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• 1541. [Article] Lodging control and yield enhancement in Morex spring barley with paclobutrazol treatment

  Lodging in cereals can cause significant decreases in yield. It is both a problem in susceptible cereal cultivars with a tall-stemmed, weak-strawed growing habit and in lodging-resistant cereal cultivars ...

  Citation × Citation Citation Abstract Copy Title: Lodging control and yield enhancement in Morex spring barley with paclobutrazol treatment Author: Morrison, Laura A. Lodging in cereals can cause significant decreases in yield. It is both a problem in susceptible cereal cultivars with a tall-stemmed, weak-strawed growing habit and in lodging-resistant cereal cultivars when they are grown under high-nitrogen, high-moisture regimes. Plant growth regulators (PGR's) are chemical growth retardants that offer a method of lodging control. For the susceptible cultivars that are not amenable to genetic shortening through plant breeding, PGR's accomplish on a seasonal basis what has not been possible through gene manipulation. For cultivars that become susceptible in the high-intensive systems of modern agriculture, PGR's can be integrated into the chemical regime to control the lodging-promoting conditions created by yield-promotion practices. Morex spring barley is a lodging-susceptible cultivar that is tall-stemmed and weak-strawed. This growth habit aggravates the lodging problem when Morex is grown under intensive yield-promoting conditions. In greenhouse and field experiments, chemical control of the Morex lodging tendency was tested with an experimental chemical, Paclobutrazol. Paclobutrazol acts on the endogenous gibberellin hormone system in the plant by inhibiting its synthesis. The chemical's effect on the cereal plant is reported to occur in the internodes which Paclobutrazol shortens by decreasing longitudinal growth and strengthens by increasing transverse growth. Lodging control is realized through height reduction which lessens the torque effect created by the weather conditions that actually cause the event of lodging to occur. Paclobutrazol caused significant shortening of the basal internodes in the greenhouse and field experiments. Uncharacteristic of the expected effect, the PGR did not strengthen the shortened internodes. Specific stem weight and breaking strength values for the treated plants were significantly lower than the corresponding control values. In the field, Paclobutrazol delayed lodging until after the critical lodging period that occurs from approximately 15 days before anthesis to 15 days after anthesis. Lodging control was reflected in yield increases. Treated plots yielded significantly higher than did the control plots. The two high treatments of 800 and 1000 g/ha also yielded significantly higher than did the low treatments of 400 and 600 g/ha. Yield increases in the treated plots can be attributed to improved seed filling given the fact that lodging in the control plots occurred during the period when yield losses are caused by poor seed development. Unfortunately, the data did not give any clear indication of other possible sources of yield enhancement. Beneficial effects of Paclobutrazol on the tillering and inflorescence development that several researchers have reported for the PGR, Chlormequat, were not evident. The experiments showed that Paclobutrazol is effective on Morex spring barley as a chemical lodging control agent and yield enhancer. A clear association of reduced height with lodging control and concomitantly with yield increases was shown by the data. The absence of improved stem strength raised questions concerning the mechanism of Paclobutrazol's effect on the barley species and the possible mechanism of its effect in combination with nitrogen fertility. Title: Lodging control and yield enhancement in Morex spring barley with paclobutrazol treatment Author: Morrison, Laura A. Lodging in cereals can cause significant decreases in yield. It is both a problem in susceptible cereal cultivars with a tall-stemmed, weak-strawed growing habit and in lodging-resistant cereal cultivars when they are grown under high-nitrogen, high-moisture regimes. Plant growth regulators (PGR's) are chemical growth retardants that offer a method of lodging control. For the susceptible cultivars that are not amenable to genetic shortening through plant breeding, PGR's accomplish on a seasonal basis what has not been possible through gene manipulation. For cultivars that become susceptible in the high-intensive systems of modern agriculture, PGR's can be integrated into the chemical regime to control the lodging-promoting conditions created by yield-promotion practices. Morex spring barley is a lodging-susceptible cultivar that is tall-stemmed and weak-strawed. This growth habit aggravates the lodging problem when Morex is grown under intensive yield-promoting conditions. In greenhouse and field experiments, chemical control of the Morex lodging tendency was tested with an experimental chemical, Paclobutrazol. Paclobutrazol acts on the endogenous gibberellin hormone system in the plant by inhibiting its synthesis. The chemical's effect on the cereal plant is reported to occur in the internodes which Paclobutrazol shortens by decreasing longitudinal growth and strengthens by increasing transverse growth. Lodging control is realized through height reduction which lessens the torque effect created by the weather conditions that actually cause the event of lodging to occur. Paclobutrazol caused significant shortening of the basal internodes in the greenhouse and field experiments. Uncharacteristic of the expected effect, the PGR did not strengthen the shortened internodes. Specific stem weight and breaking strength values for the treated plants were significantly lower than the corresponding control values. In the field, Paclobutrazol delayed lodging until after the critical lodging period that occurs from approximately 15 days before anthesis to 15 days after anthesis. Lodging control was reflected in yield increases. Treated plots yielded significantly higher than did the control plots. The two high treatments of 800 and 1000 g/ha also yielded significantly higher than did the low treatments of 400 and 600 g/ha. Yield increases in the treated plots can be attributed to improved seed filling given the fact that lodging in the control plots occurred during the period when yield losses are caused by poor seed development. Unfortunately, the data did not give any clear indication of other possible sources of yield enhancement. Beneficial effects of Paclobutrazol on the tillering and inflorescence development that several researchers have reported for the PGR, Chlormequat, were not evident. The experiments showed that Paclobutrazol is effective on Morex spring barley as a chemical lodging control agent and yield enhancer. A clear association of reduced height with lodging control and concomitantly with yield increases was shown by the data. The absence of improved stem strength raised questions concerning the mechanism of Paclobutrazol's effect on the barley species and the possible mechanism of its effect in combination with nitrogen fertility. Close

• 1542. [Article] Preparation, evaluation, and use of lyophilized, concentrated dairy starter cultures in cheese and yogurt manufacture

  Cultures of Streptococcus lactis and Streptococcus cremoris were grown in sterile 11% nonfat milk (NFM) at 32 C for 17 hr with the pH maintained at 6. 3 with sodium carbonate. The cells were harvested ...

  Citation × Citation Citation Abstract Copy Title: Preparation, evaluation, and use of lyophilized, concentrated dairy starter cultures in cheese and yogurt manufacture Author: Speckman, Calvin Albert Cultures of Streptococcus lactis and Streptococcus cremoris were grown in sterile 11% nonfat milk (NFM) at 32 C for 17 hr with the pH maintained at 6. 3 with sodium carbonate. The cells were harvested and resuspended in a medium of 5% gelatin, 5% sodium citrate, 2% monosodium glutamate and 10% sucrose (GCGS) to 1/20th the original culture volume. Suspensions were then frozen in a dryice- acetone bath and lyophilized to a residual moisture of 2%. The lyophilized culture produced was approximately 1/600th the weight of a conventional culture containing the same amount of cells. Vials containing the dry concentrate were sealed under vacuum and stored at -22° and +22° for periodic examination for cell viability and acidproducing activity. Rehydration was accomplished by the addition of a sterile solution of 20% lactose containing 1% protein hydrolysate (rehydration medium RM) which permitted maximum activity of the culture. Culture activity was assayed by simulating Cottage cheese and Cheddar cheese making procedures and measuring the final pH obtained. Appropriate dilutions of the lyophilized concentrate were made so a comparison could be made on a per cell basis with an actively-growing conventional culture. The final pH obtained for S. lactis C10 was 5.3 for both the dry and the conventional culture; this activity resulted in a period of 5 1/4 hr from milk inoculation to milling in Cheddar cheese making. Several cultures maintained activity values similar to the conventional culture for periods of up to 3 months. Cheddar and Cottage cheese were made in 800 lb vats with lyophilized concentrates and conventional cultures with results similar to ghat projected by the activity tests. This procedure was also applied to cultures commercially available as frozen concentrates with good activity retained in the lyophilized concentrate. Modifications of the above methods required for the production of lyophilized concentrates of the yogurt starter cultures included supplementation of the growth medium with 0. 1% Tween 80, growth at 37 C for 14 hr, and the use of 6% malt extract as a cryoprotective agent. With these modifications and proper culture strain selection, approximately 10% survival was observed with Lactobacillus bulgaricus and 25% for Streptococcus thermophilus. Low (30 C for 16 hr) and high temperature (42 C for 5.5 hr) yogurt manufacturing conditions were simulated for evaluation of culture activity. The activity test consisted of inoculating 100 ml of steamed (30 min) 13% NFM with equal volumes (0.25 ml of culture dried from 2. 0 -ml volume and rehydrated in 10.0 ml RM) of L. bulgaricus and S. thermophilus and measuring the final pH attained after 5.5 or 16 hr at the appropriate temperature. Lyophilized concentrates provided pH values almost as low (4. 4 to 4. 7) as those achieved with conventional yogurt cultures (4.4 to 4. 6), and required only an additional 15 to 30 min of manufacturing time. Lyophilized concentrates of flavor-producing cultures which included S. diacetilactis, Leuconostoc and Propioniibacterium retained a high level of viability (90 to 100%) with GCGS as the suspending medium. The Propioniibacterium could be grown either in milk or non-milk media without reduction of viability while Leuconostoc and S. diacetilactis required growth in milk, which in case of S. diacetilactis had to be supplemented with yeast extract. All lyophilized cultures had reduced viability when vacuum was lost during storage indicating a deleterious effect of oxygen. Rehydration medium was important in the reduction of osmoticallyinduced cell injury during rehydration and to provide peptides for required nitrogen metabolism. The cryoprotective requirements were not the same for all species studied and varied within strains. Title: Preparation, evaluation, and use of lyophilized, concentrated dairy starter cultures in cheese and yogurt manufacture Author: Speckman, Calvin Albert Cultures of Streptococcus lactis and Streptococcus cremoris were grown in sterile 11% nonfat milk (NFM) at 32 C for 17 hr with the pH maintained at 6. 3 with sodium carbonate. The cells were harvested and resuspended in a medium of 5% gelatin, 5% sodium citrate, 2% monosodium glutamate and 10% sucrose (GCGS) to 1/20th the original culture volume. Suspensions were then frozen in a dryice- acetone bath and lyophilized to a residual moisture of 2%. The lyophilized culture produced was approximately 1/600th the weight of a conventional culture containing the same amount of cells. Vials containing the dry concentrate were sealed under vacuum and stored at -22° and +22° for periodic examination for cell viability and acidproducing activity. Rehydration was accomplished by the addition of a sterile solution of 20% lactose containing 1% protein hydrolysate (rehydration medium RM) which permitted maximum activity of the culture. Culture activity was assayed by simulating Cottage cheese and Cheddar cheese making procedures and measuring the final pH obtained. Appropriate dilutions of the lyophilized concentrate were made so a comparison could be made on a per cell basis with an actively-growing conventional culture. The final pH obtained for S. lactis C10 was 5.3 for both the dry and the conventional culture; this activity resulted in a period of 5 1/4 hr from milk inoculation to milling in Cheddar cheese making. Several cultures maintained activity values similar to the conventional culture for periods of up to 3 months. Cheddar and Cottage cheese were made in 800 lb vats with lyophilized concentrates and conventional cultures with results similar to ghat projected by the activity tests. This procedure was also applied to cultures commercially available as frozen concentrates with good activity retained in the lyophilized concentrate. Modifications of the above methods required for the production of lyophilized concentrates of the yogurt starter cultures included supplementation of the growth medium with 0. 1% Tween 80, growth at 37 C for 14 hr, and the use of 6% malt extract as a cryoprotective agent. With these modifications and proper culture strain selection, approximately 10% survival was observed with Lactobacillus bulgaricus and 25% for Streptococcus thermophilus. Low (30 C for 16 hr) and high temperature (42 C for 5.5 hr) yogurt manufacturing conditions were simulated for evaluation of culture activity. The activity test consisted of inoculating 100 ml of steamed (30 min) 13% NFM with equal volumes (0.25 ml of culture dried from 2. 0 -ml volume and rehydrated in 10.0 ml RM) of L. bulgaricus and S. thermophilus and measuring the final pH attained after 5.5 or 16 hr at the appropriate temperature. Lyophilized concentrates provided pH values almost as low (4. 4 to 4. 7) as those achieved with conventional yogurt cultures (4.4 to 4. 6), and required only an additional 15 to 30 min of manufacturing time. Lyophilized concentrates of flavor-producing cultures which included S. diacetilactis, Leuconostoc and Propioniibacterium retained a high level of viability (90 to 100%) with GCGS as the suspending medium. The Propioniibacterium could be grown either in milk or non-milk media without reduction of viability while Leuconostoc and S. diacetilactis required growth in milk, which in case of S. diacetilactis had to be supplemented with yeast extract. All lyophilized cultures had reduced viability when vacuum was lost during storage indicating a deleterious effect of oxygen. Rehydration medium was important in the reduction of osmoticallyinduced cell injury during rehydration and to provide peptides for required nitrogen metabolism. The cryoprotective requirements were not the same for all species studied and varied within strains. Close

• 1543. [Article] Influence of post-harvest management practices on plant growth and seed yield of cool season grasses

  Field and controlled environment chamber studies were carried out to evaluate modes of action of post-harvest treatments on the development and seed yield of cool season grasses. Red fescue (Festuca rubra L.) ...

  Citation × Citation Citation Abstract Copy Title: Influence of post-harvest management practices on plant growth and seed yield of cool season grasses Author: Stanwood, Phillip Charles Field and controlled environment chamber studies were carried out to evaluate modes of action of post-harvest treatments on the development and seed yield of cool season grasses. Red fescue (Festuca rubra L.) was used as the primary test species. There was no difference in total biomass production of red fescue as influenced by either burning or mechanical removal of post-harvest residue. Burning did cause a shift in biomass distribution resulting in a 168% increase in seed yield. Variation in the number of fertile tillers per unit area accounted for 69% of the seed yield variation. Burned plots produced 582 fertile tillers m⁻² while mechanically removed plots produced 392 fertile tillers m⁻². Statistical analysis indicated that most of the differences in seed yield due to treatment were accounted for by the number of fertile tillers per unit area. Mechanical removal of residue resulted in the development of one axillary tiller per 10 primary tillers of red fescue by December. Burning significantly increased the rate of 16 axillary tillers per 10 primary tillers by the same date. This clearly suggests an increased availability of substrates for fall plant development. This in turn may have contributed to a greater number of fertile tillers in the spring. The overall effect was higher seed yield. Linn perennial ryegrass (Lolium perenne), Merion bluegrass (Poa pratensis), Highland bentgrass (Agrostis tenuis), and Alta tall fescue (Festuca arundinacea) all showed a significant increase in the number of axillary tillers developed by November as a result of burning postharvest residue as opposed to mechanical removal. Light energy received by the individual tiller appears to be a major factor influencing early tiller development in red fescue. This factor can be strongly influenced by tiller density. Controlled environment studies suggest that at a tiller (seedling) density of 2 per 100 cm², 47 axillary tillers per 10 primary tillers are produced. When the density is increased to 100 per 100 cm², only 8 axillary tillers per 10 primary tillers are produced. Parallel experiments with light energy showed that at 1800 μwatts cm⁻² and 2 seedlings per 100 cm², 48 axillary tillers were produced per 10 primary tillers. At 900 μwatts cm⁻² under the same conditions only 25 axillary tillers per 10 primary tillers were produced. A reduction in the day temperature from 19 C to 9 C and night temperature from 14 C to 6 C did not affect this light energy-axillary tiller production relationship. Title: Influence of post-harvest management practices on plant growth and seed yield of cool season grasses Author: Stanwood, Phillip Charles Field and controlled environment chamber studies were carried out to evaluate modes of action of post-harvest treatments on the development and seed yield of cool season grasses. Red fescue (Festuca rubra L.) was used as the primary test species. There was no difference in total biomass production of red fescue as influenced by either burning or mechanical removal of post-harvest residue. Burning did cause a shift in biomass distribution resulting in a 168% increase in seed yield. Variation in the number of fertile tillers per unit area accounted for 69% of the seed yield variation. Burned plots produced 582 fertile tillers m⁻² while mechanically removed plots produced 392 fertile tillers m⁻². Statistical analysis indicated that most of the differences in seed yield due to treatment were accounted for by the number of fertile tillers per unit area. Mechanical removal of residue resulted in the development of one axillary tiller per 10 primary tillers of red fescue by December. Burning significantly increased the rate of 16 axillary tillers per 10 primary tillers by the same date. This clearly suggests an increased availability of substrates for fall plant development. This in turn may have contributed to a greater number of fertile tillers in the spring. The overall effect was higher seed yield. Linn perennial ryegrass (Lolium perenne), Merion bluegrass (Poa pratensis), Highland bentgrass (Agrostis tenuis), and Alta tall fescue (Festuca arundinacea) all showed a significant increase in the number of axillary tillers developed by November as a result of burning postharvest residue as opposed to mechanical removal. Light energy received by the individual tiller appears to be a major factor influencing early tiller development in red fescue. This factor can be strongly influenced by tiller density. Controlled environment studies suggest that at a tiller (seedling) density of 2 per 100 cm², 47 axillary tillers per 10 primary tillers are produced. When the density is increased to 100 per 100 cm², only 8 axillary tillers per 10 primary tillers are produced. Parallel experiments with light energy showed that at 1800 μwatts cm⁻² and 2 seedlings per 100 cm², 48 axillary tillers were produced per 10 primary tillers. At 900 μwatts cm⁻² under the same conditions only 25 axillary tillers per 10 primary tillers were produced. A reduction in the day temperature from 19 C to 9 C and night temperature from 14 C to 6 C did not affect this light energy-axillary tiller production relationship. Close

• 1544. [Article] Development and application of a resource selection model for pygmy rabbits

  Pygmy rabbits (Brachylagus idahoensis) in Oregon and Washington are a sagebrush (Artemisia tridentata spp.) obligate species of concern because of declining populations and extirpation from much of their ...

  Citation × Citation Citation Abstract Copy Title: Development and application of a resource selection model for pygmy rabbits Author: Meisel, Jennifer K. Pygmy rabbits (Brachylagus idahoensis) in Oregon and Washington are a sagebrush (Artemisia tridentata spp.) obligate species of concern because of declining populations and extirpation from much of their range. Efforts are underway to establish a captive bred population of the Columbia Basin pygmy rabbit in Washington state for reintroduction into the wild. We developed a resource selection model based on soil and vegetation characteristics of occupied pygmy rabbit habitat at Hart Mountain National Antelope Refuge in Oregon. Data collected in Oregon were used to quantify relationships of pygmy rabbits with their habitat. Using logistic regression and Akaike’s Information Criterion (AICc) to identify the best model, we determined that big sagebrush height and soil percent sand content were the two habitat characteristics most predictive of occupied pygmy rabbit burrow locations. The model indicated that the odds ratio of an occupied pygmy rabbit burrow occurrence increased with an increase in percent sand content of soils and big sagebrush height. We then applied the resource selection model using a two-step approach. We first used a Geographic Information System (GIS) to determine broad scale areas of suitable habitat for the potential reintroduction of pygmy rabbits at Hanford Reach National Monument in Washington, and then collected data on the ground to determine the best suitable habitat. Using GIS procedures, we found approximately 8500 ha of potential habitat at Hanford Reach National Monument. Field data collected within the potential habitat were used to further define 3035 ha as the most suitable habitat for pygmy rabbits. Lands that currently support pygmy rabbits, or areas identified as potential habitat in Washington, can be used to prioritize management or restoration efforts for pygmy rabbits and their habitats. Title: Development and application of a resource selection model for pygmy rabbits Author: Meisel, Jennifer K. Pygmy rabbits (Brachylagus idahoensis) in Oregon and Washington are a sagebrush (Artemisia tridentata spp.) obligate species of concern because of declining populations and extirpation from much of their range. Efforts are underway to establish a captive bred population of the Columbia Basin pygmy rabbit in Washington state for reintroduction into the wild. We developed a resource selection model based on soil and vegetation characteristics of occupied pygmy rabbit habitat at Hart Mountain National Antelope Refuge in Oregon. Data collected in Oregon were used to quantify relationships of pygmy rabbits with their habitat. Using logistic regression and Akaike’s Information Criterion (AICc) to identify the best model, we determined that big sagebrush height and soil percent sand content were the two habitat characteristics most predictive of occupied pygmy rabbit burrow locations. The model indicated that the odds ratio of an occupied pygmy rabbit burrow occurrence increased with an increase in percent sand content of soils and big sagebrush height. We then applied the resource selection model using a two-step approach. We first used a Geographic Information System (GIS) to determine broad scale areas of suitable habitat for the potential reintroduction of pygmy rabbits at Hanford Reach National Monument in Washington, and then collected data on the ground to determine the best suitable habitat. Using GIS procedures, we found approximately 8500 ha of potential habitat at Hanford Reach National Monument. Field data collected within the potential habitat were used to further define 3035 ha as the most suitable habitat for pygmy rabbits. Lands that currently support pygmy rabbits, or areas identified as potential habitat in Washington, can be used to prioritize management or restoration efforts for pygmy rabbits and their habitats. Close

• 1545. [Article] The significance of glutathione conjugation for aflatoxin B₁ metabolism in rainbow trout and coho salmon

  In rodent models as well as in fish models there are significant species differences in the susceptibility toward aflatoxin B₁ (AFB₁) carcinogenesis. Mouse is less susceptible toward AFB₁ carcinogenesis than ...

  Citation × Citation Citation Abstract Copy Title: The significance of glutathione conjugation for aflatoxin B₁ metabolism in rainbow trout and coho salmon Author: Valsta, Liisa M. In rodent models as well as in fish models there are significant species differences in the susceptibility toward aflatoxin B₁ (AFB₁) carcinogenesis. Mouse is less susceptible toward AFB₁ carcinogenesis than rat. Researchers have come to the conclusion that the lower susceptibility of mice is not a result of less effective activation of AFB₁, but rather of more effective inactivation of the toxic intermediate AFB₁-2,3-epoxide, and especially inactivation through the glutathione (GSH) conjugation of the epoxide. Rainbow trout fed Oregon Test Diet are more sensitive toward AFB₁ hepatocarcinogenesis than coho salmon, or, than trout fed the inhibitors β-naphthoflavone (BNF), 1ndole-3-carbinol (I3C), or Aroclor 1254 (PCB). This study examined the role of AFB1-glutathione (AFB₁-SG) conjugation In these differences. A tritiated AFB₁-glutathione conjugate standard (³H-AFB₁-S6) was produced in vitro using mouse liver S-9 fraction as a source of GSH transferase. It was purified by reverse phase HPLC, and its structure verified by amino acid analysis and mass spectrometry. Coho salmon and rainbow trout fed the various diets were injected i.p. with ³H-AFB₁ (49μCi, 50 μg/ kg fish); bile, liver and kidney were collected at 24 h. Recovery of total aflatoxin radioactivity was determined for all three tissues, and the hepatic AFB₁-DNA binding was also determined. Bile metabolites were quantitated by reverse phase HPLC using the mouse ³H-AFB₁-SG as a standard. The resistance of coho salmon toward AFB₁ carcinogenicity was supported by a 20-fold lower hepatic AFB₁-DNA binding compared to control trout. AFB₁-SG was detected in bile only in control, BNF, and I3C fed trout, at < 1% of total recovered metabolites, and at < 0.2% of the original dose, being highest in control trout. The major conjugates were glucuronides of aflatoxicol (AFL) and aflatoxicol-M₁ (AFL-M₁) (80-902 of the total recovered metabolites). In vitro metabolism studies using isolated liver cell fractions supported the in vivo metabolism results. Less than 0.531 of the original AFB₁ dose was converted to AFB₁-SG conjugate in salmon and trout samples. In contrast, with isolated mouse liver cell fractions approximately 25% of the original AFB₁ dose was conjugated with GSH. The GSH concentration of control trout liver was 2.9 mmol/ kg. Coho salmon had GSH concentration 70% of that found in control trout. In BNF pre-fed trout liver GSH concentration was enhanced by 25% compared to controls. Liver GSH transferase activity using l-chloro-2,4- dlnitrobenzene as substrate was 1.15 μmol/min/mg protein in control trout. This enzyme activity In salmon was only 26% of that found in control trout. A 62% elevation In GSH transferase activity compared to controls was detected in trout fed BNF diet. There is no apparent correlation between liver GSH or GSH transferase activities among the various groups, and their relative sensitivities to AFB₁ carcinogenesis. This study indicates that AFB₁-SG conjugation is not a significant pathway in salmon and trout fed control diets, or trout fed various inhibitors, and cannot account for the variation In AFB₁ sensitivity. Title: The significance of glutathione conjugation for aflatoxin B₁ metabolism in rainbow trout and coho salmon Author: Valsta, Liisa M. In rodent models as well as in fish models there are significant species differences in the susceptibility toward aflatoxin B₁ (AFB₁) carcinogenesis. Mouse is less susceptible toward AFB₁ carcinogenesis than rat. Researchers have come to the conclusion that the lower susceptibility of mice is not a result of less effective activation of AFB₁, but rather of more effective inactivation of the toxic intermediate AFB₁-2,3-epoxide, and especially inactivation through the glutathione (GSH) conjugation of the epoxide. Rainbow trout fed Oregon Test Diet are more sensitive toward AFB₁ hepatocarcinogenesis than coho salmon, or, than trout fed the inhibitors β-naphthoflavone (BNF), 1ndole-3-carbinol (I3C), or Aroclor 1254 (PCB). This study examined the role of AFB1-glutathione (AFB₁-SG) conjugation In these differences. A tritiated AFB₁-glutathione conjugate standard (³H-AFB₁-S6) was produced in vitro using mouse liver S-9 fraction as a source of GSH transferase. It was purified by reverse phase HPLC, and its structure verified by amino acid analysis and mass spectrometry. Coho salmon and rainbow trout fed the various diets were injected i.p. with ³H-AFB₁ (49μCi, 50 μg/ kg fish); bile, liver and kidney were collected at 24 h. Recovery of total aflatoxin radioactivity was determined for all three tissues, and the hepatic AFB₁-DNA binding was also determined. Bile metabolites were quantitated by reverse phase HPLC using the mouse ³H-AFB₁-SG as a standard. The resistance of coho salmon toward AFB₁ carcinogenicity was supported by a 20-fold lower hepatic AFB₁-DNA binding compared to control trout. AFB₁-SG was detected in bile only in control, BNF, and I3C fed trout, at < 1% of total recovered metabolites, and at < 0.2% of the original dose, being highest in control trout. The major conjugates were glucuronides of aflatoxicol (AFL) and aflatoxicol-M₁ (AFL-M₁) (80-902 of the total recovered metabolites). In vitro metabolism studies using isolated liver cell fractions supported the in vivo metabolism results. Less than 0.531 of the original AFB₁ dose was converted to AFB₁-SG conjugate in salmon and trout samples. In contrast, with isolated mouse liver cell fractions approximately 25% of the original AFB₁ dose was conjugated with GSH. The GSH concentration of control trout liver was 2.9 mmol/ kg. Coho salmon had GSH concentration 70% of that found in control trout. In BNF pre-fed trout liver GSH concentration was enhanced by 25% compared to controls. Liver GSH transferase activity using l-chloro-2,4- dlnitrobenzene as substrate was 1.15 μmol/min/mg protein in control trout. This enzyme activity In salmon was only 26% of that found in control trout. A 62% elevation In GSH transferase activity compared to controls was detected in trout fed BNF diet. There is no apparent correlation between liver GSH or GSH transferase activities among the various groups, and their relative sensitivities to AFB₁ carcinogenesis. This study indicates that AFB₁-SG conjugation is not a significant pathway in salmon and trout fed control diets, or trout fed various inhibitors, and cannot account for the variation In AFB₁ sensitivity. Close

• 1546. [Article] Influence of abiotic and biotic factors on developmental parameters of Drosophila suzukii (Diptera: Drosophilidae)

  Drosophila suzukii (Diptera: Drosophilidae), a pest of thin-skinned fruits, has been detected worldwide recently, with new locations of establishment determined annually since it first became a concern ...

  Citation × Citation Citation Abstract Copy Title: Influence of abiotic and biotic factors on developmental parameters of Drosophila suzukii (Diptera: Drosophilidae) Author: Tochen, Samantha Drosophila suzukii (Diptera: Drosophilidae), a pest of thin-skinned fruits, has been detected worldwide recently, with new locations of establishment determined annually since it first became a concern on continental North America in 2008. Drosophila suzukii females are different from most other drosophilids as being one of two known species capable of economic injury in fruit. This is achieved via a serrated ovipositor that pierces the skin of ripening susceptible fruit, depositing eggs that will then hatch into larvae, utilizing the fruit as a food source. Current control methods involve the application of pesticides on a weekly basis upon the coloring of fruit, ending when harvest is complete. To shift back towards IPM, knowledge of D. suzukii development under different environmental factors is necessary to improve upon current management options. The first objective of this research project was to determine the developmental period, longevity, and fecundity of D. suzukii when exposed to seven constant temperatures and separately, five constant relative humidities (RHs) at 22 ± 2 ºC. Temperature had an influence on these parameters, with decreasing developmental periods as temperatures increased from 10 to 28ºC. Developmental period increased above 28ºC. The highest net reproductive rate and intrinsic rate of population increase was 22 ºC. Estimations using linear and nonlinear fit for the minimum, optimal and maximum were 7.2, 28.1, and 42.1 ºC, respectively. The minimal, optimal, and maximal temperatures for intrinsic rate of population increase were 13.4, 21.0, and 29.0 ºC . Relative humidity also had a significant influence on these parameters. The estimated minimum, optimal and maximum development thresholds for RH were 27, 79, and 100% RH, respectively. Fecundity appeared to increase with RH, with a maximum observed at 93%, however ovary dissections indicated that no differences in ovary maturation occurred between 78 and 93% RH. The second objective of this research was conducted to determine the effect of floral resource feeding on nutrient levels in female D. suzukii when provided cherry or blueberry blossoms as well as lifespan over an observed feeding period. When adults were provided cherry blossoms, they had significantly longer lifespans than their water-fed counterparts over a 41-day observation period. Adults provided blueberry blossoms exhibited longer lifespans, however, this observation could not be statistically compared with the cherry and water treatments due to availability of blossoms and a staggered start date. A nutritional assay showed higher levels of glycogen and sugar levels amongst female flies provided either blossom type or sucrose over water-fed flies. Lipid levels tended to be the same across treatments. Overall, this research discovered new information about D. suzukii biology that can be incorporated into future management strategies. The temperature-related development and fecundity study contributed to the development of a population prediction model. The humidity work will be incorporated into the D. suzukii model to refine estimates across different locations. The model will provide a tool for growers to determine management timing. The nutritional work may aide in the development of a bait spray and timing of bait spray application. Title: Influence of abiotic and biotic factors on developmental parameters of Drosophila suzukii (Diptera: Drosophilidae) Author: Tochen, Samantha Drosophila suzukii (Diptera: Drosophilidae), a pest of thin-skinned fruits, has been detected worldwide recently, with new locations of establishment determined annually since it first became a concern on continental North America in 2008. Drosophila suzukii females are different from most other drosophilids as being one of two known species capable of economic injury in fruit. This is achieved via a serrated ovipositor that pierces the skin of ripening susceptible fruit, depositing eggs that will then hatch into larvae, utilizing the fruit as a food source. Current control methods involve the application of pesticides on a weekly basis upon the coloring of fruit, ending when harvest is complete. To shift back towards IPM, knowledge of D. suzukii development under different environmental factors is necessary to improve upon current management options. The first objective of this research project was to determine the developmental period, longevity, and fecundity of D. suzukii when exposed to seven constant temperatures and separately, five constant relative humidities (RHs) at 22 ± 2 ºC. Temperature had an influence on these parameters, with decreasing developmental periods as temperatures increased from 10 to 28ºC. Developmental period increased above 28ºC. The highest net reproductive rate and intrinsic rate of population increase was 22 ºC. Estimations using linear and nonlinear fit for the minimum, optimal and maximum were 7.2, 28.1, and 42.1 ºC, respectively. The minimal, optimal, and maximal temperatures for intrinsic rate of population increase were 13.4, 21.0, and 29.0 ºC . Relative humidity also had a significant influence on these parameters. The estimated minimum, optimal and maximum development thresholds for RH were 27, 79, and 100% RH, respectively. Fecundity appeared to increase with RH, with a maximum observed at 93%, however ovary dissections indicated that no differences in ovary maturation occurred between 78 and 93% RH. The second objective of this research was conducted to determine the effect of floral resource feeding on nutrient levels in female D. suzukii when provided cherry or blueberry blossoms as well as lifespan over an observed feeding period. When adults were provided cherry blossoms, they had significantly longer lifespans than their water-fed counterparts over a 41-day observation period. Adults provided blueberry blossoms exhibited longer lifespans, however, this observation could not be statistically compared with the cherry and water treatments due to availability of blossoms and a staggered start date. A nutritional assay showed higher levels of glycogen and sugar levels amongst female flies provided either blossom type or sucrose over water-fed flies. Lipid levels tended to be the same across treatments. Overall, this research discovered new information about D. suzukii biology that can be incorporated into future management strategies. The temperature-related development and fecundity study contributed to the development of a population prediction model. The humidity work will be incorporated into the D. suzukii model to refine estimates across different locations. The model will provide a tool for growers to determine management timing. The nutritional work may aide in the development of a bait spray and timing of bait spray application. Close

• 1547. [Article] Nesting season ecology of marbled murrelets at a remote mainland fjord in southeast Alaska

  This thesis focuses on the nesting ecology and marine space use of Marbled Murrelets (Brachyramphus marmoratus) during the 2007 and 2008 nesting seasons in and around Port Snettisham, a remote mainland ...

  Citation × Citation Citation Abstract Copy Title: Nesting season ecology of marbled murrelets at a remote mainland fjord in southeast Alaska Author: Barbaree, Blake A. This thesis focuses on the nesting ecology and marine space use of Marbled Murrelets (Brachyramphus marmoratus) during the 2007 and 2008 nesting seasons in and around Port Snettisham, a remote mainland fjord in Southeast Alaska. Marbled Murrelets (murrelets) are a declining species throughout most of their range, and their conservation is a challenging endeavor because they rely on relatively large expanses of terrestrial habitat for nesting and marine habitat for food. Murrelets are especially difficult to study because they place their nests at variable and often considerable distance from the sea in largely inaccessible locations; consequently, we know relatively little about their breeding ecology and overall life history compared to other seabirds. I used radio-telemetry to gather data on reproduction, behavior, and at-sea locations of murrelets. Herein, I describe individual and population-level marine space use, identify nesting habitat, estimate reproductive success, and characterize patterns of nest visits. Mean marine home range size for adult murrelets was significantly larger in 2008 (158.6 ± 103.7 km²) than 2007 (97.8 ± 59.4 km²), suggesting that foraging conditions were relatively poor in 2008. Similarly, mean commuting distance from at-sea location to nest sites was significantly longer in 2008 (20.0 ± 2.0 km) than 2007 (12.0 ± 0.9 km), and murrelets nesting further from the coast likely reduced their foraging ranges in 2008. Central foraging hot spots were identified throughout Port Snettisham and near Holkham Bay and Tracy Arm to the south. Boundaries of these hot spots can be used to guide management of commercial fishing and tourism, and designation of marine protected areas. I located 33 active nests in mostly inaccessible sites within forest and non-forest habitat, including visually confirmed nest sites on the branches of large conifer trees and on ledges of steep cliffs near water (e.g., waterfall, lake, river, or glacier). Widespread use of rock cliff and subalpine nesting habitats (≥ 48.5% of located nests) indicated that nesting habitat models in Southeast Alaska should include these types of habitats. Nests were located further inland (range 1.0 - 52.0 km) and at higher elevations (range 42 - 1100 m) than previously documented in Alaska, including two nest sites > 15 km east of the USA/Canada border in British Columbia, Canada. The nesting season was ca. 113 days long (25 May - 16 September), and four late-season re-nesting attempts were documented. Apparent fledge success, derived by inference from behavior of radio-tagged adults, was 17.6% (n = 6 of 34). The low reproductive success at Port Snettisham was similar to estimates from south of Alaska, and unexpected because the area has relatively high densities of murrelets and seemingly ideal conditions for nesting. This information is noteworthy to future conservation planning because it provides evidence that murrelet reproduction may be low even when conditions for nesting are relatively good. Despite an adaptation to high adult survival, murrelet populations cannot sustain themselves with similarly low levels of reproduction. Based on my results future research should focus on monitoring regional population trends, identifying causes of nest failure, estimating adult survival rates, and identifying sources of adult mortality. Title: Nesting season ecology of marbled murrelets at a remote mainland fjord in southeast Alaska Author: Barbaree, Blake A. This thesis focuses on the nesting ecology and marine space use of Marbled Murrelets (Brachyramphus marmoratus) during the 2007 and 2008 nesting seasons in and around Port Snettisham, a remote mainland fjord in Southeast Alaska. Marbled Murrelets (murrelets) are a declining species throughout most of their range, and their conservation is a challenging endeavor because they rely on relatively large expanses of terrestrial habitat for nesting and marine habitat for food. Murrelets are especially difficult to study because they place their nests at variable and often considerable distance from the sea in largely inaccessible locations; consequently, we know relatively little about their breeding ecology and overall life history compared to other seabirds. I used radio-telemetry to gather data on reproduction, behavior, and at-sea locations of murrelets. Herein, I describe individual and population-level marine space use, identify nesting habitat, estimate reproductive success, and characterize patterns of nest visits. Mean marine home range size for adult murrelets was significantly larger in 2008 (158.6 ± 103.7 km²) than 2007 (97.8 ± 59.4 km²), suggesting that foraging conditions were relatively poor in 2008. Similarly, mean commuting distance from at-sea location to nest sites was significantly longer in 2008 (20.0 ± 2.0 km) than 2007 (12.0 ± 0.9 km), and murrelets nesting further from the coast likely reduced their foraging ranges in 2008. Central foraging hot spots were identified throughout Port Snettisham and near Holkham Bay and Tracy Arm to the south. Boundaries of these hot spots can be used to guide management of commercial fishing and tourism, and designation of marine protected areas. I located 33 active nests in mostly inaccessible sites within forest and non-forest habitat, including visually confirmed nest sites on the branches of large conifer trees and on ledges of steep cliffs near water (e.g., waterfall, lake, river, or glacier). Widespread use of rock cliff and subalpine nesting habitats (≥ 48.5% of located nests) indicated that nesting habitat models in Southeast Alaska should include these types of habitats. Nests were located further inland (range 1.0 - 52.0 km) and at higher elevations (range 42 - 1100 m) than previously documented in Alaska, including two nest sites > 15 km east of the USA/Canada border in British Columbia, Canada. The nesting season was ca. 113 days long (25 May - 16 September), and four late-season re-nesting attempts were documented. Apparent fledge success, derived by inference from behavior of radio-tagged adults, was 17.6% (n = 6 of 34). The low reproductive success at Port Snettisham was similar to estimates from south of Alaska, and unexpected because the area has relatively high densities of murrelets and seemingly ideal conditions for nesting. This information is noteworthy to future conservation planning because it provides evidence that murrelet reproduction may be low even when conditions for nesting are relatively good. Despite an adaptation to high adult survival, murrelet populations cannot sustain themselves with similarly low levels of reproduction. Based on my results future research should focus on monitoring regional population trends, identifying causes of nest failure, estimating adult survival rates, and identifying sources of adult mortality. Close

• 1548. [Article] Forest Successional and Disturbance Dynamics in the Southern Blue Mountains of Eastern Oregon

  The application of modern land management practices beginning at the turn of the 20th century is widely believed to have dramatically transformed forest landscapes of the inland Pacific Northwest. Restoring ...

  Citation × Citation Citation Abstract Copy Title: Forest Successional and Disturbance Dynamics in the Southern Blue Mountains of Eastern Oregon Author: Johnston, James D. (James Daniel) The application of modern land management practices beginning at the turn of the 20th century is widely believed to have dramatically transformed forest landscapes of the inland Pacific Northwest. Restoring historical conditions to make forests resilient to future climate and disturbance regimes is a major goal of federal forest managers. However, information about historical relationships between forest structure, forest composition, topography, climate, and disturbance sufficient to parameterize managers' decision-making is often lacking. This study uses dendroecological methods to reconstruct historical (1650-1900 CE) forest structure, composition, and fire disturbance, and to describe change over time across a wide range of forest types in the southern Blue Mountains of eastern Oregon. Results indicate that both fire frequency and climate controls on fire occurrence were similar across a broad range of forest types. Southern Blue Mountains forests are markedly different with respect to inherent site productivity and species composition, but frequent fire tended to equalize stand densities across the landscape prior to the exclusion of fire in the late 1800s. In the absence of fire, more productive mixed conifer sites have generally experienced the same or greater successional change as drier pine dominated sites. If restoring historical conditions is a goal, treatments appropriate to restore dry ponderosa pine forests are also appropriate for moister mixed conifer forest types. Title: Forest Successional and Disturbance Dynamics in the Southern Blue Mountains of Eastern Oregon Author: Johnston, James D. (James Daniel) The application of modern land management practices beginning at the turn of the 20th century is widely believed to have dramatically transformed forest landscapes of the inland Pacific Northwest. Restoring historical conditions to make forests resilient to future climate and disturbance regimes is a major goal of federal forest managers. However, information about historical relationships between forest structure, forest composition, topography, climate, and disturbance sufficient to parameterize managers' decision-making is often lacking. This study uses dendroecological methods to reconstruct historical (1650-1900 CE) forest structure, composition, and fire disturbance, and to describe change over time across a wide range of forest types in the southern Blue Mountains of eastern Oregon. Results indicate that both fire frequency and climate controls on fire occurrence were similar across a broad range of forest types. Southern Blue Mountains forests are markedly different with respect to inherent site productivity and species composition, but frequent fire tended to equalize stand densities across the landscape prior to the exclusion of fire in the late 1800s. In the absence of fire, more productive mixed conifer sites have generally experienced the same or greater successional change as drier pine dominated sites. If restoring historical conditions is a goal, treatments appropriate to restore dry ponderosa pine forests are also appropriate for moister mixed conifer forest types. Close

• 1549. [Article] A pharmacognostic study of the root of Heracleum mantegazzianum Somier et Levier

  A pharmacognostic study was made of the root of Heracleum mantegazzianum, an umbelliferous species which is of value as a source of natural coumarins. Three groups of seeds were tested to determine the ...

  Citation × Citation Citation Abstract Copy Title: A pharmacognostic study of the root of Heracleum mantegazzianum Somier et Levier Author: Lee, Eugene Carlton A pharmacognostic study was made of the root of Heracleum mantegazzianum, an umbelliferous species which is of value as a source of natural coumarins. Three groups of seeds were tested to determine the presence of a germination requirement for moist cold and the possible value of gibberellic acid in obviating this requirement. The first group of seeds was cold-treated for 74 days at a range of from 2 to 5°C. The second group of seeds was soaked for 20 hours in a solution containing 100 parts per million of gibberellic acid. The third group of seeds, used as controls, was soaked in water. When planted and maintained under greenhouse conditions only the cold-treated seeds germinated. The germination rate was 10.3%. Both seeds treated with gibberellic acid and the controls failed to germinate, showing that a cold requirement does exist and that treatment with gibber-ellic acid will not substitute for the cold requirement. A fourth group of seeds, cold- treated for 294 days, germinated at a rate of approximately 55%, showing that germination is proportional to total days of cold treatment. Sequential selective solvent extraction with a series of increasing polarity gave the following fractions as average percentages of dry weight: petroleum ether, 2.4; ether, anhydrous, 2.5; ether U.S.P., 2.0 alcohol 95%, 8.5; water, 19.4. Copious foaming of the aqueous fraction showed the possible presence of saponins. The description and histology of the whole root as well as the character of the powdered root was recorded. Among diagnostic characters of the powdered root are its blue coloration when moistened with iodine water, a slight yellow fluorescence under ultraviolet light turning to luminescence for several seconds following extinction of the light, and the presence of numerous clustered starch grains which gelatinize rapidly in chloral hydrate solution. Thin-layer chromatography of the ether extract of the air-dried root on Silica Gel G showed seven principal spots fluorescing under ultraviolet light. R[subscript f] values and colors corresponded to those of six standard coumarins. The following coumarins are presumed to be present: isobergapten, pimpinellin, bergapten, isopimpinellin, sphondin and umbelliferone. The seventh spot was not identified. The R[subscript f] values in two solvent systems and the fluorescent colors under ultraviolet light are reported for the extract spots as well as for six coumarins. Studies were also made to determine the relative stability of coumarins to heat. Six standard coumarins as well as the extract of the air-dried root were spotted individually on Silica Gel G plates and developed two-dimensionally. Following development in the first direction and prior to development in the second direction the plates were exposed to a temperature of 65°C. for 30 minutes in an oven. With the exception of sphondin the chromatograms of the individual coumarins showed from one to two additional spots. This indicates that coumarins as a group are subject to modification at a temperature of 65°C. Regular two-dimensional chromatography of the ether extract of the root material which had been dried at 38°C. gave spots for only five coumarins. It is concluded that the roots should be dried only at the normal air temperatures. Title: A pharmacognostic study of the root of Heracleum mantegazzianum Somier et Levier Author: Lee, Eugene Carlton A pharmacognostic study was made of the root of Heracleum mantegazzianum, an umbelliferous species which is of value as a source of natural coumarins. Three groups of seeds were tested to determine the presence of a germination requirement for moist cold and the possible value of gibberellic acid in obviating this requirement. The first group of seeds was cold-treated for 74 days at a range of from 2 to 5°C. The second group of seeds was soaked for 20 hours in a solution containing 100 parts per million of gibberellic acid. The third group of seeds, used as controls, was soaked in water. When planted and maintained under greenhouse conditions only the cold-treated seeds germinated. The germination rate was 10.3%. Both seeds treated with gibberellic acid and the controls failed to germinate, showing that a cold requirement does exist and that treatment with gibber-ellic acid will not substitute for the cold requirement. A fourth group of seeds, cold- treated for 294 days, germinated at a rate of approximately 55%, showing that germination is proportional to total days of cold treatment. Sequential selective solvent extraction with a series of increasing polarity gave the following fractions as average percentages of dry weight: petroleum ether, 2.4; ether, anhydrous, 2.5; ether U.S.P., 2.0 alcohol 95%, 8.5; water, 19.4. Copious foaming of the aqueous fraction showed the possible presence of saponins. The description and histology of the whole root as well as the character of the powdered root was recorded. Among diagnostic characters of the powdered root are its blue coloration when moistened with iodine water, a slight yellow fluorescence under ultraviolet light turning to luminescence for several seconds following extinction of the light, and the presence of numerous clustered starch grains which gelatinize rapidly in chloral hydrate solution. Thin-layer chromatography of the ether extract of the air-dried root on Silica Gel G showed seven principal spots fluorescing under ultraviolet light. R[subscript f] values and colors corresponded to those of six standard coumarins. The following coumarins are presumed to be present: isobergapten, pimpinellin, bergapten, isopimpinellin, sphondin and umbelliferone. The seventh spot was not identified. The R[subscript f] values in two solvent systems and the fluorescent colors under ultraviolet light are reported for the extract spots as well as for six coumarins. Studies were also made to determine the relative stability of coumarins to heat. Six standard coumarins as well as the extract of the air-dried root were spotted individually on Silica Gel G plates and developed two-dimensionally. Following development in the first direction and prior to development in the second direction the plates were exposed to a temperature of 65°C. for 30 minutes in an oven. With the exception of sphondin the chromatograms of the individual coumarins showed from one to two additional spots. This indicates that coumarins as a group are subject to modification at a temperature of 65°C. Regular two-dimensional chromatography of the ether extract of the root material which had been dried at 38°C. gave spots for only five coumarins. It is concluded that the roots should be dried only at the normal air temperatures. Close

• 1550. [Article] A study of the quantity and distribution of bark debris resulting from log rafting

  A study was conducted to determine the quantity and distribution of bark debris resulting from log rafting. Three distinct problems were studied: (I) the quantity of bark dislodged from the logs while ...

  Citation × Citation Citation Abstract Copy Title: A study of the quantity and distribution of bark debris resulting from log rafting Author: Williamson, Kenneth J. A study was conducted to determine the quantity and distribution of bark debris resulting from log rafting. Three distinct problems were studied: (I) the quantity of bark dislodged from the logs while being placed in the rivers and during transport in log rafts; (2) the percentage of the bark that sinks as a function of time; and (3) the amount of bark and debris in existing benthic deposits. Two major areas were studied covering both fresh and salt water: the Klamath River in South-Central Oregon and the Yaquina River estuary near Newport in Western Oregon. The logs stored in the Klamath River consisted primarily of ponderosa pine, and those in the Yaquina estuary were primarily Douglas fir. Studies by several authors listed high chemical oxygen demands and low dissolved oxygen contents in waters used for the storage of logs. Fish kills have been noted from bark deposits in lakes and streams. Photographic measurements of logs were used to determine the percentage of bark dislodged. For Douglas fir logs approximately 17 percent of the bark is dislodged during unloading and 5 percent during raft transport, for a total of 22 percent. Comparatively, the total for ponderosa pine was only 6 percent. Flotation studies showed a total of 10 percent sinkage in water within one day and 75 percent in two months, regardless of the species. The pine bark sank at a faster rate as compared to the fir bark; primarily due to the smaller size of the pine bark. Core samples were taken in areas free of log rafting, in areas of log raft storage and in areas of log dumping to determine the extent of bark debris in the benthic deposits. Samples consisting of primarily deposited bark had a volatile solids content of about 15 pounds per cubic foot. The average increase in volatile solids content in the log storage areas as compared to the control samples was approximately two pounds of volatile solids per cubic foot. For the log dumping areas this average increase ranged from 0. 5 to 15 pounds of volatile solids per cubic foot. The results of this study indicate clearly that large amounts of bark are added to the water courses used for log storage and that large amounts of bark debris presently exist in the benthic deposits of these water courses. Title: A study of the quantity and distribution of bark debris resulting from log rafting Author: Williamson, Kenneth J. A study was conducted to determine the quantity and distribution of bark debris resulting from log rafting. Three distinct problems were studied: (I) the quantity of bark dislodged from the logs while being placed in the rivers and during transport in log rafts; (2) the percentage of the bark that sinks as a function of time; and (3) the amount of bark and debris in existing benthic deposits. Two major areas were studied covering both fresh and salt water: the Klamath River in South-Central Oregon and the Yaquina River estuary near Newport in Western Oregon. The logs stored in the Klamath River consisted primarily of ponderosa pine, and those in the Yaquina estuary were primarily Douglas fir. Studies by several authors listed high chemical oxygen demands and low dissolved oxygen contents in waters used for the storage of logs. Fish kills have been noted from bark deposits in lakes and streams. Photographic measurements of logs were used to determine the percentage of bark dislodged. For Douglas fir logs approximately 17 percent of the bark is dislodged during unloading and 5 percent during raft transport, for a total of 22 percent. Comparatively, the total for ponderosa pine was only 6 percent. Flotation studies showed a total of 10 percent sinkage in water within one day and 75 percent in two months, regardless of the species. The pine bark sank at a faster rate as compared to the fir bark; primarily due to the smaller size of the pine bark. Core samples were taken in areas free of log rafting, in areas of log raft storage and in areas of log dumping to determine the extent of bark debris in the benthic deposits. Samples consisting of primarily deposited bark had a volatile solids content of about 15 pounds per cubic foot. The average increase in volatile solids content in the log storage areas as compared to the control samples was approximately two pounds of volatile solids per cubic foot. For the log dumping areas this average increase ranged from 0. 5 to 15 pounds of volatile solids per cubic foot. The results of this study indicate clearly that large amounts of bark are added to the water courses used for log storage and that large amounts of bark debris presently exist in the benthic deposits of these water courses. Close