Browsing by Subject "Fire"

Now showing 1 - 6 of 6
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    Data for divergent responses of butterflies and bees to burning and grazing management in tallgrass prairies, 2016-2017
    (2022-12-12) Leone, Julia B; Pennarola, Nora P; Larson, Jennifer L; Oberhauser, Karen; Larson, Diane L; leone050@alumni.umn.edu; Leone, Julia B
    We studied the impacts of fire and grazing management on butterfly and bee abundance and species richness in tallgrass prairies. This dataset consists of data collected at 10 burned and 10 grazed Minnesota remnant prairies during the summers of 2016 and 2017. We measured insect data (butterfly and bee species richness and abundance), vegetation data (plant species richness, forb frequency, native and invasive graminoid frequency), site characteristics (proportion of sand in the soils, percent of prairie within 1.5 km of each site, site area), and management characteristics (management type (burned or grazed), cattle stocking rate, time since last fire, number of years each site was managed) at sites owned and managed by the Minnesota DNR, U.S. Fish and Wildlife Service, The Nature Conservancy, and private landowners. These data are associated with Leone et al. (2022). Divergent responses of butterflies and bees to burning and grazing management in tallgrass prairies. Ecology and Evolution. 12(12) e9532. http://dx.doi.org/10.1002/ece3.9532. In association with this paper, we hope these data will assist land managers and conservationists in protecting and managing native grasslands and contribute to our understanding of bee and butterfly responses to fire and grazing management practices.
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    Ecology, conservation and climate-fire challenges on Uluguru Mountain biodiversity hotspot, Tanzania
    (2010-12) William, Christopher Mungo Peter
    In this research, I investigate the relationship between short-term climate variability and the fire ecology of the Uluguru Nature Forest Reserve (UNFR). I investigate the influence of relief, altitude, the Indian Ocean Dipole or Dipole Mode Index (DMI), and Niño 3.4 on short (November-December) and long rains (March, April, May) in the UNFR. Fire events correlate weakly with amount of annual local rainfall, suggesting that fire occurrence in the UNFR results from a combination of factors, such as rainfall anomalies, topography, type of vegetation (fuel), timing and use of fire by local people as a farm preparation tool, and teleconnections. A thorough understanding of fire behavior across time and space is necessary to design a successful UNFR management plan; the resulting plan must address both anthropogenic and climatic drivers of fire.
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    Floristic Differences in Permanent Openings among Ecological Land Units and after Fire
    (University of Minnesota Duluth, 1994) Host, George E
    Permanent openings are an integral part of the Forest Plan on the Chippewa National Forest. There are established across a range of ecological units using numerous methods. It is unclear, however, how floristic composition changes as a function of site or establishment method, or how quickly these changes occur. The objective of this study were: 1) To assess differences in the species composition of permanent openings among Landtype Associations (LTAs). 2) To assess the effects of mechanical treatments on species composition. 3) To assess the effects of fire on species composition, particularly on woody vegetation.
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    Multiple Disturbances and the Turbulent Forest
    (2023-08) Reed, Samuel
    I have always been drawn to change, whether I liked it or not. As a kid, I was obsessed with dinosaurs and their extinction, all while having to move constantly as a Navy brat. As an adult, I am devoted to understanding how and why systems change, likely inspired by the unending change of my childhood. However, as I matured, I realized that change is almost never spurred by a single event, but rather a multitude of shocks to the system. This dissertation focuses on the complexity of multiple ecological disturbances and highlights their importance in the world. Using several multi-disturbance experiments, I explore a wide variety of disturbance interactions in the temperate deciduous forest. The first chapter of this dissertation focuses on how deer and canopy gaps influence invasive earthworms, shedding new light on how aboveground events can change belowground communities. The second chapter builds upon the first and tests how combined deer and canopy gaps influence understory regeneration over 15 years, with some reference to invasive earthworms. Lastly, the third chapter explores how combined fire, deer, and canopy gaps change the seed bank over 13 years. Each of the aforementioned disturbances are common and influential in eastern forests, although they are not often studied together. In each chapter we find that community responses vary depending on the disturbances in question. This dissertation is meant to highlight how little we know about the many ways in which multiple disturbances change ecosystems and how critical it is that we start to study these complex drivers of change, particularly as the climate warms and disturbances become more frequent on the landscape.
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    The Revery Alone Won't Do: Fire, Grazing, and Other Drivers of Bee Communities in Remnant Tallgrass Prairie
    (2019-04) Pennarola, Nora
    The bee community in Minnesota’s tallgrass prairie is doubly threatened. The conversion of prairie to agriculture and development has fragmented the landscape nearly beyond recognition. Over vast swathes of the state, single species exist in monocultures where once highly diverse grasslands grew. On top of this, bees across the continent face pressures from parasites, pathogens, and pesticides. The pockets of remnant prairie that persist are dependent on human-mediated disturbance. Grazing and burning, which can be seen as analogues to historic disturbance patterns, are effective and important tools in maintaining prairie health. Through this thesis, I seek to parse out the differing impacts of these two management techniques on bee communities and to explore how environmental characteristics impact the suite of traits bees display in remnant prairies.
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    A two-scale thermomechanical computational model for reinforced concrete frame structures
    (2014-09) DesHarnais, Marie Gisele
    A two-scale numerical model is developed to study the behavior of reinforced concrete (RC) frame structures subject to fire loading. In this model, various structural components, such as beams, columns, and beam-column joints, are modeled by elastic elements connected by a set of nonlinear cohesive elements, which represent the potential damage zones. The thermo-dependent constitutive behavior of each cohesive element is determined by nonlinear finite elements (FE) simulations of its corresponding potential damage zone under different loading modes at different temperatures, where the thermo-dependent material properties for the FE simulations are determined based on the existing literature and a set of high-temperature experiments on concrete. The proposed two-scale model is used to simulate the behavior of a RC frame subassemblage under thermomechanical loading and the simulation results are further compared with the prediction by using the conventional finite element model. It is shown that the present model can well capture the nonlinear behavior of RC frame structures under thermomechanical loading, and due to its computational efficiency, the model provides us an efficient means to investigate the global behavior of large-scale RC frame structures under fires.