneath unexposed bark aspects. Examples of such disturbances include snow avalanches, blowdown, and snow and ice damage

Disturbance Agents and Their Associated Effects on the Health of Interior Douglas-Fir Forests in the Central Rocky Mountains

Interior Douglas-fir is a prevalent forest type throughout the central Rocky Mountains. Past management actions, specifically fire suppression, have led to an expansion of this forest type. Although Douglas-fir forests cover a broad geographic range, few studies have described the interactive effects of various disturbance agents on forest health conditions. In this paper, we review pertinent literature describing the roles, linkages, and mechanisms by which disturbances, including insect outbreaks, pathogens, fire, and other abiotic factors, affect the development, structure, and distribution of interior montane forests primarily comprised of Douglas-fir. We also discuss how these effects may influence important resource values such as water, biodiversity, wildlife habitat, timber, and recreation. Finally, we identify gaps where further research may increase our understanding of these disturbance agents, their interacting roles, and how they influence long-term forest health

Employing Older Workers: Strategies for Recruitment and Retention

The United States and Utah are currently undergoing the most dramatic demographic shift in recorded history. By the year 2020, the number of people 65+ is expected to double. This explosive age growth will impact every aspect of American society. Utah is also expected to experience an increase in its' aging population. By the year 2020, Utah's 65+ population is expected to double. With increasing costs of living, medical care and housing, many seniors will have to maintain or seek employment to meet their financial obligations. Currently, older workers are not accepted in the workforce. As employers find it more difficult to fill positions and the numbers of older adult's increases, it will become commonplace to find older workers being used in the workforce even though current stereotypes present many obstacles. Many employers do not understand the employee potential of the older worker cohort. The purpose of this master's project was to create an educational presentation about older workers that could be given to Wasatch Front employers by members of the Wasatch Front South Older Workers Advisory Council, as well as others around the state of Utah. The presentation provides employer's information on local and national aging demographics, older adults and their strengths and weaknesses, and how to recruit, hire, train and manage this older cohort. Twenty-six slides are provided to guide the presentation along with a brief description of the major points related to each slide. In addition to the presentation materials, is an annotated bibliography of six useful literature sources

Snow Avalanche Disturbance in Intermountain Spruce-fir Forests and Implications for the Spruce Bark Beetle (Coleoptera : Scolytidae)

Spruce beetle outbreaks are the primary biotic disturbance affecting forests in the Intermountain spruce-fir zone. Major snow avalanches can produce large quantities of host material for spruce beetle colonization; however, few studies have examined the influence of avalanche disturbance on outbreak initiation. The purpose of my research was to investigate potential relationships between these two disturbance agents. In the first study, I used dendro-ecological analyses to date major avalanche years on the Wasatch Plateau in south-central Utah, and then determined what climate factors were associated with avalanche occurrence. The results indicated that mean January snowfall was significantly related to the probability of major avalanche years, although model correlations were extremely low. Potential dating errors, the lack of complete historical climate data, and the absence of snow pack information may have prohibited obtaining high model correlations. In the second study, Investigated how the seasonal availability of host material influenced spruce beetle brood production. I found that significantly fewer mean numbers of spruce beetles were produced in downed spruce felled during August 1997 than from trees felled in April of 1998. More brood adults also were present in, or emerged from the bottom surfaces of sample trees than either unexposed (North, East) or exposed (South, West) bole aspects. These results provided evidence that with greater potential for spruce beetle populations to build in host material produced in the host material produced in the spring, snow avalanche disturbance could contribute to the risk of outbreaks. I constructed snow avalanche and spruce beetle outbreak chronologies from historic documents in the third study, and used classification tree analysis to predict historic spruce beetle outbreaks form manor avalanche years and historic climate data. Major snow avalanche years were not identified in this analysis as important for the occurrence of spruce beetle outbreaks. Historic spruce beetle outbreaks, however, were significantly related to generally warm fall and winter temperatures and the drought. There results indicate that climate and other factors not considered in this analysis have a greater influence on spruce beetle epidemiology than the production of host material by snow avalanches