• Landscape Control Of Thunderstorm Development In Interior Alaska

      Dissing, Dorte; Verbyla, David (2003)
      General Circulation Models suggest a future climate of warmer and possibly drier summers in the boreal forest region, which could change fire regimes in high latitudes. Thunderstorm development is a dominant factor in the continental boreal forest fire regime, through its influence as a fire starting mechanism. Global Climate Change research has identified the land-atmosphere interface as a vital area of a needed research in order to improve our predictions of climate change. This dissertation has focused on the development of thunderstorms and lightning strike activity in a boreal forest region in Interior Alaska and on how the underlying surface can influence their development. I have examined the distributions and correlations between lightning strikes, thunderclouds, thunderstorm indices (CAPE and LI), elevation, and vegetation variables in Alaska. The relationships were examined at scales ranging from the Interior region of the state to individual wildfire burn scars, and at temporal scales ranging from the annual to daily. The objective is to understand the influential factors and processes responsible for thunderstorm development in Alaska, such that we may produce well-founded predictions on future thunderstorm regimes caused by a changing climate. The scale-related studies of this dissertation show that both processes and important variables for development of thunderstorms and lightning activity vary within and between the scales. It appears that on the larger scales, the combined effects of boreal forest and elevation on increased lightning strike activity were more prevalent than at the smallest scale (local). When the scale gets too small for the boundary layer to be affected (<10km), land surface effects on lightning cannot be. My results suggest that the underlying surface (in the form of areal forest coverage and vegetation) has more of an influence on convective development on days with airmass storms than on days with synoptic storms.
    • The Treeline Ecotone In Interior Alaska: From Theory To Planning And The Ecology In Between

      Wilmking, Martin; Juday, Glenn Patrick (2003)
      Treelines have been the focus of intense research for nearly a hundred years, also because they represent one of the most visible boundaries between two ecological systems. In recent years however, treelines have been studied, because changes in forest ecosystems due to global change, e.g. treeline movement, are expected to manifest first in these areas. This dissertation focuses on the elevational and latitudinal treelines bordering the boreal forest of interior Alaska. After development of a conceptional model of ecotones as three-dimensional spaces between ecosystems, we offer a historical perspective on treeline research and its broader impact in the Brooks Range, Alaska. Dendrochronological analysis of >1500 white spruce (Picea glauca (Moench [Voss])) at 13 treeline sites in Alaska revealed both positive and negative growth responses to climate warming, challenging the widespread assumption that northern treeline trees grow better with warming climate. Hot Julys decreased growth of ~40% of white spruce at treeline in Alaska, whereas warm springs enhanced growth of others. Growth increases and decreases appear at temperature thresholds, which have occurred more frequently in the late 20th century. Based on these relationships between tree-growth and climate as well as using landscape characteristics, we modeled future tree-growth and distribution in two National Parks in Alaska and extrapolated the results into the 21 st century using climate scenarios from five General Circulation Models. In Gates of the Arctic National Park, our results indicate enhanced growth at low elevation, whereas other areas will see changes in forest structure (dieback of tree-islands, infilling of existing stands). In Denali National Park, our results indicate possible dieback of white spruce at low elevations and treeline advance and infilling at high elevations. This will affect the road corridor with a forest increase of about 50% along the road, which will decrease the possibility for wildlife viewing. Surprisingly, aspect did not affect tree growth-climate relationships. Without accounting for opposite growth responses under warming conditions, temperature thresholds, as well as meso-scale changes in forest distribution, climate reconstructions based on ring-width will miscalibrate past climate, and biogeochemical and dynamic vegetation models will overestimate carbon uptake and treeline advance under future warming scenarios.
    • Mechanisms Involved In The Cold Tolerant Trichoderma Atroviride Biocontrol

      Cheng, Mingyuan; McBeath, Jenifer H. (2004)
      Trichoderma atroviride is a cold tolerant fungus that parasitizes a wide range of plant pathogenic fungi. The mechanisms involved in biocontrol by T. atroviride are only partially understood. This research evaluated the effect of four different groups of plant pathogenic fungi (Botrytis cinerea, Phytophthora capsici, Rhizoctonia solani and Sclerotinia sclerotiorum) on enzyme expression at 22�C and 7�C. The enzymes expressed (proteinase and endo-beta-1,3-glucanase) were purified and characterized, and three 73 kDa N-acetyl-beta- D-glucosaminidase genes from three different T. atroviride biotypes were sequenced. The R-1,6-glucanase profiles and the regulation of N-acetyl-beta-D-glucosaminidases by plant pathogenic fungi were also studied. I document the production of N-acetyl-beta-D-glucosaminidase, exochitinase, endochitinase, beta-1,3-glucanase, beta-1,6-glucanase and proteinase by T. atroviride at room temperature. The timing of enzyme expression was pathogen dependent. A high concentration of glucose repressed the expression of glucanases, but had no effect on the expression of N-acetyl-beta-D-glucosaminidase. At 7�C, T. atroviride produced the same enzymes as at room temperature except beta-1,6-glucanase. The total activities of the chitinases increased over a 30 day incubation period while the expression of glucanases and proteinase depended on the inducer. A new 18.8 kDa serine proteinase and a new 77 kDa endo-beta-1,3-glucanase were purified to electrophoretical homogeneity. These two purified enzymes showed strong antifungal activity by inhibiting conidial germination of Botrytis cinerea. Three 73 kDa N-acetyl-beta-D-glucosaminidase genes were sequenced from T. atroviride biotypes 861, 453 and 603. Gene sequences of the enzyme from the T. atroviride biotypes are different from the published gene sequence of T. harzianum . This indicates that the N-acetyl-beta-D-glucosaminidase sequence can be used to differentiate the species and isolates of Trichoderma. The expression of beta-1,6-glucanase is complex and at least three different sizes of beta-1,6-glucanase were detected from T. atroviride. The expression of beta-1,6-glucanase varied with carbon source and pH. Mycelia of plant pathogen regulated the expression of N-acetyl-beta-D-glucosaminidase. Two different sizes of N-acetyl-beta-D-glucosaminidase were detected when T. atroviride was grown with S. sclerotiorum and its filtrates. Only one N-acetyl-beta- D-glucosaminidase was detected with other pathogens, autoclaved mycelia or glucose. The expression of a 73 kDa N-acetyl-beta-D-glucosaminidase was contact-dependent and regulated by an extracellular factor.
    • Carbon Cycling In Three Mature Black Spruce ( Picea Mariana [Mill.] B.S.P.) Forests In Interior Alaska

      Vogel, Jason Gene; Valentine, David (2004)
      Climate warming in high latitudes is expected to alter the carbon cycle of the boreal forest. Warming will likely increase the rate of organic matter decomposition and microbial respiration. Faster organic matter decomposition should increase plant available nutrients and stimulate plant growth. I examined these predicted relationships between C cycle components in three similar black spruce forests (Picea mariana [Mill] B.S.P) near Fairbanks, Alaska, that differed in soil environment and in-situ decomposition. As predicted, greater in-situ decomposition rates corresponded to greater microbial respiration and black spruce aboveground growth. However root and soil respiration were both greater at the site where decomposition was slowest, indicating greater C allocation to root processes with slower decomposition. It is unclear what environmental factor controls spruce allocation. Low temperature or moisture could cause spruce to increase belowground allocation because slower decomposition leads to low N availability, but foliar N concentration was similar across sites and root N concentration greater at the slow decomposition site. The foliar isotopic composition of 13C indicated soil moisture was lower at the site with greater root and soil respiration. From a literature review of mature black spruce forests, it appears drier (e.g. Alaska) regions of the boreal forest have greater soil respiration because of greater black spruce C allocation belowground. Organic matter characteristics identified with pyrolysis gas chromatography-mass spectrometry correlated with microbial processes, but organic matter chemistry less influenced C and N mineralization than did temperature. Also, differences among sites in C and net N mineralization rates were few and difficult to explain from soil characteristics. Warming had a greater influence on C and N mineralization than the mediatory effect of soil organic matter chemistry. In this study, spruce root C allocation varied more among the three stands than other ecosystem components of C cycling. Spruce root growth most affected the annual C balance by controlling forest floor C accumulation, which was remarkably sensitive to root severing. Predicting the response of black spruce to climate change will require an understanding of how spruce C allocation responds to available moisture and soil temperature.
    • An investigation of soil-plant and plant-animal mineral nutrition landscapes of agricultural areas in the Fairbanks and Delta Junction regions of Interior Alaska

      Andrews, Robin N. (2004-05)
      I attempted to identify biologically limiting minerals and assess mineral variability by collecting soil and plant samples in June, July, and August from 14 bromegrass fields and adjacent woodlands, in the Fairbanks and Delta Junction regions. Soil extractable P, K, Ca, Mg, Al, B, Cd, Co, Cr, Cu, Fe, Mn, Pb, Zn, NO⁻³ and NH⁴ as well as pH and organic matter content were measured at three depths. Bromus inermis, Calamagrostis canadensis, Epilobium angustifolium and Salix alaxensis were analyzed for N, P, K, S, Ca, Mg, Al, B, Cd, Cu, Fe, Mn, and Zn. Plant sample variability was assessed by species, date, and location. Mineral content of plants and soils among locations was highly variable with proximate sites showing little similarity. Local differences seemed more important than regional variation in determining soil and plant mineral abundances. Plant mineral content was highly affected by species, date, and location. With the exception of magnesium, plant mineral content was generally not correlated with extractable soil minerals. In most cases, organic matter content and pH were generally not correlated with plant mineral content. Plants, in these regions, may be limited by sulfur, magnesium, and boron availability. High levels of manganese and cadmium in some plant species and low levels of copper and possibly zinc in late season forages may negatively affect herbivores.
    • Growth and Yield of Black Spruce, Picea mariana (Mill.) B.S.Pl., in Alaska

      Rosner, Carolyn; Packee, Edmond; Ping, Chien-Lu; Maich, John C. (University of Alaska Fairbanks, School of Natural Resources and Agricultural Sciences, 2004-08)
      Black spruce, Picea mariana (Mill.) B.S.P., is largely overlooked in Alaska because of its small size and slow growth. Growth and yield information is therefore limited or nonexistent. Presented here are the first polymorphic site index (height-age) curves and height-diameter functions for predicting height and volume for Alaska black spruce. Models are accurate for trees up to 50 feet in height and 8 inches DBH. Predicted stem volumes range from 0.006 ft3 to 21.8 ft3 for trees between 0.5 and 11.5 inches DBH Sampled tree dimensions range from 5.5 to 78.0 feet tall and from 0.4 to 11.0 inches DBH. Sampled breast-height ages range from 49 to 257 years; average age-to-breast-height is 26 years. This research, although limited, also characterizes general stand-level structure and community composition for Alaska black spruce. 60 Permanent Sample Plots (PSPs) representing 20 stands were established throughout the Tanana Valley, with stand inventory conducted according to a consistent protocol. Stand densities range from 137 to 2,907 trees per acre; stand volumes ranged from 8 to 2,507 ft3 per acre. Stand density index values range from 6 to 453. Periodic remeasurement of PSPs will yield valuable information about stand evolution and community type change.
    • Remote sensing of burn severity and the interactions between burn severity, topography and vegetation in interior Alaska

      Epting, Justin Frederick (2004-08)
      A variety of single-band, band ratio, vegetation index, and multivariate algorithms were evaluated for mapping burn severity using Landsat TM and ETM+ imagery across four burns in interior Alaska. The Normalized Burn Ratio (NBR) outperformed all algorithms, both when tested as a single post-fire value and when tested as a differenced (prefire-postfire) value. The NBR was then used to map burn severity at a historical burn near Yukon-Charley Rivers National Preserve and a time-series of images from 1986 to 2002 was analyzed to investigate interactions between vegetation, burn severity, and topography. Strong interactions existed between vegetation and burn severity, but the only topographic variable that had a significant relationship with burn severity was elevation, presumably due to the strong control of elevation on vegetation type. The highest burn severity occurred in spruce forest, while the lowest occurred in broadleaf forest. Areas with high burn severity experienced disproportionately more shifts toward spruce woodland and shrub classes, while areas with low to moderate severity were less likely to change vegetation type. Finally, vegetation recovery, estimated using a remotely-sensed vegetation index, peaked between 8-14 years post-fire, and recovery was highest for areas with the highest burn severity.
    • A market survey of ecotourists in the Valdivian temperate forest ecoregion of Chile

      Harris, Scott (2004-12)
      A survey of ecotourists in the Valdivian Temperate Forests ecoregion of southern Chile is used to determine if the experience and activity preferences of the market match what is being developed at local community-based ecotourism projects. It also compares the motivations of the same market with the motivations outlined in the definition of ecotourism. Survey design was based on a literature review, and observations and key-informant interviews collected in the study area. Ecotourists show strong preferences for the types of accommodations and experiences that exist or are being developed at ecotourism project sites: hostels, camping, low-intensity nature-based activities, pristine environments, and simple marketing schemes. However, market demand for guide services may not meet expectations. Survey respondents who support ecotourism goals fall into a tightly defined cluster, the majority of whom are Chilean. Proponents of ecotourism development in this area have expectations that generally conform to the guidelines presented in the case study literature, and ecotourism can complement the improving, but currently weak, political capacity for conserving native forest biodiversity in this region.
    • Soil properties and forest stand characteristics along a toposequence of the Smith Lake area near Fairbanks, Alaska

      Zhu, Lijie (2004-12)
      Forests, soils and their relationships were studied along a toposequence over an elevation range from 161 meters to 213 meters near Smith Lake on the University of Alaska Fairbanks campus, Fairbanks, Alaska. Forest cover type and understory species composition change along the slope from top to bottom and are related to temperature and moisture. Aspen occurs on the ridge top. Paper birch grows best on the shoulder. White spruce, which has the greatest commercial value, is the only species present on all slope positions; it grows best on shoulder and back slopes. Black spruce dominates on the wet and cold top slope that has a thick organic layer. Organic horizon depth increases, whereas rooting depth decreases, along the toposequence from the shoulder slope to the top slope. Soil textures are mainly silt loam and fine sandy loam with slightly acidic reactions in the surface mineral horizons to calcareous reactions in subsoils. Organic carbon is concentrated in the surface organic horizons and the surface mineral horizons and decreases drastically in the subsurface horizons. This thesis was an exploratory effort; although soil properties along the Smith Lake toposequence cannot be used as quantitative predictors of forest productivity, the qualitative results provide a basis for matching species to site.
    • Distribution and ecology of exotic plants in Wrangell-St. Elias National Park and Preserve, Alaska

      McKee, Paul Christian (2004-12)
      The distribution of exotic plants and site factors influencing their abundance on roads and trails were studied in Wrangell-St. Elias National Park and Preserve during the summer of 2003. Seventeen species of exotic plants were found in the park at 173 locations. The most common species (Taraxacum officinale, Plantago major) were present at all study sites, while some (Trifolium spp., Bromus inermis, Leucanthemum vulgare) were restricted to specific disturbance types and particular areas. Though sampling was limited to areas in which exotic plants were growing, percent cover of exotics was not a significant component of sample sites, and exotic species richness was low at all sampling locations at 1.42 species per m². Data were analyzed using ordination and multiple regression to determine variables most responsible in explaining variation in exotic plant communities. Statistically significant site variables correlated with percent cover of exotics included percent cover of vascular native plants, percent cover litter, and percent bare soil at most study sites. The importance of these variables indicates that the presence of exotic plants in Wrangell-St. Elias is closely linked to disturbance, and that the invasion of exotic plants is in the initial phases.
    • Production and quality of spring sap from Alaskan birch (Betula neoalaskana sargent) in Interior Alaska

      Maher, Kimberley Anne Camille (2005-05)
      Little is known about the specifics of spring sap production in Alaskan birch Betula neoalaskana Sargent. With an emerging industry in Alaska based on the harvest of birch sap, additional information is needed. This thesis is an exploratory study that investigates the production of sap during the 2002 and 2003 spring seasons in the Fairbanks region and characterizes the dissolved solid components of the sap harvested in 2003. April 2002 and 2003 had strongly contrasting weather patterns which affected sap yields. In general, trees yielded more sap in the wet, cool spring of 2002 than the dry, warm spring of 2003. Larger diameter trees yielded more sap in both years, and this correlation was stronger during the dry, warm spring. Stand location on the hillside and indicator species were also related to sap yield. Carbohydrate content of birch sap is mostly glucose (44%) and fructose (40.3-54.6%); sucrose and galactose are also present. The relative concentration of carbohydrates varied throughout the sap season. Macronutrients (Ca, K, and Mg) and micronutrients (Mn, Fe, Al, Na, Zn and Cu) are present in the sap; their concentrations increase throughout the season.
    • Using GIS-based and remotely sensed data for early winter moose (Alces alces gigas) survey stratification

      Clyde, Karen J. (2005-05)
      Stratification of moose survey areas is a key step to reduce population estimation variance. In the Yukon and Alaska, use of fixed-area grids for early winter moose counts combined with the increasing availability of GIS and remotely sensed data provide the opportunity to develop standardized and repeatable habitat-based stratifications. I used univariate comparisons, stepwise regression and AIC modeling to describe moose distribution as a function of landscape level variables for an area in west central Yukon during 1998 and 1999. Results quantified early winter habitat use of upland shrub habitats and support previous observations for early winter moose habitat use in Alaska, Minnesota and Montana. Number of patches, in association with areas of alpine and shrubs, were found to be highly influential for survey blocks where moose are expected to be present and in high numbers. Overall, model performance based on relative abundance of moose was less predictive than for blocks where moose were present or absent. Spatial resolution of GIS and remotely sensed data used in this study (25 m grid cells) provided sufficient spatial detail to generate correlations between moose presence and habitat for a first level stratification.
    • Aspen coppice with coarse woody debris: a silvicultural system for interior Alaska moose browse production

      Nichols, Todd F. (2005-05)
      Browse production and use by moose (Alces alces gigas) in interior Alaska was investigated in 4 and 2-year-old quaking aspen (Populus tremuloides) coppice stands following clear-felling without removal of the mature aspen stems. Moose winter browse utilization, as related to distance from cover, coarse woody debris (CWD), and browse species composition, was quantified. Aspen terminal leaders were sampled to relate current annual growth (CAG) dry biomass (g) to leader diameter (mm). Stem density, current annual browse production, and browse use were estimated. Browse use was determined as 1) proportion of aspen stems browsed (stand scale), 2) proportion of browsed leaders per stem (stem scale), and 3) diameter-at-point-of-browsing (leader scale). Aspen sucker density ranged from 23,000-43,000 stems/ha. Terminal leader diameter was found to be a good estimator of individual stem CAG biomass. CWD did not impede moose utilization of stems. Browse use declined from mature stand edge to center (100 m). Beyond 15 m from mature stand edge browse use was low compared to that within 15 m of the stand edge. Clear-felling without removal of stems is a viable silvicultural method to reinitiate seral aspen in lieu of prescribed fire or mechanical treatments on south-facing hillsides.
    • Fire in boreal black spruce (Picea mariana mill.) forests: respiration, temperature sensitivity, and bioavailability of soil organic matter

      Masco, Sarah (2005-05)
      Boreal forests store large quantities of carbon (C) and currently act as atmospheric C sinks; however, predicted increases in temperature and fire frequency may change the boreal forest from a net C sink to a net source. This study evaluates the response of organic soil C and nitrogen (N) mineralization, and the bioavailability of C and N to burning in non-permafrost upland black spruce stands in Interior Alaska. Two years after an experimental wildfire, burned soils were warmer than control soils at all depths measured, and decay of common substrates was greater in the burned than in the control soils. Burned soils had higher concentrations of total C, lignin, N, and mineral N, and lower concentrations of dissolved organic carbon (DOC) and soluble organic matter. However, apparent differences in organic matter quality did not correlate well with respiration metrics. In laboratory incubations, burned soils respired less than control soils, and this difference was entirely due to differences on the first day of the incubation. Mean Q₁₀ values ranged from 2.1 to 2.5 and were greater in the burned soils than in the control soils.
    • Developing fuel models for the Anchorage wildland-urban interface using a forest inventory

      Cheyette, Daniel Louis (2005-05)
      I inventoried the forests of the Anchorage wildland-urban interface and created a hierarchical classification of twenty forest types differentiated according to tree species, tree and basal area densities and degree of spruce bark beetle mortality. The inventory included the data necessary to parameterize NEXUS - a fire behavior model that integrates surface and crown fire initiation and spread algorithms. The twenty inventory forest types consolidated into eight custom fuel models and canopy attribute sets that correspond to the cover types identified by the Anchorage Wildfire Partnership. I assessed the models using NEXUS and completed a sensitivity analysis that identified the most influential model parameters and the forest attributes that managers should prioritize in future mitigation efforts. Results indicate that needleleaf low-density forests pose the largest hazard due to large 1-hour fuel loads and fuelbed depths, low crown-base-heights and high crown bulk-densities. Stands infested by the spruce bark beetle also pose a serious hazard due to the ecological/physiological changes that promote the growth of Calamagrostis canadensis, a flash fuel that dries quickly and readily burns. The forest inventory, fire behavior predictions and sensitivity analysis demonstrate that parts of Anchorage's wildland-urban interface are at risk under extreme weather and topographic conditions.
    • Using remote sensing to examine changes of closed-basin surface water area in Interior Alaska from 1950-2002

      Riordan, Brian Alan (2005-05)
      Over the past fifty years Alaska has experienced an increase in mean annual temperature. This warming may be causing significant changes in hydrology and permafrost dynamics. In recent decades, Native Americans and land managers have reported losses of water bodies and surface water area in interior Alaska. We conducted a study to determine the degree to which these informal observations were representative of a regional trend in surface water area loss. This study examines closed-basin water bodies in nine regions across Alaska: 1) Copper River Basin, 2) Talkeetna, 3) Tetlin National Wildlife Refuge, 4) Denali National Park, 5) Innoko Flats National Wildlife Refuge, 6) Minto Flats State Game Refuge, 7) Stevens Village, 8) Yukon Flats National Wildlife Refuge, and 9) Prudhoe Bay/Arctic Coastal Plain. The study included approximately 850,000 hectares and over 40,000 water bodies. To conduct such a large-scale study, GIS and Remote Sensing techniques were applied. Water body change detection was conducted over a fifty-year time period. A minimum of three time periods were used for each area. Imagery included black and white aerial photography (1950 -1957), color infrared aerial photography (1978 -1982), Landsat TM (1986 - 1995), and Landsat ETM+ (1999 - 2002). Based on these images, water body polygons were digitized for each time period. Area was calculated for each polygon and compared to corresponding ponds from images at later times. Of the nine regions, six showed substantial reductions in surface water area: Copper River Basin, Minto Flats, Innoko Flats, Yukon Flats, Stevens Village, and Denali National Park. The Innoko Flats and Copper River Basin regions showed the most loss at 31% and 28% respectively. There are several mechanisms possible for reductions of surface water in a warming climate including increased formation of taliks, increased soil water holding capacity, increased evapotranspiration, and terrestrialization.
    • Quantifying upland boreal forest successional pathways near Fairbanks, Alaska

      Kurkowski, Thomas Andrew (2005-08)
      Previous studies have suggested that post-fire forest succession in Interior Alaska can occur in two different ways. Self-replacement occurs when pre-fire dominant species immediately replace themselves as the canopy dominants after fire. Species-dominance relay occurs when, after simultaneously establishing themselves after fire, deciduous trees relinquish canopy dominance to conifer species as the stand ages. The relative importance of these different successional processes at landscape scales in Interior Alaska is unknown. To test for the importance of these two trajectories, we built a multinomial logistic regression model explaining the relationship between classified vegetation type and topographic variables. We also determined the relative occurrence of species-dominance relay by comparing aged stands to known successional patterns. The model correctly predicted 78% of spruce distribution, and the majority of stands are not following the species-dominance relay pattern, implying that most of the study area appears to be following a self-replacement trajectory with only a small proportion of sites capable of supporting both deciduous and spruce species. These results have important implications for modeling forest succession in Interior Alaska because of the importance of these dynamics in determining the fire regime, carbon storage, and global warming scenarios.
    • The potential of lodgepole pine in Alaska

      Cushing, Alina (2005-08)
      The introduction of non-native trees should be informed by various perspectives. In the case of forestry in high-latitude regions, managers face the challenge of finding cold-hardy species adequately adapted to harsh climatic environments; Lodgepole pine (Pinus contorta Dougl. Ex. Loud.) has been introduced to three regions at or above its natural northern latitudinal extent; Alaska, Iceland, and northern Sweden. Analysis of interviews in each region revealed the structure of common arguments, including underlying assumptions and perceptions of the natural world. Results of a mail-out-survey to the Alaskan public indicate that a considerable portion of the public is concerned about the possibility for adverse ecological effects on the native ecosystem. However, acceptance of non-native trees increased under certain circumstances; e.g. small-scale ornamental plantings, and when economic benefit is demonstrated. In comparisons of twenty-year growth data of lodgepole pine in Alaska with native white spruce (Picea glauca), lodgepole pine achieved greater height, diameter, and volume. The response of lodgepole pine in all three regions to scenarios of climate change was predicted using tree-ring analysis. Results indicate a negative response (reduced growth) in the Fairbanks area, a positive response (increased growth) in Delta and Glennallen, and a positive response at all but one Icelandic site and both Swedish sites. Overall, lodgepole pine appears relatively well-adapted to the present and modeled future environments of interior Alaska, Iceland, and northern Sweden.
    • MODIS Satellite vegetation indices over partially vegetated pixels on the Arctic Coastal Plain of Alaska

      Macander, Matt (2005-08)
      The performance and response of the MODIS Normalized Difference Vegetation Index (NDVI) and Enhanced Vegetation Index (EVI) were evaluated over the Arctic coastal plain of Alaska. At the 250-l000-m resolution of moderate resolution sensors, a substantial portion of this landscape is a mixture of vegetated and non-vegetated cover types. Single-date MODIS swath scenes were used because of the higher geolocation accuracy, lack of radiometric artifacts, and temporal specificity. A higher resolution earth cover classification was used to sample pixels with a mixture of vegetation, water, and barren ground. The MODIS NDVI and EVI were compared to aggregated Landsat ETM+ NDVI. The subpixel ETM+ NDVI was a good predictor of the MODIS EVI in all mixed pixels, and of the MODIS NDVI in mixed vegetation and barren ground pixels. In these cases a simple linear relationship between subpixel ETM+ NDVI and the MODIS vegetation indices was observed. In the mixed pixels with vegetation and water, the MODIS NDVI had a curvilinear response to the ETM+ NDVI and the performance decreased as the subpixel water fraction increased. Spectral mixture modeling was then applied to synthesize mixed pixel spectral values and plot the response of the MODIS vegetation indices to subpixel non-vegetated fractions. The MODIS NDVI had a highly variable response to subpixel fractions of different non-vegetated backgrounds, while the MODIS EVI was fairly insensitive to background type. The models also suggest that large changes in observed NDVI values could occur due to changes in the spectral characteristics of the non-vegetated portion of a pixel-in particular, the conversion of ice to water in subpixel water fractions.
    • Changing strategies in Seward Peninsula reindeer (Rangifer tarandus tarandus) management

      Oleson, Heather J. (2005-12)
      Reindeer (Rangifer tarandus tarandus) management techniques have changed since the founding of the reindeer industry on the Seward Peninsula in 1891. From 1891-1915, herds were small and management was intensive. Between 1915 and 1944, community herds and joint stock companies were formed. Herd management was extensive and herds were large and relatively free roaming. A period of re-privatization followed from 1944 to 1960, during which a limited number of moderately stocked ranges were established. The era after 1960 saw the introduction of several new forms of technology, some of which became catalysts for broad changes in reindeer management. Snow machines (c. 1960s), helicopters (c. 1970s), radio telemetry (c. 1980s), and Internet use became an integral part of how reindeer were managed. Most recently, satellite telemetry and online mapping have been developed as herd management tools. Combining telemetry, mapping programs, and the Internet allows herders to monitor range use, herd movement, and whether their animals need to be moved to refuge areas to prevent mixing with caribou. Equipped with this knowledge, herders can more effectively use ATV's and aircraft to manage their herds.