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Item Impacts of forest mortality on streamflow in whitebark pine forests within the greater Yellowstone ecosystem(Montana State University - Bozeman, College of Letters & Science, 2024) Rautu, Teodora Stefana; Co-chairs, Graduate Committee: Brian V. Smithers and Danielle E. M. UlrichIncreasing forest mortality across the western U.S. raises concerns about its impact on streamflow. The hydrologic role of whitebark pine (Pinus albicaulis Engelm.) is of particular interest given its ongoing decline and prevalence at the upper treeline where precipitation is highest. Understanding the link between disturbed whitebark pine forests and streamflow is essential for better informing water resource management. In Chapter One, I investigated streamflow changes in two Wyoming whitebark pine watersheds: Upper Wind River (53% area affected by beetle outbreak) and Buffalo Fork (53% area affected by beetle outbreak and fire). Streamflow significantly increased post-beetle for Upper Wind River but did not significantly change post-disturbance for Buffalo Fork, attributed to the fire's limited spatial extent and post- beetle effects potentially occurring in the pre-disturbance period. In Chapter Two, I integrated Leaf Area Index into a hydrologic model to reflect changing canopy conditions and assessed water balance variables that drove the observed changes in streamflow in Chapter One. I found that an increase in annual precipitation primarily led to the increase in observed streamflow more so than forest mortality, and snowpack and snowmelt were consistent predictors of streamflow metrics. My findings suggest monitoring snow dynamics for accurate real-time and future streamflow forecasting. In Chapter Three, I used streamflow field data and the same hydrologic model to assess the impact of increasing tree mortality on streamflow within a whitebark pine- dominated watershed in Big Sky, Montana. After simulating mortality levels ranging from 0-90% for one year, tree mortality did not substantially impact streamflow until the 90% mortality level where annual flow and late summer flow substantially increased. Considering that mortality levels between 25-50% are more representative of whitebark pine mortality in one year, the lack of substantial impacts on snowpack and streamflow at the 25-50% mortality levels challenges the traditional assumption that whitebark pine mortality would lead to reduced snowpack and reduced late summer flow in open watersheds with 30% forest cover. Future studies should assess the multi-decade impacts of whitebark pine mortality on hydrologic processes and consider species differences in evapotranspiration as other subalpine species replace whitebark pine.Item A forest entombed in ice: a unique record of mid-Holocene climate and ecosystem change in the northern Rocky Mountains, USA(Montana State University - Bozeman, College of Letters & Science, 2022) Stahle, Daniel Kent; Chairperson, Graduate Committee: David McWethy; This is a manuscript style paper that includes co-authored chapters.Across the high alpine of the northern Rocky Mountains small vestiges of perennial ice have endured for thousands of years. These ice patches reside hundreds of meters above modern treeline, with some persisting through mid-Holocene warmth and others establishing at the onset of a cooler period that began around 5,000-5,500 years BP. Recent warming-driven melting at the margins of one ice patch high on the Beartooth Plateau of northern Wyoming exposed over 30 intact mature whitebark pine (Pinus albicaulis) tree boles, all > 25 cm in diameter. We extracted cross-sectional samples from the stems of 27 preserved logs, and radiocarbon dated annual growth rings from 11 of these trees, anchoring the chronology to a date range spanning 5,947 to 5,436 years BP + or - 51.3 years. From this fossil wood chronology, we developed estimates of warm-season, annual, and biennial average temperatures for upper-elevation treeline during the mid-Holocene. To identify the predominant climate-growth relationships of the subfossil trees, we sampled live whitebark pine trees growing at an adjacent treeline site approximately 120 m lower in elevation. Temperature was found to be the major driver of variability in tree growth at the modern treeline location, with trees producing narrower (wider) rings during periods of cooler (warmer) growing season temperatures. Using linear and non-linear transfer functions based upon the stable statistical relationship between modern tree growth and temperature, we reconstructed past temperature estimates from the ice patch subfossil ring-width chronology. Our results provide estimates of mid-Holocene warm-season (and biennial) average temperatures ranging from 5.7-6.5 °C (-0.44-0.26 °C) respectively. A multi-century regional cooling trend beginning around 5,650 years BP resulted in average temperatures declining below a warm-season (biennial) critical threshold of ~5.8 °C (-0.34 °C), likely leading to the eventual death of the whitebark pine stand and subsequent formation of the ice-patch. This high-quality paleo-ecological dataset reveals a major shift in the alpine and forest ecotone on the Beartooth Plateau following the mid-Holocene warm period and offers further insight on the thermal limits of whitebark pine trees in the Greater Yellowstone Ecosystem.Item Characteristics of whitebark pine (Pinus albicaulis) growth & defense in disturbance-prone, high-elevation, montane ecosystems of the northern Rocky Mountains(Montana State University - Bozeman, College of Letters & Science, 2022) Kichas, Nickolas Earl; Chairperson, Graduate Committee: David McWethy; This is a manuscript style paper that includes co-authored chapters.Whitebark pine (Pinus albicaulis) is a high-elevation conifer, recognized as a foundation species due to the numerous ecological benefits it provides in subalpine environments. In whitebark pine and other conifers, resin-based defenses have long been recognized as the primary mechanism by which trees respond to bark beetle attacks and several studies have linked resin duct properties to survivorship during periods of increased beetle activity. Utilizing a unique dataset of whitebark pine collected on the Flathead Indian Reservation in northwestern Montana, we set out to investigate the following research questions: (1) Are there differences in physiology (tree growth and resin duct anatomy) between trees that persisted through recent mountain pine beetle outbreaks and trees that died? (2) Does constitutive resin chemistry differ between whitebark and co-occurring lodgepole pine and are there relationships between tree growth, resin duct anatomy and resin chemistry? (3) Does competition influence constitutive resin chemistry in either whitebark or lodgepole pine? and (4) Is whitebark pine growth and/or resin duct anatomy constrained by warmer and/or regionally drier conditions? We found that whitebark pine trees that have persisted through recent stand-level disturbance produced fewer but larger resin duct structures with greater duct area compared to trees that died. We also detected important differences in the chemical composition of resin between whitebark and lodgepole pine that generally support field observations, whereby under endemic scenarios mountain pine beetle preferentially select lodgepole pine, while under outbreak scenarios, beetles successfully colonize whitebark pine trees. We found complex relationships between tree growth, resin duct anatomy and constitutive resin chemistry that present beetles with many permutations of resin-based defenses, while competition, particularly with Engelmann spruce (Picea engelmannii) can further influence constitutive resin chemistry. Lastly, we found that whitebark pine across our study sites are experiencing increased growth and defense under warmer and regionally drier conditions. Whitebark pine at our study sites exhibit differing strategies in the allocation of resources toward growth and defense. Our results support the idea that maintaining genetic variability promotes diverse response strategies to a complex array of biophysical stressors that might leave a species vulnerable to extinction across its range.Item Biophysical gradients and performance of whitebark pine plantings in the Greater Yellowstone Ecosystem(Montana State University - Bozeman, College of Letters & Science, 2019) Laufenberg, David Anton; Chairperson, Graduate Committee: Andrew J. HansenThe efficacy of planting efforts for species of conservation interest is important for ecosystem managers. Planting efforts represent an opportunity to conserve and manage species during a population crisis. Although federal agencies have been planting whitebark pine (WBP) in the Greater Yellowstone Ecosystem (GYE) for three decades, these efforts have been met with varying success. In this study, we use a combination of field sampling and remote sensing approaches in order to investigate local biophysical gradients as explanatory variables for WBP performance in GYE planting units. Present-day field sampling affords an opportunity to evaluate WBP performance relative to earlier planting and monitoring records. We used remotely-sensed temperature and precipitation alongside field measurements of elevation, aspect, slope, shading, and soils to utilize an adapted Thornthwaite-type water balance model to explain individual growth rates and site density change ratios (essentially survival and natural recruitment). We found that planting sites varied greatly in their biophysical characteristics and WBP performance. Five of twenty-nine sites had higher present-day density than at date of planting, therefore indicating some amount of natural regeneration occurring within those sites since time of planting. These sites were often higher in elevation, not south or southwest facing, and had soils that could hold moisture later in the season and for longer periods following precipitation events. Sites that experienced reductions in the density of WBP were often lower in elevation, with poorer soils, and facing south or southwest. They therefore experience greater potential evapotranspiration, and also greater water deficit when water demands are not being met. Notably, our two response variables, individual growth rate and site density change ratio represent short and long-term performance variables respectively. Although our results suggest that individual growth rates are likely more often limited by energy than water demands, the site density change ratio associated with this late to mature, long-lived species is likely a better benchmark for success. If they make it to maturity, trees planted this season will not begin to produce cones until the end of this century or the beginning of the next. Therefore, they must overcome forecasted periods of greater water stress in the coming decades and centuries. We strongly recommend planting efforts that seek to reduce the effects of increased drought stress by planting at sites with soils of greater water holding capacities (non-rhyolitic), planting on northerly and easterly aspects, and utilizing microsites particularly when planting at sites with potentially higher water stress. We also detected a negative relationship between the density of local competitors and WBP performance, but only at higher densities. Ecosystem managers will continue to plant WBP in the GYE for years to come, and this research helps to inform and identify high quality habitat during a period of changing climate and high GYE WBP mortality rates.Item Varying nonlinear dependencies in habitat selection: estimating instead of imposing functional forms(Montana State University - Bozeman, College of Letters & Science, 2016) Ebinger, Michael Ryan; Chairperson, Graduate Committee: Robert A. GarrottSpatial heterogeneity of habitats and different foraging strategies can result in dissimilar patterns of habitat selection among individuals in a population. Studies have demonstrated that incorporating individual variation can influence model inferences. Thus, individual variation is increasingly being incorporated in habitat selection studies. Our objective was to advance the concept of individual variation in habitat selection by incorporating varying shapes (i.e., function forms) of responses among individuals. We used simulation modeling to develop a new analytical framework and introduce a new habitat selection metric, the Normalized Selection Ratio (NSR). Our results demonstrated the ability of the NSR to correctly estimate the strength and shape of complex simulated patterns of habitat selection, while simultaneously protecting against over-fitting. Using a simulated population of individuals, we showed how our approach can scale-up individual responses to facilitate population-level inference. We demonstrated how hierarchical clustering of individual-level response curves can identify and quantitatively describe different types of habitat selection within a population. When applied in a temporally dynamic framework, we showed that the NSR can detect ecological dynamics in habitat selection with quantitatively different inferences from analyses that pool data over time. We illustrated application of our approach using global positioning system (GPS) telemetry data for grizzly bears (Ursus arctos) in the Greater Yellowstone Ecosystem (GYE). We investigated the direction (preference or avoidance) and shapes of grizzly bear selection for whitebark pine (Pinus albicaulis) habitat during fall from 2007 to 2014. Our general conclusions support previous findings that grizzly bears exhibit a high degree of individual variation in habitat selection. Our approach of hierarchically clustering response curves detected 4 groups of grizzly bears with distinctly different patterns of whitebark pine habitat selection. Based on the group-level mean responses, 77% of sampled bears selected for whitebark habitat and 23% selected for non-whitebark pine habitats. Among the hierarchical groups that selected for whitebark pine, we observed substantial variation in the strength and density of whitebark pine being used. These results demonstrated the ability of our approach to identify, quantify, and organize individual differences in habitat selection and improve our understanding of grizzly bear ecology in the GYE.Item A spatiotemporal analysis of climate change in the Greater Yellowstone Ecosystem and its effects on Pinus albicaulis(Montana State University - Bozeman, College of Letters & Science, 2017) Chang, Tony; Chairperson, Graduate Committee: Andrew J. Hansen; Andrew J. Hansen was a co-author of the article, 'Historic and projected climate change in the Greater Yellowstone Ecosystem' in the journal 'Yellowstone science' which is contained within this thesis.; Andrew J. Hansen and Nathan Piekielek were co-authors of the article, 'Patterns and variability of projected bioclimatic habitat for Pinus albicaulis in the Greater Yellowstone area' in the journal 'PLoS one' which is contained within this thesis.; Andrew J. Hansen, Jesse Logan, Mark C. Greenwood, David W. Roberts and Jia Hu were co-authors of the article, 'A comparative severity analysis of recent Dendroctonus ponderosae outbreak and predictive hindcasts within the Greater Yellowstone Ecosystem' which is contained within this thesis.Climate change is arguably the biggest challenge facing humanity. Successful mitigation and adaption planning vitally requires more science in regard to its impacts on ecological systems. To address knowledge gaps regarding climate change impacts within the regional level, I performed a series of analyses on an "early responder" species in the Greater Yellowstone Ecosystem and examine how its distribution may be impacted by biotic and abiotic factors. My research aids in decision making processes for regional land managers that must address climate change in their policy decisions and increases ecological understanding at a landscape level. This manuscript includes a detailed analysis of past, present, and projected climate in the Greater Yellowstone Ecosystem. I addressed the expected impacts of present and future climate shifts on the distribution of the sub-alpine tree species, whitebark pine (Pinus albicaulis) and its main disturbance agent, mountain pine beetle (Dendroctonus ponderosae). This research found a major reduction of suitable climate habitat for P.albicaulis within the Greater Yellowstone Ecosystem under multiple Global Circulation Models and Representative Concentration Pathway futures. Finally, this research determined that the recent D.ponderosae outbreak driven by climate effects in 2000-2010, that resulted in an unprecedented mortality event on P.albicaulis was more than double the risk area size of any previous outbreak since 1951. Although more studies are necessary to reduce uncertainty and make assertive recommendations for management actions, this research suggests that future sub-alpine stand structure and composition may be radically different than anything in recent history due to range shifts of suitable climate habitat and disturbance agents, and advocates for land managers to apply a multifaceted approach of competitor thinning and controlled burning to ensure the resilience and persistence of P.albicaulis.Item Restoration of whitebark pine on a burn site utilizing native Ectomycorrhizal suilloid fungi(Montana State University - Bozeman, College of Agriculture, 2017) Jenkins, Martha Lee; Chairperson, Graduate Committee: Cathy L. CrippsThe compilation of threats both natural and anthropogenic and the resulting loss of whitebark pine has led scientists and land managers to actively pursue a strategy for restoration of this keystone species. A range-wide strategy for restoration has been developed by leading managers in the field and focuses on promoting rust resistance, conserving genetic diversity, saving seed sources, and employing restoration treatments (Keane et al. 2012). These strategies are applied across the range of whitebark pine and rely on the collaboration of land managers, scientists, and academics. Seed Source The most promising strategy for restoration of whitebark pine is the out-planting of blister rust resistant seedlings (Keane et al. 2012). Due to the continuous loss of mature cone-bearing whitebark pine, it is necessary to collect seed for blister rust resistance screening, genetic conservation, and out-planting... For the large-scale planting of 36,000 whitebark pine seedlings on the Eureka Basin Burn in the Beaverhead-Deerlodge National Forest, the first year survival of the 800 seedling subsample was high overall (94%). A method for examining how seedling-level planting variables such as colonization by suilloid ectomycorrhizal fungi, microsite type and position, slope, and potential soil moisture (TWI) affect seedling health and survival was developed and seedlings were monitored 3 and 14 months after planting. Further monitoring will continue to examine how long term seedling success is affected by these variables.Item Trends in whitebark pine health in the Greater Yellowstone Ecosystem(Montana State University - Bozeman, College of Letters & Science, 2015) Shanahan, Erin Kathleen; Chairperson, Graduate Committee: David Roberts; Kathryn M. Irvine, Dave Roberts, Andrea R. Litt, Kristin Legg and Rob Daley were co-authors of the article, 'Status of whitebark pine in the Greater Yellowstone Ecosystem; a step-trend analysis comparing 2004-2007 to 2008-2011' in the journal 'Natural resource technical report NPS/GRYN/NRTR' which is contained within this thesis.; Dave Roberts, Kathryn M. Irvine and Andrea R. Litt were co-authors of the article, 'White pine blister rust in whitebark pine stands: infection and infection transition probability' submitted to the journal 'Natural areas journal' which is contained within this thesis.; Kathryn M. Irvine, Dave Roberts and Andrea R. Litt were co-authors of the article, 'Objective 4 of the interagency whitebark pine protocol: assessment of regeneration/recruitment protocol' submitted to the journal 'Interagency whitebark pine monitoring protocol for the Greater Yellowstone Ecosystem, version 1.1' which is contained within this thesis.Whitebark pine (Pinus albicaulis) occurs at high elevations and in subalpine communities in the Pacific Northwest and Northern Rocky Mountains. It is a key component in the upper ranges of these ecosystems where it provides a variety of ecological roles, including regulating snowpack and providing high-energy food sources to birds and mammals. As a stone pine species, it produces indehiscent cones and relies primarily on birds for seed dispersal. In mixed and dominant stands, whitebark pine occurs in over two million acres within the six national forests and two national parks that comprise the Greater Yellowstone Ecosystem (GYE). Currently, whitebark pine is impacted by multiple ecological disturbances. White pine blister rust (Cronartium ribicola), mountain pine beetle (Dendroctonus ponderosae), wildfires, and warming temperature all pose significant threats to the persistence of healthy whitebark pine populations on the landscape. Substantial declines in whitebark pine populations have been documented throughout its range. In 2004, an interagency whitebark pine long-term monitoring program was established. The objectives of the whitebark pine monitoring program are to detect and monitor changes in the health and status of whitebark pine populations across the GYE due to infection by white pine blister rust, attack by mountain pine beetle, and damage by other environmental and anthropogenic agents. Here we present work done in three areas of whitebark pine ecology; trends in white pine blister rust infection and overall health status, infection and infection transition probability, and methods for monitoring understory (< or = 1.4-m tall) populations of whitebark pine.Item Post-logging stand characteristics and crown development of whitebark pine (Pinus albicaulis)(Montana State University - Bozeman, College of Letters & Science, 1992) Kipfer, Todd RogerItem Biotic and microsite factors affecting Pinus albicaulis establishment and survival(Montana State University - Bozeman, College of Letters & Science, 1990) McCaughey, Ward Wells