Intrinsic Temperature Sensitivity Research Articles

Intrinsic microbial temperature sensitivity and soil organic carbon decomposition in response to climate change.

Soil microbes are essential for regulating carbon stocks under climate change. However, the uncertainty surrounding how microbial temperature responses control carbon losses under warming conditions highlights a significant gap in our climate change models. To address this issue, we conducted a fine-scale analysis of soil organic carbon composition under different temperature gradients and characterized the corresponding microbial growth and physiology across various paddy soils spanning 4000 km in China. Our results showed that warming altered the composition of organic matter, resulting in a reduction in carbohydrates of approximately 0.026% to 0.030% from humid subtropical regions to humid continental regions. These changes were attributed to a decrease in the proportion of cold-preferring bacteria, leading to significant soil carbon losses. Our findings suggest that intrinsic microbial temperature sensitivity plays a crucial role in determining the rate of soil organic carbon decomposition, providing insights into the temperature limitations faced by microbial activities and their impact on soil carbon-climate feedback.

Alterable interferential fineness for high temperature sensing calibration based on Bragg hollow core fiber.

We propose, what we believe to be, a novel method for high temperature sensing calibration based on the mechanism of alterable interferential fineness in Bragg hollow core fiber (BHCF). To verify the proof-of-concept, the fabricated sensing structure is sandwiched by two sections with different length of BHCF. Two interferential fineness fringes dominate the transmission spectrum, where the high-fineness fringes formed by anti-resonant reflecting optical waveguide (ARROW) plays the role for high temperature measurement. Meanwhile, the low-fineness fringes induced by short Fabry-Perot (F-P) cavity are exploited as temperature calibration. The experimental results show that the ARROW mechanism-based temperature sensitivity can reach 26.03 pm/°C, and the intrinsic temperature sensitivity of BHCF is 1.02 pm/°C. Here, the relatively lower magnitude of the temperature sensitivity is considered as the standard value since it merely relies on the material properties of silicon. Additionally, a large dynamic temperature range from 100 °C to 800 °C presents linear response of the proposed sensing structure, which may shine the light on the sensing applications in the harsh environment.

Evolution of an extreme hemoglobin phenotype contributed to the sub-Arctic specialization of extinct Steller's sea cows.

The extinct Steller's sea cow (Hydrodamalis gigas; †1768) was a whale-sized marine mammal that manifested profound morphological specializations to exploit the harsh coastal climate of the North Pacific. Yet despite first-hand accounts of their biology, little is known regarding the physiological adjustments underlying their evolution to this environment. Here, the adult-expressed hemoglobin (Hb; a2β/δ2) of this sirenian is shown to harbor a fixed amino acid replacement at an otherwise invariant position (β/δ82Lys→Asn) that alters multiple aspects of Hb function. First, our functional characterization of recombinant sirenian Hb proteins demonstrate that the Hb-O2 affinity of this sub-Arctic species was less affected by temperature than those of living (sub)tropical sea cows. This phenotype presumably safeguarded O2 delivery to cool peripheral tissues and largely arises from a reduced intrinsic temperature sensitivity of the H. gigas protein. Additional experiments on H. gigas β/δ82Asn→Lys mutant Hb further reveal this exchange renders Steller's sea cow Hb unresponsive to the potent intraerythrocytic allosteric effector 2,3-diphosphoglycerate, a radical modification that is the first documented example of this phenotype among mammals. Notably, β/δ82Lys→Asn moreover underlies the secondary evolution of a reduced blood-O2 affinity phenotype that would have promoted heightened tissue and maternal/fetal O2 delivery. This conclusion is bolstered by analyses of two Steller's sea cow prenatal Hb proteins (Hb Gower I; z2e2 and HbF; a2g2) that suggest an exclusive embryonic stage expression pattern, and reveal uncommon replacements in H. gigas HbF (g38Thr→Ile and g101Glu→Asp) that increased Hb-O2 affinity relative to dugong HbF. Finally, the β/δ82Lys→Asn replacement of the adult/fetal protein is shown to increase protein solubility, which may have elevated red blood cell Hb content within both the adult and fetal circulations and contributed to meeting the elevated metabolic (thermoregulatory) requirements and fetal growth rates associated with this species cold adaptation.

Evaluation of the intrinsic temperature sensitivity of ecosystem respiration in typical ecosystems of an endorheic river basin

Evaluation of the intrinsic temperature sensitivity of ecosystem respiration in typical ecosystems of an endorheic river basin

Clumped‐Isotope Constraint on Upper‐Tropospheric Cooling During the Last Glacial Maximum

AbstractIce cores and other paleotemperature proxies, together with general circulation models, have provided information on past surface temperatures and the atmosphere's composition in different climates. Little is known, however, about past temperatures at high altitudes, which play a crucial role in Earth's radiative energy budget. Paleoclimate records at high‐altitude sites are sparse, and the few that are available show poor agreement with climate model predictions. These disagreements could be due to insufficient spatial coverage, spatiotemporal biases, or model physics; new records that can mitigate or avoid these uncertainties are needed. Here, we constrain the change in upper‐tropospheric temperature at the global scale during the Last Glacial Maximum (LGM) using the clumped‐isotope composition of molecular oxygen trapped in polar ice cores. Aided by global three‐dimensional chemical transport modeling, we exploit the intrinsic temperature sensitivity of the clumped‐isotope composition of atmospheric oxygen to infer that the upper troposphere (effective mean altitude 10–11 km) was 6–9°C cooler during the LGM than during the late preindustrial Holocene. A complementary energy balance approach supports a minor or negligible steepening of atmospheric lapse rates during the LGM, which is consistent with a range of climate model simulations. Proxy‐model disagreements with other high‐altitude records may stem from inaccuracies in regional hydroclimate simulation, possibly related to land‐atmosphere feedbacks.

An experimental and empirical assessment of machining damage of hybrid glass-carbon FRP composite during abrasive water jet machining

Fiber reinforced polymer (FRP) composite materials have huge demand in various fields due to their low weight and better mechanical qualities. Machining of FRP composite materials without damage is quite difficult using traditional machining systems owing to their intrinsic anisotropy, heterogeneity, and temperature sensitivity. Abrasive water jet machining (AWJM) is a known versatile technique to address the machining of FRP composite with minimal damage. However, kerf taper and delamination are the significant damages usually recorded in AWJM. The present work aims to minimize the above-said damages by applying a hybrid grey relational analysis (GRA)-principal component analysis (PCA) mathematical model. The glass and carbon fibers are used as reinforcements in the epoxy matrix. Nine experiments are conducted by considering hydraulic pressure, the mass flow of abrasive, standoff distance and transverse speed as machining parameters at three different levels each. The experimental and empirical results reveal that the mass flow of abrasive and hydraulic pressure are significant parameters to minimize the kerf damage, whereas the mass flow of abrasive and standoff distance are the parameters to reduce the delamination damage. The confirmation experiment based on the recommended optimized parameter records the reduction in delamination damage and kerf width damage to 33.9% and 11.72%, respectively. The adequacy and accuracy of the proposed mathematical model is being performed with the value of indicators R2 and adjR2, which are all closer to one.

Distinct body-size responses to warming climate in three rodent species.

In mammals, body-size responses to warming climates are diverse, and the mechanisms underlying these different responses have been little investigated. Using temporal and spatial datasets of three rodent species distributed across different climatic zones in China, we investigated temporal and spatial trends of body size (length and mass), identified the critical drivers of these trends, and inferred the potential causes underlying the distinct body-size responses to the critical drivers. We found that body mass of all species remained stable over time and across space. Body length, however, increased in one species over time and in two species across space. Generally, body-length variation was predicted best by minimum ambient temperature. Moreover, in two species, body length changed linearly with temperature differences between ancestral and colonization areas. These distinct temperature-length patterns may jointly be caused by species-specific temperature sensitivities and experienced magnitudes of warming. We hypothesize that species or populations distributed across distinct temperature gradients evolved different intrinsic temperature sensitivities, which affect how their body sizes respond to warming climates. Our results suggest that size trends associated with climate change should be explored at higher temporal and spatial resolutions, and include clades of species with similar distributions.

When does temperature matter for ecosystem respiration?

The temperature response of ecosystem processes is key to understand and predict impacts of climate change. This is especially true for respiration, given its high temperature sensitivity and major role in the global carbon cycle. However, similar intrinsic temperature sensitivity for respiration does not mean comparable temperature effects across ecosystems and biomes because non-temperature factors can be more important. Here we analyzed soil and sediment respiration data and found that in temperature ranges corresponding to high latitude mean temperatures, absolute respiration rates are more sensitive to non-temperature factors than to projected direct temperature effects. However, at higher temperatures (>20 °C) the direct effect of temperature mediated by temperature sensitivity will likely be more important over changes in non-temperature factors in shaping how respiration change over time. This supports past suggestions that the relatively small projected temperature increase at low (tropical) latitudes may have a large direct impact on absolute respiration. In contrast, absolute respiration rates at high (boreal/arctic) latitudes will likely be more sensitive on the development of the non-temperature factors than on the direct effects of the large projected temperature increase there. Social media abstract. Respiration may be less dependent to changes in temperature at higher than lower latitudes.

Temperature and pH mediate stoichiometric constraints of organically derived soil nutrients.

It remains unclear how warming will affect resource flows during soil organic matter (SOM) decomposition, in part due to uncertainty in how exoenzymes produced by microbes and roots will function. Rising temperatures can enhance the activity of most exoenzymes, but soil pH can impose limitations on their catalytic efficiency. The effects of temperature and pH on enzyme activity are often examined in environmental samples, but purified enzyme kinetics reveal fundamental attributes of enzymes’ intrinsic temperature responses and how relative release of decay‐liberated resources (their flow ratios) can change with environmental conditions. In this paper, we illuminate the principle that fundamental, biochemical limitations on SOM release of C, N, and P during decay, and differential exoenzymes’ responses to the environment, can exert biosphere‐scale significance on the stoichiometry of bioavailable soil resources. To that end, we combined previously published intrinsic temperature sensitivities of two hydrolytic enzymes that release C and N during decay with a novel data set characterizing the kinetics of a P‐releasing enzyme (acid phosphatase) across an ecologically relevant pH gradient. We use these data to estimate potential change in the flow ratios derived from these three enzymes’ activities (C:N, C:P, and N:P) at the global scale by the end of the century, based on temperature projections and soil pH distribution. Our results highlight how the temperature sensitivity of these hydrolytic enzymes and the influence of pH on that sensitivity can govern the relative availability of bioavailable resources derived from these enzymes. The work illuminates the utility of weaving well‐defined kinetic constraints of microbes’ exoenzymes into models that incorporate changing SOM inputs and composition, nutrient availability, and microbial functioning into their efforts to project terrestrial ecosystem functioning in a changing climate.

Sensitivity of soil respiration rate with respect to temperature, moisture and oxygen under freezing and thawing

In alpine environments, the decomposition rate of soil organic carbon (SOC) is controlled by several biotic and abiotic factors, which mostly change simultaneously and often lead to freezing and thawing cycles. However, it is highly uncertain whether the temperature sensitivity of decomposition around the freezing point of water is similar as in higher temperature ranges. In this study, we conducted a full factorial incubation experiment using soil samples from a grassland site in the Tibetan Plateau. A manipulative freeze-thaw cycle was imposed to these soils by continuously changing temperature, from −5 to 10 °C. Additional treatments included 4 levels of soil moisture at 15, 30, 60 and 90% of water-filled pore space (WFPS), and two levels of O2 concentration at 0 and 20%. We fitted the Arrhenius equation into the flux data to estimate the activation energy (Ea) and base flux rate (A) for each treatment level. Then, we predicted the dependence and sensitivity of decomposition rate (k) by implementing the Dual Arrhenius and Michaelis-Menten (DAMM) model using a Bayesian optimization approach. While soil temperature had the strongest control on SOC decomposition rate at all soil moisture and O2 levels, its intrinsic temperature sensitivity (Δk/ΔT) remained nearly constant across the entire temperature range except around 0 °C. We found that Ea was higher in nearly dry or anoxic conditions, suggesting that in these extremes more energy is required for microbial activity to take place. These intrinsic sensitivities revealed that temperature (energy) is the main factor that limits decomposition in cold environments provided that moisture and oxygen are sufficiently available. Intrinsic sensitivities with respect to soil moisture and oxygen concentration were only relevant at very narrow ranges, when soils were almost dry or partially anoxic, and small changes within these narrow ranges may lead to very strong changes in decomposition rates.

Ion channel reconstitution in lipid bilayers.

Incorporation of ion channels in planar lipid bilayers allows detecting and measuring ion channel activity in a well-controlled system. This technique provides critical information about ion channel kinetics, ion selectivity, gating mechanism, open probability, unitary conductance, subconductance states, voltage dependence, and burst opening events, particularly at the single molecule level. Planar lipid bilayers provide a unique controllable environment that enables maintaining specific regulatory components, including lipids, ligands, inhibitors, particular ions, and proteins, as well as the temperature that can modulate activity of many ion channels. Thus, this system provides explicit details about ion channel gating mechanism and enables identifying its particular regulatory molecules or components. This chapter will describe the planar lipid bilayer method using the example of a transient receptor potential (TRP) ion channel family member. The planar lipid bilayer electrophysiological approach has proven to be useful in studying intrinsic properties of TRP channels. This method is particularly valuable for our understanding of intrinsic temperature sensitivity of thermoreceptors such as TRP channels and direct effects of TRP channels agonists, antagonists, co-factors, and other modifiers.

Highly swelling, tough intelligent self-healing hydrogel with body temperature-response

Achieving hydrogels with mechanical and self-healing properties is highly desirable for their expanding applications, yet remains an ongoing challenge. The synergistic design of dynamic reversible chemical bond opens a new research direction for this material. Herein, a molecular design strategy is proposed via dynamic reversible ionic bond formed between amino and sulfonic acid groups endow self-healing properties for hydrogels while introducing the N-isopropylacrylamide (NIPAm) crosslinked network realized the strength property including high compressive strength and high ductility, and intrinsic temperature sensitivity due to its unique amphiphilic structure for water. By adjusting the mass ratios of NIPAm, 2-acrylamido-2-methylpropanesulfonic acid (AMPS) and chitosan (CS), the optimal synthesis conditions for the P(AMPS-NIPAm)/CS hydrogel were obtained. Importantly, this intelligent P(AMPS-NIPAm)/CS hydrogel reveals a successful balance between mechanical and self-healing properties into advanced materials. The self-healing efficiency is as high as 98.51%. Furthermore, the lower critical solution temperature (LCST) of sample AMPS/CS-1.4:1 is 37 ℃, which is closest to the human body temperature. These characteristics open a novel pathway to intelligent self-healing hydrogels in terms of drug delivery and wound dressings.

The temperature responsive mechanism of fiber surface plasmon resonance sensor

The temperature responsive mechanism of the optical fiber Surface Plasmon Resonance (SPR) sensor is analyzed. It is found that, both the gold film and the fiber core change with increasing temperature and affect the temperature sensitivity of the SPR sensor, but the main factor of the intrinsic temperature sensitivity of the sensor is the temperature dependent SPR response of the gold coating. The gold film plasma frequency plays a critical role in the temperature response mechanism of the sensor. Experimental and simulation results show that the SPR wavelength shift due to the change of the gold film temperature contributes 19.6 % to the total, as the sensor surrounded with ethanol and the environment temperature increases from 0°C to 50°C. The reason is that the plasma frequency of the gold film rises significantly as the external temperature increases. The rising rate of plasma frequency with temperature is related to the morphology and the deposition method of the gold film. This result has provided a novel insight on the physical properties of optical fiber SPR sensors and has improved the capability of SPR sensors for measuring signals in a temperature-changing environment.

Steam-based thermotherapy for managing nematodes in strawberry transplants.

Aerated steam-based thermotherapy was developed and evaluated for its efficacy in managing three nematode species (Aphelenchoides besseyi, Meloidogyne hapla, and Pratylenchus penetrans) that are often transported as quiescent passengers on strawberry transplants shipped to Florida from out-of-state nurseries. Initial studies were focused on evaluating the intrinsic temperature sensitivity of each nematode species to hot water in laboratory conditions. Each nematode species was exposed to hot water at 40, 44, 48, and 52°C for 1, 5, 10, 30, 60, 120, and 240 min. Exposure for 60 min or higher at 40°C paralyzed all three nematode species when examined immediately after heat treatment. Examination of the nematodes 24 hr post-treatment suggested that 100% mortality of all three nematode species was achieved when nematodes were exposed to hot water at a minimum temperature of 44°C for 120 min. Further studies were conducted to evaluate the efficacy of aerated steam to kill all three nematode species by exposing nematode-infested strawberry transplants at 44°C for 60, 120, and 240 min. Exposure of nematode inoculated plants to steam for 60 or 120 min reduced the populations of all three nematode species, but this was not enough to completely eradicate any of the three nematode species. Exposure for 240 min, however, was the most effective in reducing the populations of the three nematode species. A 240 min of exposure to aerated steam completely eradicated A. besseyi and M. hapla while P. penetrans populations were reduced only by 85%. Furthermore, the aerated steam had minimal to no adverse effect on plant biomass. Results from both the laboratory and greenhouse studies indicated that M. hapla was more sensitive to heat treatment followed by A. besseyi and P. penetrans. Results from this study suggested that aerated steam-based thermotherapy has good potential as a non-chemical method of management of nematodes of strawberry transplants.

Biochar changes thermal activation of greenhouse gas emissions in a rice–lettuce rotation microcosm experiment

Abstract Despite numerous studies of the effects of biochar amendments on soil greenhouse gas (GHG) emissions in recent years, the intrinsic temperature sensitivity of GHG emissions in biochar-amended soils is still not clear. In order to investigate the effects of biochar on the thermal activation of GHG emissions, the GHG emissions and their activation energies (Ea) were analyzed in a rice-lettuce rotation microcosm experiment. The experiment had five treatments: control (CK), chemical fertilizers (NPK), and three biochar application rates that are equivalent to 10 Mg ha−1 biochar (BC10), 20 Mg ha−1 biochar (BC20) and 40 Mg ha−1 biochar (BC40). The study showed that biochar treatments reduced CO2 and N2O emissions by lowering their Ea compared with the NPK treatment in the rice cultivation season. The biochar amendment treatments significantly reduced N2O cumulative emissions by 55.2–72.9% compared with the NPK treatment in the lettuce cultivation season largely due to the thermally deactivated impact of soil temperature on N2O emissions. Microbial biomass carbon was increased in the lower rates of biochar amendment in both crop cultivation seasons. These findings suggest that biochar amendment of soil has the potential to decrease the positive and increase the negative Ea of GHG emissions, with the implication of mitigating GHG emissions from cropland soils that would otherwise be increased by applying chemical fertilizers in the context of rising global temperature. Production of biochar from agricultural wastes, which is a method of cleaner production, and its application to the soil shows its potential for reducing GHG emissions by changing the thermal activation of the emissions during rice–lettuce crop rotation.

Environmental constraints’ sensitivity of soil organic carbon decomposition to temperature, management practices and climate change

Abstract Intrinsic temperature sensitivity of soil organic carbon (SOC) pools is the inherent response of their decomposition rate to temperature. It primarily depends on the chemical structure of SOC pool and ambient temperature. The apparent temperature sensitivity of SOC pools refers to the observable temperature sensitivity which primarily depends on environmental constraints (ECs) The Environmental constraints are key indicators that determine the apparent temperature sensitivities of different SOC pools. The ECs are the processes and or factors that slow down organic carbon (OC) decomposition rates and dampen intrinsic temperature sensitivities. These are broadly classified as physical, chemical, biological and biochemical processes those impart relative stability to SOC. The major ECs include; soil aggregation, flooding, clay associated-C and microbial secreted exo-polysachharide, etc. However, the matter of concern is that the ECs are also sensitive to temperature, management practices and climate change. Uncertainties exist with the stability and sensitivity of ECs to various management systems and climate induced anticipated changes. We reviewed in details the various types of ECs and how they are sensitive to management practices like tillage, land use changes, nutrient and water management, priming effect due to carbon dioxide (CO2) fertilization, vegetation composition and microbial manipulation.

TRP Channel Reconstitution in Lipid Bilayers.

The family of the transient receptor potential (TRP) proteins presents a diverse group of polymodal ion channels intertwined in the regulation of various physiological processes. Currently, TRP channels are well established in temperature-sensation, thermoregulation, pain sensation, and mineral homeostasis. Furthermore, new evidence suggests that TRP channels are also implicated in hormonal signaling, where the channels are responsible for propagating hormone-induced signals along the neural circuitry and also regulating cellular processes of nonexcitable cells. Due to this wide assortment of actions, TRP channels have been attracting immense scientific interest in various fields.In this chapter, I describe incorporation and characterization of several TRP channels using an electrophysiological approach known as planar lipid bilayers. This technique features measurements of functional activities of ion channels in a well-defined reconstituted system. The priority of this electrophysiological approach is identifying intrinsic properties of ion channels, which is particularly valuable in appreciating intrinsic temperature sensitivity concerning thermo-TRP channels, but also direct mechanisms of channels agonists, antagonists, cofactors, and other modifiers.

Decomposition temperature sensitivity of biochars with different stabilities affected by organic carbon fractions and soil microbes

The soil carbon (C) sequestration potential of biochar is affected by their intrinsic temperature sensitivities. The objective of this study was to quantify temperature sensitivities of decomposed biochars affected by organic C fractions and soil microbes. The hypotheses to be tested included that increasingly condensation and corrosion in biochar should increase biochar temperature sensitivity and that soil microbes should affect biochar temperature sensitivity. Rice (Oryza sativa L.) straw-derived biochars were pyrolyzed at 300, 500, and 800 °C to represent lowly, intermediately, and highly condensed biochars (denoted as LBC, MBC, and HBC), respectively. Bulk, dissolved, and chemically corroded biochars were incubated with and without soil microbial inoculation, respectively, under ambient temperatures from 5 to 45 °C for 119 d. The temperature sensitivity of biochar was characterized using the Q10 value (i.e., the proportional increase in respiration per 10 °C rise). Results showed that Q10 values of the biochars increased from 2.13 to 3.13 with increasing condensation, attributable to transformation of easily-degraded alkanes with intermediate chain lengths (C10-C24) in LBC to oxygen-containing aromatic hydrocarbon and ester in MBC and HBC. With accumulation of silica-occluding C, the decomposition of corroded biochars showed the highest Q10 values (2.47 to 3.90). The Q10 values of biochars decreased over time and became stable in range of 1.25 - 1.66 because of greater decrease in labile C and microbial enzyme activity at higher temperature. Additionally, as microbial community evolved to degrade recalcitrant C with increasing temperature, relatively low decomposition rate at higher temperature led to decreasing Q10 values of biochars. Therefore, temperature sensitivities of decomposed biochars were determined by the C structures and decreased with time by changes in soil microbial properties, showing the C sequestration potential of biochar application under warming.

Microbial temperature sensitivity and biomass change explain soil carbon loss with warming.

Soil microorganisms control carbon losses from soils to the atmosphere1–3, yet their responses to climate warming are often short-lived and unpredictable4–7. Two mechanisms, microbial acclimation and substrate depletion, have been proposed to explain temporary warming effects on soil microbial activity8–10. However, empirical support for either mechanism is unconvincing. Here we used geothermal temperature gradients (> 50 years of field warming)11 and a short-term experiment to show that microbial activity (gross rates of growth, turnover, respiration and carbon uptake) is intrinsically temperature sensitive and does not acclimate to warming (+ 6 ºC) over weeks or decades. Permanently accelerated microbial activity caused carbon loss from soil. However, soil carbon loss was temporary because substrate depletion reduced microbial biomass and constrained the influence of microbes over the ecosystem. A microbial biogeochemical model12–14 showed that these observations are reproducible through a modest, but permanent, acceleration in microbial physiology. These findings reveal a mechanism by which intrinsic microbial temperature sensitivity and substrate depletion together dictate warming effects on soil carbon loss via their control over microbial biomass. We thus provide a framework for interpreting the links between temperature, microbial activity and soil carbon loss on timescales relevant to Earth’s climate system.

Temperature sensitivity of soil organic carbon decomposition increased with mean carbon residence time: Field incubation and data assimilation.

Temperature sensitivity of soil organic carbon (SOC) decomposition is one of the major uncertainties in predicting climate-carbon (C) cycle feedback. Results from previous studies are highly contradictory with old soil C decomposition being more, similarly, or less sensitive to temperature than decomposition of young fractions. The contradictory results are partly from difficulties in distinguishing old from young SOC and their changes over time in the experiments with or without isotopic techniques. In this study, we have conducted a long-term field incubation experiment with deep soil collars (0-70cm in depth, 10cm in diameter of PVC tubes) for excluding root C input to examine apparent temperature sensitivity of SOC decomposition under ambient and warming treatments from 2002 to 2008. The data from the experiment were infused into a multi-pool soil C model to estimate intrinsic temperature sensitivity of SOC decomposition and C residence times of three SOC fractions (i.e., active, slow, and passive) using a data assimilation (DA) technique. As active SOC with the short C residence time was progressively depleted in the deep soil collars under both ambient and warming treatments, the residences times of the whole SOC became longer over time. Concomitantly, the estimated apparent and intrinsic temperature sensitivity of SOC decomposition also became gradually higher over time as more than 50% of active SOC was depleted. Thus, the temperature sensitivity of soil C decomposition in deep soil collars was positively correlated with the mean C residence times. However, the regression slope of the temperature sensitivity against the residence time was lower under the warming treatment than under ambient temperature, indicating that other processes also regulated temperature sensitivity of SOC decomposition. These results indicate that old SOC decomposition is more sensitive to temperature than young components, making the old C more vulnerable to future warmer climate.