Search

Search Results

• 1571. [Article] Biochemical and Physical Characterization of Fish Protein Isolate and Surimi for their Compatibility

  There are presently two successful methods used to refine fish muscle proteins: surimi and fish protein isolate (FPI). Both surimi and FPI have the ability to form an elastic gel upon comminution and heating. ...

  Citation × Citation Citation Abstract Copy Title: Biochemical and Physical Characterization of Fish Protein Isolate and Surimi for their Compatibility Author: Kobayashi, Yuka There are presently two successful methods used to refine fish muscle proteins: surimi and fish protein isolate (FPI). Both surimi and FPI have the ability to form an elastic gel upon comminution and heating. However, their gelation behaviors are different as they are refined in a biochemically opposite way based on the nature of protein denaturation. The focus of this study was to compare surimi and FPI under various processing conditions, such as rigor mortis, frozen storage, comminution conditions, and blending effect, and how these conditions can affect their functional properties including gel texture. The structural changes and rheological properties of tilapia protein prepared using FPI and surimi with pre- and post-rigor muscle were evaluated. No rigor effect was observed on the gel-forming ability of FPI, although higher storage modulus (G’) and better gel texture were obtained in surimi made from pre-rigor tilapia compared to surimi made from post-rigor tilapia. Results suggested pre-rigor processing may improve gel-formation properties of surimi, but not as much for the gelation of FPI. Storing fish in a freezer for extended periods of time can adversely affect the gel-forming ability of muscle proteins. The effect of frozen storage (0, 1, and 3 mo) on the biochemical and physical characterization of FPI and surimi made from tilapia was elucidated. The Ca²⁺ATPase activity of tilapia fillet continuously reduced throughout the frozen storage; however, the decline trend of its activity was slower than cold or temperate water species. As reported by storage modulus (G’), storing whole fish frozen for 3 mo did not affect the gelling ability of FPI and surimi. The results from surface hydrophobicity, surface reactive sulfhydryl (SRSH) content, and differential scanning calorimetry also corresponded to the results from storage modulus. Thus, frozen tilapia, if stored up to 3 mo, may be used like fresh fish in the processing of FPI and surimi and no negative effects on gel qualities. The uniqueness of tropical fish tilapia was thought due to its high thermal stability. The quality of surimi gels was affected more so under various rigor stages and frozen storage compared to FPI gels. Conversely, the addition of salt into FPI induced a higher degree of unfolding protein structure prior to gelation compared to surimi. In addition, comminution conditions affected the quality of FPI gel more than that of surimi gel. A significant increase in puncture gel texture was observed when FPI and surimi were chopped at 25°C for 18 min compared to samples chopped at 5°C for 6 min. The comparable results were detected as measured by storage modulus. FPI chopped with 3% salt at 5°C for 6 min showed the lowest gel texture among all treatments, possibly because protein structure was not disintegrated appropriately and formed larger protein aggregates and coarser gels demonstrated by microscopic analyses. Results suggested controlling chopping temperature and time, and the addition of salt, may be significant factors to enhance production of high quality gel in FPI and surimi. Moreover, the effect of various comminution conditions on structural changes were investigated using Fourier transform infrared (FT-IR) and Raman spectroscopy. Both procedures exhibited increasing chopping temperature and time, adding salt, promoted a higher degree of unfolding protein structure in FPI and surimi paste made from tilapia, when they were chopped at 25°C for 18 min compared to samples chopped at 5°C for 6 min. Also, FPI and surimi gels prepared after chopping at 25°C for 18 min revealed higher β-sheet contents and more chemical bonds such as hydrophobic interactions and disulfide bonds than those at 5°C for 6 min. Controlling comminution conditions may be one of the important factors to produce high quality gels from FPI and surimi using tropical fish like tilapia. Additionally, FT-IR and Raman spectroscopy are useful complementary tools, allowing a better interpretation of the structural changes in FPI and surimi under various comminution conditions. The gelation properties of blending two different fish proteins obtained from surimi and FPI at different ratios was evaluated. Effects of blending surimi and FPI on gel functionality (whiteness, hardness, and cohesiveness) demonstrated a linear pattern when the proportion of surimi is larger than or equal to that of FPI. Also, breaking force and penetration distance decreased significantly when the ratio of surimi to FPI decreased. Results indicated gels cooked in a water bath tended to exhibit a higher breaking force than gels cooked ohmically. On the other hand, a higher penetration distance was observed for gels cooked ohmically compared to gels cooked in a water bath. Blending surimi and FPI did not affect the inter-molecular interactions of protein in a linear pattern, like mixing various grades of surimi, but this might be feasible only when the proportion of FPI does not exceed 50%. Title: Biochemical and Physical Characterization of Fish Protein Isolate and Surimi for their Compatibility Author: Kobayashi, Yuka There are presently two successful methods used to refine fish muscle proteins: surimi and fish protein isolate (FPI). Both surimi and FPI have the ability to form an elastic gel upon comminution and heating. However, their gelation behaviors are different as they are refined in a biochemically opposite way based on the nature of protein denaturation. The focus of this study was to compare surimi and FPI under various processing conditions, such as rigor mortis, frozen storage, comminution conditions, and blending effect, and how these conditions can affect their functional properties including gel texture. The structural changes and rheological properties of tilapia protein prepared using FPI and surimi with pre- and post-rigor muscle were evaluated. No rigor effect was observed on the gel-forming ability of FPI, although higher storage modulus (G’) and better gel texture were obtained in surimi made from pre-rigor tilapia compared to surimi made from post-rigor tilapia. Results suggested pre-rigor processing may improve gel-formation properties of surimi, but not as much for the gelation of FPI. Storing fish in a freezer for extended periods of time can adversely affect the gel-forming ability of muscle proteins. The effect of frozen storage (0, 1, and 3 mo) on the biochemical and physical characterization of FPI and surimi made from tilapia was elucidated. The Ca²⁺ATPase activity of tilapia fillet continuously reduced throughout the frozen storage; however, the decline trend of its activity was slower than cold or temperate water species. As reported by storage modulus (G’), storing whole fish frozen for 3 mo did not affect the gelling ability of FPI and surimi. The results from surface hydrophobicity, surface reactive sulfhydryl (SRSH) content, and differential scanning calorimetry also corresponded to the results from storage modulus. Thus, frozen tilapia, if stored up to 3 mo, may be used like fresh fish in the processing of FPI and surimi and no negative effects on gel qualities. The uniqueness of tropical fish tilapia was thought due to its high thermal stability. The quality of surimi gels was affected more so under various rigor stages and frozen storage compared to FPI gels. Conversely, the addition of salt into FPI induced a higher degree of unfolding protein structure prior to gelation compared to surimi. In addition, comminution conditions affected the quality of FPI gel more than that of surimi gel. A significant increase in puncture gel texture was observed when FPI and surimi were chopped at 25°C for 18 min compared to samples chopped at 5°C for 6 min. The comparable results were detected as measured by storage modulus. FPI chopped with 3% salt at 5°C for 6 min showed the lowest gel texture among all treatments, possibly because protein structure was not disintegrated appropriately and formed larger protein aggregates and coarser gels demonstrated by microscopic analyses. Results suggested controlling chopping temperature and time, and the addition of salt, may be significant factors to enhance production of high quality gel in FPI and surimi. Moreover, the effect of various comminution conditions on structural changes were investigated using Fourier transform infrared (FT-IR) and Raman spectroscopy. Both procedures exhibited increasing chopping temperature and time, adding salt, promoted a higher degree of unfolding protein structure in FPI and surimi paste made from tilapia, when they were chopped at 25°C for 18 min compared to samples chopped at 5°C for 6 min. Also, FPI and surimi gels prepared after chopping at 25°C for 18 min revealed higher β-sheet contents and more chemical bonds such as hydrophobic interactions and disulfide bonds than those at 5°C for 6 min. Controlling comminution conditions may be one of the important factors to produce high quality gels from FPI and surimi using tropical fish like tilapia. Additionally, FT-IR and Raman spectroscopy are useful complementary tools, allowing a better interpretation of the structural changes in FPI and surimi under various comminution conditions. The gelation properties of blending two different fish proteins obtained from surimi and FPI at different ratios was evaluated. Effects of blending surimi and FPI on gel functionality (whiteness, hardness, and cohesiveness) demonstrated a linear pattern when the proportion of surimi is larger than or equal to that of FPI. Also, breaking force and penetration distance decreased significantly when the ratio of surimi to FPI decreased. Results indicated gels cooked in a water bath tended to exhibit a higher breaking force than gels cooked ohmically. On the other hand, a higher penetration distance was observed for gels cooked ohmically compared to gels cooked in a water bath. Blending surimi and FPI did not affect the inter-molecular interactions of protein in a linear pattern, like mixing various grades of surimi, but this might be feasible only when the proportion of FPI does not exceed 50%. Close

• 1572. [Article] Overstory composition and stand structure shifts within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone

  Ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta var. murrayana) forests of south-central Oregon have been extensively researched over the last century. However, little information has ...

  Citation × Citation Citation Abstract Copy Title: Overstory composition and stand structure shifts within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone Author: Shuffield, Chaylon D. Ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta var. murrayana) forests of south-central Oregon have been extensively researched over the last century. However, little information has been reported on overstory composition and stand structure shifts associated with fire exclusion within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone. In recent time, the lack of disturbance history and quantitative information needed to reconstruct historic stand conditions has become a growing concern for many ecologists. The need to collect quantitative information from remnant old-growth stands is imperative to improve restoration activities, incorporate stand-level diversity, identify the degree of successional departure, and to ensure valuable data is archived for future reference and ecological analysis. In Chapter 1, an exhaustive search for published information on early land-use practices specific to our study area was performed to: (1) identify the degree of Native American influence on vegetation; (2) identify direct and indirect Euro-American disturbances involving the loss of natural processes; and (3) establish a reference period for appropriate representation of historic conditions. In Chapter 2, remnant old-growth stands were analyzed using dendrochronological techniques and statistical comparisons to quantify: (1) shifts in overstory composition and stand structure; (2) growth and development of ponderosa pine and lodgepole pine across time; and to (3) characterize the influence of climate and fire on species recruitment. Our analysis indicated successional trajectory shifts occurred shortly after the loss of Native American influence beginning around 1850 and associated affects of intensive grazing following 1880. Age reconstruction displayed an exponential pattern of recruitment between 1880 and 1950. Since 1850, our analysis revealed a reduction in average tree basal area growth and height development of understory ponderosa pine and lodgepole pine. Ponderosa pine greater than 150 years old accounted for less than 5.0% of the total contemporary density, but composed 45.0% of the total basal area. Lodgepole pine greater than 100 years old accounted for approximately 3.0% of the total contemporary density and composed 12.8% of the total basal area. Stand density for our study area averaged 25.3 trees per hectare for ponderosa pine greater than 53.3 centimeters diameter at 1.4 meters. We report low levels of lodgepole pine recruitment (2/hectare/decade) prior to 1880 and suggest the long-term development of less fire-resistant lodgepole pine has been favored since fire exclusion. Furthermore, contemporary settings support conditions associated to atypical mountain pine beetle outbreaks and fire behavior known to cause mortality of large diameter ponderosa pine. Restoration of remnant inter-mixed stands requires the aggressive removal of lodgepole pine and re-introduction of fire to provide long-term sustainability of ecosystem health and preservation of large diameter ponderosa pine. Title: Overstory composition and stand structure shifts within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone Author: Shuffield, Chaylon D. Ponderosa pine (Pinus ponderosa) and lodgepole pine (Pinus contorta var. murrayana) forests of south-central Oregon have been extensively researched over the last century. However, little information has been reported on overstory composition and stand structure shifts associated with fire exclusion within inter-mixed ponderosa pine and lodgepole pine stands of the south-central Oregon pumice zone. In recent time, the lack of disturbance history and quantitative information needed to reconstruct historic stand conditions has become a growing concern for many ecologists. The need to collect quantitative information from remnant old-growth stands is imperative to improve restoration activities, incorporate stand-level diversity, identify the degree of successional departure, and to ensure valuable data is archived for future reference and ecological analysis. In Chapter 1, an exhaustive search for published information on early land-use practices specific to our study area was performed to: (1) identify the degree of Native American influence on vegetation; (2) identify direct and indirect Euro-American disturbances involving the loss of natural processes; and (3) establish a reference period for appropriate representation of historic conditions. In Chapter 2, remnant old-growth stands were analyzed using dendrochronological techniques and statistical comparisons to quantify: (1) shifts in overstory composition and stand structure; (2) growth and development of ponderosa pine and lodgepole pine across time; and to (3) characterize the influence of climate and fire on species recruitment. Our analysis indicated successional trajectory shifts occurred shortly after the loss of Native American influence beginning around 1850 and associated affects of intensive grazing following 1880. Age reconstruction displayed an exponential pattern of recruitment between 1880 and 1950. Since 1850, our analysis revealed a reduction in average tree basal area growth and height development of understory ponderosa pine and lodgepole pine. Ponderosa pine greater than 150 years old accounted for less than 5.0% of the total contemporary density, but composed 45.0% of the total basal area. Lodgepole pine greater than 100 years old accounted for approximately 3.0% of the total contemporary density and composed 12.8% of the total basal area. Stand density for our study area averaged 25.3 trees per hectare for ponderosa pine greater than 53.3 centimeters diameter at 1.4 meters. We report low levels of lodgepole pine recruitment (2/hectare/decade) prior to 1880 and suggest the long-term development of less fire-resistant lodgepole pine has been favored since fire exclusion. Furthermore, contemporary settings support conditions associated to atypical mountain pine beetle outbreaks and fire behavior known to cause mortality of large diameter ponderosa pine. Restoration of remnant inter-mixed stands requires the aggressive removal of lodgepole pine and re-introduction of fire to provide long-term sustainability of ecosystem health and preservation of large diameter ponderosa pine. Close

• 1573. [Article] Measuring costs of sequestering carbon in forest stands with different management regimes in western Oregon

  This project was a part of larger work that compared major factors controlling patterns of carbon dynamics in two regions of the globe, the Pacific Northwest, USA and northwestern Russia. It was funded ...

  Citation × Citation Citation Abstract Copy Title: Measuring costs of sequestering carbon in forest stands with different management regimes in western Oregon Author: Zyrina, Olga A. This project was a part of larger work that compared major factors controlling patterns of carbon dynamics in two regions of the globe, the Pacific Northwest, USA and northwestern Russia. It was funded through the NASA foundation (grant # NAG5- 6242). Human economic activity is causing the release of pollutants such as carbon dioxide. The increased concentration of pollutants in the atmosphere is thought to cause greenhouse effect, in other words - the warming of the earth and lower atmosphere. Different methods are proposed to reduce concentration of greenhouse gases (GHG) in the atmosphere. Some involve development of more clean technologies. Some involve reductions in the use of fossil fuels. Another possibility is to store carbon (C) as live biomass. Plants use C for growth and development. Using forests to sequester C is one strategy for mitigating effects of GHG emissions. There are many methods in forestry to grow trees and produce wood products. Some of them include clearcutting, thinning, fertilizing, burning, and partial cutting. This project had three purposes. First, was to investigate the effect of a wide variety of silvicultural treatments on C storage and the economic value of harvested forest products. We measured economic value as soil expectation value. Second, was to use Data Envelopment Analysis to determine the efficient set of treatments, which make up the Production Possibility Frontier (PPF) in terms of C and economic value. Third, was to use the PPF to measure the marginal cost of carbon storage in moving from high SEV and relatively low C storage to lower SEV and relatively high C storage. C storage and timber harvest were simulated using the STANDCARB model for forest types common in north-western Oregon with two tree species, Douglas fir (Pseudotsuga menziesii) and Western hemlock (Tsuga heterophylla). Fifty silvicultural regimes were investigated. They included clearcutting with rotations of 50, 70, 90, 110, 130, and 150. Each of the six rotation ages had eight combinations of silvicultural treatments consisting of artificial and natural regeneration, growth enhancement (GE) and thinning. Two partial cutting regimes: group selection and single-tree selection were also used in the analysis. C storage was calculated for every output year of each model run as a sum of live, dead, and stable C. C storage for each silvicultural regime was measured as the average over five full rotations from the steady state portion of the run. The analysis showed that average C increases with rotation age from 335.99 MgC/ha with 50-year rotation with natural regeneration and thinning to 826.36 MgCIha with 150-year rotation with artificial regeneration and GE. The use of artificial regeneration compared to natural regeneration gave a 20-30 MgC/ha improvement for all regimes. The total harvest from thinning and clearcutting over the rotation period averaged for several runs varied from 505.34 m3/ha (with 50-year rotation no treatment) to 1782.24 m3/ha (with 150-year rotation with GE and thinning) The use of artificial compared to natural regeneration gave a 20-50 m3/ha increase in harvest for all regimes. SEV is the present value of net revenues from perpetually growing tree crops following the specified regime. It measures the economic value of each regime. Generally, SEV has a negative correlation with rotation length. Using a 3.5 percent real discount rate, the maximum SEV ($7904.3/hectare) was obtained from 50-year rotation with artificial regeneration, GE and thinning In contrast, SEV for 130-year rotation with artificial regeneration was only $446.68/hectare. Using Data Envelopment Analysis (OnFront software) we found that 8 of the 50 regimes investigated were efficient in their ability to store C and produce economic value. The efficient regimes included 50, 110, 130 and 150-year rotations with artificial regeneration, GE and thinning; 110, 130 and 150-year rotations with natural regeneration, GE and thinning, and the 150-year rotation with natural regeneration and GE. When regimes with GE were excluded, we found 7 efficient regimes: 50 and 150-year rotations with artificial regeneration and thinning, 50, 110, 130 and 150-year rotations with natural regeneration and thinning, and the 150-year rotation with natural regeneration. The marginal cost of C storage is the SEV lost per unit of C due to change in silvicultural regimes that results in increase of average C stored. Marginal cost analysis indicated that marginal cost values were similar for regimes with GE and without. As C storage increased, the marginal cost generally increased. The increase in C storage from 428 MgC/ha to 589 MgC/ha implied a marginal cost of $13.28IMgC. In case of increasing C storage from 683 MgC/ha to 802.7 MgC/ha, the marginal cost would increase to $32.79JMgC. Title: Measuring costs of sequestering carbon in forest stands with different management regimes in western Oregon Author: Zyrina, Olga A. This project was a part of larger work that compared major factors controlling patterns of carbon dynamics in two regions of the globe, the Pacific Northwest, USA and northwestern Russia. It was funded through the NASA foundation (grant # NAG5- 6242). Human economic activity is causing the release of pollutants such as carbon dioxide. The increased concentration of pollutants in the atmosphere is thought to cause greenhouse effect, in other words - the warming of the earth and lower atmosphere. Different methods are proposed to reduce concentration of greenhouse gases (GHG) in the atmosphere. Some involve development of more clean technologies. Some involve reductions in the use of fossil fuels. Another possibility is to store carbon (C) as live biomass. Plants use C for growth and development. Using forests to sequester C is one strategy for mitigating effects of GHG emissions. There are many methods in forestry to grow trees and produce wood products. Some of them include clearcutting, thinning, fertilizing, burning, and partial cutting. This project had three purposes. First, was to investigate the effect of a wide variety of silvicultural treatments on C storage and the economic value of harvested forest products. We measured economic value as soil expectation value. Second, was to use Data Envelopment Analysis to determine the efficient set of treatments, which make up the Production Possibility Frontier (PPF) in terms of C and economic value. Third, was to use the PPF to measure the marginal cost of carbon storage in moving from high SEV and relatively low C storage to lower SEV and relatively high C storage. C storage and timber harvest were simulated using the STANDCARB model for forest types common in north-western Oregon with two tree species, Douglas fir (Pseudotsuga menziesii) and Western hemlock (Tsuga heterophylla). Fifty silvicultural regimes were investigated. They included clearcutting with rotations of 50, 70, 90, 110, 130, and 150. Each of the six rotation ages had eight combinations of silvicultural treatments consisting of artificial and natural regeneration, growth enhancement (GE) and thinning. Two partial cutting regimes: group selection and single-tree selection were also used in the analysis. C storage was calculated for every output year of each model run as a sum of live, dead, and stable C. C storage for each silvicultural regime was measured as the average over five full rotations from the steady state portion of the run. The analysis showed that average C increases with rotation age from 335.99 MgC/ha with 50-year rotation with natural regeneration and thinning to 826.36 MgCIha with 150-year rotation with artificial regeneration and GE. The use of artificial regeneration compared to natural regeneration gave a 20-30 MgC/ha improvement for all regimes. The total harvest from thinning and clearcutting over the rotation period averaged for several runs varied from 505.34 m3/ha (with 50-year rotation no treatment) to 1782.24 m3/ha (with 150-year rotation with GE and thinning) The use of artificial compared to natural regeneration gave a 20-50 m3/ha increase in harvest for all regimes. SEV is the present value of net revenues from perpetually growing tree crops following the specified regime. It measures the economic value of each regime. Generally, SEV has a negative correlation with rotation length. Using a 3.5 percent real discount rate, the maximum SEV ($7904.3/hectare) was obtained from 50-year rotation with artificial regeneration, GE and thinning In contrast, SEV for 130-year rotation with artificial regeneration was only $446.68/hectare. Using Data Envelopment Analysis (OnFront software) we found that 8 of the 50 regimes investigated were efficient in their ability to store C and produce economic value. The efficient regimes included 50, 110, 130 and 150-year rotations with artificial regeneration, GE and thinning; 110, 130 and 150-year rotations with natural regeneration, GE and thinning, and the 150-year rotation with natural regeneration and GE. When regimes with GE were excluded, we found 7 efficient regimes: 50 and 150-year rotations with artificial regeneration and thinning, 50, 110, 130 and 150-year rotations with natural regeneration and thinning, and the 150-year rotation with natural regeneration. The marginal cost of C storage is the SEV lost per unit of C due to change in silvicultural regimes that results in increase of average C stored. Marginal cost analysis indicated that marginal cost values were similar for regimes with GE and without. As C storage increased, the marginal cost generally increased. The increase in C storage from 428 MgC/ha to 589 MgC/ha implied a marginal cost of $13.28IMgC. In case of increasing C storage from 683 MgC/ha to 802.7 MgC/ha, the marginal cost would increase to $32.79JMgC. Close

• 1574. [Article] Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest

  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 ...

  Citation × Citation Citation Abstract Copy Title: Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest Author: Danielson, Rachel E. 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 β-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 NO₃⁻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. Title: Response of Soil Microbially Mediated Nutrient Cycling and Community Structure to Timber Harvest in the Pacific Northwest Author: Danielson, Rachel E. 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 β-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 NO₃⁻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. Close

• 1575. [Article] Four centuries of soil carbon and nitrogen change after severe fire in a Western Cascades forest landscape

  Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare. Consequently, long-term effects of fire on soils are often ...

  Citation × Citation Citation Abstract Copy Title: Four centuries of soil carbon and nitrogen change after severe fire in a Western Cascades forest landscape Author: Giesen, Thomas William Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare. Consequently, long-term effects of fire on soils are often hypothesized from short-term effects. In a chronosequence study, I studied 24 western Cascades (Oregon) forest stands thought to have been initiated in fire. Twelve of those burned about 150 years ago (“young” sites), and the other 12 burned an average of 550 years ago (“old” sites). I hypothesized that young stands would have less carbon (C) and nitrogen (N) in forest floor and in 0 -10 cm mineral soil than old stands. I found that forest floor N pools of old sites (average = 1,823 kg/ha ± s.e. = 132 kg/ha) were significantly greater than young sites (1,450 ± 98 kg/ha). Similarly, forest floor C pools of old sites (62,980 ± 5,403 kg/ha) were significantly greater than young sites (49,032 ± 2,965 kg/ha). Greater N and C pools in forest floor of old sites resulted from greater forest floor mass in old sites; concentrations of both N and C, and C:N ratios, did not differ significantly by forest age class. In mineral soil, neither concentrations nor pools of N and C differed between young and old sites. Despite overall similarity of C:N ratios in young versus old sites, potential N mineralization rates were twice as high in forest floor of old sites (average = 60 ± 7.3 mg N / g soil) than young sites (26 ± 3.5 mg N / g soil), . Nitrate accounted for only 2% or less of total N mineralized in forest floor samples. In mineral soil, potential net N mineralization did not differ by forest age class. The pattern of high net N mineralization and low nitrification in old forests is consistent with other studies of fire-prone forests, yet contrasts with many studies of forests that lack fire, and suggests that ammonium is not the sole control over nitrification in fire-prone ecosystems. Overall, fire appears to impart a longterm legacy of reduced forest floor N and C pools in this western Oregon Cascades landscape, which suggests that current fire-suppression activities in the region may increase forest floor N and C storage over historical conditions within several centuries. The differences in forest floor and soil N cycling processes that I observed by forest age class raise the further possibility that fire exclusion in these forests may change the relative abundance of soil inorganic N forms to favor ammonium over nitrate. Such changes may have unknown consequences for relative competitive abilities of plant and microbial species that rely preferentially on different N-forms to meet N nutrition requirements. While forest floor N and C pools increase from young to old stands, forest floor and soil N and C pools are not different, or decline, between 450 year old stands and the oldest stands at 800+ years, That, and other, anomalous changes in values from ~450 to 800+ years, suggest possible changes in ecosystem functions, and may indicate that this landscape could be a fruitful study area for examinations of a mature, steady-state ecosystem Title: Four centuries of soil carbon and nitrogen change after severe fire in a Western Cascades forest landscape Author: Giesen, Thomas William Fire is a major disturbance process in many forests. Long-term studies of the biogeochemical effects of fires, especially on soils, are very rare. Consequently, long-term effects of fire on soils are often hypothesized from short-term effects. In a chronosequence study, I studied 24 western Cascades (Oregon) forest stands thought to have been initiated in fire. Twelve of those burned about 150 years ago (“young” sites), and the other 12 burned an average of 550 years ago (“old” sites). I hypothesized that young stands would have less carbon (C) and nitrogen (N) in forest floor and in 0 -10 cm mineral soil than old stands. I found that forest floor N pools of old sites (average = 1,823 kg/ha ± s.e. = 132 kg/ha) were significantly greater than young sites (1,450 ± 98 kg/ha). Similarly, forest floor C pools of old sites (62,980 ± 5,403 kg/ha) were significantly greater than young sites (49,032 ± 2,965 kg/ha). Greater N and C pools in forest floor of old sites resulted from greater forest floor mass in old sites; concentrations of both N and C, and C:N ratios, did not differ significantly by forest age class. In mineral soil, neither concentrations nor pools of N and C differed between young and old sites. Despite overall similarity of C:N ratios in young versus old sites, potential N mineralization rates were twice as high in forest floor of old sites (average = 60 ± 7.3 mg N / g soil) than young sites (26 ± 3.5 mg N / g soil), . Nitrate accounted for only 2% or less of total N mineralized in forest floor samples. In mineral soil, potential net N mineralization did not differ by forest age class. The pattern of high net N mineralization and low nitrification in old forests is consistent with other studies of fire-prone forests, yet contrasts with many studies of forests that lack fire, and suggests that ammonium is not the sole control over nitrification in fire-prone ecosystems. Overall, fire appears to impart a longterm legacy of reduced forest floor N and C pools in this western Oregon Cascades landscape, which suggests that current fire-suppression activities in the region may increase forest floor N and C storage over historical conditions within several centuries. The differences in forest floor and soil N cycling processes that I observed by forest age class raise the further possibility that fire exclusion in these forests may change the relative abundance of soil inorganic N forms to favor ammonium over nitrate. Such changes may have unknown consequences for relative competitive abilities of plant and microbial species that rely preferentially on different N-forms to meet N nutrition requirements. While forest floor N and C pools increase from young to old stands, forest floor and soil N and C pools are not different, or decline, between 450 year old stands and the oldest stands at 800+ years, That, and other, anomalous changes in values from ~450 to 800+ years, suggest possible changes in ecosystem functions, and may indicate that this landscape could be a fruitful study area for examinations of a mature, steady-state ecosystem Close

• 1576. [Article] Road networks, timber harvest, and the spread of Phytophthora root rot infestations of Port-Orford-­cedar in southwest Oregon

  Phytophthora lateralis is the causal agent of cedar root rot, a fatal forest pathogen whose principal host is Chamaecyparis lawsoniana (Port-Orford-cedar), a predominantly riparian-restricted endemic tree ...

  Citation × Citation Citation Abstract Copy Title: Road networks, timber harvest, and the spread of Phytophthora root rot infestations of Port-Orford-­cedar in southwest Oregon Author: Clark, William C. Phytophthora lateralis is the causal agent of cedar root rot, a fatal forest pathogen whose principal host is Chamaecyparis lawsoniana (Port-Orford-cedar), a predominantly riparian-restricted endemic tree species of ecological, economical, and cultural importance to coastal Oregon and California. Local scale distribution of P. lateralis is thought to be associated with timber harvest and road-building disturbances. However, knowledge of the landscape-scale factors that contribute to successful invasions of P. lateralis is also important for effective land management of Port-Orford-cedar. P. lateralis is able to infest in wet conditions via stream networks (zoospore) and dry conditions via road networks (resting spore). This study tested the hypothesis that vehicles spread P. lateralis by relating its distribution to traffic intensive, anthropogenic disturbances (i.e. a road network, timber harvest) over a 31-yr period in a 3,910-km² portion of the Rogue River-Siskiyou National Forest in the Siskiyou Mountains of Oregon. Indices of road disturbance (presence/absence, configuration, length, density, road-stream network connectivity) and timber harvest (presence/absence, area, density, frequency) were related to locations of infested cedar populations from a USFS survey dataset using a geographic information system (GIS). About 40% of 934 7th-field catchments were infested with the pathogen. Total road length of the study site was 5,070 km; maximum road density was 8.2 km/km2 and averaged 1.6 km/km² in roaded catchments (n = 766). Timber activities extracted 17,370 ha (2,338 cutting units) of forest across 509 catchments; 345 catchments were cut ≥ twice. Maximum harvest density was 0.92 km²/km² ([mean] = 0.04). Both road networks and timber harvest patchworks were significantly related to cedar root rot heterogeneity. Chi-squared contingency tables showed that infestation rates were 2.2 times higher in catchments with roads compared to roadless catchments and 1.4 times higher in catchments with road-stream intersections compared to those that were unconnected. Infestation was twice as likely in catchments with both harvest and road presence than road presence alone. Single-variable logistic regression showed that a one percent increase in harvest density increased infestation odds 25% and a one-unit (km/km²) increase in road density increased infestation odds 80%. Road and stream network configuration was also important to pathogen distribution: 1) uninfested catchments are most likely to be spatially removed from infested, roaded catchments, 2) only 11% of 287 roaded catchments downstream of infested, roaded catchments were uninfested, and 3) only 12% of 319 catchments downstream of infested catchments were uninfested. Road networks and timber harvest patchworks appear to reduce landscape heterogeneity by providing up-catchment and down-catchment access to host populations by linking pathogenic materials to the stream network. Timber harvest data suggest that while infestation risk to Port-Orford-cedar populations remains high, management policies may have curbed infestation risk in timber-harvested catchments; if this is a result of specific P. lateralis mitigation policies adopted in the late 1980's or broader, region-wide conservation policies (i.e. the Northwest Forest Plan) is yet unclear. Title: Road networks, timber harvest, and the spread of Phytophthora root rot infestations of Port-Orford-­cedar in southwest Oregon Author: Clark, William C. Phytophthora lateralis is the causal agent of cedar root rot, a fatal forest pathogen whose principal host is Chamaecyparis lawsoniana (Port-Orford-cedar), a predominantly riparian-restricted endemic tree species of ecological, economical, and cultural importance to coastal Oregon and California. Local scale distribution of P. lateralis is thought to be associated with timber harvest and road-building disturbances. However, knowledge of the landscape-scale factors that contribute to successful invasions of P. lateralis is also important for effective land management of Port-Orford-cedar. P. lateralis is able to infest in wet conditions via stream networks (zoospore) and dry conditions via road networks (resting spore). This study tested the hypothesis that vehicles spread P. lateralis by relating its distribution to traffic intensive, anthropogenic disturbances (i.e. a road network, timber harvest) over a 31-yr period in a 3,910-km² portion of the Rogue River-Siskiyou National Forest in the Siskiyou Mountains of Oregon. Indices of road disturbance (presence/absence, configuration, length, density, road-stream network connectivity) and timber harvest (presence/absence, area, density, frequency) were related to locations of infested cedar populations from a USFS survey dataset using a geographic information system (GIS). About 40% of 934 7th-field catchments were infested with the pathogen. Total road length of the study site was 5,070 km; maximum road density was 8.2 km/km2 and averaged 1.6 km/km² in roaded catchments (n = 766). Timber activities extracted 17,370 ha (2,338 cutting units) of forest across 509 catchments; 345 catchments were cut ≥ twice. Maximum harvest density was 0.92 km²/km² ([mean] = 0.04). Both road networks and timber harvest patchworks were significantly related to cedar root rot heterogeneity. Chi-squared contingency tables showed that infestation rates were 2.2 times higher in catchments with roads compared to roadless catchments and 1.4 times higher in catchments with road-stream intersections compared to those that were unconnected. Infestation was twice as likely in catchments with both harvest and road presence than road presence alone. Single-variable logistic regression showed that a one percent increase in harvest density increased infestation odds 25% and a one-unit (km/km²) increase in road density increased infestation odds 80%. Road and stream network configuration was also important to pathogen distribution: 1) uninfested catchments are most likely to be spatially removed from infested, roaded catchments, 2) only 11% of 287 roaded catchments downstream of infested, roaded catchments were uninfested, and 3) only 12% of 319 catchments downstream of infested catchments were uninfested. Road networks and timber harvest patchworks appear to reduce landscape heterogeneity by providing up-catchment and down-catchment access to host populations by linking pathogenic materials to the stream network. Timber harvest data suggest that while infestation risk to Port-Orford-cedar populations remains high, management policies may have curbed infestation risk in timber-harvested catchments; if this is a result of specific P. lateralis mitigation policies adopted in the late 1980's or broader, region-wide conservation policies (i.e. the Northwest Forest Plan) is yet unclear. Close

• 1577. [Article] The physiology of seasonal growth in tall fescue varieties (Festuca arundinacea Schreb.)

  The winter and summer growth of varieties of tall fescue (Festuca arundinacea Schreb.) that had originated from the Mediterranean region (Oregon 1000 and Tunisia) and northern Europe (Alta) were studied ...

  Citation × Citation Citation Abstract Copy Title: The physiology of seasonal growth in tall fescue varieties (Festuca arundinacea Schreb.) Author: Blacklow, Warren Marcus The winter and summer growth of varieties of tall fescue (Festuca arundinacea Schreb.) that had originated from the Mediterranean region (Oregon 1000 and Tunisia) and northern Europe (Alta) were studied outdoors in the Mediterranean climate of western Oregon, and in greenhouses and controlled environment chambers. Treatments of temperature, photoperiod and gibberellic acid (GA) were imposed in order to establish the limitations to winter and summer forage production. Measurements of photosynthesis and the distribution of assimilates were made by growth analysis and the level and nature of reserve carbohydrates by the copper-iodometric method. In western Oregon, the varieties that had originated from the Mediterranean region made more foliar growth during the winter but less during the summer than Alta. These two different patterns of seasonal growth were interpreted as ecotypic variation that had enabled the species to survive seasons of stress in the regions of origin--freezing winters of northern Europe and summer droughts of the Mediterranean. Cubes of sod taken during the winter months from swards of Alta and Tunisia showed that Alta had a greater density of tillers and buds, and a higher level of reserve carbohydrates than Tunisia. This result suggested that Tunisia utilized photosynthate during the winter for the production of leaves rather than storing it as carbohydrates. During the winter of 1967 the foliar growth of both Alta and Oregon 1000 was increased by a temperature of 15 to 20C, a foliar spray of 0.1% GA, and possibly by a long photoperiod. The suggestion was that winter growth was limited more by the internal growth regulator balance than the external weather, and that relative rather than true dormancy was involved. Although the chlorophyll concentration in the foliage was reduced by GA the total chlorophyll was actually increased by 10 to 30% and, consequently, the chlorosis may not be deleterious to pasture production. The rate of regrowth of Tunisia was greater at 7/3C than Alta but this difference was eliminated by GA. Rate of regrowth may be an important determinant of winter growth of ecotypes of forages grasses and GA may promote the mobilization, or utilization, or both, of reserve carbohydrate--reserves that were found to be higher in Alta than Tunisia. At the end of a prolonged exposure of 18 weeks in a simulated winter environment of 7/3C and 19 ly/day (400 to 750 nm) the total weight of Tunisia was greater than Alta and proportionately more dry weight was present in the leaves than roots. The total available carbohydrates (TAG) extracted with 0.2N H₂SO₄ was similar for Alta and Tunisia; it was 20% of the dry weight of stems. Gibberellic acid increased the concentration of TAC 6% in Alta and 4% in Tunisia. The total water soluble carbohydrates (WSC) were 14 and 9% of the stems of Tunisia and Alta respectively, and 6% of the leaves and 5% of the roots of both varieties. Fructosans were the main component of WSC, and sucrose and reducing sugars were of lesser concentrations. The WSC were increased by GA in all parts of the plants and the increase was greatest in Alta; sucrose showed the greatest increase. Subtraction of WSC from TAG gave an estimation of starch; it was unexpectedly high with concentrations as high as fructosans and indicated that 0.2N H₂SO₄ may have extracted structural carbohydrates. The superior growth rate of Alta in the summer was established in June. At the end of June 1968 the relative growth rate of both Alta and Tunisia was increased by GA due to a stimulation of net assimilation rates. The WSC were highest in the stems and were 14 and 9% of the stems of Alta and Tunisia respectively. Fructosans were the main WSC and the higher level of WSC in Alta was due to a higher level of fructosans. Gibberellic acid increased the WSC by 1% of the dry weight during the treatment time of 8 days. The measurement of photosynthesis of leaf segments of tall fescue by manometry was unreliable. The activity of isolated chloroplasts was also unreliable although some improvement was obtained by isolating in the presence of polyvinylpyrrolidone. The concept developed in this thesis was that when an ecotype is introduced to a new environment, or used as a basis for a new variety, the production and utilization of photosynthate may be controlled by an internal growth regulator balance which is not well coordinated with the weather. In such a circumstance, the possibility exists that the growth regulator balance may be adjusted by a timely application of the appropriate growth regulators in order that the variety may grow to the limit of its genetic capacity during periods of favorable weather. Title: The physiology of seasonal growth in tall fescue varieties (Festuca arundinacea Schreb.) Author: Blacklow, Warren Marcus The winter and summer growth of varieties of tall fescue (Festuca arundinacea Schreb.) that had originated from the Mediterranean region (Oregon 1000 and Tunisia) and northern Europe (Alta) were studied outdoors in the Mediterranean climate of western Oregon, and in greenhouses and controlled environment chambers. Treatments of temperature, photoperiod and gibberellic acid (GA) were imposed in order to establish the limitations to winter and summer forage production. Measurements of photosynthesis and the distribution of assimilates were made by growth analysis and the level and nature of reserve carbohydrates by the copper-iodometric method. In western Oregon, the varieties that had originated from the Mediterranean region made more foliar growth during the winter but less during the summer than Alta. These two different patterns of seasonal growth were interpreted as ecotypic variation that had enabled the species to survive seasons of stress in the regions of origin--freezing winters of northern Europe and summer droughts of the Mediterranean. Cubes of sod taken during the winter months from swards of Alta and Tunisia showed that Alta had a greater density of tillers and buds, and a higher level of reserve carbohydrates than Tunisia. This result suggested that Tunisia utilized photosynthate during the winter for the production of leaves rather than storing it as carbohydrates. During the winter of 1967 the foliar growth of both Alta and Oregon 1000 was increased by a temperature of 15 to 20C, a foliar spray of 0.1% GA, and possibly by a long photoperiod. The suggestion was that winter growth was limited more by the internal growth regulator balance than the external weather, and that relative rather than true dormancy was involved. Although the chlorophyll concentration in the foliage was reduced by GA the total chlorophyll was actually increased by 10 to 30% and, consequently, the chlorosis may not be deleterious to pasture production. The rate of regrowth of Tunisia was greater at 7/3C than Alta but this difference was eliminated by GA. Rate of regrowth may be an important determinant of winter growth of ecotypes of forages grasses and GA may promote the mobilization, or utilization, or both, of reserve carbohydrate--reserves that were found to be higher in Alta than Tunisia. At the end of a prolonged exposure of 18 weeks in a simulated winter environment of 7/3C and 19 ly/day (400 to 750 nm) the total weight of Tunisia was greater than Alta and proportionately more dry weight was present in the leaves than roots. The total available carbohydrates (TAG) extracted with 0.2N H₂SO₄ was similar for Alta and Tunisia; it was 20% of the dry weight of stems. Gibberellic acid increased the concentration of TAC 6% in Alta and 4% in Tunisia. The total water soluble carbohydrates (WSC) were 14 and 9% of the stems of Tunisia and Alta respectively, and 6% of the leaves and 5% of the roots of both varieties. Fructosans were the main component of WSC, and sucrose and reducing sugars were of lesser concentrations. The WSC were increased by GA in all parts of the plants and the increase was greatest in Alta; sucrose showed the greatest increase. Subtraction of WSC from TAG gave an estimation of starch; it was unexpectedly high with concentrations as high as fructosans and indicated that 0.2N H₂SO₄ may have extracted structural carbohydrates. The superior growth rate of Alta in the summer was established in June. At the end of June 1968 the relative growth rate of both Alta and Tunisia was increased by GA due to a stimulation of net assimilation rates. The WSC were highest in the stems and were 14 and 9% of the stems of Alta and Tunisia respectively. Fructosans were the main WSC and the higher level of WSC in Alta was due to a higher level of fructosans. Gibberellic acid increased the WSC by 1% of the dry weight during the treatment time of 8 days. The measurement of photosynthesis of leaf segments of tall fescue by manometry was unreliable. The activity of isolated chloroplasts was also unreliable although some improvement was obtained by isolating in the presence of polyvinylpyrrolidone. The concept developed in this thesis was that when an ecotype is introduced to a new environment, or used as a basis for a new variety, the production and utilization of photosynthate may be controlled by an internal growth regulator balance which is not well coordinated with the weather. In such a circumstance, the possibility exists that the growth regulator balance may be adjusted by a timely application of the appropriate growth regulators in order that the variety may grow to the limit of its genetic capacity during periods of favorable weather. Close

• 1578. [Article] Energy recovery from biodiesel waste : performance of microbial electrochemical systems on glycerol

  Pure glycerol and the crude waste glycerin byproduct of biodiesel production were tested as substrates for electricity production in single-chamber, air-cathode microbial fuel cells (MFCs) and in single-chamber ...

  Citation × Citation Citation Abstract Copy Title: Energy recovery from biodiesel waste : performance of microbial electrochemical systems on glycerol Author: Chignell, Jeremy Pure glycerol and the crude waste glycerin byproduct of biodiesel production were tested as substrates for electricity production in single-chamber, air-cathode microbial fuel cells (MFCs) and in single-chamber microbial electrolysis cells (MECs), using pure and mixed microbial cultures as anode biocatalyst. Current densities of 0.40 A/m² and 0.13 A/m² were generated on 50 mM glycerol in aircathode MFCs by pure cultures of Shewanella oneidensis MR-1 and Rhodopseudomonas palustris ATCC 17001, respectively, after aerobic flask culture. A mixed culture of bacteria originally derived from wastewater generated higher current and power densities than any of the pure cultures and, at 10 mM glycerol, achieved an average maximum power density of 2.70 ± 0.15 W/m² anode surface area (47.8 ± 2.6 W/m³ reactor volume) at a current density of 7.66 ± 0.21 A/m² anode surface area. At an optimal fixed external resistance of 210 Ω the mixed culture MFC followed Michaelis-Menten saturation kinetics, resulting in a Km of 2.92 mM glycerol and a theoretical Vmax of 0.437 volts. Coulombic efficiencies decreased linearly with increased glycerol concentration. Power was generated by mixed culture MFCs from raw waste glycerin byproduct of biodiesel manufacture both with and without methanol, and with and without potassium salts and soaps. Maximum volumetric current and power densities achieved on waste glycerin (147.7 A/m³ and 56.8 W/m³) were greater than those reported in previous studies, but CE values (10-17.6%) were significantly lower, likely due to losses from aerobic respiration in the micro-aerobic environment of an MFC. Decreases in maximum current density of 43.4% and 65.1% were observed over successive batches of waste glycerin with and without methanol, respectively. Decreases in performance were attributed primarily to the presence of potassium salts, soaps, FFAs, and residual catalyst in the waste glycerin, rather than to methanol. MFCs operating on waste glycerin from which these salts and soaps had been precipitated did not show the same pattern of decreasing maximum current density over multiple batches. Cathode potentiometry indicated a decrease in cathode performance after development of a thick biofilm on the cathode surface during batches of glycerol and glycerin. The best fit lines of cathode potential vs. current density before and after cathode biofilm development during batches of glycerol were used to predict a 30.2% decrease in power density, a result that corresponded well to the 25.7% decrease in power density that was actually observed. Single chamber, membrane-free mixed culture MECs were able to produce hydrogen successfully from both pure glycerol and waste glycerin byproduct from biodiesel manufacture. At an applied voltage of 0.6 V, a maximum current density of 7.5 ± 0.4 A/m² (238.6 ± 12.7 A/m³) was observed, the highest reported current density for a MEC operating on glycerol. Maximum current densities on 0.5% waste glycerin with and without methanol were 0.1-0.2 A/m² less than previously reported values. Maximum hydrogen yields from the mixed culture MEC on 50 mM glycerol were 1.8 ± 0.1 mol hydrogen/mol glycerol, at an energy efficiency of 117.7%. Hydrogen yields on waste glycerin were an order of magnitude lower, though energy efficiencies were greater than those for pure glycerol. Hydrogen production rates were highest at 50 mM glycerol, reaching 1.3 ± 0.1 m³/day/m³. Methane formation reduced hydrogen recoveries by 30.4% and 36.8% for 50 mM and 10 mM glycerol, respectively, assuming cathodic losses of electrons went to methane formation. A culture dominated by a member of the genus Citrobacter produced high current densities of ~2.0 A/m² in MECs on 50 mM glycerol, at yields of 0.93 ± 0.05 mol hydrogen/mol glycerol, energy efficiency greater than 100%, and hydrogen production rate greater than that of fermentative hydrogen production from glycerol by this species and by a genetically altered E. coli strain. The results of this study suggest that, ideally with removal of potassium salts, soaps, and catalyst, and with some method to minimize biofilm formation on the surface of MFC air-cathodes, MFCs and MECs represent promising treatment methods to generate electricity or hydrogen gas while treating the waste products of biodiesel manufacture. These results represent an important step in improving the economic viability of the ever-growing biodiesel industry as the world energy economy continues to shift from fossil fuels to renewable energy sources. Title: Energy recovery from biodiesel waste : performance of microbial electrochemical systems on glycerol Author: Chignell, Jeremy Pure glycerol and the crude waste glycerin byproduct of biodiesel production were tested as substrates for electricity production in single-chamber, air-cathode microbial fuel cells (MFCs) and in single-chamber microbial electrolysis cells (MECs), using pure and mixed microbial cultures as anode biocatalyst. Current densities of 0.40 A/m² and 0.13 A/m² were generated on 50 mM glycerol in aircathode MFCs by pure cultures of Shewanella oneidensis MR-1 and Rhodopseudomonas palustris ATCC 17001, respectively, after aerobic flask culture. A mixed culture of bacteria originally derived from wastewater generated higher current and power densities than any of the pure cultures and, at 10 mM glycerol, achieved an average maximum power density of 2.70 ± 0.15 W/m² anode surface area (47.8 ± 2.6 W/m³ reactor volume) at a current density of 7.66 ± 0.21 A/m² anode surface area. At an optimal fixed external resistance of 210 Ω the mixed culture MFC followed Michaelis-Menten saturation kinetics, resulting in a Km of 2.92 mM glycerol and a theoretical Vmax of 0.437 volts. Coulombic efficiencies decreased linearly with increased glycerol concentration. Power was generated by mixed culture MFCs from raw waste glycerin byproduct of biodiesel manufacture both with and without methanol, and with and without potassium salts and soaps. Maximum volumetric current and power densities achieved on waste glycerin (147.7 A/m³ and 56.8 W/m³) were greater than those reported in previous studies, but CE values (10-17.6%) were significantly lower, likely due to losses from aerobic respiration in the micro-aerobic environment of an MFC. Decreases in maximum current density of 43.4% and 65.1% were observed over successive batches of waste glycerin with and without methanol, respectively. Decreases in performance were attributed primarily to the presence of potassium salts, soaps, FFAs, and residual catalyst in the waste glycerin, rather than to methanol. MFCs operating on waste glycerin from which these salts and soaps had been precipitated did not show the same pattern of decreasing maximum current density over multiple batches. Cathode potentiometry indicated a decrease in cathode performance after development of a thick biofilm on the cathode surface during batches of glycerol and glycerin. The best fit lines of cathode potential vs. current density before and after cathode biofilm development during batches of glycerol were used to predict a 30.2% decrease in power density, a result that corresponded well to the 25.7% decrease in power density that was actually observed. Single chamber, membrane-free mixed culture MECs were able to produce hydrogen successfully from both pure glycerol and waste glycerin byproduct from biodiesel manufacture. At an applied voltage of 0.6 V, a maximum current density of 7.5 ± 0.4 A/m² (238.6 ± 12.7 A/m³) was observed, the highest reported current density for a MEC operating on glycerol. Maximum current densities on 0.5% waste glycerin with and without methanol were 0.1-0.2 A/m² less than previously reported values. Maximum hydrogen yields from the mixed culture MEC on 50 mM glycerol were 1.8 ± 0.1 mol hydrogen/mol glycerol, at an energy efficiency of 117.7%. Hydrogen yields on waste glycerin were an order of magnitude lower, though energy efficiencies were greater than those for pure glycerol. Hydrogen production rates were highest at 50 mM glycerol, reaching 1.3 ± 0.1 m³/day/m³. Methane formation reduced hydrogen recoveries by 30.4% and 36.8% for 50 mM and 10 mM glycerol, respectively, assuming cathodic losses of electrons went to methane formation. A culture dominated by a member of the genus Citrobacter produced high current densities of ~2.0 A/m² in MECs on 50 mM glycerol, at yields of 0.93 ± 0.05 mol hydrogen/mol glycerol, energy efficiency greater than 100%, and hydrogen production rate greater than that of fermentative hydrogen production from glycerol by this species and by a genetically altered E. coli strain. The results of this study suggest that, ideally with removal of potassium salts, soaps, and catalyst, and with some method to minimize biofilm formation on the surface of MFC air-cathodes, MFCs and MECs represent promising treatment methods to generate electricity or hydrogen gas while treating the waste products of biodiesel manufacture. These results represent an important step in improving the economic viability of the ever-growing biodiesel industry as the world energy economy continues to shift from fossil fuels to renewable energy sources. Close

• 1579. [Article] Effects of medicinal herbs on contraction rate of cultured cardiomyocyte. Possible mechanisms involved in the chronotropic effects of hawthorn and berberine in neonatal murine cardiomyocyte

  Herbs have been used for many centuries in diverse civilizations for the treatment of heart disease. Only a few natural supplements claim to have direct cardiovascular actions including hawthorn (Crataegus ...

  Citation × Citation Citation Abstract Copy Title: Effects of medicinal herbs on contraction rate of cultured cardiomyocyte. Possible mechanisms involved in the chronotropic effects of hawthorn and berberine in neonatal murine cardiomyocyte Author: Salehi, Satin Herbs have been used for many centuries in diverse civilizations for the treatment of heart disease. Only a few natural supplements claim to have direct cardiovascular actions including hawthorn (Crataegus spp.) and berberine derived from the Berberidaceae family. Several different studies indicate important cardiovascular effects of hawthorn and berberine. For example, both exert positive inotropic effects and have been used in the treatment of congestive heart failure. Recently, it was shown that hawthorn extract preparations cause negative chronotropic effects in a cultured neonatal murine cardiomyocyte assay independent of beta-adrenergic receptor blockade. The aim of this study was to further characterize the effect of hawthorn extract to decrease the contraction rate of cultured cardiomyocytes. We hypothesized that hawthorn extract may be acting through muscarinic receptors to decrease contraction rate of cardiomyocytes. Atrial and ventricular cardiomyocytes were treated with hawthorn extract in the presence of atropine or himbacine. Changes in the contraction rate of cultured cardiomyocytes revealed that both muscarinic antagonists significantly attenuated the negative chronotropic activity of hawthorn extract. Using quinuclidinyl benzilate, L-[benzylic-4,4'-3H] ([³H]-QNB) as a radioligand antagonist, the effect of a partially purified hawthorn extract fraction to inhibit muscarinic receptor binding was quantified. Hawthorn extract fraction 3 dose-dependently inhibited [³H]-QNB binding to mouse heart membranes. These findings suggest that muscarinic receptors may be involved in the negative chronotropic effect of hawthorn extracts in neonatal murine cardiomyocytes. Berberine exhibits variable positive and negative chronotropic effects in different species. Our first aim was to examine the effect of berberine in a cultured neonatal murine cardiomyocyte assay. Our study demonstrates that berberine has significant negative chronotropic actions on cardiomyocytes which is not an effect of beta-adrenergic receptor blockade. Pertussis toxin (PTX), a Gi/o protein inhibitor, blocked the negative chronotropic activity of berberine. Muscarinic, adenosine, opioid, and α₂ receptors are coupled through a G-protein (Gi/o) to adenylyl cyclase in an inhibitory fashion. Activation of these receptors are primarily responsible for PTX-sensitive negative chronotropic effects in heart. We hypothesized that berberine may be acting through one of these receptor type to decrease contraction rate of cardiomyocytes. For this purpose, we studied the effects of the muscarinic-receptor antagonists, atropine, himbacine, or AF- DX 116 on the negative chronotropic activity of berberine. Muscarinic antagonists completely blocked the effect of berberine on contraction rate of cardiomyocytes, whereas the bradycardic effect of berberine was not inhibited by the opioid, adenosine, or α2 receptor antagonists naloxone, CGS 15943, or phentolamine, respectively. Using [³H]QNB as a radioligand, we demonstrated that berberine bound to muscarinic receptors of adult mouse heart membranes with relatively high affinity. Furthermore, berberine dose-dependently inhibited [³H]QNB binding to muscarinic M2 receptors exogenously expressed in HEK 293 cells. Therefore, the findings of the present study suggest that berberine has muscarinic agonist effects in cultured neonatal murine cardiomyocytes, potentially explaining reported physiological effects of berberine. Cardiac hypertrophy represents the most important factor in the development of congestive heart failure. We investigated the inhibitory effect of berberine on hypertrophy of H9c2 cells. In rat heart-derived H9c2 myoblast cells treated with different hypertrophic agonists such as insulin growth factor II (IGF-II), arginine vasopressin (AVP), phenylephrine, and isoproterenol, protein content and size of cells were significantly increased compared to control group. However, the number of H9c2 cells after treatment with hypertrophic agonists did not differ significantly compared to control. The increases in area of cells and protein content induced by the hypertrophic agonists were inhibited by treatment with berberine in a concentration-dependent manner. Our findings have provided the first scientific evidence that berberine may have an inhibitory effect on hypertrophy of heart-derived cells, and provide a rationale for further studies to evaluate berberine's cardiac activity. Title: Effects of medicinal herbs on contraction rate of cultured cardiomyocyte. Possible mechanisms involved in the chronotropic effects of hawthorn and berberine in neonatal murine cardiomyocyte Author: Salehi, Satin Herbs have been used for many centuries in diverse civilizations for the treatment of heart disease. Only a few natural supplements claim to have direct cardiovascular actions including hawthorn (Crataegus spp.) and berberine derived from the Berberidaceae family. Several different studies indicate important cardiovascular effects of hawthorn and berberine. For example, both exert positive inotropic effects and have been used in the treatment of congestive heart failure. Recently, it was shown that hawthorn extract preparations cause negative chronotropic effects in a cultured neonatal murine cardiomyocyte assay independent of beta-adrenergic receptor blockade. The aim of this study was to further characterize the effect of hawthorn extract to decrease the contraction rate of cultured cardiomyocytes. We hypothesized that hawthorn extract may be acting through muscarinic receptors to decrease contraction rate of cardiomyocytes. Atrial and ventricular cardiomyocytes were treated with hawthorn extract in the presence of atropine or himbacine. Changes in the contraction rate of cultured cardiomyocytes revealed that both muscarinic antagonists significantly attenuated the negative chronotropic activity of hawthorn extract. Using quinuclidinyl benzilate, L-[benzylic-4,4'-3H] ([³H]-QNB) as a radioligand antagonist, the effect of a partially purified hawthorn extract fraction to inhibit muscarinic receptor binding was quantified. Hawthorn extract fraction 3 dose-dependently inhibited [³H]-QNB binding to mouse heart membranes. These findings suggest that muscarinic receptors may be involved in the negative chronotropic effect of hawthorn extracts in neonatal murine cardiomyocytes. Berberine exhibits variable positive and negative chronotropic effects in different species. Our first aim was to examine the effect of berberine in a cultured neonatal murine cardiomyocyte assay. Our study demonstrates that berberine has significant negative chronotropic actions on cardiomyocytes which is not an effect of beta-adrenergic receptor blockade. Pertussis toxin (PTX), a Gi/o protein inhibitor, blocked the negative chronotropic activity of berberine. Muscarinic, adenosine, opioid, and α₂ receptors are coupled through a G-protein (Gi/o) to adenylyl cyclase in an inhibitory fashion. Activation of these receptors are primarily responsible for PTX-sensitive negative chronotropic effects in heart. We hypothesized that berberine may be acting through one of these receptor type to decrease contraction rate of cardiomyocytes. For this purpose, we studied the effects of the muscarinic-receptor antagonists, atropine, himbacine, or AF- DX 116 on the negative chronotropic activity of berberine. Muscarinic antagonists completely blocked the effect of berberine on contraction rate of cardiomyocytes, whereas the bradycardic effect of berberine was not inhibited by the opioid, adenosine, or α2 receptor antagonists naloxone, CGS 15943, or phentolamine, respectively. Using [³H]QNB as a radioligand, we demonstrated that berberine bound to muscarinic receptors of adult mouse heart membranes with relatively high affinity. Furthermore, berberine dose-dependently inhibited [³H]QNB binding to muscarinic M2 receptors exogenously expressed in HEK 293 cells. Therefore, the findings of the present study suggest that berberine has muscarinic agonist effects in cultured neonatal murine cardiomyocytes, potentially explaining reported physiological effects of berberine. Cardiac hypertrophy represents the most important factor in the development of congestive heart failure. We investigated the inhibitory effect of berberine on hypertrophy of H9c2 cells. In rat heart-derived H9c2 myoblast cells treated with different hypertrophic agonists such as insulin growth factor II (IGF-II), arginine vasopressin (AVP), phenylephrine, and isoproterenol, protein content and size of cells were significantly increased compared to control group. However, the number of H9c2 cells after treatment with hypertrophic agonists did not differ significantly compared to control. The increases in area of cells and protein content induced by the hypertrophic agonists were inhibited by treatment with berberine in a concentration-dependent manner. Our findings have provided the first scientific evidence that berberine may have an inhibitory effect on hypertrophy of heart-derived cells, and provide a rationale for further studies to evaluate berberine's cardiac activity. Close

• 1580. [Article] A computer simulation study of the relative efficiency of several forest sampling techniques as influenced by the spatial distribution of trees found in five major forest types of the Pacific Northwest

  This study was initiated to determine the relative efficiency of systematic, stratified and simple random sampling for crown area and tree frequency estimation of five of the major forest types found in ...

  Citation × Citation Citation Abstract Copy Title: A computer simulation study of the relative efficiency of several forest sampling techniques as influenced by the spatial distribution of trees found in five major forest types of the Pacific Northwest Author: Payandeh, Bijan This study was initiated to determine the relative efficiency of systematic, stratified and simple random sampling for crown area and tree frequency estimation of five of the major forest types found in the Pacific Northwest. Several of the more common methods of estimating spatial distribution coefficients were evaluated. Finally the effect of spatial distribution of trees in these forest types on the relative efficiency of two-dimensional systematic sampling was analyzed. Crown maps of five 48-acre tracts of the following types were made from large scale (1:2500) aerial photographs and photographically enlarged to the scale of 1:624: 1.Typical ponderosa-pine of Eastern Oregon 2.Mixed species of Oregon’s Coastal type 3.Mixed pine stands of Northeastern Oregon 4.Even aged Douglas-fir stands common to the Pacific Northwest 5.Typical old growth Douglas-fir of the Pacific Northwest. The basic data consisted of the location (by grid coordinates) and size of each tree crown as obtained from crown maps. These data were committed to the memory of the CDC 3300 computer and the entire analyses executed through computer simulation techniques as follows: Exhaustive two-dimensional systematic sampling was taken using one quarter acre sampling units, Sample mean variances were computed for the three sampling schemes using analysis of variance principles. Relative efficiency of systematic and stratified sampling was also computed. The same parameters were also estimated by variable plot sampling based on 24 points systematically located at the middle 24 acre of each type. The same principles were used to compute variances as close approximations. Eight of the more common non-randomness measures were compared. To evaluate these methods and obtain the required data for examining the effect of spatial variation on relative efficiency of systematic sampling, four new populations were generated from each forest type. These newly computer generated populations were sampled in the same way as for the original forest types. Spatial distribution coefficients of these populations were also computed. Multiple regression analysis was employed using stepwise computer program to establish relationships between the relative efficiency of systematic sampling and the coefficients of randomization. Logarithmic transformation was used to satisfy equality of variances in establishing regression equations. The results of this study indicated that the relative efficiency of two-dimensional systematic sampling may vary greatly depending on the parameter being estimated. For tree frequency estimation (a discrete variable) of the original forest types the gain in precision of systematic sampling varied from 20 to 167 percent. In estimating crown area (a continuous variable) systematic sampling was less precise than simple random sampling on one forest type, while yielding gains in precision ranging from 10 to 179 percent for the other original forest types. There were no significant differences in precision obtained by the three sampling schemes for estimating both parameters when applied to completely randomly dispersed populations. Systematic sampling was less precise than both stratified and random sampling when applied to uniformly spaced populations. The loss in precision in this case ranged from 15 to about 79 percent. Of the eight non-randomness measures (measures of spatial distribution) the point method proved to be best. Grosenbaugh' s Q-factor which is considered to be the most practical method was rejected as being invalid. All original forest types were found to be clustered. Regression equations of relative efficiency on the coefficient of randomization for crown area estimation of the five forest types were mostly non-linear. Since these predicting models produced low correlations and were obviously different from each other, no attempt was made to establish a generalized model. Relative efficiency of systematic sampling for tree frequency estimation was highly correlated with the coefficient of randomization. Of the five equations established, four were not significantly different from each other, thus they were pooled and a generalized model developed which turned out to be y = 1.402x with simple correlation coefficient of r=0.81 where: y = common log of relative efficiency of systematic sampling x = common log of spatial distribution coefficient measured by the point method. Therefore, when an estimate of spatial distribution of trees in a forest is known, the relative efficiency of systematic plot sampling can be predicted with a high degree of accuracy. Such relationships could also be applied as adjustment factors to systematic sampling variance when being treated as simple random samples. Title: A computer simulation study of the relative efficiency of several forest sampling techniques as influenced by the spatial distribution of trees found in five major forest types of the Pacific Northwest Author: Payandeh, Bijan This study was initiated to determine the relative efficiency of systematic, stratified and simple random sampling for crown area and tree frequency estimation of five of the major forest types found in the Pacific Northwest. Several of the more common methods of estimating spatial distribution coefficients were evaluated. Finally the effect of spatial distribution of trees in these forest types on the relative efficiency of two-dimensional systematic sampling was analyzed. Crown maps of five 48-acre tracts of the following types were made from large scale (1:2500) aerial photographs and photographically enlarged to the scale of 1:624: 1.Typical ponderosa-pine of Eastern Oregon 2.Mixed species of Oregon’s Coastal type 3.Mixed pine stands of Northeastern Oregon 4.Even aged Douglas-fir stands common to the Pacific Northwest 5.Typical old growth Douglas-fir of the Pacific Northwest. The basic data consisted of the location (by grid coordinates) and size of each tree crown as obtained from crown maps. These data were committed to the memory of the CDC 3300 computer and the entire analyses executed through computer simulation techniques as follows: Exhaustive two-dimensional systematic sampling was taken using one quarter acre sampling units, Sample mean variances were computed for the three sampling schemes using analysis of variance principles. Relative efficiency of systematic and stratified sampling was also computed. The same parameters were also estimated by variable plot sampling based on 24 points systematically located at the middle 24 acre of each type. The same principles were used to compute variances as close approximations. Eight of the more common non-randomness measures were compared. To evaluate these methods and obtain the required data for examining the effect of spatial variation on relative efficiency of systematic sampling, four new populations were generated from each forest type. These newly computer generated populations were sampled in the same way as for the original forest types. Spatial distribution coefficients of these populations were also computed. Multiple regression analysis was employed using stepwise computer program to establish relationships between the relative efficiency of systematic sampling and the coefficients of randomization. Logarithmic transformation was used to satisfy equality of variances in establishing regression equations. The results of this study indicated that the relative efficiency of two-dimensional systematic sampling may vary greatly depending on the parameter being estimated. For tree frequency estimation (a discrete variable) of the original forest types the gain in precision of systematic sampling varied from 20 to 167 percent. In estimating crown area (a continuous variable) systematic sampling was less precise than simple random sampling on one forest type, while yielding gains in precision ranging from 10 to 179 percent for the other original forest types. There were no significant differences in precision obtained by the three sampling schemes for estimating both parameters when applied to completely randomly dispersed populations. Systematic sampling was less precise than both stratified and random sampling when applied to uniformly spaced populations. The loss in precision in this case ranged from 15 to about 79 percent. Of the eight non-randomness measures (measures of spatial distribution) the point method proved to be best. Grosenbaugh' s Q-factor which is considered to be the most practical method was rejected as being invalid. All original forest types were found to be clustered. Regression equations of relative efficiency on the coefficient of randomization for crown area estimation of the five forest types were mostly non-linear. Since these predicting models produced low correlations and were obviously different from each other, no attempt was made to establish a generalized model. Relative efficiency of systematic sampling for tree frequency estimation was highly correlated with the coefficient of randomization. Of the five equations established, four were not significantly different from each other, thus they were pooled and a generalized model developed which turned out to be y = 1.402x with simple correlation coefficient of r=0.81 where: y = common log of relative efficiency of systematic sampling x = common log of spatial distribution coefficient measured by the point method. Therefore, when an estimate of spatial distribution of trees in a forest is known, the relative efficiency of systematic plot sampling can be predicted with a high degree of accuracy. Such relationships could also be applied as adjustment factors to systematic sampling variance when being treated as simple random samples. Close