Does root respiration of subtropical Chinese fir seedlings acclimate to seasonal temperature variation or experimental soil warming?

2021 ◽  
Vol 308-309 ◽  
pp. 108612
Author(s):  
Tingting Chen ◽  
Chengfang Lin ◽  
Taotao Song ◽  
Ruanquan Guo ◽  
Yingyin Cai ◽  
...  
Keyword(s):  
Temperature Variation ◽  
Root Respiration ◽  
Chinese Fir ◽  
Seasonal Temperature ◽  
Soil Warming ◽  
Seasonal Temperature Variation ◽  
Experimental Soil

scholarly journals Metagenomic Insights into the Effects of Seasonal Temperature Variation on the Activities of Activated Sludge

2019 ◽  
Vol 7 (12) ◽  
pp. 713 ◽  
Author(s):  
Chenbing Ai ◽  
Zhang Yan ◽  
Han Zhou ◽  
Shanshan Hou ◽  
Liyuan Chai ◽  
...  
Keyword(s):  
Microbial Community ◽  
Glutamine Synthetase ◽  
Activated Sludge ◽  
Temperature Variation ◽  
Nitrogen Metabolism ◽  
Metagenomic Data ◽  
Seasonal Temperature ◽  
Simulated Temperature ◽  
Genes Encoding ◽  
Seasonal Temperature Variation

It is well acknowledged that the activities of activated sludge (AS) are influenced by seasonal temperature variation. However, the underlying mechanisms remain largely unknown. Here, the activities of activated sludge under three simulated temperature variation trends were compared in lab-scale. The TN, HN3-H, and COD removal activities of activated sludge were improved as temperature elevated from 20 °C to 35 °C. While, the TN, HN3-H, COD and total phosphorus removal activities of activated sludge were inhibited as temperature declined from 20 °C to 5 °C. Both the extracellular polymer substances (EPS) composition (e.g., total amount, PS, PN and DNA) and sludge index of activated sludge were altered by simulated seasonal temperature variation. The variation of microbial community structures and the functional potentials of activated sludge were further explored by metagenomics. Proteobacteria, Actinobacteria, Acidobacteria and Bacteroidetes were the dominant phyla for each activated sludge sample under different temperatures. However, the predominant genera of activated sludge were significantly modulated by simulated temperature variation. The functional genes encoding enzymes for nitrogen metabolism in microorganisms were analyzed. The enzyme genes related to ammonification had the highest abundance despite the changing temperature, especially for gene encoding glutamine synthetase. With the temperature raising from 20 °C to 35 °C. The abundance of amoCAB genes encoding ammonia monooxygenase (EC:1.14.99.39) increased by 305.8%. Meanwhile, all the enzyme genes associate with denitrification were reduced. As the temperature declined from 20 °C to 5 °C, the abundance of enzyme genes related to nitrogen metabolism were raised except for carbamate kinase (EC:2.7.2.2), glutamate dehydrogenase (EC:1.4.1.3), glutamine synthetase (EC:6.3.1.2). Metagenomic data indicate that succession of the dominant genera in microbial community structure is, to some extent, beneficial to maintain the functional stability of activated sludge under the temperature variation within a certain temperature range. This study provides novel insights into the effects of seasonal temperature variation on the activities of activated sludge.

scholarly journals The impact of seasonality on niche breadth, distribution range and species richness: a theoretical exploration of Janzen's hypothesis

2016 ◽  
Vol 283 (1835) ◽  
pp. 20160349 ◽  
Author(s):  
Xia Hua
Keyword(s):  
Temperature Variation ◽  
Empirical Studies ◽  
Tropical Species ◽  
Seasonal Temperature ◽  
Thermal Niche ◽  
Trade Offs ◽  
Seasonal Temperature Variation ◽  
Latitudinal Patterns ◽  
The Tropics ◽  
The Impact

Being invoked as one of the candidate mechanisms for the latitudinal patterns in biodiversity, Janzen's hypothesis states that the limited seasonal temperature variation in the tropics generates greater temperature stratification across elevations, which makes tropical species adapted to narrower ranges of temperatures and have lower effective dispersal across elevations than species in temperate regions. Numerous empirical studies have documented latitudinal patterns in species elevational ranges and thermal niche breadths that are consistent with the hypothesis, but the theoretical underpinnings remain unclear. This study presents the first mathematical model to examine the evolutionary processes that could back up Janzen's hypothesis and assess the effectiveness of limited seasonal temperature variation to promote speciation along elevation in the tropics. Results suggest that trade-offs in thermal tolerances provide a mechanism for Janzen's hypothesis. Limited seasonal temperature variation promotes gradient speciation not due to the reduction in gene flow that is associated with narrow thermal niche, but due to the pleiotropic effects of more stable divergent selection of thermal tolerance on the evolution of reproductive incompatibility. The proposed modelling approach also provides a potential way to test a speciation model against genetic data.

scholarly journals Simulation models of dengue transmission in Funchal, Madeira Island: influence of seasonality

2019 ◽  
Author(s):  
Donald Salami ◽  
César Capinha ◽  
Carla Alexandra Sousa ◽  
Maria do Rosário Oliveira Martins ◽  
Cynthia Lord
Keyword(s):  
Aedes Aegypti ◽  
Temperature Variation ◽  
Local Control ◽  
Mitigation Strategies ◽  
Peak Time ◽  
Seasonal Temperature ◽  
Arrival Date ◽  
Madeira Island ◽  
Epidemic Dynamics ◽  
Seasonal Temperature Variation

AbstractThe recent emergence and established presence of Aedes aegypti in the Autonomous Region of Madeira, Portugal, was responsible for the first autochthonous outbreak of dengue in Europe. The island has not reported any dengue cases since the outbreak in 2012. However, there is a high risk that an introduction of the virus would result in another autochthonous outbreak given the presence of the vector and permissive environmental conditions. Understanding the dynamics of a potential epidemic is critical for targeted local control strategies.Here, we adopt a deterministic model for the transmission of dengue in Aedes aegypti mosquitoes. The model integrates empirical and mechanistic parameters for virus transmission, under seasonally varying temperatures for Funchal, Madeira Island. We examine the epidemic dynamics as triggered by the arrival date of an infectious individual; the influence of seasonal temperature mean and variation on the epidemic dynamics; and performed a sensitivity analysis on the following quantities of interest: the epidemic peak size, time to peak and the final epidemic size.Our results demonstrate the potential for summer to early winter transmission of dengue, with the arrival date significantly affecting the distribution of the timing and peak size of the epidemic. Mid-summer to early autumn arrivals are more likely to produce larger epidemics within a short peak time. Epidemics within this favorable period had an average of 18% of the susceptible population infected at the peak, at an average peak time of 70 days. We also demonstrated that seasonal temperature variation dramatically affects the epidemic dynamics, with warmer starting temperatures producing peaks more quickly after an introduction and larger epidemics. Overall, our quantities of interest were most sensitive to variance in the date of arrival, seasonal temperature, biting rate, transmission rates, and the mosquito population; the magnitude of sensitivity differs across quantities.Our model could serve as a useful guide in the development of effective local control and mitigation strategies for dengue fever in Madeira Island.Author SummaryThe presence of Aedes aegypti mosquitoes in Madeira Island had recently caused the first local outbreak of dengue in Europe. The island is at risk of another local transmission if triggered by the introduction of the dengue virus by an infected person. Using a mathematical model for the transmission of dengue, we examine the dynamics of a potential epidemic triggered by the arrival of an infected person on the island. We also examine the impact of seasonal temperature variation on the epidemic dynamics. Our results show the potential for summer to early winter transmission of dengue on the island, and that the arrival date of an infectious person affects the distribution of the timing and peak size of the epidemic. Arrival dates during mid-summer to early autumn were more likely to produce larger epidemic peak size within a short time. We also show that seasonal temperature variation dramatically affects the epidemic dynamics. With warmer starting temperatures, epidemics peak more rapidly and produce a larger epidemic size. Our model could be useful to estimate the risk of an epidemic outbreak and as a guide for local control and mitigation strategies for dengue on the island.

scholarly journals The effects of oscillating boundary conditions on thermal ignition

2020 ◽  
Vol 61 ◽  
pp. C45-C58
Author(s):  
Matthew Berry ◽  
Mark Nelson ◽  
Brian Monaghan ◽  
Ben Whale
Keyword(s):  
Temperature Variation ◽  
Filter Cake ◽  
Seasonal Temperature ◽  
Ambient Conditions ◽  
Ambient Temperatures ◽  
Temperature Oscillations ◽  
Seasonal Temperature Variation ◽  
Oscillating Boundary ◽  
Diurnal Temperature Variation ◽  
Ignition Times

We investigate the effect that oscillating ambient temperatures have on the ignition times of supercritical stockpiles. Large stockpiles are exposed to seasonal and diurnal temperature variation. We analyse the effects of seasonal temperature variation. When considering ignition within a year of construction, stockpiles built in spring ignited with a lower critical parameter than those built at other times. Consequently, seasonal temperature variation needs to be accounted for when predicting stockpile ignition times. References P. C. Bowes. Self-heating: evaluating and controlling the hazards. Dept. of the Environment, Building Research Establishment, 1984. R. J. Longbottom, B. J. Monaghan, G. Zhang, D. J. Pinson, and S. J. Chew. Self-sintering of BOS filter cake for improved recyclability. ISIJ Int., 59(3):432–441, 2019. doi:10.2355/isijinternational.ISIJINT-2018-627. V. Novozhilov. Thermal explosion in oscillating ambient conditions. Sci. Rep., 6:29730, 07 2016. doi:10.1038/srep29730. N. C. Roy. Convection characteristics in a closed vessel in the presence of exothermic combustion and ambient temperature oscillations. Int. J. Heat Mass Trans., 116:655–666, 2018. doi:10.1016/j.ijheatmasstransfer.2017.09.058.

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