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J. A. Trofymow - One of the best experts on this subject based on the ideXlab platform.
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Microbial Respiration and biomass (Substrate-Induced Respiration) in soils of old-growth and regenerating forests on northern Vancouver Island, British Columbia
Biology and Fertility of Soils, 1996Co-Authors: Scott X. Chang, J. A. TrofymowAbstract:In studying the basal Respiration, microbial biomass (Substrate-Induced Respiration, SIR), and metabolic quotient (qCO2) in western red cedar (Thuja plicata Donn ex D. Don)-western hemlock [(Tsuga heterophylla Raf.) Sarg.] ecosystems (old-growth forests, 3- and 10-year-old plantations) on northern Vancouver Island, British Columbia, Canada, we predicted that (1) soil basal Respiration would be reduced by harvesting and burning, reflecting the reduction in microbial biomass and activities; (2) the microbial biomass would be reduced by harvesting and slash-burning, due to the excessive heat of the burning or due to reduced Substrate availability; (3) microbial biomass in the plantations would tend to recover to the preharvesting levels with growth of the trees and increased Substrate availability; and (4) microbial biomass measured by the SIR method would compare well with that measured by the fumigation-extraction (FE) method. Decaying litter layer (F), woody F (Fw) and humus layer (H) materials were sampled four times in the summer of 1992. The results obtained supported the four predictions. Microbial biomass was reduced in the harvested and slash-burned plots. Both SIR and FE methods provided equally good estimates of microbial biomass in the samples [SIR microbial C (mg g-1)=0.227+0.458 FE microbial C (mg g-1), r=0.63, P=0.0001] and proved suitable for microbial biomass measurements in this strongly acidic soil. Basal Respiration was significantly greater in the old-growth forests than in the young plantations (P
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microbial Respiration and biomass Substrate Induced Respiration in soils of old growth and regenerating forests on northern vancouver island british columbia
Biology and Fertility of Soils, 1996Co-Authors: Scott X. Chang, J. A. TrofymowAbstract:In studying the basal Respiration, microbial biomass (Substrate-Induced Respiration, SIR), and metabolic quotient (qCO2) in western red cedar (Thuja plicata Donn ex D. Don)-western hemlock [(Tsuga heterophylla Raf.) Sarg.] ecosystems (old-growth forests, 3- and 10-year-old plantations) on northern Vancouver Island, British Columbia, Canada, we predicted that (1) soil basal Respiration would be reduced by harvesting and burning, reflecting the reduction in microbial biomass and activities; (2) the microbial biomass would be reduced by harvesting and slash-burning, due to the excessive heat of the burning or due to reduced Substrate availability; (3) microbial biomass in the plantations would tend to recover to the preharvesting levels with growth of the trees and increased Substrate availability; and (4) microbial biomass measured by the SIR method would compare well with that measured by the fumigation-extraction (FE) method. Decaying litter layer (F), woody F (Fw) and humus layer (H) materials were sampled four times in the summer of 1992. The results obtained supported the four predictions. Microbial biomass was reduced in the harvested and slash-burned plots. Both SIR and FE methods provided equally good estimates of microbial biomass in the samples [SIR microbial C (mg g-1)=0.227+0.458 FE microbial C (mg g-1), r=0.63, P=0.0001] and proved suitable for microbial biomass measurements in this strongly acidic soil. Basal Respiration was significantly greater in the old-growth forests than in the young plantations (P<0.05) in both F and H layers, but not in the Fw layer. For the 3- and 10-year-old plantations, there was no difference in basal Respiration in F, Fw, and H layers. Basal Respiration was related to changes in air temperature, precipitation, and the soil moisture contant at the time of sampling. The qCO2 values were higher in the old-growth stands than in the plantations. Clear-cutting followed by prescribed burning did not increase soil microbial Respiration, but CO2 released from slash-burning and that contributed from other sources may be of concern to increasing atmospheric CO2 concentrations.
William L Hargrove - One of the best experts on this subject based on the ideXlab platform.
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characterization of a Substrate Induced Respiration method for measuring fungal bacterial and total microbial biomass on plant residues
Agriculture Ecosystems & Environment, 1991Co-Authors: M H Beare, Constance L Neely, D C Coleman, William L HargroveAbstract:Abstract A Substrate-Induced Respiration (SIR) method is described to measure the contributions of fungi and bacteria to total glucose-Induced microbial Respiration on plant residues of differing composition. Relationships between fungal, bacterial and total SIR and biomass were used to develop regression equations for predicting microbial biomass C from measures of SIR. Total SIR rates (100–2000 μg CO2-C g−1 h−1) and biomass-specific SIR rates (64–72 ng CO2-C h−1 μg−1 biomass C) from plant residues were considerably greater than those calculated from the literature for soils. Results of longer term decomposition studies indicate that the C:N ratios of plant residues through time account for the greatest amount of the variation in total SIR. Annual decomposition rate constants (k) for plant residues were positively correlated (r2=0.99) to overall mean estimates of total SIR. The plant residue SIR method has advantages over conventional direct count methods because it distinguishes a physiologically active component of the microbial biomass. Furthermore, it allows separation of fungal and bacterial components that may aid in understanding microbial controls on plant residue decomposition.
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relationships between fungal and bacterial Substrate Induced Respiration biomass and plant residue decomposition
Soil Biology & Biochemistry, 1991Co-Authors: Constance L Neely, M H Beare, William L Hargrove, David C ColemanAbstract:Abstract Residues of six plant species were incubated in the field and analyzed for decomposition rates, fungal, bacterial and total Substrate-Induced Respiration (SIR), total fungal and bacterial biomass and changes in residue composition during 161 days. Plant residues included crimson clover ( Trifolium incarnatum L.), hairy vetch ( Vicia villosa Roth), crabgrass [ Digitaria sanguinalis , (L.) Scop.], winter rye ( Secale cereale L.), grain sorghum ( Sorghum bicolor L. Moench) and chestnut oak ( Quercus prinus L.) leaves. Plant residues were incubated in litterbags placed on the soil surface in no-tillage ( T. incarnatum, V. villosa, S. bicolor, S. cereale ), old-field ( D. sanguinalis ) or hardwood forest ( Q. prinus ) plots at the Horseshoe Bend Experimental Area in Athens, Ga and collected periodically for analyses. Decomposition rate constants ( k ) were greatest for V. villosa followed by T. incarnatum, D. sanguinalis, S. cereale, S. bicolor and Q. prinus . Net N loss generally followed the pattern of dry matter loss. Net N gain was observed after 100 days of decay for those residues with high initial C:N ratios. Initial N concentration was exponentially related with the annual decay rale constant ( r 2 = 0.93) for all species; however, on an individual species basis, lignin content was best correlated to dry matter weight loss. Total SIR was greatest on T. incarnatum and V. villosa followed by D. sanguinalis, S. bicolor, S. cereale and Q. prinus . Across all sample dates, residue carbon-to-nitrogen ratio was the best predictor of total SIR. Measurements of potential fungal and bacterial activity by SIR as well as biomass-C estimates by direct counts indicated that fungi were the dominant decomposers of these surface residues. For most residues, lignin content through time exerted the greatest influence on fungal SIR and fungal biomass-C ( r = −0.56 to −0.93). Total SIR, fungal SIR and total fungal biomass tended to decrease through time as residues decomposed. Total SIR, on any given sample date, was significantly correlated with residue dry weight remaining and annual decay rate constants were exponentially related to overall mean values of total SIR for all residues excluding S. cereale ( r 2 = 0.99). Residue SIR rates as a measure of the potentially active microbial biomass reflected the resource qualities of the plant residues investigated here and were positively correlated to their decomposition rates.
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a Substrate Induced Respiration sir method for measurement of fungal and bacterial biomass on plant residues
Soil Biology & Biochemistry, 1990Co-Authors: M H Beare, David C Coleman, Constance L Neely, William L HargroveAbstract:Abstract The Substrate-Induced Respiration (SIR) method was modified and adapted to measure fungal, bacterial and total microbial contributions to glucose-Induced Respiration and the potentially active microbial biomass on decaying plant residues of differing composition. Decomposing residues from natural and agricultural ecosystems were chopped and sieved to include the > 1 mm fraction for routine SIR analyses on a continuous flow-through Respiration system. SIR procedures were optimized for sample size (0.5–1.0g dry wt), glucose concentration (80mg g−1), antibiotic concentrations (16mg streptomycin g−1; 80 mg cycloheximide g−1), total solution volume (5 ml), antibiotic preincubation conditions (12 h at 4 C), and total assay time following glucose addition (2–3 h). Analyses of antibiotic selectivities for target populations were made from agar plate culture experiments with mixed residue-microbial populations under in vitro and in situ exposure to antibiotics. The results support those concentrations optimized by SIR and emphasize the importance of independent analysis of antibiotic selectivity. Measures of fungal, bacterial and total SIR (μg CO2-C g−1 dry residue h−1) were linearly correlated (P
P C Brookes - One of the best experts on this subject based on the ideXlab platform.
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an evaluation of the Substrate Induced Respiration method
Soil Biology & Biochemistry, 1999Co-Authors: P C BrookesAbstract:Abstract Two ways of measuring Substrate-Induced Respiration (SIR) following addition of glucose to soil, viz. solid glucose or glucose in solution, were tested on 13 soils sampled from arable, grassland and woodland sites ranging from pH 3.2 to 7.5. Generally similar patterns of CO2 evolution were found between soils following addition of glucose as liquid or solid (r=0.93) for unamended, ryegrass-amended and fumigated soils. Glucose added in solution to adjust the soils to 1.2-fold WHC was therefore preferred for analytical convenience. The optimum time of CO2 measurement was between 0.5 and 2.5 h for routine use. It was found to be unnecessary to make any correction for CO2 dissolved in the soil solution for soils below pH 6.5. Maximum inhibition of bacterial Respiration was obtained at 4 to 8 mg added streptomycin and of fungal Respiration at 8–12 mg added cyclohexamide g−1 soil. In a grassland soil (24% clay) the bacteria comprised 19±4.2% and the fungi 82±4.0% of the total biomass and in a grass ley (8% clay) the proportions were 25±1.2% for bacteria and 76±4.5% for fungal biomass.
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comparison of Substrate Induced Respiration selective inhibition and biovolume measurements of microbial biomass and its community structure in unamended ryegrass amended fumigated and pesticide treated soils
Soil Biology & Biochemistry, 1999Co-Authors: P C BrookesAbstract:Abstract Two UK grassland soils, one from Rothamsted (24% clay) and the other from Woburn (8% clay) were incubated at 25°C, unamended or amended with ryegrass followed by fumigation 20 d later followed by a further 20 d incubation. Other portions of the Rothamsted grassland soil were treated separately with a fungicide (Captan), a bacteriocide (Bronopol), or a herbicide (Dinoseb). The Substrate-Induced Respiration (SIR) method coupled with use of antibiotics (selective inhibition) and biovolume measurements by direct microscopy were used to comparatively measure total microbial biomass and the proportions of fungal and bacterial biomass in these two treated soils. Both methods gave similar estimates of total microbial biomass and the proportions of bacteria and fungi in the two soils. The different treatments did not significantly change the proportions of bacteria and fungi in the soil microbial biomass. It was concluded that both SIR and biovolume measurements are equally valid in measuring total biomass as are selective inhibition and biovolume measurements in measuring the proportions of fungi and bacteria in soils which are either unamended or undergoing rapid changes in metabolism due to Substrate amendment, fumigation or biocidal treatments.
Harvey Bolton - One of the best experts on this subject based on the ideXlab platform.
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relationships between soil microbial biomass determined by chloroform fumigation extraction Substrate Induced Respiration and phospholipid fatty acid analysis
Soil Biology & Biochemistry, 2002Co-Authors: Vanessa L Bailey, Aaron D Peacock, Jeffrey L Smith, Harvey BoltonAbstract:Abstract The soil microbial biomass (SMB) is responsible for many of the cycles and transformations of nutrients in soils. Three methods of measuring and describing this pool in soil are: (1) chloroform fumigation–extraction (CFE), (2) Substrate-Induced Respiration, and (3) total extractable phospholipid fatty acids (PLFA). This study was conducted to seek a relationship between microbial PLFA and measures of SMB. Microbial PLFA was best predicted by CFE ( R 2 =0.77); 1 nmol of PLFA corresponded to a flush of 2.4 μg C released by fumigation. This conversion factor will be useful in discussions of microbial populations and diversity and allow comparisons to literature in which only CFE is used to describe the size of the microbial biomass.
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Relationships between soil microbial biomass determined by chloroform fumigation–extraction, Substrate-Induced Respiration, and phospholipid fatty acid analysis
Soil Biology & Biochemistry, 2002Co-Authors: Vanessa L Bailey, Aaron D Peacock, Jeffrey L Smith, Harvey BoltonAbstract:Abstract The soil microbial biomass (SMB) is responsible for many of the cycles and transformations of nutrients in soils. Three methods of measuring and describing this pool in soil are: (1) chloroform fumigation–extraction (CFE), (2) Substrate-Induced Respiration, and (3) total extractable phospholipid fatty acids (PLFA). This study was conducted to seek a relationship between microbial PLFA and measures of SMB. Microbial PLFA was best predicted by CFE ( R 2 =0.77); 1 nmol of PLFA corresponded to a flush of 2.4 μg C released by fumigation. This conversion factor will be useful in discussions of microbial populations and diversity and allow comparisons to literature in which only CFE is used to describe the size of the microbial biomass.
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short communication relationships between soil microbial biomass determined by chloroform fumigation extraction Substrate Induced Respiration and phospholipid fatty acid analysis
2002Co-Authors: Vanessa L Bailey, Harvey BoltonAbstract:The soil microbial biomass (SMB) is responsible for many of the cycles and transformations of nutrients in soils. Three methods of measuring and describing this pool in soil are: (1) chloroform fumigation –extraction (CFE), (2) Substrate-Induced Respiration, and (3) total extractable phospholipid fatty acids (PLFA). This study was conducted to seek a relationship between microbial PLFA and measures of SMB. Microbial PLFA was best predicted by CFE ðR 2 ¼ 0:77Þ; 1 nmol of PLFA corresponded to a flush of 2.4 mg C released by fumigation. This conversion factor will be useful in discussions of microbial populations and diversity and allow comparisons to literature in which only
M H Beare - One of the best experts on this subject based on the ideXlab platform.
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characterization of a Substrate Induced Respiration method for measuring fungal bacterial and total microbial biomass on plant residues
Agriculture Ecosystems & Environment, 1991Co-Authors: M H Beare, Constance L Neely, D C Coleman, William L HargroveAbstract:Abstract A Substrate-Induced Respiration (SIR) method is described to measure the contributions of fungi and bacteria to total glucose-Induced microbial Respiration on plant residues of differing composition. Relationships between fungal, bacterial and total SIR and biomass were used to develop regression equations for predicting microbial biomass C from measures of SIR. Total SIR rates (100–2000 μg CO2-C g−1 h−1) and biomass-specific SIR rates (64–72 ng CO2-C h−1 μg−1 biomass C) from plant residues were considerably greater than those calculated from the literature for soils. Results of longer term decomposition studies indicate that the C:N ratios of plant residues through time account for the greatest amount of the variation in total SIR. Annual decomposition rate constants (k) for plant residues were positively correlated (r2=0.99) to overall mean estimates of total SIR. The plant residue SIR method has advantages over conventional direct count methods because it distinguishes a physiologically active component of the microbial biomass. Furthermore, it allows separation of fungal and bacterial components that may aid in understanding microbial controls on plant residue decomposition.
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relationships between fungal and bacterial Substrate Induced Respiration biomass and plant residue decomposition
Soil Biology & Biochemistry, 1991Co-Authors: Constance L Neely, M H Beare, William L Hargrove, David C ColemanAbstract:Abstract Residues of six plant species were incubated in the field and analyzed for decomposition rates, fungal, bacterial and total Substrate-Induced Respiration (SIR), total fungal and bacterial biomass and changes in residue composition during 161 days. Plant residues included crimson clover ( Trifolium incarnatum L.), hairy vetch ( Vicia villosa Roth), crabgrass [ Digitaria sanguinalis , (L.) Scop.], winter rye ( Secale cereale L.), grain sorghum ( Sorghum bicolor L. Moench) and chestnut oak ( Quercus prinus L.) leaves. Plant residues were incubated in litterbags placed on the soil surface in no-tillage ( T. incarnatum, V. villosa, S. bicolor, S. cereale ), old-field ( D. sanguinalis ) or hardwood forest ( Q. prinus ) plots at the Horseshoe Bend Experimental Area in Athens, Ga and collected periodically for analyses. Decomposition rate constants ( k ) were greatest for V. villosa followed by T. incarnatum, D. sanguinalis, S. cereale, S. bicolor and Q. prinus . Net N loss generally followed the pattern of dry matter loss. Net N gain was observed after 100 days of decay for those residues with high initial C:N ratios. Initial N concentration was exponentially related with the annual decay rale constant ( r 2 = 0.93) for all species; however, on an individual species basis, lignin content was best correlated to dry matter weight loss. Total SIR was greatest on T. incarnatum and V. villosa followed by D. sanguinalis, S. bicolor, S. cereale and Q. prinus . Across all sample dates, residue carbon-to-nitrogen ratio was the best predictor of total SIR. Measurements of potential fungal and bacterial activity by SIR as well as biomass-C estimates by direct counts indicated that fungi were the dominant decomposers of these surface residues. For most residues, lignin content through time exerted the greatest influence on fungal SIR and fungal biomass-C ( r = −0.56 to −0.93). Total SIR, fungal SIR and total fungal biomass tended to decrease through time as residues decomposed. Total SIR, on any given sample date, was significantly correlated with residue dry weight remaining and annual decay rate constants were exponentially related to overall mean values of total SIR for all residues excluding S. cereale ( r 2 = 0.99). Residue SIR rates as a measure of the potentially active microbial biomass reflected the resource qualities of the plant residues investigated here and were positively correlated to their decomposition rates.
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a Substrate Induced Respiration sir method for measurement of fungal and bacterial biomass on plant residues
Soil Biology & Biochemistry, 1990Co-Authors: M H Beare, David C Coleman, Constance L Neely, William L HargroveAbstract:Abstract The Substrate-Induced Respiration (SIR) method was modified and adapted to measure fungal, bacterial and total microbial contributions to glucose-Induced Respiration and the potentially active microbial biomass on decaying plant residues of differing composition. Decomposing residues from natural and agricultural ecosystems were chopped and sieved to include the > 1 mm fraction for routine SIR analyses on a continuous flow-through Respiration system. SIR procedures were optimized for sample size (0.5–1.0g dry wt), glucose concentration (80mg g−1), antibiotic concentrations (16mg streptomycin g−1; 80 mg cycloheximide g−1), total solution volume (5 ml), antibiotic preincubation conditions (12 h at 4 C), and total assay time following glucose addition (2–3 h). Analyses of antibiotic selectivities for target populations were made from agar plate culture experiments with mixed residue-microbial populations under in vitro and in situ exposure to antibiotics. The results support those concentrations optimized by SIR and emphasize the importance of independent analysis of antibiotic selectivity. Measures of fungal, bacterial and total SIR (μg CO2-C g−1 dry residue h−1) were linearly correlated (P
