Response Of Soil Microbially Mediated Nutrient Cycling And Community Structure To Timber Harvest In The Pacific Northwest

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Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest

Author : Rachel E. Danielson
Publisher :
ISBN 13 :
Total Pages : 208 pages
Book Rating : 4.:/5 (922 download)

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Book Synopsis Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest by : Rachel E. Danielson

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.

The Effect of Timber Harvesting on Soil Microbial Nutrient Cycling

Author : James A. Entry
Publisher :
ISBN 13 :
Total Pages : 276 pages
Book Rating : 4.:/5 (417 download)

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Book Synopsis The Effect of Timber Harvesting on Soil Microbial Nutrient Cycling by : James A. Entry

Download or read book The Effect of Timber Harvesting on Soil Microbial Nutrient Cycling written by James A. Entry and published by . This book was released on 1984 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Functional Profiles of Soil Microbial Communities in Second-growth Douglas-fir Forests of the Pacific Northwest

Author : Megan L. McGinnis
Publisher :
ISBN 13 :
Total Pages : 94 pages
Book Rating : 4.:/5 (859 download)

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Book Synopsis Functional Profiles of Soil Microbial Communities in Second-growth Douglas-fir Forests of the Pacific Northwest by : Megan L. McGinnis

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.

Environmental Effects of Forest Residues Management in the Pacific Northwest

Author : Owen P. Cramer
Publisher :
ISBN 13 :
Total Pages : 572 pages
Book Rating : 4.X/5 (1 download)

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Book Synopsis Environmental Effects of Forest Residues Management in the Pacific Northwest by : Owen P. Cramer

Download or read book Environmental Effects of Forest Residues Management in the Pacific Northwest written by Owen P. Cramer and published by . This book was released on 1974 with total page 572 pages. Available in PDF, EPUB and Kindle. Book excerpt:

The Effects of Forest Harvesting and Land-use Change on Soil Carbon and Nutrient Cycling

Author : Jason James
Publisher :
ISBN 13 :
Total Pages : 180 pages
Book Rating : 4.:/5 (19 download)

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Book Synopsis The Effects of Forest Harvesting and Land-use Change on Soil Carbon and Nutrient Cycling by : Jason James

Download or read book The Effects of Forest Harvesting and Land-use Change on Soil Carbon and Nutrient Cycling written by Jason James and published by . This book was released on 2018 with total page 180 pages. Available in PDF, EPUB and Kindle. Book excerpt: The properties and processes of deep soil horizons remain an important gap in knowledge due to the long history of shallow soil sampling. The majority of soil carbon and nitrogen can be found beneath the A horizon in most soils, particularly those deeper than one meter to bedrock. Such soils are common in many parts of the world, especially the Pacific Northwest where the combination of age (hundreds of thousands of years in many places) and high precipitation lead to rapid development of subsoil pedogenic features. My dissertation seeks to explore deep soils to better understand the relationships between nutrient cycles and the impact of land-use change and forest harvesting on soil carbon. In a series of 36 soil profiles sampled to 3 meters depth across the Pacific Northwest, pedogenesis frequently extended deeper than the upper 2 meters that is arbitrarily defined as the maximum soil depth for soil taxonomy. The combination of landslides, volcanic activity, and flooding have buried soils in many forests across the region, and these horizons can be important repositories of plant nutrients. In several cases, B horizon development extended deeper than could be excavated with a backhoe (3+ meters). The diversity of parent materials, climate gradients (with both latitude and orography), and soil carbon and nitrogen cycles directly control exchangeable cation cycling across the Pacific Northwest. Soils that experience more precipitation and contain higher levels of carbon and nitrogen hold less exchangeable calcium and magnesium in the whole soil profile, and also have more deeply distributed stocks of exchangeable cations within the profile. Consequently, human disturbances that alter soil carbon can have repercussions for plant nutrition. Millions of acres of forest in the US are actively managed for timber production, but the type and intensity of soil disturbance varies considerably. In a meta-analysis examining the response of soil carbon to forest management from 112 publications, I found that harvesting reduces soil carbon by 11% overall. This loss is predominately driven by O horizon losses (-30%), but there were also losses in surface mineral soil (0-15 cm; -3%). Loss of soil carbon extends deep into the soil with increasing average losses at each depth interval examined; however, very few studies examined soils deeper than 30 cm, leading to extremely wide confidence intervals in deeper soil. Land-use change, even converting one forest type for another, can substantially alter soil carbon cycling, as well. In the Brazilian Cerrado, over half of the natural vegetation has been lost to agriculture, silviculture or urban development, with a substantial portion of the landscape planted with Eucalyptus trees. The shift in the aboveground plant community increases aliphatic functional groups in water-soluble organic matter (WSOM), which may lead to reduced microbial biomass in Eucalyptus plantations that lack native understory trees. The difference in radiocarbon age between WSOM and bulk soil carbon is smaller under Eucalyptus relative to Cerrado, suggesting either mineralization or leaching of aged organic matter under this land use. The consequences of land-use change extend deep into the soil profile, particularly in the Oxisol soils of Brazil which are especially reliant upon soil organic matter for critical ecosystem services like nutrient recycling and water holding capacity.

Understanding Key Issues of Sustainable Wood Production in the Pacific Northwest

Author :
Publisher :
ISBN 13 :
Total Pages : 76 pages
Book Rating : 4.:/5 (319 download)

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Book Synopsis Understanding Key Issues of Sustainable Wood Production in the Pacific Northwest by :

Download or read book Understanding Key Issues of Sustainable Wood Production in the Pacific Northwest written by and published by . This book was released on 2005 with total page 76 pages. Available in PDF, EPUB and Kindle. Book excerpt: Researchers involved with the Pacific Northwest (PNW) Research Station Sustainable Wood Production Initiative have outlined some of the barriers and opportunities for sustainable wood production in the region. Sustainable wood production is defined as the capacity of forests to produce wood, products, and services on a long-term basis and in the context of human activity and use. The collective findings of these papers suggest that in the future, the regions wood supply will primarily come from private land, and the barriers and opportunities related to sustainable wood production will have more to do with future markets, harvest potential, land use changes, and sustainable forestry options than with traditional sustained yield outputs. Private lands in the PNW should be able to sustain recent historical harvest levels over the next 50 years, but regional changes in sawmilling capacity and uncertain market conditions may affect wood production in the region. Public perceptions of forestry, land use changes, and alternative forestry options are also discussed. These papers present preliminary findings and proposals for future work designed to help us understand the key issues related to sustainable wood production.

Meteorological and Geoastrophysical Abstracts

Author :
Publisher :
ISBN 13 :
Total Pages : 492 pages
Book Rating : 4.3/5 (91 download)

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Book Synopsis Meteorological and Geoastrophysical Abstracts by :

Download or read book Meteorological and Geoastrophysical Abstracts written by and published by . This book was released on 1997 with total page 492 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Nitrogen Cycling and Microbial Communities of Alpine Soils in the Pacific Northwest

Author : Anna Simpson
Publisher :
ISBN 13 :
Total Pages : 160 pages
Book Rating : 4.:/5 (18 download)

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Book Synopsis Nitrogen Cycling and Microbial Communities of Alpine Soils in the Pacific Northwest by : Anna Simpson

Download or read book Nitrogen Cycling and Microbial Communities of Alpine Soils in the Pacific Northwest written by Anna Simpson and published by . This book was released on 2018 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt: The alpine Pacific Northwest is an environment of stunning beauty and environmental extremes, with acidic, low-nutrient soils, snow cover often exceeding 4-5 m, and snow periods occasionally exceeding 9 months out of the year. Nitrogen (N) deposition from increasing urbanization and intensive agriculture can cause changes in alpine soil chemistry and plant species abundance and increase leaching of inorganic N into streams and lakes. In the state of Washington has already exceeded critical N loads for shifts in alpine lichen communities (Geiser et al., 2010) and alpine lake microbiota (Sheibley et al., 2014). The effects of climate change, which could include earlier snowmelt, increased fall rains, and even the complete disappearance of permanent snowfields and glaciers, threaten to exacerbate effects of N deposition even further by causing changes in plant phenology and increasing decomposition of soil organic matter. In this study I used fertilizer treatment of 0, 3, 5 and 10 kg NH4NO3-N ha−1 yr−1 to simulate increased N deposition at three alpine meadows of the Pacific Northwest at Mount Rainier, North Cascades and Olympic National Parks. Using the indicator of increased soil NO3-N availability to alpine plants and microbes, I define the empirical critical load upper limit for Pacific Northwest alpine meadows to be 6 kg N ha−1 yr−1. I found that increased fall microbial N uptake in these meadows appears to serve as a buffer for inorganic N loss with fall rains. No increases in plant species were observed during the course of the study. In soils with available soil inorganic N from slow depolymerization and mineralization, N pollution accumulated in plots with higher N and greater abundance of forbs and graminoid species. In very N-limited soils, N deposition was evenly dispersed among plant communities. I also sampled the soil microbial communities of barren, permanent snowfield soils at Mount Rainier and North Cascades National Parks. I used 16SrRNA metagenomic amplicon sequencing to examine the differences between the microbial communities in samples taken in dry soil that had only been covered by seasonal snow, and soil underneath permanent snowpack. Photoautotrophic bacteria were not present in samples taken under snowpack and comprised less than 1% of reads in samples taken from exposed soils. Soils were dominated by Deltaproteobacteria from the genus Anaeromyxobacter, which were particularly abundant under snowpack, and a number of bacteria from the phylum Gemmatimonadetes. Overall, permanent snowfield soils of the Pacific Northwest contain diverse heterotrophic and chemoautolithotrophic communities of bacteria but have very low overall biomass, comparable to barren soils sampled in the Himalayas. Soil bacterial communities probably depend at least partially on organic matter from atmospheric deposition and carbon fixation from seasonal snow algae for survival in this harsh environment.

The Plant Holobiont Volume II: Impacts of the Rhizosphere on Plant Health

Author : Nadia Lombardi
Publisher : Frontiers Media SA
ISBN 13 : 288974292X
Total Pages : 228 pages
Book Rating : 4.8/5 (897 download)

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Book Synopsis The Plant Holobiont Volume II: Impacts of the Rhizosphere on Plant Health by : Nadia Lombardi

Download or read book The Plant Holobiont Volume II: Impacts of the Rhizosphere on Plant Health written by Nadia Lombardi and published by Frontiers Media SA. This book was released on 2022-02-07 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Impact of Forest Harvesting on Soil Microbial Communities and Nutrient Cycling in Forest Soils of the Boreal Plain, Alberta

Author : Holly Hynes
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (13 download)

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Book Synopsis Impact of Forest Harvesting on Soil Microbial Communities and Nutrient Cycling in Forest Soils of the Boreal Plain, Alberta by : Holly Hynes

Download or read book Impact of Forest Harvesting on Soil Microbial Communities and Nutrient Cycling in Forest Soils of the Boreal Plain, Alberta written by Holly Hynes and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Ecological Society of America ... Annual Meeting Abstracts

Author : Ecological Society of America. Meeting
Publisher :
ISBN 13 :
Total Pages : 612 pages
Book Rating : 4.F/5 ( download)

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Book Synopsis Ecological Society of America ... Annual Meeting Abstracts by : Ecological Society of America. Meeting

Download or read book Ecological Society of America ... Annual Meeting Abstracts written by Ecological Society of America. Meeting and published by . This book was released on 2004 with total page 612 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Response of Soil Temperature, Moisture, and Respiration Two Years Following Intensive Organic Matter and Compaction Manipulations in Oregon Cascade Forests

Download Response of Soil Temperature, Moisture, and Respiration Two Years Following Intensive Organic Matter and Compaction Manipulations in Oregon Cascade Forests PDF Online Free

Author : Adrian Carlos Gallo
Publisher :
ISBN 13 :
Total Pages : 67 pages
Book Rating : 4.:/5 (97 download)

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Book Synopsis Response of Soil Temperature, Moisture, and Respiration Two Years Following Intensive Organic Matter and Compaction Manipulations in Oregon Cascade Forests by : Adrian Carlos Gallo

Download or read book Response of Soil Temperature, Moisture, and Respiration Two Years Following Intensive Organic Matter and Compaction Manipulations in Oregon Cascade Forests written by Adrian Carlos Gallo and published by . This book was released on 2017 with total page 67 pages. Available in PDF, EPUB and Kindle. Book excerpt: Forest soils contain a substantial portion of global terrestrial carbon stores. Forest management can influence the soil carbon pool and how soil organic matter functions. The long-term productivity of forests is an ongoing goal where land managers utilize biomass and timber. A site-specific understanding of intensively managed forests can ensure achievements of this goal. Within a managed forest in the western Oregon Cascades, treatments were installed to harvest three levels of biomass, with and without compaction, to monitor impacts to growing season characteristics of Douglas-fir roots. Soil temperature and moisture conditions were continuously monitored from 10 to 100cm depth, and three sources of soil respiration were measured monthly for two years immediately following treatments. Negligible differences in the length of growing season were detected, however the daily-10cm average, maximum, and diel flux of soil temperatures significantly increased by 1.5, 2.7, and 2.5°C, respectively, with increasing biomass harvesting. Organic matter removal strongly influenced growing season soil characteristics down to a 100cm depth. Diel temperature flux at 100cm for the least and most impacted treatments were 5.7 and 7.8°C, respectively, a magnitude equivalent to seasonal shifts in soil temperature at the same depth. In spite of favorable temperature and moisture conditions with less organic matter left on the surface, soil respiration was moderately higher on bole only harvests. A priming effect may explain why these sites with more surface biomass, although significantly cooler, had the highest rates of soil respiration. The combination of increased temperatures throughout the soil profile after forest harvesting, and higher additions of dissolved organic matter from forest residuals, could have an impact on deep soil carbon. These responses have implications for long-term nutrient cycling that have yet to be elucidated for deeper soils; but this should be considered when land managers are planning forest fertilization and rotation lengths.

Peatland Microbial Community Structure and Function Along a Metal Contamination Gradient in Sudbury, Ontario

Author : Shanay Williams-Johnson
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (124 download)

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Book Synopsis Peatland Microbial Community Structure and Function Along a Metal Contamination Gradient in Sudbury, Ontario by : Shanay Williams-Johnson

Download or read book Peatland Microbial Community Structure and Function Along a Metal Contamination Gradient in Sudbury, Ontario written by Shanay Williams-Johnson and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The Sudbury, Ontario region has had over a century of metal mining/smelter activity that has led to significant sulphur and metal deposition and this has negatively affected both freshwater and terrestrial ecosystems, including peatlands. Peatlands store organic materials, regulate nutrient turnover and act as a carbon sink for global climate change, yet relatively little is known in regards to the impact of the mining legacy of this region and the potential microbial communities affected. Eleven peatland sites (poor to intermediate fens) around Sudbury were chosen in order to study the microbial diversity and function that control decomposition and nutrient cycling. The analysis of microbial communities was accomplished via high-throughput sequencing of 16S rRNA genes in bacteria and archaea on the Illumina MiSeq platform, while the analysis of microbial function was conducted through the Sinsabaugh enzyme protocol and gas chromatography of in situ greenhouse gases. There was a difference across the site gradient with microbial diversity, community structure, and microbially mediated gas efflux differing between areas closest to current and historical smelters to areas 55-km away. There was also a difference within each peatland where vertical profiles in microbial enzyme function varied over four depths, with the surface depth having the highest enzyme activity. Metal impact and pH are major drivers of microbial diversity and community with pH driving metal availability. This is seen where the sites with the lowest pH having the lowest microbial diversity and unique communities, and sites with the highest pH having the highest microbial diversity and distinct communities. We can also deduce that microbial function differs over depth because of the difference between the aerobic and the anaerobic communities, where the aerobic communities appear to be more active. We can reason that methane efflux was higher in impacted sites because of the increased concentrations of Nickel, Copper, pH and possibly Sulphur creating restrains on microbially mediated gas effluxes through the inhibition of methane production.

Soil Respiration, Carbon and Nitrogen Leaching, and Nitrogen Availability in Response to Harvest Intensity and Competing Vegetation Control in Douglas-fir (Pseudotsuga Menziesii) Forests of the Pacific Northwest

Download Soil Respiration, Carbon and Nitrogen Leaching, and Nitrogen Availability in Response to Harvest Intensity and Competing Vegetation Control in Douglas-fir (Pseudotsuga Menziesii) Forests of the Pacific Northwest PDF Online Free

Author : Robert A. Slesak
Publisher :
ISBN 13 :
Total Pages : 406 pages
Book Rating : 4.:/5 (251 download)

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Book Synopsis Soil Respiration, Carbon and Nitrogen Leaching, and Nitrogen Availability in Response to Harvest Intensity and Competing Vegetation Control in Douglas-fir (Pseudotsuga Menziesii) Forests of the Pacific Northwest by : Robert A. Slesak

Download or read book Soil Respiration, Carbon and Nitrogen Leaching, and Nitrogen Availability in Response to Harvest Intensity and Competing Vegetation Control in Douglas-fir (Pseudotsuga Menziesii) Forests of the Pacific Northwest written by Robert A. Slesak and published by . This book was released on 2009 with total page 406 pages. Available in PDF, EPUB and Kindle. Book excerpt: Management practices following forest harvest can affect long-term soil productivity through alteration of soil carbon (C) and nitrogen (N) pools, but processes contributing to change are poorly understood. I assessed effects of three levels of logging-debris retention in combination with initial or annual applications of competing vegetation control (CVC) following forest harvesting on soil C flux, N leaching, foliar N of planted Douglas-fir, and changes in soil N and C pools for two years at two sites with contrasting soil properties. Soil C flux was lower when heavy amounts of logging debris were retained, due largely to lower bulk soil and microbial respiration as there was no difference in dissolved organic C (DOC) flux among logging-debris treatments. Increased soil C when heavy amounts of logging debris were retained at the site with lower initial soil C reflected the lower C flux, but soil C was increased at both sites when logging debris was removed, likely due to greater decomposition of belowground organic matter (OM). There was no difference in DOC leaching or soil C between CVC treatments at either site, despite lower OM inputs to mineral soil with annual CVC. Higher bulk soil respiration in the initial CVC treatment indicated that OM inputs from competing vegetation were rapidly consumed, and contributed little to mineral soil C. The most pronounced effects on N leaching and foliar N were associated with annual CVC, which increased Douglas-fir foliar N at both sites, and total N leaching below the rooting zone at the high-N site. However, estimated mass of leached N was small relative to the site soil N pool, and it is unlikely that the loss will negatively affect soil productivity. Logging-debris retention had little influence on Douglas-fir foliar status or N leaching, but soil N was higher at the end of the experiment when heavy amounts of logging debris were retained at the low-N site. There appears to be small potential for logging-debris removal and annual CVC to reduce soil productivity at these sites after harvesting, but logging-debris retention may improve soil productivity, particularly at sites with low initial pools of C and N.

The Link Between Nitrogen Cycling and Soil Microbial Community Composition in Forest Soils of Western Oregon

Author : Stephanie A. Boyle
Publisher :
ISBN 13 : 9781109914719
Total Pages : 142 pages
Book Rating : 4.9/5 (147 download)

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Book Synopsis The Link Between Nitrogen Cycling and Soil Microbial Community Composition in Forest Soils of Western Oregon by : Stephanie A. Boyle

Download or read book The Link Between Nitrogen Cycling and Soil Microbial Community Composition in Forest Soils of Western Oregon written by Stephanie A. Boyle and published by . This book was released on 2007 with total page 142 pages. Available in PDF, EPUB and Kindle. Book excerpt: The objectives of this thesis were to examine the links between soil microbial community composition and function using the nitrogen (N) cycle as a model for these interactions and to assess the impact of environmental factors such as microclimate, vegetation type, and nutrient availability on microbial diversity and N transformations in forest soils. The first study consisted of a reciprocal transfer experiment where soil cores were transferred between high-elevation forest and adjacent meadow environments. It focused on bacterial denitrifying communities by measuring denitrification enzyme activity and community composition as determined by terminal restriction fragment length polymorphism (T-RFLP) profiles targeting the gene for nitrous oxide reductase (nosZ). Results from this experiment showed that while transferring meadow soils into forests increased denitrification rate, denitrifying community composition did not appear to change after two years. The second study examined N cycling and microbial community composition in soils from 20-year-old experimental tree plantations with pure stands of Douglas fir (Pseudotsuga menziesii) and red alder (Alnus rubra) in a high- and a low-productivity forest. 15N isotope dilution was combined with antibiotics to assess the roles of bacteria and fungi in N mineralization and nitrification. Data showed that nitrification was a major sink for NH4+ in all soil types and bacteria were the primary nitrifiers. Increased ammonification following antibiotic additions suggested that organic N may be important for the growth of heterotrophic bacteria and fungi. Results of nitrification potential assays showed that most nitrification was acetylene insensitive (autotrophic). Community composition of ammonia-oxidizing bacteria and archaea were assessed by targeting bacterial and archaeal ammonia-monooxygenase (amoA) genes. The composition and population size of ammonia-oxidizing bacteria differed between Douglas fir and red alder and tended to group with Nitrosospira clusters 2 and 4. Archaeal amoA was only amplified from the high-productivity site and grouped with other archaeal clones from soil and estuary sediments. Environmental factors affected rates of N cycling within two years, but community compositional changes responded more slowly, e.g., nitrifying communities differed between 20-year-old tree stands. This suggests that if environmental changes persist they may lead to changes in microbial community composition.

Estimation of Available Phosphorus in Soils by Extraction with Sodium Bicarbonate

Author : Sterling Robertson Olsen
Publisher :
ISBN 13 :
Total Pages : 20 pages
Book Rating : 4.:/5 (31 download)

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Book Synopsis Estimation of Available Phosphorus in Soils by Extraction with Sodium Bicarbonate by : Sterling Robertson Olsen

Download or read book Estimation of Available Phosphorus in Soils by Extraction with Sodium Bicarbonate written by Sterling Robertson Olsen and published by . This book was released on 1954 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Oil and Wildfire Effects on Nutrient Cycling and Microbial Diversity in Subarctic Mineral Soils

Author : Jessica I. Garron
Publisher :
ISBN 13 :
Total Pages : 246 pages
Book Rating : 4.:/5 (137 download)

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Book Synopsis Oil and Wildfire Effects on Nutrient Cycling and Microbial Diversity in Subarctic Mineral Soils by : Jessica I. Garron

Download or read book Oil and Wildfire Effects on Nutrient Cycling and Microbial Diversity in Subarctic Mineral Soils written by Jessica I. Garron and published by . This book was released on 2007 with total page 246 pages. Available in PDF, EPUB and Kindle. Book excerpt: "In 1976 crude oil was experimentally spilled on a plot near Fairbanks, Alaska to mimic an oil pipeline spill. The plot and surrounding area were further disturbed by wildfire in 2004. Although the fire burned organic matter on the plot surface, substantial subsurface oil remained. After the fire, soil samples from oiled/burned, burned, and control plots were collected to evaluate the effects of disturbance on nutrient cycling and soil bacterial communities. Samples were analyzed for total nitrogen (N), soil carbon (C) and N mineralization, N fixation, total bacterial diversity (16S rDNA), and functional genetic diversity (nifH). Inorganic N was low in all soil types. In control and burned soils there was net N mineralization, but in oiled/burned soils there was significant N immobilization. Carbon mineralization was much higher in oiled/burned soils than control or burned soils. While the highest N fixation potential was measured in oiled/burned soils, the diversity of the N-fixing bacterial community in those soils was about the same as that of the control. For 16S rDNA, diversity was higher in control and burned soils than in oiled/burned soils. Overall, the type of disturbance and the length of time since disturbance both affected microbial function and diversity"--Leaf iii.