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Browsing by Author "Battaglia, Mike, committee member"

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    Impacts of treatments on forest structure and fire behavior in dry western forests
    (Colorado State University. Libraries, 2014) Ziegler, Justin, author; Hoffman, Chad, advisor; Battaglia, Mike, committee member; Sibold, Jason, committee member
    Forest managers are increasingly using mechanical treatments in dry forests of the western US in order to produce stands with spatially complex structure while also reducing crown fire potential. However, there has been a lack of evaluation of these treatments on spatial patterns in dry forest types of the western US. In addition, the implications of heterogeneous fuels complexes on fire behavior are not well understood due to a lack of experimental data and the use of semi empirical models which cannot account for the structural complexity of fuel beds. The lack of well quantified studies on changes in spatial heterogeneity and limitations on quantifying the associated fire behavior suggest there are gaps in our knowledge regarding the implications of mechanical fuels treatments. The primary emphasis of this thesis is in Chapter 1. I comprehensively stem-mapped seven 4 ha plots, after treatment in dry, coniferous treated stands across the Southern Rockies and Colorado Plateau. Then, I estimated pre-treatment structure by constructing linear allometric regressions of tree characteristics and applying these to mapped stumps thus producing stem-maps before treatment. To investigate how these treatments altered structural complexity, I used spatial statistical analyses to assess spatial relationships of trees, before and after treatment, occurring at stand and within-stand scales as well as horizontal and vertical dimensions. Then, I assessed the cumulative effects of the reduction and spatial alterations of structure on potential fire behavior, measured by rate of spread, fireline intensity and percent of canopy consumed, across a range of open wind speeds using the Wildland urban-interface Dynamics Simulator (WFDS). WFDS is a physics-based model capable of representing the 3-D complexities of the fuels complex and captures fuel-atmosphere-fire dynamics through space and time. Results from this chapter suggest (1) treatments impact facets of structural complexity in varying ways, though avoided large-scale homogenization of forest structure, (2) within canopy wind speeds increase following treatments and, (3) fire behavior can be altered in two distinct manners following treatments. In most cases, the alterations in the fuels complex coupled with greater within canopy wind speeds resulted in an overall decrease in potential fire behavior and crown fire activity, especially at high open wind velocities. However, in two cases I examined there were increases in fire behavior following mechanical treatments. In these cases the increases were primarily associated with increased surface fire behavior. The results from this chapter suggest that these mechanical treatments may not always enhance, but can promote, a degree of structural complexity, and that mechanical treatments are effective if implemented strategically. Chapter 2 reports on litter bulk density values for use by managers to improve fuel loading assessments. Litter bulk density as a factor, in conjunction with litter depth, is used to estimate litter load necessary for fuel hazard assessments as litter is a primary carrier of fire and its load impacts potential rate of spread, fireline intensity and smoke production. In addition litter load estimation is needed for estimating carbon and wildlife habitat availability. However, available litter bulk density factors are limited by region, forest type, and site history. This chapter uses data collected on litter bulk density in both ponderosa (Pinus ponderosa Lawson) dominated and dry mixed conifer stands throughout the southern Rockies across sites that have been recently mechanically treated and in recently undisturbed sites. Results show litter bulk density was much lower in ponderosa pine forest than mixed conifer, and the impact of treatment was relatively negligible. These results provide managers in the southern Rockies with a regionalized value that may improve accuracy for estimation of litter load.
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    The influence of provenance on radial growth and drought resilience of lodgepole pine in Fraser Experimental Forest, Colorado, U.S.A.
    (Colorado State University. Libraries, 2024) Warnick, Katarina J., author; Hart, Sarah, advisor; Tinkham, Wade, advisor; Battaglia, Mike, committee member; Dahl, Jamie, committee member
    Climate change poses unprecedented challenges to forested ecosystems, particularly in drought-affected areas in the western United States, where increased temperatures and shifting precipitation regimes are negatively impacting locally adapted tree species. In response, researchers and land managers are exploring innovative forest adaptation strategies to maintain forest resilience, such as assisted migration. This study examines the potential of lodgepole pine (Pinus contorta Dougl. var. latifolia Engelm.) to be utilized in forest assisted migration efforts in western North America, drawing from the understanding that this widespread species displays intraspecies variation in growth-climate associations due to local adaptations across its extensive geographic range. We make use of a provenance study established in the early 1980s in Fraser Experimental Forest, Colorado, U.S.A. to examine the effect of seed source, or provenance, on growth-climate responses and drought resilience of lodgepole pine in its southernmost range. We investigate two primary research questions. First, does provenance climate influence the radial growth response of lodgepole pine trees? Second, do lodgepole pine trees from climatically drier provenances exhibit greater resilience to drought, as measured by annual radial growth before and after drought events? To address our first question, we employed dendrochronological methods and a generalized linear mixed-effects modeling approach utilizing climate data to analyze the variation in overall radial growth of trees explained by the difference in provenance and study site climates during our study period, 1992-2021. In addressing our second question, we utilized the Standardized Precipitation Evapotranspiration Index (SPEI) and metrics of quantifying drought resilience to determine the impact of provenance site aridity on tolerance to drought during our selected drought period, 2001-2002. Our analyses revealed significant differences in radial growth between trees from different provenances. Specifically, we found that trees originating from provenance sites with greater growing season average vapor pressure deficit, yet higher precipitation, exhibited increased radial growth. In analyzing drought resilience, we found that trees from provenances with higher average temperatures and greater evapotranspiration showed greater resilience to drought, aligning with previous research linking seed source climate aridity to drought tolerance. Interestingly, we also found that trees from sites with greater climate moisture index compared to their growing site exhibited greater radial growth resilience to drought, suggesting that certain populations may be less sensitive to moisture deficits. Our research sheds light on the relationship between provenance climate with radial growth response and drought resilience in an assisted migration context. Our findings suggest that provenance climate aridity may confer resilience to trees during resource-limited events. More broadly, our study underscores the potential of utilizing local adaptations and intraspecies variability of tree species in climate adaptation efforts aimed at mitigating the impact of climate change in forested ecosystems.