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1
Shi, Andong, and Petra Marschner. "Changes in microbial biomass C, extractable C and available N during the early stages of decomposition of residue mixtures." Soil Research 52, no. 4 (2014): 366. http://dx.doi.org/10.1071/sr13128.
Повний текст джерелаАнотація:
Decomposition of mixed residues is common in many ecosystems, with residues from different species or above- and below-ground residues from the same species. Although decomposition of litter mixtures has been extensively studied, little is known about the changes in microbial biomass carbon (C) and available nitrogen (N) in the early stages of decomposition of mixtures of shoots and roots. An incubation experiment was carried out in a sandy clay loam with shoot and root residues of two grasses, annual barley (Hordeum vulgare L.), and perennial Stipa sp., added separately or as mixtures. Soil respiration was measured continuously, and soil microbial biomass C, extractable C and available N were measured by destructive sampling on days 0, 3, 6, 9, 12 and 18. Cumulative respiration and microbial biomass C concentration were higher with barley shoots alone or in mixtures than with Stipa residues alone. In the mixture of Stipa shoots and roots, which had similar decomposition rates when incubated individually, the measured cumulative respiration was greater than the expected value (average of the cumulative respiration of the individual residues), but this did not result in greater microbial biomass or changes in available N concentration compared with the individual residues. Cumulative respiration of barley shoots alone was higher than of barley root and Stipa shoot incubated individually. In the mixtures of barley shoots with barley roots or Stipa shoots, the measured cumulative respiration was either lower than the expected value or similar. Compared with barley shoots alone, microbial biomass C concentrations in the mixtures were generally lower in the first 3 days. It is concluded that mixing of residues with similar decomposition rates can stimulate microbial activity (respiration) but has little effect on microbial growth or concentrations of available N. Further, our findings provide information about extractable C and N dynamics during the early stages of decomposition of individual residue and residue mixtures.
2
Madritch, Michael D., Lisa M. Jordan, and Richard L. Lindroth. "Interactive effects of condensed tannin and cellulose additions on soil respiration." Canadian Journal of Forest Research 37, no. 10 (October 2007): 2063–67. http://dx.doi.org/10.1139/x07-047.
Повний текст джерелаАнотація:
Plant polyphenolics are receiving increased attention for their influences on belowground processes. Tannins are of particular interest because of their predominance in natural systems, their wide variation in both quality and quantity, and their protein-binding abilities. Current theory holds that simple phenolics increase microbial activity by acting as carbon substrates, while larger tannins decrease microbial activity by binding with organic nitrogen such as proteins. Here, we present results from a simple microcosm experiment that demonstrates that the influence of condensed tannins on soil respiration depends on the availability of additional carbon substrates. We purified tannins from trembling aspen ( Populus tremuloides Michx.) and crossed three levels of tannin additions with three levels of cellulose additions in laboratory microcosms. Soil respiration was measured over 36 days. In the absence of cellulose, high amounts of condensed tannins increased cumulative soil respiration. In the presence of abundant cellulose, condensed tannins decreased cumulative soil respiration. The positive and negative effects of purified tannins on soil respiration are time dependent, such that initial respiration is likely tannin induced, while later respiration is cellulose induced and tannin limited.
3
Tian, Xiaokun, Xiaogai Ge, Benzhi Zhou, and Maihe Li. "The Linkage of Soil CO2 Emissions in a Moso Bamboo (Phyllostachysedulis (Carriere) J. Houzeau) Plantation with Aboveground and Belowground Stoichiometry." Forests 12, no. 8 (August 7, 2021): 1052. http://dx.doi.org/10.3390/f12081052.
Повний текст джерелаАнотація:
Understanding the effects of soil stoichiometry and nutrient resorption on soil CO2 emissions is critical for predicting forest ecosystem nutritional demands and limitations tooptimal forest growth. In this study, we examined the effects of above- and belowground stoichiometry on soil CO2 emissions and their mediating effect on soil respiration in subtropical moso bamboo (Phyllostachys edulis) plantations. Our results showed that the soil respiration rate did not differ significantly among four bamboo stands. Nitrogen (N) and phosphorous (P) concentrations were higher in bamboo leaves than litter, whereas the C:N and C:P ratios showed the opposite trend. Significant positive correlations of soil cumulative CO2 emission with litter C:P (p = 0.012) and N:P (p = 0.041) ratios indicated that litter stoichiometry was a better predictor of soil respiration than aboveground stoichiometry. Cumulative soil CO2 emissions were significantly negatively correlated with soil microbe C:N (p = 0.021) and C:N (p = 0.036) ratios, and with soil respiratory quotients (p < 0.001). These results suggest that litter and soil stoichiometry are reliable indicators of the soil respiration rate. This study provides important information about the effects of ecosystem stoichiometry and soil microbial biomass on soil CO2 emissions and highlights them editing role of soil nutritional demands and limitations in the association between soil respiration rates and aboveground plant tissues.
4
Hasbullah, H., and P. Marschner. "Effect of residue mixtures on response of cumulative respiration to salinity." Journal of soil science and plant nutrition, ahead (2016): 0. http://dx.doi.org/10.4067/s0718-95162016005000028.
Повний текст джерела
5
Zhang, Xiao Long, Xue Yang, Kai Di Tian, Bing Shen, and Quan Quan. "Analysis of Observed and DNDC Modeled Soil Respiration of Winter Wheat in Guanzhong Plain." Advanced Materials Research 1073-1076 (December 2014): 1216–21. http://dx.doi.org/10.4028/www.scientific.net/amr.1073-1076.1216.
Повний текст джерелаАнотація:
The application of the DeNitrification-DeComposition (DNDC) model in soil respiration of winter wheat at the Ecological Experimental Station of Fuping County, China is researched for the year 2013-2014. The applied results indicate that DNDC is available to research soil respiration in cropland agroecosystems of Guanzhong Plain, China. Also the cumulative and seasonal variation emissions of soil respiration and components (root respiration, soil heterotrophic respiration) are estimated. Based on the simulated results, it can be seen that a significant variation appears in winter wheat growing season, where a downward trend starts from planting season to wintering season, and a steady low level at about 8.3 kg C·hm-2·d-1 keeps until the overwintering, then a significant upward to harvest, where the top point is almost 101.84 kg C·hm-2·d-1, with the total amount is 8342.35 kg C·hm-2. The seasonal amount of root respiration is 5345.47 kg C·hm-2, occupies 61.1% of soil respiration emissions.
6
Yang, Meng, Guirui Yu, Nianpeng He, John Grace, Qiufeng Wang, and Yan Zhou. "A Method for Estimating Annual Cumulative Soil/Ecosystem Respiration and CH4 Flux from Sporadic Data Collected Using the Chamber Method." Atmosphere 10, no. 10 (October 16, 2019): 623. http://dx.doi.org/10.3390/atmos10100623.
Повний текст джерелаАнотація:
Measurements of greenhouse gas fluxes over many ecosystems have been made as part of the attempt to quantify global carbon and nitrogen cycles. In particular, annual flux observations are of great value for regional flux assessments, as well as model development and optimization. The chamber method is a popular approach for soil/ecosystem respiration and CH4 flux observations of terrestrial ecosystems. However, in situ flux chamber measurements are usually made with non-continuous sampling. To date, efficient methods for the application of such sporadic data to upscale temporally and obtain annual cumulative fluxes have not yet been determined. To address this issue, we tested the adequacy of non-continuous sampling using multi-source data aggregation. We collected 330 site-years monthly soil/ecosystem respiration and 154 site-years monthly CH4 flux data in China, all obtained using the chamber method. The data were randomly divided into a training group and verification group. Fluxes of all possible sampling months of a year, i.e., 4094 different month combinations were used to obtain the annual cumulative flux. The results showed a good linear relationship between the monthly flux and the annual cumulative flux. The flux obtained during the warm season from May to October generally played a more important role in annual flux estimations, as compared to other months. An independent verification analysis showed that the monthly flux of 1 to 4 months explained up to 67%, 89%, 94%, and 97% of the variability of the annual cumulative soil/ecosystem respiration and 92%, 99%, 99%, and 99% of the variability of the annual cumulative CH4 flux. This study supports the use of chamber-observed sporadic flux data, which remains the most commonly-used method for annual flux estimating. The flux estimation method used in this study can be used as a guide for designing sampling programs with the intention of estimating the annual cumulative flux.
7
Zhang, Huan, Yanhong Liu, Zhiyong Zhou, and Yueying Zhang. "Inorganic Nitrogen Addition Affects Soil Respiration and Belowground Organic Carbon Fraction for a Pinus tabuliformis Forest." Forests 10, no. 5 (April 28, 2019): 369. http://dx.doi.org/10.3390/f10050369.
Повний текст джерелаАнотація:
The capability of forest ecosystems to sequester carbon from the atmosphere largely depends on the interaction of soil organic matter and nitrogen, and thus, this process will be greatly influenced by nitrogen deposition under the future scenario of global change. To clarify this interaction, the current study explored the variations in soil carbon fraction and soil respiration with different levels of nitrogen deposition. NH4NO3 was added at concentrations of 0, 50, 100, 200, and 400 kg N ha−1 year−1 separately on twenty 100 m2 plots in a Pinus tabuliformis Carr forest in northern China. Soil samples were analyzed for their nutrient content and biophysical properties two years after nitrogen application, and the soil respiration rate was measured every month during the study period. Seasonal variation and nitrogen addition significantly affected soil respiration rate. On average, nitrogen addition significantly reduced the annual soil respiration rate by 23.74%. Fine root biomass significantly decreased by an average of 43.55% in nitrogen treatment plots compared to the control plot. However, the average proportions of autumn and winter soil respiration rates out of the annual cumulative soil respiration rate greatly increased from 23.57% and 11.04% to 25.90% and 12.18%, respectively. The soil microbial biomass carbon content in the control plot was 342.39 mg kg−1, 23.50% higher than the average value in nitrogen treatment plots. The soil dissolved organic carbon was reduced by 22.60%, on average, following nitrogen addition. Significant correlations were detected between fine root biomass and the annual cumulative soil respiration rate, soil microbial biomass carbon content, and soil dissolved organic carbon content. This demonstrates that nitrogen addition affects soil organic carbon transformation and carbon emission, mainly by depressing fine root production.
8
Mavi, Manpreet S., and Petra Marschner. "Salinity affects the response of soil microbial activity and biomass to addition of carbon and nitrogen." Soil Research 51, no. 1 (2013): 68. http://dx.doi.org/10.1071/sr12191.
Повний текст джерелаАнотація:
Addition of carbon (C) and nitrogen (N) to soil can enhance microbial tolerance to salinity, but it is not known if salinity changes the response of microbial activity and biomass to addition of C and N, or how nutrient addition affects microbial tolerance to salinity. We prepared salinity treatments of non-saline soil [electrical conductivity (EC1 : 5) 0.1 dS m–1] without salt addition or adjusted to four salinity levels (2.5, 5.0, 7.5, 10 dS m–1) using a combination of CaCl2 and NaCl. The soils were amended with 2.5 mg C g–1 as glucose or as mature wheat straw (C/N ratio 47 : 1), with NH4Cl added to glucose to achieve a C/N ratio similar to that of wheat straw, or with NH4Cl added to glucose or wheat straw to achieve a C/N ratio of 20. Soil respiration was measured over 30 days. Microbial biomass C and N (MBC, MBN), dissolved organic C (DOC), and total dissolved N (TDN) were measured on day 30. Cumulative respiration and MBC concentration decreased with increasing EC, less so with glucose than with wheat straw. The MBC concentration was more sensitive to EC than was cumulative respiration, irrespective of C source. Addition of N to glucose and wheat straw to bring the C/N ratio to 20 significantly decreased cumulative respiration and MBC concentration at a given EC. This study showed that in the short term, addition of a readily available and easily decomposable source of energy improves the ability of microbes to tolerate salinity. The results also suggest that in saline soils, irrespective of the C substrate, N addition has no impact, or a negative impact, on microbial activity and growth.
9
Hasbullah, Hasbullah, and Petra Marschner. "Multiple additions of rapidly decomposable residue alleviate the negative impact of salinity on microbial activity." Soil Research 54, no. 6 (2016): 692. http://dx.doi.org/10.1071/sr15103.
Повний текст джерелаАнотація:
In previous research, we found that the reduction in soil respiration with increasing salinity was smaller in soils amended with rapidly decomposable residues (low C:N ratio) compared with slowly decomposable residues (high C:N ratio). However, with a single residue addition, available organic carbon will be quickly decomposed until only recalcitrant compounds remain. A more consistent supply of residues may improve the tolerance of microbes to salinity, but this effect could depend on residue decomposability. A 56-day incubation experiment was conducted with four loam soils having electrical conductivity (EC1:5) of 0.1, 1, 2.7 and 3.7dSm–1 amended 1–4 times with finely ground slowly decomposable canola (C:N=82) and rapidly decomposable kikuyu residues (C:N=19) with a total addition of 10gCkg–1 soil. There was a greater reduction in soil respiration with increasing salinity following addition of canola than addition of kikuyu. At all salinity levels and with both residues, cumulative respiration two weeks after addition of 10gCkg–1 was higher with multiple additions than with a single addition. The reduction of cumulative respiration with increasing salinity was smaller with repeated addition of rapidly decomposable residue than with only a single addition. However, this was not the case with slowly decomposable residue. The results suggest that for amelioration of saline soils, addition of rapidly decomposable residue is more effective than adding slowly decomposable residues, particularly when rapidly decomposable residues are added repeatedly.
10
Niederlehner, B. R., and John Cairns Jr. "Community Response to Cumulative Toxic Impact: Effects of Acclimation on Zinc Tolerance of Aufwuchs." Canadian Journal of Fisheries and Aquatic Sciences 49, no. 10 (October 1, 1992): 2155–63. http://dx.doi.org/10.1139/f92-238.
Повний текст джерелаАнотація:
Aufwuchs communities were developed on artificial substrates in a local pond. Second-generation communities were developed on identical substrates in laboratory systems receiving three levels of zinc (Zn): background, 73, and 172 μg∙L−1. After 21 d, second-generation communities were exposed to five concentrations of Zn ranging from background to 10 078 μg∙L−1 for 48 h. Protozoan communities developed under Zn stress were initially less rich taxonomically but subsequently lost fewer species in response to acute Zn exposures. Richness remaining after exposure to high Zn levels [Formula: see text] was similar for all groups. Taxonomic composition changed less in acclimated communities than in the control in response to secondary stress. Gross primary productivity was less impaired by secondary stress in communities acclimated to Zn. Community respiration, algal biomass, total biomass, respiration to biomass ratios, and ratios of soluble to total reactive phosphates did not differ in response to secondary stress. In general, communities developed under Zn stress were initially impaired but changed less in response to additional stress relative to their initial state.
11
van Iersel, Marc W., and Lynne Seymour. "Growth Respiration, Maintenance Respiration, and Carbon Fixation of Vinca: A Time Series Analysis." Journal of the American Society for Horticultural Science 125, no. 6 (November 2000): 702–6. http://dx.doi.org/10.21273/jashs.125.6.702.
Повний текст джерелаАнотація:
Respiration is important in the overall carbon balance of plants, and can be separated into growth (Rg) and maintenance respiration (Rm). Estimation of Rg and Rm throughout plant development is difficult with traditional approaches. Here, we describe a new method to determine ontogenic changes in Rg and Rm. The CO2 exchange rate of groups of 28 `Cooler Peppermint' vinca plants [Catharanthus roseus (L.) G. Don.] was measured at 20 min intervals for 2 weeks. These data were used to calculate daily carbon gain (DCG, a measure of growth rate) and cumulative carbon gain (CCG, a measure of plant size). Growth and maintenance respiration were estimated based on the assumption that they are functions of DCG and CCG, respectively. Results suggested a linear relationship between DCG and Rg. Initially, Rm was three times larger than Rg, but they were similar at the end of the experiment. The decrease in the fraction of total available carbohydrates that was used for Rm resulted in an increase in carbon use efficiency from 0.51 to 0.67 mol·mol-1 during the 2-week period. The glucose requirement of the plants was determined from Rg, DCG, and the carbon fraction of the plant material and estimated to be 1.39 g·g-1, while the maintenance coefficient was estimated to be 0.031 g·g-1·d-1 at the end of the experiment. These results are similar to values reported previously for other species. This suggests that the use of semicontinuous CO2 exchange measurements for estimating Rg and Rm yields reasonable results.
12
Taylor, Barry R., and Dennis Parkinson. "Respiration and mass loss rates of aspen and pine leaf litter decomposing in laboratory microcosms." Canadian Journal of Botany 66, no. 10 (October 1, 1988): 1948–59. http://dx.doi.org/10.1139/b88-267.
Повний текст джерелаАнотація:
Respiration rates and mass losses of decomposing pine (Pinus contorta Loud. × P. banksiana Lamb.) and aspen (Populus tremuloides Michx.) leaf litter were compared in laboratory microcosms for a range of temperature and moisture levels. For both litter types, a pair of high-temperature treatments (18, 26 °C) and a pair of low-temperature treatments (2, 10 °C) were distinguishable on the basis of respiration rate, mass loss, shape of the respiration curve, and (for pine) estimated microbial efficiency. Respiration rates in high-temperature treatments showed an initial increase to a wide peak (wider and later at 18 than at 26 °C), followed by a sharp decline; respiration of low-temperature treatments was nearly constant through time or declined slowly. Moisture level (15, 30, or 60 mL∙week−1 watering rate) was less important than temperature in determination of mass losses or respiration rates. Aspen respiration at 18 and 26 °C peaked sooner and declined more rapidly at higher moisture levels than at lower ones; at 2 and 10 °C, higher moisture levels inhibited respiration owing to saturation. Mass loss of pine needles after 153 days decay was a linear function of temperature (R2 = 0.92). The best regression describing mass loss of aspen litter after 130 days decay was a linear function of both temperature and moisture, without interaction (R2 = 0.82). Moisture level became more influential as temperature increased. Researchers are cautioned about the limitations of cumulative respiration curves, and alternatives, such as ANOVA, correlation, and the runs test, are suggested.
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Tomczyk, Nathan J., Amy D. Rosemond, Anna Kaz, and Jonathan P. Benstead. "Contrasting activation energies of litter-associated respiration and P uptake drive lower cumulative P uptake at higher temperatures." Biogeosciences 20, no. 1 (January 12, 2023): 191–204. http://dx.doi.org/10.5194/bg-20-191-2023.
Повний текст джерелаАнотація:
Abstract. Heterotrophic microbes play key roles in regulating fluxes of energy and nutrients, which are increasingly affected by globally changing environmental conditions such as warming and nutrient enrichment. While the effects of temperature and nutrients on microbial mineralization of carbon have been studied in some detail, much less attention has been given to how these factors are altering uptake rates of nutrients. We used laboratory experiments to simultaneously evaluate the temperature dependence of soluble reactive phosphorus (SRP) uptake and respiration by leaf-litter-associated microbial communities from temperate headwater streams. Additionally, we evaluated the influence of the initial concentration of SRP on the temperature dependence of P uptake. Finally, we used simple simulation models to extrapolate our results and estimate the effect of warming and P availability on cumulative gross uptake. We found that the temperature dependence of P uptake was lower than that of respiration (0.48 vs. 1.02 eV). Further, the temperature dependence of P uptake increased with the initial concentration of SRP supplied, ranging from 0.12 to 0.48 eV over an 11 to 212 µg L−1 gradient in initial SRP concentration. Finally, despite our laboratory experiments showing increases in mass-specific rates of gross P uptake with temperature, our simulation models predict declines in cumulative P uptake with warming, because the increased rates of respiration at warmer temperatures more rapidly depleted benthic carbon substrates and consequently reduced the biomass of the benthic microbial community. Thus, even though mass-specific rates of P uptake were higher at the warmer temperatures, cumulative P uptake was lower over the residence time of a pulsed input of organic carbon. Our results highlight the need to consider the combined effects of warming, nutrient availability, and resource availability and/or magnitude on carbon processing as important controls of nutrient processing in heterotrophic ecosystems.
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Elmajdoub, Bannur, Petra Marschner, and Richard G. Burns. "Addition of glucose increases the activity of microbes in saline soils." Soil Research 52, no. 6 (2014): 568. http://dx.doi.org/10.1071/sr13104.
Повний текст джерелаАнотація:
Adaptation of soil microbes to salinity requires substantial amounts of energy. We hypothesised that addition of glucose would increase microbial activity and growth and alleviate the negative effect of salinity on microbes. An incubation experiment was conducted with four salinity levels by using one non-saline and three saline soils of similar texture (sandy clay loam), with electrical conductivities (EC1:5) of 0.1, 1.1, 3.1 and 5.2 dS m–1. Glucose was added to achieve five organic carbon concentrations (0, 0.5, 1, 2.5, 5 g C kg–1). Soluble nitrogen (N) and phosphorus (P) were added to achieve a carbon (C) : N ratio of 20 and a C : P ratio of 200 to ensure that these nutrients did not limit microbial growth. A water content of 50% of the water-holding capacity (optimal for microbial activity in soils of this texture) was maintained throughout the incubation. Soil respiration was measured continuously over 21 days; microbial biomass C and available N and P were determined on days 2, 5, 14 and 21. Cumulative respiration was increased by addition of glucose and was reduced by salinity. The percentage decrease in cumulative respiration in saline soils compared with non-saline soil was greatest in the unamended soil and lowest with addition of 5 g C kg–1. At this rate of C addition, the percentage decrease in cumulative respiration increased with increasing salinity level. Microbial biomass C (MBC) concentration on days 2 and 5 was strongly increased by ≥1 g C kg–1 but decreased over time with the strongest decrease at the highest C addition rate. The MBC concentration was negatively correlated with EC at all C rates at each sampling date. Addition of C resulted in N and P immobilisation in the first 5 days. Biomass turnover as a result of depletion of readily available C released previously immobilised N and P after day 5, particularly in the soils with low salinity. This study showed that over a period of 3 weeks, addition of glucose increased microbial activity and growth in saline soils and alleviated the negative impact of salinity on microbes.
15
Francioni, Matteo, Paride D’Ottavio, Roberto Lai, Laura Trozzo, Katarina Budimir, Lucia Foresi, Ayaka Wenhong Kishimoto-Mo, et al. "Seasonal Soil Respiration Dynamics and Carbon-Stock Variations in Mountain Permanent Grasslands Compared to Arable Lands." Agriculture 9, no. 8 (July 27, 2019): 165. http://dx.doi.org/10.3390/agriculture9080165.
Повний текст джерелаАнотація:
Permanent grasslands provide a wide array of ecosystem services. Despite this, few studies have investigated grassland carbon (C) dynamics, and especially those related to the effects of land-use changes. This study aimed to determine whether the land-use change from permanent grassland to arable lands resulted in variations in the soil C stock, and whether such variations were due to increased soil respiration or to management practices. To address this, seasonal variations of soil respiration, sensitivity of soil respiration to soil temperature (Q10), and soil C stock variations generated by land-use changes were analyzed in a temperate mountain area of central Italy. The comparisons were performed for a permanent grassland and two adjacent fields, one cultivated with lentil and the other with emmer, during the 2015 crop year. Soil respiration and its heterotrophic component showed different spatial and temporal dynamics. Annual cumulative soil respiration rates were 6.05, 5.05 and 3.99 t C ha−1 year−1 for grassland, lentil and emmer, respectively. Both soil respiration and heterotrophic soil respiration were positively correlated with soil temperature at 10 cm depth. Derived Q10 values were from 2.23 to 6.05 for soil respiration, and from 1.82 to 4.06 for heterotrophic respiration. Soil C stock at over 0.2 m in depth was 93.56, 48.74 and 46.80 t C ha−1 for grassland, lentil and emmer, respectively. The land-use changes from permanent grassland to arable land lead to depletion in terms of the soil C stock due to water soil erosion. A more general evaluation appears necessary to determine the multiple effects of this land-use change at the landscape scale.
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Qadeer, Abdul. "Interactive effects of salinity and drought stresses on soil respiration and microbial activities." Pakistan Journal of Agricultural Sciences 59, no. 01 (January 1, 2022): 35–42. http://dx.doi.org/10.21162/pakjas/22.1263.
Повний текст джерелаАнотація:
Increasing frequency of droughts and problems related to salinization in irrigated areas may directly affect soil biological functions and soil respiration. An incubation study was designed to elucidate the effects of salinity and water intercross stresses on soil respiration and microbial activities. Three different moisture levels: optimum moisture conditions (80% water holding capacity (WHC)), moderate drought (50% WHC) and severe drought stress (30% WHC) were maintained in normal (ECe=1.48 dS m-1 ) and saline (ECe=8 dS m-1 ) soils. Our results showed that drought stress resulted in significant increase (p < 0.05) in microbial biomass carbon (MBC) (601+79 mg C kg-1 soil) and cumulative C-CO2 emissions (1153+96 mg C kg-1 soil). While under drought stress, extracellular enzyme activities showed no significant difference except leucine aminopeptidase with significant increase in its activity. Similarly, under saline conditions, MBC and soil respiration were significantly higher compared with normal soil. Extracellular enzyme activities were also significantly increased under salinity stress. In contrast, when combined stresses of drought and salinity were applied, cumulative C-CO2 emissions were significantly decreased (968+91 mg C kg-1 soil) as evident by decreased β-glucosidase activity, involved in C cycling. In contrast, chitinase activity increased under combined abiotic stresses, confirming the availability of chitin from microbial dead biomass degradation. It was concluded that microbes adopted drought and salinity stresses when applied individually but combined salinity with drought stress limited microbial biomass and microbial activities in soil.
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Mauritz, M., and D. L. Lipson. "Altered phenology and temperature sensitivity of invasive annual grasses and forbs changes autotrophic and heterotrophic respiration rates in a semi-arid shrub community." Biogeosciences Discussions 10, no. 4 (April 3, 2013): 6335–75. http://dx.doi.org/10.5194/bgd-10-6335-2013.
Повний текст джерелаАнотація:
Abstract. Many invasions, like the wide-spread establishment of annual grasses and forbs in semi-arid shrublands, are associated with climate change. In order to predict ecosystem carbon (C) storage it is critical that we understand how invasion affects soil respiration (Rt). Because plants and microbes have different seasonal dynamics, determining the relative contribution of autotrophic (Ra) and heterotrophic (Rh) respiration provides critical insight into soil C processes. Using automated soil respiration measurements and root exclusion cores we evaluated the moisture and temperature sensitivity of Rt and Rh and calculated the contribution of Ra in native shrub and invaded areas. Invasion increased cumulative Rt by 40% from 695 (±51) g C m−2 under shrubs to 1050 g C m−2 (±44) in invaded areas. Cumulative Rh did not change but invasion altered the seasonal pattern of Rh. Throughout the season Rt and Rh responded positively to temperature increases when soils were wet and negatively when soils were dry. Invasion increased temperature sensitivity of Rt and Rh in wet soils and decreased temperature sensitivity in dry soils. The altered temperature sensitivity of invasives was attributed largely to differences in phenology. Early phenology of invasive grasses caused rapid Ra increases early in the season; late phenology of invasive forbs resulted in the surprising maintenance of diurnal Ra and Rh signals despite high temperatures and low soil moisture. Invasion extended the respiration season of the system. Ability of the invasive community to withstand high temperatures and drought could confer greater resilience if temperature and precipitation patterns in the region change. The high contribution of Ra by invasive annuals means ecosystem C storage will depend heavily on seasonal rainfall dynamics and productivity of invasive annuals. In semi-arid ecosystems even small scale changes in plant community composition alter Rt, Ra and Rh and should be considered when attempting to predict Rt.
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Zhang, Jiaying, Zhongbing Lin, Renduo Zhang, and Jing Shen. "Effects of simulated rainfall events on soil carbon transformation." Soil Research 48, no. 5 (2010): 404. http://dx.doi.org/10.1071/sr09182.
Повний текст джерелаАнотація:
The storage of carbon (C) in soils can be influenced by rainfall patterns that affect both inputs from plant productivity and losses through soil respiration. The aim of this study was to investigate the effect of rainfall on the soil C transformation. A laboratory experiment was conducted using soil columns with different treatments, including a control with constant water content, and rainfall treatments with applications of 3, 6, and 10 simulated rainfall events during an experimental period of 31 days. Results showed that pulses of soil respiration rates occurred after the first 3 rainfall events, associated with soil water content and CO2 concentration pulses in the soil profile, while subsequent rainfall events did not result in similar increases in CO2 concentrations and respiration rates. Relative to the control treatment, the treatments with low (3 rainfall events) and moderate (6 rainfall events) amounts of total water applied resulted in 181% and 72% increases, respectively, in cumulative CO2 emission. In contrast, the high frequency rainfall treatment with the greatest amount of water resulted in a 40% reduction in cumulative CO2 emission. Soil microbial biomass C slightly increased under treatments with low and moderate rainfall treatments, but decreased under the treatment with 10 rainfall events. The results indicate that rainfall events with a high frequency and increased amount of water, and associated saturation of soils, can significantly reduce soil C losses during the wet season. The rainfall frequency and amount are of importance in controlling soil C emissions and should be incorporated into models of soil C dynamics.
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Zhou, Jiacong, Xiaofei Liu, Jinsheng Xie, Maokui Lyu, Yong Zheng, Zhangtian You, Yuexin Fan, et al. "Nitrogen Addition Affects Soil Respiration Primarily through Changes in Microbial Community Structure and Biomass in a Subtropical Natural Forest." Forests 10, no. 5 (May 20, 2019): 435. http://dx.doi.org/10.3390/f10050435.
Повний текст джерелаАнотація:
Forest soil respiration plays an important role in global carbon (C) cycling. Owing to the high degree of C and nitrogen (N) cycle coupling, N deposition rates may greatly influence forest soil respiration, and possibly even global C cycling. Soil microbes play a crucial role in regulating the biosphere–atmosphere C exchange; however, how microbes respond to N addition remains uncertain. To better understand this process, the experiment was performed in the Castanopsis kawakamii Hayata Nature Reserve, in the subtropical zone of China. Treatments involved applying different levels of N (0, 40, and 80 kg ha−2 year−1) over a three-year period (January 2013–December 2015) to explore how soil physicochemical properties, respiration rate, phospholipid fatty acid (PLFA) concentration, and solid state 13C nuclear magnetic resonance responded to various N addition rate. Results showed that high levels of N addition significantly decreased soil respiration; however, low levels of N addition significantly increased soil respiration. High levels of N reduced soil pH and enhanced P and C co-limitation of microorganisms, leading to significant reductions in total PLFA and changes in the structure of microbial communities. Significant linear relationships were observed between annual cumulative respiration and the concentration of microbial biomass (total PLFA, gram-positive bacteria (G+), gram-negative bacteria (G−), total bacteria, and fungi) and the microbial community structure (G+: G− ratio). Taken together, increasing N deposition changed microbial community structure and suppressed microbial biomass, ultimately leading to recalcitrant C accumulation and soil C emissions decrease in subtropical forest.
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Hedley, C. B., S. M. Lambie, and J. L. Dando. "Edaphic and environmental controls of soil respiration and related soil processes under two contrasting manuka and kanuka shrubland stands in North Island, New Zealand." Soil Research 51, no. 5 (2013): 390. http://dx.doi.org/10.1071/sr12248.
Повний текст джерелаАнотація:
The conversion of marginal pastoral land in New Zealand to higher biomass shrubland consisting of manuka (Leptospermum scoparium) and kanuka (Kunzea ericoides var. ericoides) offers opportunity for carbon (C) sequestration, with potential co-benefits of soil erosion control. We therefore selected two areas with different soils in different climatic regions to investigate and compare soil respiration rates, methane and nitrous oxide emission profiles, and key carbon exchange processes controlling carbon sequestration. In addition, two shrubland stands of different ages were selected in each area, providing four sites in total. Regular (almost monthly) soil respiration measurements were made over a 2-year period, with less frequent methane and nitrous oxide flux measurements, and soil sampling once at the end of the study. The cooler, wetter volcanic soils had higher total organic C (6.39 ± 0.12% v. 5.51 ± 0.17%), soil C : nitrogen (N) ratios (20.55 ± 0.20 v. 18.45 ± 0.23), and slightly lower mineral N (3.30 ± 0.74 v. 4.89 ± 0.57 mg/kg) and microbial biomass C (1131 ± 108 v. 1502 ± 37 mg/kg) than the more drought-prone, stony, sedimentary soils. Mineral-N contents at all sites indicated N-limited ecosystems for allocation of below- and above-ground C. The estimated mean annual cumulative respiration rate recorded in the volcanic soil was 10.26 ± 7.45 t CO2-C/ha.year compared with 9.85 ± 8.63 t CO2-C/ha.year in the stony sedimentary soil for the 2 years of our study. Older shrubland stands had higher respiration rates than younger stands in both study areas. Methane oxidation was estimated to be higher in the volcanic soil (4.10 ± 2.13 kg CH4-C/ha.year) than the sedimentary soil sites (2.51 ± 2.48 kg CH4-C/ha.year). The measured natural background levels of nitrous oxide emissions from these shrubland soils ranged between negligible and 0.30 ± 0.20 kg N2O-N/ha.year. A strong climatic control (temperature and moisture) on gas fluxes was observed at all sites. Our sampling strategy at each of the four sites was to estimate the mean soil respiration rates (n = 25) from an 8 by 8 m sampling grid positioned into a representative location. Soil respiration rates were also measured (by additional, less frequent sampling) in two adjacent grids (1-m offset and 100-m distant grid) to test the validity of these representative mean values. The 1-m offset grid (n = 25) provided a statistically different soil respiration rate from the main grid (n = 25) in 25% of the 12 sampling events. The 100-m grid (n = 25) provided a statistically different respiration rate to the main grid in 38% of the 26 sampling events. These differences are attributed to the spatially variable and sporadic nature of gaseous emissions from soils. The grid analysis tested the prediction uncertainty and it provides evidence for strong spatial and temporal control by edaphic processes in micro-sites. A partial least-squares regression model was used to relate the 2009 annual cumulative soil respiration to site-specific edaphic characteristics, i.e. biomass, nutrient availability, porosity and bulk density, measured at the end of that year. The model explained ≥80% of the variance at three of the four sites.
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Weese-Mayer, D. E., L. M. Klemka, R. T. Brouillette, and C. E. Hunt. "Effects of almitrine on respiration in unanesthetized newborn rabbits." Journal of Applied Physiology 64, no. 2 (February 1, 1988): 817–22. http://dx.doi.org/10.1152/jappl.1988.64.2.817.
Повний текст джерелаАнотація:
We previously demonstrated that almitrine, a peripheral chemoreceptor stimulant, increased tidal volume (VT), expired minute ventilation (VE), and respiratory frequency (f) and decreased inspiratory (TI) and expiratory time (TE) in sleeping adult cats. We now hypothesized that almitrine would induce an increase in ventilation in a young animal model. Respiration was studied by the barometric method in 11 unanesthetized New Zealand White rabbit pups between 3 and 6 days of age. Recordings were made in 0.21 FIO2 at base line and after cumulative intraperitoneal infusions of almitrine (2.5, 5.0, and 7.5 mg/kg). The chamber pressure deflection (proportional to VT after appropriate calculation) was computer sampled at 200 Hz. At least 100 breaths for each dose in each animal were analyzed. We found that a 7.5-mg/kg intraperitoneal dose of almitrine increased f to 135 +/- 9% (SE) of base line and decreased TE and TI to 72 +/- 8% and 79 +/- 8% of base line, respectively. Changes in VE, VT/TI, and VT were not significant. Recognizing that apnea is associated with inadequate ventilation and a prolonged TE (failure of the "inspiratory on-switch"), these results, particularly the increase in f and decrease in TE, suggest that almitrine might be useful in treating apnea in preterm infants.
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Hill, M. J., and C. R. Johnstone. "HEAT DAMAGE AND DRYING EFFECTS ON SEED QUALITY." NZGA: Research and Practice Series 2 (January 1, 1985): 53–57. http://dx.doi.org/10.33584/rps.2.1985.3301.
Повний текст джерелаАнотація:
Heat damage to seed can occur as a result of the cumulative effects of respiration and fungal heating, and by the accumulation and retention of radiant heat within the seed mass following harvest - both situations being collectively referred to as 'field heating'. Another type of heating damage occurs in heated air drying systems. Excessive drying air temperature can have deleterious effects on seed quality - this is generally referred to as "drying damage". Both 'field heating' and 'drying damage' result in loss of quality due to the thermosensitivity of seeds. This is a characteristic which is markedly influenced by the seed moisture content, by the extent and duration of heat production, and by the retention of heat within the seed mass. The role of the thermophilic fungi, Aspergillus spp., in accentuating heat damage, and the effects of both 'field heat' and 'drying damage' on the market acceptability and quality of seed is also discussed. Keywords: Respiration heating, fungal heating, Aspergillus, seed quality
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Yang, Zhen, Jiming Cheng, Qingjie Qi, Xin Li, and Yuning Wang. "A Method of UWB Radar Vital Detection Based on P Time Extraction of Strong Vital Signs." Journal of Sensors 2021 (September 18, 2021): 1–10. http://dx.doi.org/10.1155/2021/7294604.
Повний текст джерелаАнотація:
The vital sign information in the echo signal of the UWB radar is weak, because of the interference of complex noise. In this paper, a method named P times extraction of strong vital signs for processing echo signals of UWB radars is proposed. Different noises can be distinguished by the cumulative probability distribution of the echo signal and using different methods for processing according to corresponding characteristics. The vital sign information which most clearly represents the trapped person is selected using P times extraction of strong vital signs; then, the respiration and heartbeat rates are extracted. At 5 different distances, multiple sets of tests were carried out on static trapped persons and micromovement trapped persons and using a computer to extract vital signs from the obtained data. Experimental data shows that the algorithm proposed in this paper can extract the respiration and heartbeat rates of trapped persons, with small relative errors and variances, and has a certain reference value for UWB radar signal processing.
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van Straaten, O., E. Veldkamp, M. Köhler, and I. Anas. "Spatial and temporal effects of drought on soil CO<sub>2</sub> efflux in a cacao agroforestry system in Sulawesi, Indonesia." Biogeosciences 7, no. 4 (April 9, 2010): 1223–35. http://dx.doi.org/10.5194/bg-7-1223-2010.
Повний текст джерелаАнотація:
Abstract. Climate change induced droughts pose a serious threat to ecosystems across the tropics and sub-tropics, particularly to those areas not adapted to natural dry periods. In order to study the vulnerability of cacao (Theobroma cacao) – Gliricidia sepium agroforestry plantations to droughts a large scale throughfall displacement roof was built in Central Sulawesi, Indonesia. In this 19-month experiment, we compared soil surface CO2 efflux (soil respiration) from three roof plots with three adjacent control plots. Soil respiration rates peaked at intermediate soil moisture conditions and decreased under increasingly dry conditions (drought induced), or increasingly wet conditions (as evidenced in control plots). The roof plots exhibited a slight decrease in soil respiration compared to the control plots (average 13% decrease). The strength of the drought effect was spatially variable – while some measurement chamber sites reacted strongly (responsive) to the decrease in soil water content (up to R2=0.70) (n=11), others did not react at all (non-responsive) (n=7). A significant correlation was measured between responsive soil respiration chamber sites and sap flux density ratios of cacao (R=0.61) and Gliricidia (R=0.65). Leaf litter CO2 respiration decreased as conditions became drier. The litter layer contributed approximately 3–4% of the total CO2 efflux during dry periods and up to 40% during wet periods. Within days of roof opening soil CO2 efflux rose to control plot levels. Thereafter, CO2 efflux remained comparable between roof and control plots. The cumulative effect on soil CO2 emissions over the duration of the experiment was not significantly different: the control plots respired 11.1±0.5 Mg C ha−1 yr−1, while roof plots respired 10.5±0.5 Mg C ha−1 yr−1. The relatively mild decrease measured in soil CO2 efflux indicates that this agroforestry ecosystem is capable of mitigating droughts with only minor stress symptoms.
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Haney, R. L., W. F. Brinton, and E. Evans. "Soil CO2 respiration: Comparison of chemical titration, CO2 IRGA analysis and the Solvita gel system." Renewable Agriculture and Food Systems 23, no. 2 (May 27, 2008): 171–76. http://dx.doi.org/10.1017/s174217050800224x.
Повний текст джерелаАнотація:
AbstractThe measurement of soil carbon dioxide respiration is a means to gauge biological soil fertility. Test methods for respiration employed in the laboratory vary somewhat, and to date the equipment and labor required have somewhat limited more widespread adoption of such methodologies. The purpose of this research is to compare the results of measured soil CO2 respiration using three methods: (1) titration method; (2) infrared gas analysis (IRGA); and (3) the Solvita gel system for soil CO2 analysis. We acquired 36 soil samples from across the USA for comparison, which ranged in pH from 4.5 to 8.5, organic C from 0.8 to 4.6% and the clay content from 6 to 62%. All three methods were highly correlated with each other after 24-h of incubation (titration and Solvita r2=0.82, respirometer and Solvita r2=0.79 and titration versus respirometer r2=0.95). The 24-h (1-day) CO2 release from all three methods was also highly correlated to both basal soil respiration (7–28 days) and cumulative 28-day CO2 respiration. An additional 24 soil samples were acquired and added to the original 36, for a total of 60 soil samples. These samples were used for calibration of the Solvita gel digital color reader results using CO2-titration results and regression analysis. Regression analysis resulted in the equation y=20.6∗(Solvita number)−16.5 with an r2 of 0.83. The data suggest that the Solvita gel system for soil CO2 analysis could be a simple and easily used method to quantify soil microbial activity. Applications may also exist for the gel system for in situ measurements in surface gas chambers. Once standardized soil sampling and laboratory analysis protocols are established, the Solvita method could be easily adapted to commercial soil testing labs as an index of soil microbial activity.
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Peng, Ying-Jie, and Nanduri R. Prabhakar. "Reactive oxygen species in the plasticity of respiratory behavior elicited by chronic intermittent hypoxia." Journal of Applied Physiology 94, no. 6 (June 1, 2003): 2342–49. http://dx.doi.org/10.1152/japplphysiol.00613.2002.
Повний текст джерелаАнотація:
Long-term facilitation (LTF) of breathing elicited by episodic hypoxia (EH) is an extensively studied example of plasticity of respiratory motor behavior. Previous studies employed the paradigm of EH wherein each episode of hypoxia was 5 min. This paradigm is rarely encountered in nature. Brief episodes of hypoxia are encountered frequently with recurrent apneas, wherein hypoxic episodes last a few seconds only. Recent studies suggest that chronic intermittent hypoxia (CIH) represents a form of oxidative stress involving reactive O2species. The objectives of the present study were to determine 1) whether acute, repeated, brief EH (15 s) elicit LTF in breathing and 2) whether prior conditioning with CIH modulates acute EH-induced LTF of breathing, and if so whether reactive O2 species are involved. Experiments were performed on anesthetized, vagotomized, paralyzed, and mechanically ventilated rats, and efferent phrenic nerve activity was monitored as an index of respiratory motor output. In control animals, acute EH (15-s hypoxia; 10 episodes; n = 9) increased minute neural respiration, which persisted during 60 min of the posthypoxic period, suggesting LTF of breathing. EH-induced LTF of respiration was markedly augmented in CIH-conditioned animals (15-s hypoxia, 9 episodes/h, 8 h/day for 10 days; n = 9). By contrast, conditioning with a comparable, cumulative duration of sustained hypoxia (4-h hypoxia; n = 8) did not augment LTF elicited by acute EH. Systemic administration of manganese (III) tetrakis (1-methyl-4-pyridyl) porphyrin pentachloride (5 mg · kg−1 · day−1for 10 days), a potent scavenger of O[Formula: see text]·, prevented CIH-induced potentiation of LTF ( n = 9). These results demonstrate that 1) acute, brief EH elicits LTF in respiratory motor output; 2) prior conditioning with CIH, but not with comparable, cumulative duration of sustained hypoxia, augments LTF elicited by acute EH; and 3) O[Formula: see text]· radical scavenger prevents CIH-induced potentiation of LTF of respiration.
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Shi, Andong, Nan Yan, and Petra Marschner. "Cumulative respiration in two drying and rewetting cycles depends on the number and distribution of moist days." Geoderma 243-244 (April 2015): 168–74. http://dx.doi.org/10.1016/j.geoderma.2014.12.019.
Повний текст джерела
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Babych, Yu, A. Stadnychenko, and O. Uvayeva. "Effect of Cr (III) ions on respiration parameters of the allospecies of Planorbarius corneus s. L. (Mollusca, Gastropoda, Planorbidae) of the hydrological network of Ukraine." Visnyk of Lviv University. Biological series, no. 86 (July 7, 2022): 47–57. http://dx.doi.org/10.30970/vlubs.2022.86.04.
Повний текст джерелаАнотація:
The peculiarities of the influence of Cr (III) ions within the concentrations of 0.5 MPC to 3 MPC were studied on the indicators of pulmonary and direct diffuse respiration in snails of the “western” and “eastern” genetic vicariant allospecies of Planorbarius corneus s. lato in the hydrological network of Ukraine. These mollusсs, like all Pulmonata, have a bimodal respiration pattern. Oxygen is obtained by pulmonary respiration from the air, and by direct diffuse (surface) respiration from the water. Pulmonary respiration is performed with true lungs in both allospecies, while diffuse respiration is caused by the inflow of oxygen through the thin-walled cell membranes of the epithelial surfaces of their bodies into the cells of neighboring tissues. To P. corneus s. l., Cr (III) ions are an eхogenous toxicant of localized action with high cumulative properties. The presence of snails of both “western” and “eastern” allospecies in a contaminated Cr (III) medium was associated with the primary accumulation of this microelement in their hepatopancreas, followed by redistribution of the cumulant between other tissues and organs of the mollusсs poisoned due to the circulation of their liquid internal environment, the hаemolymph. At 0.5 MPC of Cr (III) in the environment containing the specimens of both allospecies, the parameters of their pulmonary and diffuse percutaneous respiration were in the range of normal values. That was the latent phase, the longest of all phases of the pathological process of poisoning. The increase in the concentration of Cr (III) to the level of MPC, and then to 2 MPC was accompanied by an increase in the respiratory activity of mollusсs in response to the concentrations of involved toxicants, which corresponded to the phase of stimulation of the poisoning process. At 3 MPC Cr (III), there was a sharp drop in the values of all studied parameters of both respiratory modes in the experimental animals to a level lower than the values obtained for the control group. The values of studied parameters of both pulmonary and diffuse respiration were significantly lower for the snails of the “eastern” allospecies than for those for “western” allospecies at all used Cr (III) concentrations, This indicates a greater sensitivity and lesser tolerance of snails of the “eastern” allospecies to the action of the toxic factor under discussion.
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Khoo, Michael C. K., and Patjanaporn Chalacheva. "Respiratory modulation of peripheral vasoconstriction: a modeling perspective." Journal of Applied Physiology 127, no. 5 (November 1, 2019): 1177–86. http://dx.doi.org/10.1152/japplphysiol.00111.2019.
Повний текст джерелаАнотація:
Although respiratory sinus arrhythmia and blood pressure variability have been investigated extensively, there have been far fewer studies of the respiratory modulation of peripheral blood flow in humans. Existing studies have been based primarily on noninvasive measurements using digit photoplethysmography and laser-Doppler flowmetry. The cumulative knowledge derived from these studies suggests that respiration can contribute to fluctuations in peripheral blood flow and volume through a combination of mechanical, hemodynamic, and neural mechanisms. However, the most convincing evidence suggests that the sympathetic nervous system plays the predominant role under normal, resting conditions. This mini-review provides a consolidation and interpretation of the key findings reported in this topical area. Given the need to extract dynamic information from noninvasive measurements under largely “closed-loop” conditions, we propose that the application of analytical tools based on systems theory and mathematical modeling can be of great utility in future studies. In particular, we present an example of how the transfer relation linking respiration to peripheral vascular conductance can be derived using measurements recorded during spontaneous breathing, spontaneous sighs, and ventilator-induced sighs.
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Shi, Andong, and Petra Marschner. "Drying and rewetting frequency influences cumulative respiration and its distribution over time in two soils with contrasting management." Soil Biology and Biochemistry 72 (May 2014): 172–79. http://dx.doi.org/10.1016/j.soilbio.2014.02.001.
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Sun, Q., W. S. Meyer, G. R. Koerber, and P. Marschner. "Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wildfire." Biogeosciences 12, no. 16 (August 27, 2015): 5093–101. http://dx.doi.org/10.5194/bg-12-5093-2015.
Повний текст джерелаАнотація:
Abstract. Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wildfire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content, which could be further modulated by wildfire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy mallee woodland, where part of the woodland experienced a wildfire which destroyed or damaged most of the aboveground plant parts 4 months before sampling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80 % of maximum water holding capacity (WHC) for 19 days; in DRW, soils were dried for 4 days, kept dry for another 5 days, then rewetted to 80 % WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period; rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per gram of soil in CM and DRW was greater under trees, but lower when expressed per gram of total organic carbon (TOC). Organic matter content, available P, and microbial biomass C, but not available N, were greater under trees than in open areas. Wild fire decreased the flush of respiration per gram of TOC in the open areas and under shrubs, and reduced TOC and microbial biomass C (MBC) concentrations only under trees, but had little effect on available N and P concentrations. We conclude that the impact of wildfire and DRW events on nutrient cycling differs among vegetation patches of a native semi-arid woodland which is related to organic matter amount and availability.
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Psarras, Georgios, Ian A. Merwin, Alan N. Lakso, and John A. Ray. "Root Growth Phenology, Root Longevity, and Rhizosphere Respiration of Field Grown `Mutsu' Apple Trees on `Malling 9' Rootstock." Journal of the American Society for Horticultural Science 125, no. 5 (September 2000): 596–602. http://dx.doi.org/10.21273/jashs.125.5.596.
Повний текст джерелаАнотація:
A 2-year field study of `Mutsu' apple [Malus sylvestris (L.) Mill. var. domestica (Borkh.) Mansf.] on `Malling 9' (M.9) rootstock was conducted to observe root growth in situ, and compare patterns of root growth, root maturation and turnover rates, and soil-root respiration. Rhizosphere respiration was monitored with a portable chamber connected to an infrared gas analyzer; root emergence, browning, and turnover rates were measured by direct observation through minirhizotron tubes inserted in the root zone. Negligible root growth was observed before the onset of shoot growth in mid-May. In both years, a main peak of new root emergence in late June and early July coincided partially with major phases of shoot and fruit growth. A smaller peak of root emergence during August to September 1997 consisted primarily of new roots at 20 to 45 cm soil depths. Most roots remained <1 mm in diameter and developed in the upper 25 cm soil profile; no roots were observed at any time below 50 cm, due to a compacted soil layer at that depth. The cumulative survivorship of new roots was 38% in 1996 and 64% in 1997, and 50% of emergent white roots turned brown or senesced within 26 days in 1996 and 19 days in 1997. Root turnover rates were highest in mid-August both years. Rhizosphere respiration was correlated (r2 = 0.36 and 0.59, P = 0.01 and 0.004) with soil temperatures in 1996 and 1997, with Q10 values of 2.3 in both years. The Q10 for root-dependent respiration (the difference between soil only and combined soil-root respiration) in 1997 was 3.1, indicating that roots were more sensitive than soil microflora to soil temperature. The temporal overlap of high rates of shoot, root and fruit growth from late May to mid-July suggests this is a critical period for resource allocations and competition in temperate zone apple trees.
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Sun, Q., W. S. Meyer, G. Koerber, and P. Marschner. "Response of respiration and nutrient availability to drying and rewetting in soil from a semi-arid woodland depends on vegetation patch and a recent wild fire." Biogeosciences Discussions 12, no. 11 (June 12, 2015): 8723–45. http://dx.doi.org/10.5194/bgd-12-8723-2015.
Повний текст джерелаАнотація:
Abstract. Semi-arid woodlands, which are characterised by patchy vegetation interspersed with bare, open areas, are frequently exposed to wild fire. During summer, long dry periods are occasionally interrupted by rainfall events. It is well-known that rewetting of dry soil induces a flush of respiration. However, the magnitude of the flush may differ between vegetation patches and open areas because of different organic matter content which could be further modulated by wild fire. Soils were collected from under trees, under shrubs or in open areas in unburnt and burnt sandy Mallee woodland, where part of the woodland experienced a wild fire which destroyed or damaged most of the aboveground plant parts four months before sampling. In an incubation experiment, the soils were exposed to two moisture treatments: constantly moist (CM) and drying and rewetting (DRW). In CM, soils were incubated at 80% of maximum water holding capacity for 19 days; In DRW, soils were dried for four days, kept dry for another five days, then rewet to 80% WHC and maintained at this water content until day 19. Soil respiration decreased during drying and was very low in the dry period; rewetting induced a respiration flush. Compared to soil under shrubs and in open areas, cumulative respiration per g soil in CM and DRW was greater under trees, but lower when expressed per g TOC. Organic matter content, available P, and microbial biomass C, but not available N were greater under trees than in open areas. Wild fire decreased the flush of respiration per g TOC in the open areas and under shrubs, and reduced TOC and MBC concentrations only under trees, but had little effect on available N and P concentrations. We conclude that of the impact wild fire and DRW events on nutrient cycling differ among vegetation patches of a native semiarid woodland which is related to organic matter amount and availability.
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Mahangade, Priyanka Sharad, Indra Mani, Randolph Beaudry, Norbert Müller, and Sangeeta Chopra. "Using Amaranth as a Model Plant for Evaluating Imperfect Storages: Assessment of Solar-refrigerated and Evaporatively-cooled Structures in India." HortScience 55, no. 11 (November 2020): 1759–65. http://dx.doi.org/10.21273/hortsci15249-20.
Повний текст джерелаАнотація:
Some storages have limited control over their internal environment and undergo daily and seasonal fluctuations in both temperature and humidity, which cause variation in the metabolic activity of stored products. As a result, it is difficult to assess and compare the performance of these imperfect storages using measures of environmental control. We propose using measures of plant senescence as a proxy for estimating storage performance of these “imperfect” storages based on the premise that physiological processes integrate changes of temperature and/or humidity in a predictable, mathematically describable manner. We evaluated amaranth (Amaranthus tricolor L.) as a model plant for evaluating imperfect storages using a red-leaf cultivar Pusa lal chaulai and a green-leaf cultivar Pusa kiran. Amaranth is a leafy vegetable grown worldwide and is a highly nutritious and versatile food. Cumulative respiration, a measure of integrated metabolic activity, was regressed against leaf abscission, chlorophyll loss, and leaf yellowing of amaranth stems for four storages having different, variable, temperature profiles. Storages included 1) an evaporatively cooled (EC) structure; 2) a solar-refrigerated and evaporatively cooled (SREC) structure; 3) an uncooled laboratory (UL); and 4) a household refrigerator (REF). We found that the rate of abscission, chlorophyll loss, and leaf yellowing differed markedly for the four storages; however, these measures of senescence were linearly related to estimates of cumulative respiration. The ease of measuring leaf abscission, chlorophyll loss, and leaf yellowing permits data collection even with minimal resources. We propose that amaranth would make an effective model plant for comparing the performance of storages differing dramatically in temperature control. A 10% leaf abscission in amaranth is proposed as a target for comparing storages.
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Mendham, D. S., A. M. O'Connell, and T. S. Grove. "Organic matter characteristics under native forest, long-term pasture, and recent conversion to Eucalyptus plantations in Western Australia: microbial biomass, soil respiration, and permanganate oxidation." Soil Research 40, no. 5 (2002): 859. http://dx.doi.org/10.1071/sr01092.
Повний текст джерелаАнотація:
The influence of land-use management on Walkley-Black soil carbon (C) concentration, 3 concentrations of permanganate oxidisable C (33, 167, and 333 mm), microbial biomass, and soil respiration in a laboratory incubation was tested in surface soil from 10 sites in south-western Australia. The sites ranged in total C concentration from 1.9 to 8.3%, and represented a broad climatic and soil-type distribution across south-western Australia. At each of the sites, 0-10 cm soil was collected from plots in pasture (20-71 years old), Eucalyptus globulus plantation (7-10 years old, established on ex-pasture), and native vegetation. Soil profiles and position in the landscape for each of the land-use types were matched as closely as possible at each site to minimise influences other than land use. Total C was highly correlated with clay content. Land use caused no significant change in the relationship between total C and soil texture, and land use had little effect on total C concentration. Permanganate-oxidisable C was highly correlated with Walkley-Black organic C (R2�>�0.90) for all 3 concentrations that were investigated. Only the most dilute concentration of permanganate-oxidisable C (33 mm) was sensitive enough to detect small changes in soil organic matter with land use (P = 0.045). Microbial biomass and respiration at 25 kPa matric potential moisture content and 35°C temperature were used as biological indicators of soil organic matter lability. Cumulative respired C was more sensitive to land use than Walkley-Black organic C, with lower respiration in native soils compared with managed soils with low C concentrations, but higher than the managed soils at sites with high C concentrations. Microbial biomass was not significantly affected by land use. Microbial biomass and cumulative respired C were strongly influenced by soil texture, with the microbial quotient (proportion of microbial biomass in total carbon) and the proportion of total C respired significantly lower in soils with higher silt and clay contents. Land use had no significant effect on these relationships. Overall, land use caused only minor differences in the biological and chemical indicators of organic matter quality across a broad range of sites in south-western Australia.
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Mori, Akinori. "Greenhouse Gas Emissions from Cut Grasslands Renovated with Full Inversion Tillage, Shallow Tillage, and Use of a Tine Drill in Nasu, Japan." Agriculture 10, no. 2 (January 24, 2020): 31. http://dx.doi.org/10.3390/agriculture10020031.
Повний текст джерелаАнотація:
To restore the productivity of a deteriorated sward due to weed invasion, renovation (re-sowing) is necessary. However, the renovation method used can affect the sward’s greenhouse gas (GHG) emissions and herbage yield. This study compared the effects of renovation using full inversion tillage (F), shallow tillage (S), or a tine drill (T) on the GHG emissions and herbage yield of a grassland in Nasu, Japan. Two adjacent grasslands were renovated in September 2015 (year 1) and 2016 (year 2). In each year, F, S, and T plots (5 m × 20 m each) were arranged in a randomized complete block design with four replications and then orchardgrass (Dactylis glomerata L.) was seeded. All plots received 40 kg-N ha−1 for renovation and 190 kg-N ha−1 y−1 the following year. Carbon balance (i.e., the difference between C input through crop residue and C output through heterotrophic respiration), methane (CH4) and nitrous oxide (N2O) emissions, and herbage yield were measured over a period of 411 or 412 days. Cumulative N2O emissions were significantly smaller from F and S plots than from T plots, however, there was no significant difference in the sum of GHG emissions (i.e., C balance plus cumulative CH4 and N2O emissions) among F, S, and T plots. The cumulative total herbage yields of the F, S, and T plots did not differ significantly from each other. Consequently, the GHG intensity—i.e., the sum of GHG emissions per cumulative total herbage yield—was not significantly different among the F, S, and T plots.
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Oludare AbdulganiyU, Olu-Ogbera. "SOIL MICROBIAL ACTIVITY AS BIOINDICATORS DURING THE DECOMPOSITION OF GRASS RESIDUES IN SANDY CLAY LOAM SOIL." International Journal of Engineering Applied Sciences and Technology 6, no. 7 (November 1, 2021): 68–75. http://dx.doi.org/10.33564/ijeast.2021.v06i07.012.
Повний текст джерелаАнотація:
Assessing the quality of the soil is an important method in determining the sustainability and environmental impact of agricultural ecosystems. Soil microbial indices like microbial biomass and microbial activity are important criteria for the determination of soil quality. Laboratory incubation study was undertaken to examine the influence of 2 grass residues on changes in soil microbial indices {(microbial (Cmic: Corg), metabolic (qCO2), carbon mineralization (qM) and microbial biomass change rate (qC) quotients)} in a sandy clay loam soil. Both P.maximum and D.horizontalis amended soil showed maximum soil respiration rate (11.90 mgCO2-C g-1 soil) while P.maximum had maximum cumulative respiration rate (199.90 mgCO2-C g-1 soil) .Microbial biomass C was significantly improved by both P.maximum and D.horizontalis residues under study (158.08 and 162 mg/g respetively). The qCO2 among different grass residues ranged from 1.23 to 1.24μg CO2- C μg-biomass-C -1 on the 82nd day. The results showed that incorporation of both grass residues impacted a positive effect on microbial flora and their activity. The study suggests that the despite the high C:N ratio of grasses, its seems to be of advantage in the maintenance of soil quality in a sandy clay loam soil.
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Hou, Tingting, Yanping Wang, Fuxing Guo, Qiong Jia, Xinnan Wu, Enguang Wang, and Jingbo Hong. "Soil Respiration Characteristics and Influencing Factors for Apple Orchards in Different Regions on the Loess Plateau of Shaanxi Province." Sustainability 13, no. 9 (April 24, 2021): 4780. http://dx.doi.org/10.3390/su13094780.
Повний текст джерелаАнотація:
To explore the characteristics of the spatial and temporal variation in soil respiration (SR) in orchard ecosystems in different regions of the Loess Plateau of Shaanxi Province and to distinguish the controlling factors, representative orchards were studied from April to October 2019. We conducted SR measurements in five locations, including Mizhi dangta (MZ), Ansai Liuzhuang (AS), Luochuan houzitou (LC), Fuping meijiaping (FP), and Yangling Wuquan (YL). The results indicated that the SR of each orchard showed clear seasonal variation. The SR increased with the distance from the trunk at the tree scale, while gradually increasing from north to south on the regional scale (p < 0.05). The soil temperature and soil moisture were the main factors controlling the seasonal changes in SR in the orchards. On the tree scale, the fine root biomass was the main factor causing the tree-scale spatial variability. At the regional scale, SR was mainly influenced by the differences in the soil temperature, soil moisture, soil organic carbon, soil bulk density and pH. In agricultural management practices, the cumulative soil respiration was higher with irrigated treatment than with non-irrigated (NI) treatment (p < 0.05). In addition, traditional surface drip irrigation (SDI) and root injection irrigation (RII) showed great differences in soil respiration in the early and late stages of irrigation (p < 0.05), and the soil moisture was the main controlling factor. Compared with no tillage (NI), green cover (GC), deep tillage (DT), and shallow tillage (ST) increased the SR by 57%, 36% and 14%, respectively (p < 0.05). Due to the great temporal and spatial variation in the SR in our study area, we determined that the soil respiration in the orchards was affected not only by environmental factors but also by agricultural measures. Therefore, greater attention should be paid to human factors when exploring SR to ensure that orchard management can promote the economic benefits of the orchards without greatly impacting the environment.
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Guerrero, César, Jorge Mataix-Solera, Ignacio Gómez, Fuensanta García-Orenes, and Manuel M. Jordán. "Microbial recolonization and chemical changes in a soil heated at different temperatures." International Journal of Wildland Fire 14, no. 4 (2005): 385. http://dx.doi.org/10.1071/wf05039.
Повний текст джерелаАнотація:
Samples of a Mediterranean forest soil were exposed in a muffle furnace to seven temperatures (100–700°C) for 15 min to simulate different fire intensities. Heated soils were incubated for 100 days after re-inoculation with fresh unheated soil. Immediately after heating, the extractable organic C increased with the heating temperature, reaching a maximum at 400°C. This increase in extractable organic C and nutrients in soils heated below 400°C allowed a rapid recolonization of bacteria, increasing the basal respiration. During the 100-day incubation, the cumulative values of basal respiration and carbon mineralization rates generally followed a double exponential equation in unheated and heated samples. Heating at 200°C caused a reduction of 99.6% for fungi (measured as culturable fungal propagules), which showed lower recolonization capacity than that of bacteria. Heating also caused a decrease in the organic C content of the soils, especially for the highest temperatures. As a consequence, the microbial biomass carbon recovery was short lived in heated soils. The varied effects of heating and incubation on the inorganic and organic nitrogen changes, available nutrients and metabolic quotients are also discussed. This study demonstrates that changes in soils exposed to comparatively high temperatures (>500°C) have a particularly strong impact on microbial population.
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Tanaka, T., S. Alliouane, R. G. J. Bellerby, J. Czerny, A. de Kluijver, U. Riebesell, K. G. Schulz, A. Silyakova, and J. P. Gattuso. "Metabolic balance of a plankton community in a pelagic water of a northern high latitude fjord in response to increased <i>p</i>CO<sub>2</sub>." Biogeosciences Discussions 9, no. 8 (August 17, 2012): 11013–39. http://dx.doi.org/10.5194/bgd-9-11013-2012.
Повний текст джерелаАнотація:
Abstract. The effect of ocean acidification on the balance between gross community production (GCP) and community respiration (CR) (i.e. net community production, NCP) of plankton communities was investigated in summer 2010 in Kongsfjorden, West of Svalbard. Surface water, which was characterized by low concentrations of dissolved inorganic nutrients and chlorophyll, was enclosed in 9 mesocosms and subjected to 8 pCO2 levels (2 replicated controls and 7 enhanced pCO2 treatments) for one month. Nutrients were added to all mesocosms on day 13 of the experiment, and thereafter increase of chlorophyll (index of phytoplankton biomass) was provoked in all mesocosms. No clear trend in response to increasing pCO2 was found in the daily values of NCP, CR, and GCP. For further analysis, these parameters were cumulated for the following three periods: phase 1: end of CO2 manipulation until nutrient addition (t4 to t13); phase 2: nutrient addition until the second chlorophyll minimum (t14 to t21); phase 3: the second chlorophyll minimum until the end of this study (t22 to t28). Significant response was detected as a decrease of NCP with increasing pCO2 during phase 3. CR was relatively stable throughout the experiment in all mesocosms. As a result, the cumulative GCP significantly decreased with increasing pCO2 during phase 3. After the nutrient addition, the ratios of cumulative NCP to cumulative consumption of NO3 and PO4 showed significant decrease during phase 3 with increasing pCO2. The results suggest that elevated pCO2 influenced cumulative NCP and stoichiometric C and nutrient coupling of the plankton community in a high latitude fjord only for a limited period. However provided that there were some differences or weak correlations between NCP data based on different methods in the same experiment, this conclusion should be taken with caution.
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Tanaka, T., S. Alliouane, R. G. B. Bellerby, J. Czerny, A. de Kluijver, U. Riebesell, K. G. Schulz, A. Silyakova, and J. P. Gattuso. "Effect of increased <i>p</i>CO<sub>2</sub> on the planktonic metabolic balance during a mesocosm experiment in an Arctic fjord." Biogeosciences 10, no. 1 (January 23, 2013): 315–25. http://dx.doi.org/10.5194/bg-10-315-2013.
Повний текст джерелаАнотація:
Abstract. The effect of ocean acidification on the balance between gross community production (GCP) and community respiration (CR) (i.e., net community production, NCP) of plankton communities was investigated in summer 2010 in Kongsfjorden, west of Svalbard. Surface water, which was characterized by low concentrations of dissolved inorganic nutrients and chlorophyll a (a proxy of phytoplankton biomass), was enclosed in nine mesocosms and subjected to eight pCO2 levels (two replicated controls and seven enhanced pCO2 treatments) for one month. Nutrients were added to all mesocosms on day 13 of the experiment, and thereafter increase of chlorophyll a was provoked in all mesocosms. No clear trend in response to increasing pCO2 was found in the daily values of NCP, CR, and GCP. For further analysis, these parameters were cumulated for the following three periods: phase 1 – end of CO2 manipulation until nutrient addition (t4 to t13); phase 2 – nutrient addition until the second chlorophyll a minimum (t14 to t21); phase 3 – the second chlorophyll a minimum until the end of this study (t22 to t28). A significant response was detected as a decrease of NCP with increasing pCO2 during phase 3. CR was relatively stable throughout the experiment in all mesocosms. As a result, the cumulative GCP significantly decreased with increasing pCO2 during phase 3. After the nutrient addition, the ratios of cumulative NCP to cumulative consumption of NO3 and PO4 showed a significant decrease during phase 3 with increasing pCO2. The results suggest that elevated pCO2 influenced cumulative NCP and stoichiometric C and nutrient coupling of the plankton community in a high-latitude fjord only for a limited period. However provided that there were some differences or weak correlations between NCP data based on different methods in the same experiment, this conclusion should be taken with caution.
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Zona, D., D. A. Lipson, J. H. Richards, G. K. Phoenix, A. K. Liljedahl, M. Ueyama, C. S. Sturtevant, and W. C. Oechel. "Delayed responses of an Arctic ecosystem to an extremely dry summer: impacts on net ecosystem exchange and vegetation functioning." Biogeosciences Discussions 10, no. 12 (December 9, 2013): 19189–217. http://dx.doi.org/10.5194/bgd-10-19189-2013.
Повний текст джерелаАнотація:
Abstract. The importance and mode of action of extreme events on the global carbon budget are inadequately understood. This includes the differential impact of extreme events on various ecosystem components, lag effects, recovery times, and compensatory processes. Summer 2007 in Barrow, Arctic Alaska, experienced unusually high air temperatures (fifth warmest over a 65 yr period) and record low precipitation (lowest over a 65 yr period). These abnormal conditions resulted in strongly reduced net Sphagnum CO2 uptake, but no effect neither on vascular plant development nor on net ecosystem exchange (NEE) from this arctic tundra ecosystem. Gross primary production (GPP) and ecosystem respiration (Reco) were both generally greater during most of this extreme summer. Cumulative ecosystem C uptake in 2007 was similar to the previous summers, showing the capacity of the ecosystem to compensate in its net ecosystem exchange (NEE) despite the impact on other functions and structure such as substantial necrosis of the Sphagnum layer. Surprisingly, the lowest ecosystem C uptake (2005–2009) was observed during the 2008 summer, i.e the year directly following the extremely summer. In 2008, cumulative C uptake was ∼70% lower than prior years. This reduction cannot solely be attributed to mosses, which typically contribute with ∼40% – of the entire ecosystem C uptake. The minimum summer cumulative C uptake in 2008 suggests that the entire ecosystem experienced difficulty readjusting to more typical weather after experiencing exceptionally warm and dry conditions. Importantly, the return to a substantial cumulative C uptake occurred two summers after the extreme event, which suggest a high resilience of this tundra ecosystem. Overall, these results show a highly complex response of the C uptake and its sub-components to atypically dry conditions. The impact of multiple extreme events still awaits further investigation.
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Luckai, N., G. R. Larocque, L. Archambault, D. Paré, R. Boutin, and A. Groot. "Using the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) to examine the impact of harvest and fire on carbon dynamics in selected forest types of the Canadian Boreal shield." Forestry Chronicle 88, no. 04 (August 2012): 426–38. http://dx.doi.org/10.5558/tfc2012-079.
Повний текст джерелаАнотація:
The objective of the study was to assess the responsiveness of the Carbon Budget Model of the Canadian Forest Sector (CBM-CFS3) to management scenarios that included three rotation lengths (50, 100 and 250 years) under harvest and fire disturbances in six forest types (poplar deep soil, black spruce deep soil, jack pine deep and shallow soils, hardwood mixedwood and other conifer lowland). Outputs from five carbon (C) pools were considered: merchantable stemwood (stump height of 30 cm, minimum DBH of 9 cm and a minimum top diameter of 7 cm), deadwood, soil C, total ecosystem C and cumulative total ecosystem C emissions. Yield curves strongly affected the predicted size of all five pools. Longer rotation lengths led to larger pools with the relative differences between rotation lengths varying with stand types. Pools associated with poplar were usually the largest while those of jack pine on shallow sites were generally the smallest. When compared to the starting point of the simulations, cumulative total ecosystem C and C emissions increased with the 100- and 250-year harvest rotations (HARV100 and HARV250, respectively) and declined with the 50-year harvest rotation (HARV50). Fire disturbances resulted in stable pools of cumulative ecosystem C and declines in C emissions. CBM-CFS3 provided realistic pool values but the authors suggest further development of the model depiction of ecosystem processes, especially with respect to the treatment of respiration. In general, the authors recommend that forest management planners consider using an integrated approach that links multiple proven and accepted models under appropriate model linking software.
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van Iersel, M. W., and B. Bugbee. "A Multiple Chamber, Semicontinuous, Crop Carbon Dioxide Exchange System: Design, Calibration, and Data Interpretation." Journal of the American Society for Horticultural Science 125, no. 1 (January 2000): 86–92. http://dx.doi.org/10.21273/jashs.125.1.86.
Повний текст джерелаАнотація:
Long-term, whole-crop CO2 exchange measurements can be used to study factors affecting crop growth. These factors include daily carbon gain, cumulative carbon gain, and carbon use efficiency, which cannot be determined from short-term measurements. We describe a system that measures semicontinuously crop CO2 exchange in 10 chambers over a period of weeks or months. Exchange of CO2 in every chamber can be measured at 5 min intervals. The system was designed to be placed inside a growth chamber, with additional environmental control provided by the individual gas exchange chambers. The system was calibrated by generating CO2 from NaHCO3 inside the chambers, which indicated that accuracy of the measurements was good (102% and 98% recovery for two separate photosynthesis systems). Since the systems measure net photosynthesis (Pnet, positive) and dark respiration (Rdark, negative), the data can be used to estimate gross photosynthesis, daily carbon gain, cumulative carbon gain, and carbon use efficiency. Continuous whole-crop measurements are a valuable tool that complements leaf photosynthesis measurements. Multiple chambers allow for replication and comparison among several environmental or cultural treatments that may affect crop growth. Example data from a 2 week study with petunia (Petunia ×hybrida Hort. Vilm.-Andr.) are presented to illustrate some of the capabilities of this system.
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Schlag, Christoph, Alexandra Wörner, Stefan Wagenpfeil, Eberhard F. Kochs, Roland M. Schmid, and Stefan von Delius. "Capnography Improves Detection of Apnea During Procedural Sedation for Percutaneous Transhepatic Cholangiodrainage." Canadian Journal of Gastroenterology 27, no. 10 (2013): 582–86. http://dx.doi.org/10.1155/2013/852454.
Повний текст джерелаАнотація:
BACKGROUND: Capnography provides noninvasive monitoring of ventilation and can enable early recognition of altered respiration patterns and apnea.OBJECTIVE: To compare the detection of apnea and the prediction of oxygen desaturation and hypoxemia using capnography versus clinical surveillance during procedural sedation for percutaneous transhepatic cholangiodrainage (PTCD).METHODS: Twenty consecutive patients scheduled for PTCD were included in the study. All patients were sedated during the procedure using midazolam and propofol. Aside from standard monitoring, additional capnographic monitoring was used and analyzed by an independent observer.RESULTS: The mean (± SD) cumulative duration of apnea demonstrated by capnography was significantly longer than the mean cumulative duration of clinically detected apnea (207.5±348.8 s versus 8.2±17.9 s; P=0.015). The overall number of detected episodes of apnea was also significantly different (113 versus seven; P=0.012). There were 15 events of oxygen desaturation (decrease in oxygen saturation [SaO2] ≥5%), which were predicted in eight of 15 cases by capnography and in one of 15 cases by clinical observation. There were three events of hypoxemia (SaO2<90%) that were predicted in three of three cases by capnography and in one of three cases by clinical observation.CONCLUSION: Capnographic monitoring was superior to clinical surveillance in the detection of apnea and in the prediction of oxygen desaturation during procedural sedation for PTCD.
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Sengupta, Aditi, Sarah J. Fansler, Rosalie K. Chu, Robert E. Danczak, Vanessa A. Garayburu-Caruso, Lupita Renteria, Hyun-Seob Song, Jason Toyoda, Jacqueline Wells, and James C. Stegen. "Disturbance triggers non-linear microbe–environment feedbacks." Biogeosciences 18, no. 16 (August 24, 2021): 4773–89. http://dx.doi.org/10.5194/bg-18-4773-2021.
Повний текст джерелаАнотація:
Abstract. Conceptual frameworks linking microbial community membership, properties, and processes with the environment and emergent function have been proposed but remain untested. Here we refine and test a recent conceptual framework using hyporheic zone sediments exposed to wetting–drying transitions. Our refined framework includes relationships between cumulative properties of a microbial community (e.g., microbial membership, community assembly properties, and biogeochemical rates), environmental features (e.g., organic matter thermodynamics), and emergent ecosystem function. Our primary aim was to evaluate the hypothesized relationships that comprise the conceptual framework and contrast outcomes from the whole and putatively active bacterial and archaeal communities. Throughout the system we found threshold-like responses to the duration of desiccation. Membership of the putatively active community – but not the whole bacterial and archaeal community – responded due to enhanced deterministic selection (an emergent community property). Concurrently, the thermodynamic properties of organic matter (OM) became less favorable for oxidation (an environmental component), and respiration decreased (a microbial process). While these responses were step functions of desiccation, we found that in deterministically assembled active communities, respiration was lower and thermodynamic properties of OM were less favorable. Placing the results in context of our conceptual framework points to previously unrecognized internal feedbacks that are initiated by disturbance and mediated by thermodynamics and that cause the impacts of disturbance to be dependent on the history of disturbance.
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Thierron, Viviane, and H. Laudelout. "Contribution of root respiration to total CO2 efflux from the soil of a deciduous forest." Canadian Journal of Forest Research 26, no. 7 (July 1, 1996): 1142–48. http://dx.doi.org/10.1139/x26-127.
Повний текст джерелаАнотація:
The measurement of CO2 efflux from forest soils has become of great importance in evaluating the role of forests as sequestering agents of atmospheric CO2. In this regard, it is important to know the part of total efflux that originates from root respiration. We have tried to evaluate it by measuring efflux in the field with a portable infrared gas analyzer, while at the same time, the 0–10 cm soil layer was sampled and incubated in the laboratory during 30–40 days. Comparison of field and laboratory measurements was made by conversion to a common temperature (10 °C) using the Arrhenius equation for both processes. Results indicated an Arrhenius apparent activation energy of 25 kcal (1 kcal = 4.1855 kJ) in the field and 15 kcal in the laboratory. Comparison of the results was also made possible by modelling the cumulative CO2 efflux in the laboratory so that we eliminated the initial flush of mineralization, the value of which was temperature dependent. The grand average of CO2 efflux from the forest soil calculated for the whole year from the temperature of the soil and the Arrhenius equation was 70 Mg•ha−1•year−1, of which 90% originated from the roots.
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Paré, David, Jérôme Laganière, Guy R. Larocque, and Robert Boutin. "Effects of a warmer climate and forest composition on soil carbon cycling, soil organic matter stability and stocks in a humid boreal region." SOIL 8, no. 2 (October 26, 2022): 673–86. http://dx.doi.org/10.5194/soil-8-673-2022.
Повний текст джерелаАнотація:
Abstract. The maintenance of the large soil organic carbon (SOC) stocks of the boreal forest under climate change is a matter of concern. In this study, major soil carbon pools and fluxes were assessed in 22 closed-canopy forests located along an elevation and latitudinal climatic gradient expanding 4 ∘C in mean annual temperature (MAT) for two important boreal conifer forest stand types: balsam fir (Abies balsamea), a fire avoider, and black spruce (Picea mariana), a fire-tolerant species. SOC stocks were not influenced by a warmer climate or by forest type. However, carbon fluxes, including aboveground litterfall rates, as well as total soil respiration (Rs) and heterotrophic (Rh) and autotrophic soil respiration (Ra), were linearly related to temperature (cumulative degree days >5 ∘C). The sensitivity of soil organic matter (SOM) degradation to temperature, assessed by comparing Q10 (rate of change for a T increase of 10 ∘C) of soil respiration and Rs10 (soil respiration rates corrected to 10 ∘C), did not vary along the temperature gradient, while the proportion of bioreactive carbon and nitrogen showed higher values for balsam fir and for warmer sites. Balsam fir forests showed a greater litterfall rate, a better litter quality (lower C : N ratio) and a higher Rs10 than black spruce ones, suggesting that their soils cycle a larger amount of C and N under a similar climate regime. Altogether, these results suggest that a warmer climate and a balsam fir forest composition induce a more rapid SOC turnover. Contrary to common soil organic matter stabilisation hypotheses, greater litter input rates did not lead to higher total SOC stocks, and a warmer climate did not lead to the depletion of bioreactive soil C and N. Positive effects of warming both on fluxes to and from the soil as well as a potential saturation of stabilised SOC could explain these results which apply to the context of this study: a cold and wet environment and a stable vegetation composition along the temperature gradient. While the entire study area is subject to a humid climate, a negative relationship was found between aridity and SOM stocks in the upper mineral soil layer for black spruce forests, suggesting that water balance is more critical than temperature to maintain SOM stocks.
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Guan, Chao, Xinrong Li, Peng Zhang, and Chenhui Li. "Effect of global warming on soil respiration and cumulative carbon release in biocrust-dominated areas in the Tengger Desert, northern China." Journal of Soils and Sediments 19, no. 3 (October 20, 2018): 1161–70. http://dx.doi.org/10.1007/s11368-018-2171-4.
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Riachi, Marc, Jean Himms-Hagen, and Mary-Ellen Harper. "Percent relative cumulative frequency analysis in indirect calorimetry: application to studies of transgenic mice." Canadian Journal of Physiology and Pharmacology 82, no. 12 (December 1, 2004): 1075–83. http://dx.doi.org/10.1139/y04-117.
Повний текст джерелаАнотація:
Indirect calorimetry is commonly used in research and clinical settings to assess characteristics of energy expenditure. Respiration chambers in indirect calorimetry allow measurements over long periods of time (e.g., hours to days) and thus the collection of large sets of data. Current methods of data analysis usually involve the extraction of only a selected small proportion of data, most commonly the data that reflects resting metabolic rate. Here, we describe a simple quantitative approach for the analysis of large data sets that is capable of detecting small differences in energy metabolism. We refer to it as the percent relative cumulative frequency (PRCF) approach and have applied it to the study of uncoupling protein-1 (UCP1) deficient and control mice. The approach involves sorting data in ascending order, calculating their cumulative frequency, and expressing the frequencies in the form of percentile curves. Results demonstrate the sensitivity of the PRCF approach for analyses of oxygen consumption ([Formula: see text]02) as well as respiratory exchange ratio data. Statistical comparisons of PRCF curves are based on the 50th percentile values and curve slopes (H values). The application of the PRCF approach revealed that energy expenditure in UCP1-deficient mice housed and studied at room temperature (24 °C) is on average 10% lower (p < 0.0001) than in littermate controls. The gradual acclimation of mice to 12 °C caused a near-doubling of [Formula: see text] in both UCP1-deficient and control mice. At this lower environmental temperature, there were no differences in [Formula: see text] between groups. The latter is likely due to augmented shivering thermogenesis in UCP1-deficient mice compared with controls. With the increased availability of murine models of metabolic disease, indirect calorimetry is increasingly used, and the PRCF approach provides a novel and powerful means for data analysis.Key words: thermogenesis, oxygen consumption, metabolic rate, uncoupling protein, UCP.