Download or read book Vegetation and Soil Microbial Communities Three Years After Wildfire in Spruce fir Forests of Northwestern Wyoming written by Jennifer Suzanne Hooke and published by . This book was released on 2005 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: The Normalized Burn Ratio and Composite Burn Index were used to classify burn severity in three sites that experienced lightning-ignited wildfire in the year 2000. The effect of burn severity (unburned, low, moderate, and high severity classes) was investigated on vegetation and soil microbial community composition. Vegetation communities showed a strong response to burn severity, with distinct communities associated with each burn severity class. Indicator Species Analysis was used to identify plant species associated with each burn severity class; one interesting result from ISA was that trembling aspen (Populus tremuloides) seedlings emerged as an indicator of the moderate severity class. Species richness and tree seedling density differed among burn severity classes. Soil microbial communities were analyzed using Phospholipid Fatty Acid analysis and showed moderate variation among burn severity classes and study sites. Total soil carbon and nitrogen did not differ with burn severity. The C:N ratio, total soil S, and soil pH differed significantly among burn severity classes. While the effect of burn severity is pronounced upon vegetation three years post-fire, effects on soil microbial communities are less evident. This could be attributed to the insulating properties of soils, the time elapsed after fire, or it could be an artifact of the sampling technique.
Download or read book Linking Soil Ecology with the Restoration of Ponderosa Pine Forests Following a High severity Wildfire in the Laramie Mountains of Wyoming written by Stephanie M. Winters and published by . This book was released on 2019 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: In July 2012, a lightning strike started the Arapaho Fire in the Laramie Mountains burning approximately 39,700 ha. Ponderosa pine (Pinus ponderosa P. & C. Lawson) mortality due to the high-severity fire was 95% at the Rogers Research Site (RRS). The research property is managed by the James C. Hageman Sustainable Agriculture Research and Extension Center (SAREC) and is owned by the University of Wyoming (UW). Ponderosa pine recruitment post high-severity wildfire is limited in semi-arid and mid-elevation forests in the US Rocky Mountain region due to reduction of seed supplies from living trees, warm temperatures, and limited precipitation. Wildfire intensity and frequency is predicted to increase with climate change and ponderosa pine forests are susceptible to this dramatic shift. More research is required for applicable and impactful restoration practices that national, state, and local land managers can implement post-wildfire. The purpose of this research was to determine the best restoration treatments for ponderosa pine regeneration and survival, while quantifying the relationship between soil microbiology and vegetation community composition, in a Wyoming ponderosa pine forest post high-severity fire. Our results indicate that the pine introduction treatment ‘hand-planted seedlings’ was the most effective restoration treatment at increasing ponderosa pine seedling presence in semi-arid, mid elevation sites, although survival rates of seedlings was very low. Overall, restoration treatments three years after implementation did not result in significantly different vegetation communities, soil abiotic and biotic properties, or bacterial communities. However, a change in the bacterial community was highly correlated with changes in extracellular enzymatic profiles, indicating that the different bacterial communities had unique functional properties. Potential reasons for the lack of restoration effects on community and environmental variables at the RRS are likely the high landscape heterogeneity attributed to differing slopes and aspects coupled with the short time frame (2-3 years) since implementation of the restoration treatments at the site. Further research is needed to determine if restoration treatments will have greater impact on ponderosa pine survival and regeneration in the midterm (6-10) years post implementation, and if, and how, regeneration and growth is linked with the soil microbial community.
Download or read book Fire s influence on wildlife habitat on the Bridger Teton National Forest Wyoming written by George E. Gruell and published by . This book was released on 1980 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Shifts in Microbial Community Structure as a Result of a Wildfire in the New Jersey Pinelands written by Robyn Ann Mikita and published by . This book was released on 2012 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt: As the threat of wildfires in the United States increases due to global warming, understanding their effects on the soil biological community becomes central to recovery efforts. Therefore, it is important to study microbial community dynamics in forest soils impacted by fires from the view of elucidating how the new state compares with the original state of the microbial community. For this study, wildfires were hypothesized to cause a shift in the microbial community structure with dominant microbes being those best capable of responding to changes in their environment caused by the perturbation. The objectives of this research were to examine the recovery of the forest soil microbial communities after a wildfire and to investigate the state of the communities more than two years post-fire. After a wildfire occurred in the New Jersey Pinelands in 2007, soil samples were collected from the organic and mineral layers of two severely burned sites and an unburned control site over the span of two years following the fire. Microbial community composition was evaluated by principal component analysis and multivariate analysis of variance of molecular fingerprint data for bacterial, archaeal, and fungal-specific amplicons from denaturing gradient gel electrophoresis. The bacterial communities in the samples collected from 2 and 5 months following the fire clustered separately from those collected 13 and 17 months post-fire in two-dimensional space, indicating that the soil bacterial community structure changed with time following the fire. Deeper evaluation of the bacterial, archaeal, and fungal community patterns revealed that even though there were common bands between the unburned and the severely burned samples, the community structure of the samples from the unburned site grouped separately from those of the severely burned sites collected 2, 13, and 25 months post-fire. Generally, the microbial community composition in the unburned samples did not change significantly over two years. These data support the hypothesis that the soil microbial community was selected by both the direct and indirect effects associated with the wildfire in the initial two years after the perturbation. Rather than return to the predisturbance state, the soil microbial communities may reflect an alternate state two years following the fire.
Download or read book Effects of Wildfire Burn Severity on Soil Microbial Communities and Invasive Plant Species in the Cascade Range of Oregon written by Cassie Lenae Hebel and published by . This book was released on 2007 with total page 126 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fire suppression in the last several decades has resulted in unprecedented accumulations of organic matter on the landscape, leading to an increase in large, intense wildfires. This study investigated the soil microbial community (using phospholipid fatty acid analysis) across recently burned forests on the eastern slope of the Cascade Range in Oregon to examine the effects this belowground community has on the growth of native and non-native plant species in severely burned "red" soil and in less severely burned "black" soil. Long duration, smoldering conditions creating red soils drastically altered both soil nutrients and microbial community structure. Changes in soil properties and biota affected plant growth in a controlled growth chamber, as well as vegetative colonization on red soil plots in natural field conditions. Differential growth was observed between native and non-native plant species when grown in soil from the two burn severities. Native plant growth did not differ between black and red soil, while non-native plants showed reduced growth in red soil. Although it previously had been reported that fire increased the likelihood of invasion by non-native plant species in a burn area, these results do not support the notion that red soil conditions are more susceptible than moderately burned soil to non-native, invasive plant species colonization. While many factors in addition to mycorrhizal colonization and burn severity influence plant growth, such as soil nutrient availability, our results suggest that a variety of strategies allow plants to grow in disturbed environments. Continued monitoring of microbial communities and re-vegetation in red soil sites could further our understanding of the length of post-fire recovery time of severely burned red soil.
Download or read book Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest written by Rachel E. Danielson and published by . This book was released on 2015 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: Forest harvest persists as one of the most globally important industries, and crucially provides raw wood products for both building and fuel materials. Mechanistically complex abiotic and biotic processes curb ecosystem recovery following timber harvest and it is of great importance to understand the effects of this practice on biogeochemical cycling and ecosystem function to determine the potential for long-term sustainability. This thesis was motivated by a lack of comprehensive understanding as to the consistency of preexisting and post-harvest microbially mediated process rates and community composition across a large region of the same dominant vegetation type. I sought to determine how timber harvest across the Pacific Northwest impacts microbial biogeochemical cycling activity and community structure of both prokaryotic and fungal communities in response to harvest. At nine managed Douglas-fir forests, samples were collected from exact locations within sites one year prior to and twelve to fifteen months following clear-cut harvesting. The objective of the first study was to determine the degree of variability in microbially mediated process rates and pools of C and N, and generalized trends that are evident across sites one year following harvest. Samples were analyzed for various C and N pools, and the potential activities of biogeochemically important extracellular enzymes were measured. Soil incubations were performed to determine respiration rate and N production over time. Soil DNA isolates were used to quantify 16S rRNA and ITS gene copy numbers using qPCR, and all measurements were statistically compared between pre-and post-harvest samples. Total soil C and N did not change significantly following harvest, but the C: N ratio of dissolved components decreased consistently and biomass C: N ratios generally increased. Activities of [beta]-glucosidase and cellobiohydrolase increased significantly whereas activities of phenol oxidase and peroxidase decreased significantly. Cumulative respiration over the incubation period declined substantially, and total N pools changed from primarily DON pre-harvest, to primarily NO3p−post-harvest. Changes in activity rates and pool sizes following harvest were generally related to C to N balances. Pre-harvest measurements suggested communities may be co-limited by C and N, while the emergence of strong C limitation was evident post-harvest. The generalized trends identified from this study can be used in future research as reference points for ecosystem status during forest succession, and for correlation with an investigation of changes in microbial community composition and structure. The objective of the second study was to determine the factors shaping soil microbial communities of Douglas-fir forests in the Pacific Northwest, and to identify generalized short-term effects of timber harvest on the richness, diversity, and structureof these communities. DNA was extracted from soils and sequenced using the Illumina® Miseq platform to determine differences in prokaryotic and fungal communities. When communities were considered separately pre-and post-harvest, pH most consistently explained community dissimilarity among sites. Although community dispersion did not vary between pre-and post-harvest samples, OTU richness was consistently and significantly higher following tree removal. Both prokaryotic and fungal community structures were significantly different in post-compared to pre-harvest soils, even when just OTUs representing the top 50% of sequences were considered. Relative abundance of the dominant three bacterial phyla (Proteobacteria, Acidobacteria, and Verrucomicrobia) did not change significantly following harvest, but some less-represented phyla decreased (Actinobacteria) or increased (Bacteroidetes) significantly in relative abundance. Basidiomycota abundance decreased significantly whereas Ascomycota and Zygomycota abundance increased. Ectomycorrhizal fungi were enriched across pre-harvest samples, whereas many known saprotrophic species were enriched post-harvest. In conclusion, general alterations in fungal communities, as well as select bacterial and archaeal taxa, may serve as appropriate indicators of disturbance and ecosystem status across this region.
Download or read book Functional Profiles of Soil Microbial Communities in Second growth Douglas fir Forests of the Pacific Northwest written by Megan L. McGinnis and published by . This book was released on 2013 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt: Forests are one of the largest repositories of terrestrial C. Understanding factors that drive organic matter transformations and nutrient efflux from these systems is therefore highly important. Temperate forests are of particular significance due to the large fraction of C that is stored below ground in the soil. Characterizing nutrient transformations, especially for C and N, and factors that influence their mineralization is critical in managing these ecosystems sustainably. The objective of this study was to characterize the metabolic function of the soil microbial community as it relates to C and N cycling in managed second-growth Douglas-fir forests of the Pacific Northwest. In the first study, extracellular enzyme profiles were characterized and correlated with a wide range of environmental variables present at nine sites located in western Oregon and Washington. Enzyme profiles were also correlated with measures of microbial biomass and with C and N mineralization rates obtained from a two-month incubation. Sites varied significantly from one another in all enzymes. C-cycling enzymes were correlated with respired C, and N-cycling enzymes, in addition to phosphatase and oxidative enzymes, were correlated with released N. Enzyme profiles grouped similarly for sites of the same soil type. Abiotic factors such as CEC, EC, and cation concentrations were correlated strongly with many enzymes, suggesting that soil physical and chemical properties influence extracellular enzyme function. In the second study, a year-long soil microcosm incubation measured respired C as well as total released N: NO3−, NH4, and dissolved organic N (DON). These cumulative mineralization measurements were fitted with kinetic models to characterize C and N cycling in the same nine soils. Mineralization rates, and their descriptive parameters derived from the models, were correlated with the same set of environmental characteristics and enzyme activities from the previous study. Total soil C and N, as well as microbial biomass, were strongly positively correlated with both C and N mineralization. However, abiotic factors such as soil chemical components also had significant effects. This, coupled with anomalous behavior noted in C mineralization in response to leaching treatments, may suggest substrate supply to microorganisms constrains much of C mineralization. N mineralization seemed strongly tied to biotic factors in addition to abiotic factors. Often in studies of N dynamics in soil, only mineralized N (NO3− and NH4) are examined; our study revealed that DON was the largest fraction of released N in these systems, and dynamics of DON in N cycle warrant further research. Together, these studies provide insights into factors that drive soil microbial community function across a broad range of site conditions for Douglas-fir dominated forests of the Pacific Northwest region and could serve as a baseline for future research.
Download or read book Ecological Effects of the Wickersham Dome Fire Near Fairbanks Alaska written by Pacific Northwest Forest and Range Experiment Station (Portland, Or.) and published by . This book was released on 1979 with total page 80 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Wildland Fire in Ecosystems written by and published by . This book was released on 2005 with total page 262 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Forest Ecology written by Daniel M. Kashian and published by John Wiley & Sons. This book was released on 2023-03-13 with total page 788 pages. Available in PDF, EPUB and Kindle. Book excerpt: FOREST ECOLOGY Authoritative resource covering traditional plant ecology topics and contemporary components such as climate change, invasive species, ecosystem services, and more Forest Ecology provides comprehensive coverage of the field, focusing on traditional plant ecology topics of tree structure and growth, regeneration, effects of light and temperature on tree physiology, forest communities, succession, and diversity. The work also reviews abiotic factors of light, temperature, physiography (landforms and topography), soil, and disturbance (especially fire), and provides coverage of ecosystem-level topics including carbon storage and balance, nutrient cycling, and forest ecosystem productivity. The 5th edition of Forest Ecology retains the readability and accessibility of the previous editions and includes important additional topical material that has surfaced in the field. All topics are approached with a landscape ecosystem or geo-ecological view, which places biota (organisms and communities) in context as integral parts of whole ecosystems that also include air (atmosphere and climate), topography, soil, and water. As such, the book fills a niche utilized by no other forest ecology text on the market, helping students and researchers consider whole ecosystems at multiple scales. Sample topics covered in Forest Ecology include: Contemporary components of forest ecology, including climate change, invasive species, diversity, ecological forestry, landscape ecology, and ecosystem services. Characteristics of physiography important for forest ecosystems, including its effects on microclimate, disturbance, soil, and vegetation. Genetic diversity of woody plants and genecological differentiation of tree species, including the importance of hybridization, polyploidy, and epigenetics. Site quality estimation using tree height and ground flora, and multiple-factor approaches to forest site and ecosystem classification and mapping. Forest Ecology is a highly accessible text for students, but it also serves as an excellent reference for academics. In addition, practitioners of forest ecology can also harness the information within to gain better insight into the field for practical application of concepts.
Download or read book Patterns and Trajectories of Postfire Plant Communities in Greater Yellowstone written by Nathaniel Kiel and published by . This book was released on 2024 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Changing global drivers are eroding ecosystem resilience. As change continues, determining the implications of ecosystem transformations must be coupled with "climate change education" and evidence-based undergraduate biology curricula to train the next generation of scientists. My dissertation addresses each need in turn. First, I use remote sensing and field studies to understand the drivers and effects of poor subalpine forest recovery following large, stand-replacing wildfire in the U.S. Northern Rocky Mountains. I ask: (1) how extensive is forest conversion to sparse or non-forest three decades after the 1988 Yellowstone fires, and what drives its distribution? (2) how does forest conversion affect subalpine forest understory plant communities, aboveground carbon stocks, and the potential for forest recovery? and (3) how do anomalously frequent (30-year fire-return interval) stand-replacing wildfires in forests adapted to historically infrequent (125-year fire-return interval) fires alter understory plant communities? I complement these studies with the development and assessment of new undergraduate curricula on systems thinking and biogeochemical cycling, incorporating gameplay and simple simulation modeling to ask: how do student attitudes toward and understanding of the nitrogen cycle change following game- and inquiry-based learning? Subalpine forest conversion 30 years after the 1988 fires was extensive, covering ~41,000 hectares of previously forested area primarily at higher elevations and further from surrounding unburned forest. While much of this area appears "locked in" to sparse or non-forest, other areas may yet recover to forest owing to seed pressure from ex situ and in situ sources. Understory plant communities increasingly resembled meadow communities where tree densities were lowest, and aboveground carbon stock recovery was diminished. Understory communities were also affected by minimal forest recovery following anomalously frequent fire, with shifts toward shade-intolerant species and species from lower elevation zones adapted to drier conditions. Finally, undergraduate students in an intermediate general ecology course self-identified improved attitudes toward and understanding of the nitrogen cycle, largely attributing these changes to gameplay of "The N Game" and active lecture. This research elucidates how changing climate and disturbance will alter forest ecosystems and how evidence-based teaching approaches may help train undergraduate students to address these and other global challenges.
Download or read book Nitrogen Plant and Microbial Community Dynamics in Sites Recovering from Wildfire and Surface Mining in the Athabasca Oil Sands Region written by Jillian M. Martin and published by . This book was released on 2016 with total page 72 pages. Available in PDF, EPUB and Kindle. Book excerpt: For reclamation to be considered successful, an ecosystem must be self-sustaining and have a recovery trajectory that falls within the range of variability of ecosystem function in natural ecosystems. This study compared the soil nitrogen availability, soil microbial community, and understory vegetation following natural (wildfire) disturbance and anthropogenic (reclamation) disturbance, in the Athabasca Oil Sands Region. Eleven natural (aged 2-131 years) and five reclaimed sites (aged 4-27 years) from upland aspen/ spruce stands were compared. Soil available nitrogen was assessed in-situ with ionic resin capsules and potentially mineralizable nitrogen was determined by anaerobic incubation. Microbial respiration was measured as an indicator of activity, and microbial community fingerprints and biomass were determined using phospholipid fatty acid analysis. The vegetation was characterized by canopy cover, plant functional group, and composition survey at the genus level. No significant difference for nitrate or ammonium availability was observed at the site level; however, there were trends with time and canopy cover. The potentially mineralizable nitrogen trend with time was much higher on the natural sites than the reclaimed sites. Non-metric multi-dimensional scaling ordinations of the soil microbial community and understory vegetation composition revealed that reclaimed and unburned sites had significantly different communities with a low degree of similarity. The burned sites (aged 2-39 years) were more variable and bridged the difference between the reclaimed and mature sites. The microbial community of the oldest reclaimed sites were most similar to naturally disturbed sites. This work shows that young naturally disturbed sites may be a more relevant comparison when evaluating reclamation trajectory than mature stands.
Download or read book Belowground Biodiversity Following Herbicide Application Post Wildfire written by Tanner Scott Hoffman and published by . This book was released on 2023 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Recent increases in wildfire occurrence and non-native plant invasion have led to unique opportunities to study the impacts of natural and anthropogenic disturbances on the soil microbiome. Our aim was to understand responses of the soil microbial diversity and function to the application of herbicide immediately post wildfire in a sagebrush steppe/mixed grass prairie ecosystem. Sites were selected for soil sampling representing burned and unburned ecosystems across the Mullen wildfire impacted area that were either treated or not treated with indaziflam, a pre-emergent cellulose biosynthesis inhibiting herbicide. A variety of soil analyses were done to compliment a vegetation surveying effort by the USDA Forest Service to observe the effectiveness of this herbicide and measure any unintended consequences on native vegetation. We performed amplicon sequencing and phospholipid fatty acid analysis to capture soil microbial diversity and biomass of bacteria and fungi, extracellular enzyme assays for microbial functional traits, and soil available nutrients to measure potential changes in the soil conditions. Results indicate increased enzymatic activity two months following herbicide application, with activities dropping off to pre-treatment levels the following year. Changes in fungal community composition were correlated with herbicide application, but bacteria were not. Overall, our results suggest that indaziflam application post wildfire has minimal, short-lived effects on soil microbial function, does not seem to strongly affect soil microbial community composition, and has little to no effect on soil chemical properties. Given our results that showed changes in fungal community structure, further research on indaziflam’s impact on fungi should be done.
Download or read book Soil Microbial Community Dynamics in Reponse to Prescribed Extreme Fires Following Juniperus Virginiana Invasion in the Loess Canyons of Nebraska written by Julie A. Fowler and published by . This book was released on 2021 with total page 157 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Nebraska and other regions of the Great Plains, the conifer Juniperus virginiana (eastern redcedar) is converting grasslands to dense woodlands. This is driven by the interacting drivers of fire suppression, altered grazing regimes, climate change and other anthropogenic factors, impacting the provisioning of ecosystem services. This vegetation state transition modifies water resource regulation and biogeochemical cycles leading to altered edaphic properties including soil microbial community composition. To restore these grasslands and control J. virginiana spread, prescribed extreme burns are implemented as a management tool through local prescribed burn associations. We hypothesized that the alternative state transition to dense J. virginiana woodlands leads to a corresponding state transition below-ground that persists post-extreme burn and may facilitate J. virginiana re-establishment. To address this hypothesis, paired grasslands and J. virginiana woodlands in the Loess Canyons of Central Nebraska were subjected to one prescribed extreme burn between 2005 and 2019 to provide a natural burn chronosequence. We quantified J. virginiana re-establishment, soil chemistry, soil microbial biomass and microbial community composition in these paired sites across the chronosequence. Our results partially supported our hypothesis where differences in edaphic variables between J. virginiana sites and grassland sites observed post-burn were largely temporary; however, differences in soil magnesium and microbial community composition were more persistent (> 14 years post-burn). Soil magnesium values were significantly higher in the J. virginiana sites both pre-burn and post-burn across the 14 year chronosequence. Microbial communities were also distinct between J. virginiana and grassland sites pre-burn and across the burn chronosequence. Rapid recovery and/or persistence of specific edaphic factors and soil microbial communities in J. virginiana woodlands post-burn may facilitate early J. virginiana re-establishment. Restoration of historical fire intervals is needed to prevent long term changes to soil function that may facilitate J. virginiana re-establishment.
Download or read book Wildfire Burn Susceptibility to Non native Plant Invasions in Black Spruce Forests of Interior Alaska written by Katie Lin Villano and published by . This book was released on 2008 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: "As the climate changes, Alaska's boreal forest faces the simultaneous threats of rising invasive plant abundances and increasing area burned by wildfire. Highly flammable and widespread black spruce forest represents a boreal habitat that may be increasingly susceptible to non-native plant invasion. In other biomes, non-native plant invasions are generally greatest in high severity burns that are only a few years old. The relationship between fire and non-native plant invasion has not been investigated in the northern boreal forest. To assess the invasibility of burned black spruce forests, I used burned field sites that spanned a gradient of burn severities, moisture levels, and burn ages. I conducted both field surveys and a greenhouse experiment using soil taken from burn sites. Contrary to generalizations from other biomes, I found soils from low severity burns and burns between 10 and 20 years old support greater invasive plant growth in black spruce forests than do high severity and more recent burns. In addition, regional differences between burn complexes outweighed burn severity and site moisture in determining the invasibility of burned black spruce sites. Finally, rebounding native vegetation appears to offer burned areas a level of resistance to invasive plant establishment"--Leaf iii.
Download or read book Soil Microbial Community Responses to Fire written by Sam Fox and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Fires, both wild and prescribed, have lasting impacts on the landscape and environment. Factors such as fire return interval, timing, and fire intensity and severity all play a role in the direct and indirect impacts fires have on the soil microbial communities (bacteria and fungi). Soil microbes play vital roles in soil stability, nutrient exchange, and many other ecosystem functions. Understanding how fires impact these communities is important for future land management decisions, especially in areas predicted to have more frequent and severe fires. In my dissertation, I first provide a synthetic review of what is currently known about the subject of fire impacts on fungi. This includes ecological frameworks, fungal fire traits, key fire-responsive fungal species, and community dynamics and trajectories. While this review is detailed and explores many facets of fungal responses to fire, I also address areas that still need to be explored, such as functional gene analysis following a fire, and having more controlled fire experiments. Second, I explored how fire frequency impacts the microbial communities residing in different soil horizons- A (topmost), E, and B (bottommost) as well as abiotic attributes that may be indirect drivers of community dynamics such as; Total N, Total C, SOM, inorganic N, P, and pH. For this project, we utilized an experimental infrastructure that had sixty years of continuously maintained, controlled fire regimes. This experiment included replicated experimental units that had been burned annually, every two years, and every four years, as well as a fire exclusion treatment that had not been burned in over sixty years. We observed that fire frequency impacts the microbial communities, but does so mainly in the topmost soil profile. The fire exclusion treatment differed from others when we compared the topmost soil horizons (where most microbial activity occurs). In almost all of our community and abiotic parameters, the fire interval manipulation treatments differed in the topmost A horizon, whereas the two deeper horizons E and B, had only a few parameters that differed between the fire interval treatments. Lastly, I investigate effects of low and high severity fires in a mid- to long-term experiment. This experiment manipulated fire severity and compared high and low severity fires to determine how the microbial communities change over a six-year time span. We also collected samples before the fire samples to enable comparisons to samples after fire to assess community recovery. My results suggested that the high-severity fires had a greater impact on the microbial communities compared to the low severity fires for both bacteria and fungi. Within the high severity fire sites, the communities remained distinct six years post-fire. In the low severity treatments, the communities started to resemble those before the fire, especially richness and diversity of the bacterial communities. This project allowed us to gain valuable understanding in microbial community trajectories following fire, and could aid in planning future restoration projects. Taken together, my dissertation research has allowed us to answer whether and how fire severity and frequency impact the soil microbial community. Indicator taxon analyses that I employed in both studies, identified taxa that seem to drive the community distinctions amongst the treatments, such as fungal taxa, Anthrocobia, Morchella, Pholiolata, and Pyronema which are described as pyrophilous taxa in my synthetic review. My dissertation research strongly indicates that microbial communities change with fire events and that these responses depend on fire interval and severity contexts. Whilst my studies provide considerable insight into the microbial responses to fire, the underlying reasons why they respond still remain complex and poorly understood. In all, fire changes soil chemistry, plant physiology and community composition, soil fauna, and many other system attributes that interact with microbial communities in soil. Exploring which of the many potential drivers are most important for microbial community fire responses and recovery remain a lingering area of research that needs to be explored.
Download or read book Comprehensive Dissertation Index written by and published by . This book was released on 1984 with total page 792 pages. Available in PDF, EPUB and Kindle. Book excerpt:
