Respiration and mass loss rates of aspen and pine leaf litter decomposing in laboratory microcosms

1988 ◽  
Vol 66 (10) ◽  
pp. 1948-1959 ◽  
Author(s):  
Barry R. Taylor ◽  
Dennis Parkinson
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Mass Loss ◽  
Linear Function ◽  
Leaf Litter ◽  
Populus Tremuloides ◽  
Moisture Level ◽  
Respiration Rates ◽  
Mass Losses ◽  
Low Temperature Treatments

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.

Decomposition of Populustremuloides leaf litter accelerated by addition of Alnuscrispa litter

1989 ◽  
Vol 19 (5) ◽  
pp. 674-679 ◽  
Author(s):  
Barry R. Taylor ◽  
William F. J. Parsons ◽  
Dennis Parkinson
Keyword(s):  
Mass Loss ◽  
Leaf Litter ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Rocky Mountain ◽  
Litter Type ◽  
Litter Bags ◽  
Mass Losses ◽  
Mixed Litter ◽  
Aspen Forest

Decomposition of a slow-decaying litter type is expected to be faster in the presence of a nutrient-rich, fast-decaying litter type, but this effect has never been conclusively demonstrated for deciduous leaves. In a Rocky Mountain aspen forest, we followed decomposition of leaf litter of trembling aspen (Populustremuloides), a relatively slow-decomposing, nutrient-poor species, and green alder (Alnuscrispa), a nutrient-rich, faster-decomposing species, as well as a mixture of the two, for 2 years. Mass losses over the first winter were greatest for aspen alone, probably as a result of loss of solubles, but the mass loss rate overall was lowest for aspen (k = −0.191/year) and greatest for alder (k = −0.251/year). Mass loss rate for mixed litter (k = −0.245/year) was much closer to the rate for alder than for aspen, demonstrating a marked acceleration of mass loss rates in the mixed-litter bags. At these rates, 95% mass loss would be achieved by aspen, alder, and mixed litter in 14.5, 11.5, and 11.6 years, respectively.

scholarly journals The Influence of Temperature and Host Gender on Bacterial Communities in the Asian Citrus Psyllid

Insects ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1054
Author(s):  
Rui-Xu Jiang ◽  
Feng Shang ◽  
Hong-Bo Jiang ◽  
Wei Dou ◽  
Tomislav Cernava ◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
High Throughput ◽  
Bacterial Communities ◽  
High Temperature Treatment ◽  
Asian Citrus Psyllid ◽  
Abiotic Factor ◽  
Insect Physiology ◽  
And Gender ◽  
Low Temperature Treatments

The Asian citrus psyllid, D. citri Kuwayama is the primary vector for Candidatus Liberibacter asiaticus (CLas), which causes a destructive disease in citrus plants. Bacterial symbionts are important determinants of insect physiology, and they can be impacted by many external factors. Temperature is an important abiotic factor affecting insect physiology, and it is also known that differences in symbiont proportions may vary in different insect genders. To date, it is unclear how the symbionts of D. citri are affected by temperature and gender. This study used high-throughput sequencing of 16S ribosomal RNA amplicons to determine how temperature and gender affect the bacterial communities present in D. citri. We identified 27 amplicon sequence variants (ASVs) belonging to 10 orders, seven classes, and five phyla. The dominant phylum was Proteobacteria (99.93%). Other phyla, including Firmicutes, Bacteroidota, Deinococcota, Cyanobacteria, and Actinobacteriota, were less abundant (<0.1%). Profftella (71.77–81.59%) and Wolbachia (18.39–28.22%) were the predominant taxa in all samples. Under high-temperature treatment, Profftella was more common in females, while Wolbachia had a higher abundance in males. In males, Profftella was more abundant under low-temperature treatments than under high-temperature treatments. In contrast, Wolbachia showed a higher abundance under high-temperature treatments than under low-temperature treatments. An RT-qPCR (quantitative real-time PCR) approach confirmed the results obtained with high-throughput DNA sequencing. Our results provide a basis for understanding the co-adaptation of D. citri and its symbionts to environmental temperature stress.

Aspen and pine leaf litter decomposition in laboratory microcosms. I. Linear versus exponential models of decay

1988 ◽  
Vol 66 (10) ◽  
pp. 1960-1965 ◽  
Author(s):  
Barry R. Taylor ◽  
Dennis Parkinson
Keyword(s):  
Mass Loss ◽  
Leaf Litter ◽  
Populus Tremuloides ◽  
Pinus Contorta ◽  
Exponential Model ◽  
Plant Litter ◽  
Adverse Conditions ◽  
Negative Exponential Model ◽  
Negative Exponential ◽  
Moisture Conditions

Leaf litter of trembling aspen (Populus tremuloides Michx.) and lodgepole–jack pine (Pinus contorta Loud, × P. banksiana Lamb.) was decomposed in laboratory microcosms at 2, 10, 18, or 26 °C and three watering rates (15, 30, or 60 mL∙week−1) for 16 weeks. Aspen litter lost 5.0–37.3% of original mass, and pine litter lost 7.8–14.9%. Decay curves fit a sample linear model equally as well as the negative exponential model regardless of temperature or moisture conditions or species of litter. A general explanation of circumstances promoting apparently linear mass loss from decaying plant litter is derived from these data, a survey of the literature, and the assumption that all decay curves are ultimately curvilinear. Mass loss rates are expected to appear linear from slowly decaying substrates such as bole wood or when decay of rapidly decomposing substrates is not followed past the inflection point of the curve. Climatic variables that favour decomposer activity are hypothesized to increase the concavity of decay curves, while adverse conditions do the opposite.

scholarly journals Temperature-induced Glucosinolate Accumulation Is Associated with Expression of BrMYB Transcription Factors

HortScience ◽  
2013 ◽  
Vol 48 (1) ◽  
pp. 47-52 ◽  
Author(s):  
Veronica L. Justen ◽  
Vincent A. Fritz
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Gene Expression Analysis ◽  
Tissue Type ◽  
Temperature Dependent ◽  
Temperature Regimes ◽  
Health Promoting ◽  
Transcription Factor Expression ◽  
Low Temperature Treatments

Turnips (Brassica rapa. subsp. rapa L.) produce glucosinolates (GSLs), thioglucosides whose hydrolyzed derivatives have been shown to provide chemopreventive benefits. Two cultivars of turnips [‘Just Right’ (JR) and ‘Scarlet Queen’ (SQ)] were grown under three different temperature regimes to assess the role of temperature on GSL production in roots and shoots. When compared with low-temperature treatments, high-temperature treatments increased total and individual GSLs in a tissue- and genotype-specific manner. When compared with low-temperature treatments, total GSLs were ≈70% and 130% higher in JR shoots and roots, respectively, grown at high-temperature treatments. High temperatures also increased total GSLs in SQ shoots and roots by ≈80% and 85%, respectively, when compared with low temperatures. Gluconasturtiin (GNS, 2-phenylethyl GSL) concentration was inversely correlated with temperature with high-temperature treatments resulting in 20% and 48% less GNS than low-temperature treatments in JR and SQ roots, respectively. The indolic GSL, 1-methoxyglucobrassicin (1MGB; 1-methoxy-3-ylmethyl GSL), was the root GSL most elevated by increased temperature resulting in a 1000% increase on average in both cultivars between the low- and high-temperature treatments. These results show promise for the use of temperature to enhance the health-promoting properties of turnip because 1MGB has potent chemopreventive effects. Gene expression analysis suggests that some BrMYB transcription factor expression levels are associated with temperature-dependent changes in GSL accumulation; however, this association varies between cultivar and tissue type.

scholarly journals Mass loss of platinum-rhodium thermocouple wires at 1324°C

2021 ◽  
Author(s):  
Sivahami Uthayakumaar ◽  
Stuart Davidson ◽  
Jonathan Pearce
Keyword(s):  
High Temperature ◽  
Oxygen Partial Pressure ◽  
Partial Pressure ◽  
Mass Loss ◽  
High Temperatures ◽  
High Precision ◽  
Elapsed Time ◽  
Mass Losses ◽  
Wide Range

It is known that Pt-Rh thermocouples exhibit mass loss when in the presence of oxygen at high temperatures due to the formation of volatile oxides of Pt and Rh. The mass losses of Pt, Pt-6%Rh and Pt-30%Rh wires, commonly used for thermocouples, were considered in this paper to characterise the mass loss of wires of the three compositions due to formation and evaporation of the oxides PtO2 and RhO2 under the conditions that would be seen by thermocouples used at high temperature. For the tests, the wires were placed in thin alumina tubes to emulate the thermocouple format, and the measurements were performed in air at a temperature of 1324 °C, i.e. with oxygen partial pressure of 21.3 kPa. It was found that the mass loss of the three wires increases linearly with elapsed time, consistent with other investigations, up to an elapsed time of about 150 hours, but after that, a marked acceleration of the mass loss is observed. Remarkably, previous high precision studies have shown that a cross-over after about 150 hours at 1324 °C is also observed in the thermoelectric drift of a wide range of Pt-Rh thermocouples, and the current results are compared with those studies. The mass loss was greatest for Pt-30%Rh, followed by Pt 6%Rh, then Pt.

Litter mass-loss rates and decomposition patterns in some needle and leaf litter types. Long-term decomposition in a Scots pine forest. VII

1991 ◽  
Vol 69 (7) ◽  
pp. 1449-1456 ◽  
Author(s):  
Björn Berg ◽  
Gunnar Ekbohm
Keyword(s):  
Mass Loss ◽  
Leaf Litter ◽  
Litter Decomposition ◽  
Loss Rate ◽  
Mass Loss Rate ◽  
Nitrogen Concentration ◽  
White Birch ◽  
Litter Mass ◽  
Mass Losses ◽  
Litter Mass Loss

The decomposition dynamics of four types of needle litter and three types of leaf litter were followed for 4 years. Mass losses and certain chemical changes were studied. Most of the nutrient-rich litters appeared to decompose relatively quickly during the first 12–18 months. After 3–4 years, however, their accumulated mass losses were lower compared with litter types that intially had lower rates. Thus the more nutrient-rich litters had considerably lower mass-loss rates in the later stages. This pattern was even more pronouced for extract-free lignocellulose: its mass-loss rate was negatively related to the lignin concentration, which increased progressively as litter decomposition proceeded. During late stages in litter with a high nitrogen content, there was also a clear negative relation between nitrogen concentration and lignin mass-loss rate, as well as between nitrogen concentration and litter mass-loss rate. By extrapolation of measured mass-loss values, maximum values for accumulated litter–mass loss were estimated. A nonlinear statistical model predicted that the proportion of mass lost through decomposition should be 50% for grey alder leaves, 54% for green leaves of white birch, and 57% for brown leaves of white birch. For Scots pine the predicted maximums for accumulated mass loss were 68% for green needles and 89% for brown needles, whereas corresponding values for lodgepole pine needles were 81% (green) and 100% (brown). Lodgepole pine is an introduced species in this system. Key words: litter, decomposition, lignin, nitrogen, maxium mass loss.

Exsolution and inversion in pigeonite from the Whin Sill, Northern England

1978 ◽  
Vol 36 (1) ◽  
pp. 474-475
Author(s):  
P.P.K. Smith
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Homogeneous Nucleation ◽  
Silicate Mineral ◽  
Antiphase Boundaries ◽  
Two Phase ◽  
Primitive Form ◽  
The Core ◽  
Nucleation Mechanisms ◽  
And Inversion

Grains of pigeonite, a calcium-poor silicate mineral of the pyroxene group, from the Whin Sill dolerite have been ion-thinned and examined by TEM. The pigeonite is strongly zoned chemically from the composition Wo8En64FS28 in the core to Wo13En34FS53 at the rim. Two phase transformations have occurred during the cooling of this pigeonite:- exsolution of augite, a more calcic pyroxene, and inversion of the pigeonite from the high- temperature C face-centred form to the low-temperature primitive form, with the formation of antiphase boundaries (APB's). Different sequences of these exsolution and inversion reactions, together with different nucleation mechanisms of the augite, have created three distinct microstructures depending on the position in the grain.In the core of the grains small platelets of augite about 0.02μm thick have farmed parallel to the (001) plane (Fig. 1). These are thought to have exsolved by homogeneous nucleation. Subsequently the inversion of the pigeonite has led to the creation of APB's.

Superconducting Wind Generators with Capacities of 10 MW and Larger

2020 ◽  
Vol 10 (10) ◽  
pp. 59-67
Author(s):  
Victor N. ANTIPOV ◽  
◽  
Andrey D. GROZOV ◽  
Anna V. IVANOVA ◽  
◽  
...  
Keyword(s):  
High Temperature ◽  
Low Temperature ◽  
Wind Power ◽  
State Of The Art ◽  
Superconducting Materials ◽  
Commercial Application ◽  
Synchronous Generators ◽  
High Temperature Superconducting ◽  
Wind Generators ◽  
Main Factor

The overall dimensions and mass of wind power units with capacities larger than 10 MW can be improved and their cost can be decreased by developing and constructing superconducting synchronous generators. The article analyzes foreign conceptual designs of superconducting synchronous generators based on different principles: with the use of high- and low-temperature superconductivity, fully superconducting or only with a superconducting excitation system, and with the use of different materials (MgB2, Bi2223, YBCO). A high cost of superconducting materials is the main factor impeding commercial application of superconducting generators. In view of the state of the art in the technology for manufacturing superconductors and their cost, a conclusion is drawn, according to which a synchronous gearless superconducting wind generator with a capacity of 10 MW with the field winding made of a high-temperature superconducting material (MgB2, Bi-2223 or YBCO) with the «ferromagnetic stator — ferromagnetic rotor» topology, with the stator diameter equal to 7—9 m, and with the number of poles equal to 32—40 has prospects for its practical use in the nearest future.

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