• Biology and Management of White Spruce Seed Crops Reforestation in Subarctic Taiga Forests

      Alden, J. (School of Agriculture and Land Resources Management, Agricultural and Forestry Experiment Station, 1985-03)
      Seed production is the most dramatic event in the life cycle of trees and is the first step in forest regeneration. Embryos of white spruce are fragile during germination, and they depend on vigorous seeds for survival and growth. Mortality of white spruce seeds and seedlings is high in northern forests because climate and microhabitat are often unfavorable for seed germination and seedling establishment. Large quantities of high-quality seed are required for natural and artificial regeneration of white spruce forests at high latitudes. The first chapter of this bulletin describes the reproductive process of white spruce and factors that affect cone and seed production and seed quality. Knowledge of the reproduction cycle and factors that affect seed production and quality of white spruce is essential for forecasting and managing seed crops. Evidence that white spruce is a genetically variable species in northern forests is summarized in the second chapter. This chapter includes recommendations for maintaining the gene pool of natural populations and for seed transfer in afforesting sites that do not have endemic populations. A procedure for delineating planting zones for adapted seed sources is described as an alternative for provisional seed zones that only reduce the risk of maladaptation from long-range seed transfer . The final chapter outlines steps in harvesting white spruce seed crops and can be used as a working manual . Practical procedures are described for evaluating quality and quantity of white spruce seed crops , certifying the geographic origin of seed parents , collecting cones , and processing seeds to mainatin viability for many years. The genetic structure of white spruce and the environment-embryology relationships that effect seed production and maturation have not been studied in detail . The need for research in the areas of genetics, biochemistry, physiology, and ecology is discussed in each chapter. The results of such research will help to improve seed yields and make the management of white spruce crops more profitable in Alaska and Yukon.
    • Developing Stable Isotope Biomarkers Of Yup'ik Traditional And Market Foods To Detect Associations With Chronic Disease Risk

      Nash, Sarah H.; O'Brien, Diane; Bersamin, Andrea; Boher, Bert; Kristal, Alan (2013)
      This dissertation addresses the need for valid measures of dietary intake for use in studies of chronic disease risk in the Yup'ik population of Southwest Alaska. The Yup'ik people have experienced dietary changes over the past century, as consumption of traditional foods has been increasingly supplemented or replaced by market-purchased foods. Determining whether this dietary change is associated with increases in chronic disease risk is important for making nutritional recommendations for disease prevention. However, monitoring dietary change is challenging, in part due to the limitations of self-reported methods of dietary assessment. Dietary biomarkers are promising alternatives to self-reported methods, because they can provide unbiased, reliable estimates of intake. In this dissertation, I present evidence towards the validation of stable isotope dietary biomarkers. Stable isotope ratios vary among foods that are important in Yup'ik diets, and are incorporated into tissues, including several commonly collected biological sample types. They are simple, inexpensive and reliable measures that would be powerful tools for dietary assessment if they could be validated as biomarkers of certain foods. This work was conducted with two Yup'ik study populations that participated in studies conducted by the Center for Alaska Native Health Research. I begin by showing that the nitrogen isotope ratio is a marker of the marine component of traditional food intake, and the carbon isotope ratio is a marker of market food intake. I then calibrate a model of sugar intake based on both the carbon and nitrogen isotope ratios. I focus specifically on sugars because intake of sugary foods and beverages has been linked to obesity-related disease risk in other US populations. Finally, I use this dual isotope model to assess associations of sugar intake with chronic disease risk factors. I find that sugar intake is associated with blood pressure, blood lipids, leptin and adiponectin, suggesting a potential adverse effect of sugar intake on Yup'ik health. The findings of this dissertation provide substantial evidence to support carbon and nitrogen isotope ratios as markers of Yup'ik dietary intake, and demonstrate their potential to be informative in studies of associations between dietary intake and the health of Yup'ik people.
    • Nutrient And Contaminant Dynamics In The Marine Food Web Of Kotzebue Sound (Alaska)

      Moses, Sara K.; O'Hara, Todd (2010)
      The objectives of these studies were to document nutrient and contaminant concentrations in upper trophic level organisms of the Kotzeue, Alaska marine food web; address associated risks and benefits to human consumers of these species; understand the drivers of nutrient and contaminant patterns and concentrations; and test the limitations of chemical feeding ecology tools used to trace nutrient and contaminant pathways within this food web. Tissues of subsistence harvested animals were analyzed for nutrients, contaminants and stable isotopes (delta13C and delta15N). Foods derived from sheefish (Stenodus leucicthys) and spotted seal (Phoca largha) provide numerous essential nutrients, with limited risk from contaminant exposure. Food processing altered nutrient and contaminant concentrations and stable isotope ratios, warranting the evaluation of foods as they are ultimately consumed when determining the risks and benefits of traditional diets. delta13C and delta15N, common chemical tracers of feeding ecology and contaminant pathways in food webs, varied widely by tissue type. delta15N and mercury did not differ consistently among seal tissues. Consequently, when utilizing stable isotopes as tracers of feeding ecology and mercury exposure, the specific tissue consumed and the processed state of the tissue should be considered. Bioaccumulation patterns differed between sheefish and spotted seals in relation to their respiratory physiology and persistent organic pollutant (POP) partitioning behavior between lipids and the respiratory medium (i.e., air versus water). Certain POPs that do not bioaccumulate in fish due to rapid excretion across the gills into surrounding waters (low KOW) do bioaccumulate in seals if not efficiently eliminated via the lungs to the air (high K OA). Thus, KOW alone cannot predict bioaccumulation in mammals. Regulatory guidelines must incorporate KOA into chemical risk-assessments for air-breathing species, including humans and marine mammals. Ringed ( Phoca hispida), spotted and bearded (Erignathus barbatus ) seals had distinct blubber fatty acid (FA) signatures. Blubber of ringed and spotted seals exhibited significant stratification relative to both FA degree of unsaturation and carbon chain length. FA stratification appears largely driven by the steep temperature gradient of blubber, except in the case of polyunsaturated FA (PUFA) which may be maintained in the inner blubber for rapid mobilization to meet physiological requirements.
    • The Foraging Behavior, Habitat Use, And Diet Of Arctic Foxes (Alopex Lagopus) In A Goose Nesting Area Near Kokechik Bay, Alaska

      Stickney, Alice Allgood; Murphy, Edward C. (1989)
      The foraging behavior, habitat use, and diet of arctic foxes were observed in a goose nesting area near Kokechik Bay, Alaska during the summers of 1985 and 1986. The foraging patterns of arctic foxes changed after birds started nesting in the study area, adding an abundant egg resource to a previously limited prey base. The duration of search bouts decreased and success rate increased, yielding an increased prey capture rate. Over 80% of the eggs taken by foxes during the nesting stage were cached, rather than eaten immediately. Differences in search patterns among foxes were probably related to the different prey available within the range of each fox. Egg caches extended fox access to a temporally clumped resource, and increased the impact of foxes on the nesting success of geese. Eggs were the primary prey of foxes during the nesting stage in both years, regardless of variations in microtine abundance. <p>