Effects Of Soil Temperature Research Articles

Examining the bias of pitfall traps with enclosure experiments and removal sampling

Abstract Pitfall trapping is among the most widely used sampling methods for ground‐dwelling beetles. However, the sampled ground‐dwelling beetle abundance in pitfall traps may be biased, which can lead to difficulties when comparing the sampled abundance between different habitats. To better understand the comparability of the sampled abundance, we focused on two sampling processes: a temporary migration process (referring to the individual movements into and out of the effective trap area) and a removal process (determining the number of individuals collected given the number of individuals within the trap area). To examine the effects of the temporary migration process, we compared the sampled abundance of 10 ground‐dwelling beetle species inside and outside enclosures in 2 habitats (clear‐cut and forested sites) and found that installing the enclosure decreased the sampled abundance in both habitats, but the effects did not differ among habitats. To examine the effects of the removal process, we examined the effects of daily soil temperature on the daily sampled abundance (removal probability) of Pterostichus thunbergi using removal sampling within enclosures. We found that soil temperature increased the removal probability, but this effect was limited and not consistent across survey periods. The results suggest that the effects of the temporary migration process may not be habitat dependent and that the effects of the removal process may be small. Therefore, the traditional use of pitfall traps is, to some extent, a robust and comparable measure of the sampled abundance of ground‐dwelling beetles among different habitats.

Effect of soil temperature on the morphological and physiological traits of Kandelia obovata seedlings

Effect of soil temperature on the morphological and physiological traits of Kandelia obovata seedlings

Interactive effects of soil moisture, nitrogen fertilizer, and temperature on the kinetic and thermodynamic properties of ammonia emissions from alkaline soil

Soil moisture and nitrogen fertilizer application rates are among the key factors affecting ammonia (NH3) emission, particularly in alkaline soil. However, the dynamic and thermodynamic properties of NH3 emissions from alkaline soils have not been extensively studied. In this study, we conducted an incubation experiment and theoretical analysis to investigate NH3 emission dynamics and thermodynamic properties under treatments involving different moisture levels (5%, 15%, 25%, and 35%), nitrogen fertilizer application rates (0, 172.4, and 344.8 mg kg−1), and temperatures (10, 20, 30, and 40 °C). The accumulative NH3 emissions varied significantly among the different moisture, temperature, and nitrogen treatment conditions and exhibited a logarithmic growth trend over time. The highest accumulative NH3 emissions occurred under the following conditions: 344.8 mg kg−1 nitrogen fertilizer, 5% moisture, and 40 °C temperature. The highest average emission rate constant (KN) throughout the entire incubation period was obtained at 40 °C. The KN of NH3 emissions in the high-temperature region (30–40 °C) was more sensitive to temperature. With increasing soil moisture content, the activated free energy (ΔG) initially increased and then decreased. As the nitrogen fertilizer application rate increased, the ΔG decreased, thereby leading to higher NH3 emissions. Combining the kinetic and thermodynamic parameters revealed that temperature, soil moisture, and nitrogen fertilizer application rate were key factors influencing NH3 emissions in alkaline soil, with the nitrogen fertilizer application rate having a greater impact than that of temperature, soil moisture, and their coupling. These findings provide valuable insights into the thermodynamic and kinetic control mechanisms of NH3 emissions, which can be regulated by fertilization and irrigation methods that consider the nitrogen cycle in alkaline soils.

Spatial and temporal patterns of methane emissions from mountain peatlands in the northern Andes across a disturbance gradient

Methane emitted by wetlands accounts for nearly 30% of the global methane emissions and is expected to double by 2,100. Methane fluxes from peatlands are related to m soil temperature, water table, and vegetation. Disturbances, mostly drainage, are considered to have a more limited impact on CH4 fluxes from peatlands. Here, we studied the temporal and spatial patterns of methane emissions from four peatlands across and elevation and disturbance gradient in the northern Andes. Our research seeks to understand the effects of disturbance legacies and soil temperature, flooding patterns, and vegetation on methane emissions in Andean peatlands. Our results indicated a strong control of CH4 emissions by soil temperature with a stronger effect at intermediate elevations. The removal of peat forming vegetation from the surface had the higher effect on CH4 emissions, increasing methane fluxes by an order of magnitude. Methane fluxes from conserved cushion vascular plants were low, but nearby hollows had relatively high emissions. Our research provides evidence of high methane emissions from degraded peatlands in the tropical Andes. However, the role of climate change and disturbance legacies on methane emissions from tropical Andean peatlands remains unknown affecting our ability to predict future emission patterns and our ability to incorporate climate mitigation strategies.

Trend for Soil CO2 Efflux in Grassland and Forest Land in Relation with Meteorological Conditions and Root Parameters

The key process in understanding carbon dynamics under different ecosystems is quantifying soil CO2 efflux. However, this process can change annually as it depends on environmental variables. The results of this paper present the effects of root network, soil temperature, and volumetric water content on soil CO2 efflux, which were investigated on Retisol of two types of land uses in Western Lithuania in 2017–2019: forest and grassland. It was determined that the average soil CO2 efflux in the grassland was 32% higher than in the forest land. The CO2 efflux, average across land uses, tended to increase in the following order: 2017 < 2018 < 2019. Dry weather conditions with high temperatures during the vegetation period governed the soil CO2 efflux increase by 14%. Soil temperature (up to 20 °C) and volumetric water content (up to 23–25%) had a positive effect on the soil CO2 efflux increase on Retisol. We established that the root’s activity plays one of the main roles in the CO2 production rate—in both land uses, the soil CO2 efflux was influenced by the root length density and the root volume.

Interactive effects of the El Niño-Southern Oscillation and Indian Ocean Dipole on the tropical net ecosystem productivity

El Niño-Southern Oscillation (ENSO) and Indian Ocean Dipole (IOD) can exert abiotic stresses on biota to influence regional terrestrial carbon cycling. Here, we investigated their interactive effects on tropical net ecosystem productivity (NEP) when ENSO and IOD simultaneously occur (mainly El Niño & positive IOD [pIOD] and La Niña & negative IOD [nIOD]), based on TRENDYv9 multi-model simulations. Results suggest that NEP anomalies were dominated by IOD over South America near 20°S and Africa south of the Equator, but by ENSO over India and northern South America, and controlled by their amplifying effects over eastern Africa, the Indo-China peninsula, and most of Australia during September-October-November (SON). In the following December-January-February (DJF), IOD legacy effects generally enhanced ENSO-induced NEP anomalies over most of South America, eastern and southern Africa, and Australia. During March-April-May (MAM), the influence of IOD gradually disappeared. Our analysis revealed the dominant role of gross primary productivity (GPP) in these NEP anomalies. We further found asymmetric effects of soil moisture and temperature on NEP anomalies, showing higher correlation coefficients with soil moisture in El Niño & pIOD, but basically with temperature in La Niña & nIOD. Additionally, considering the simultaneous extreme of pIOD and El Niño activity in 1997/98, we calculated their seasonal individual contributions to NEP anomalies. We found that the pIOD event had the greatest influence in SON. During SON in 1997, individual contributions of pIOD and El Niño to NEP caused a land carbon source of −0.34 ± 0.15 and −0.35 ± 0.32 PgC yr−1 over South America, a carbon sink and source of 0.5 ± 0.19 and −0.54 ± 0.14 PgC yr−1 over Africa, and source of −0.08 ± 0.25 and −0.42 ± 0.37 PgC yr−1 over Asia-Pacific, respectively. Understanding interactive effects of IOD and ENSO on regional carbon cycling is crucial due to the more frequent extreme IOD and ENSO events under future climate warming.

Long-term axial performance of continuous-flight pile in frozen soil

A number of buildings in the Canadian Arctic communities have failed or showed signs of failure of pile foundations caused by climate-change-induced excessive settlements. Effects of climate change warrant alternative pile types and new installation methods. Installing a pile into frozen soils by the torque method is rare in current practice of the Canadian Arctic. The continuous-flight pile is a new foundation type that is installed by torque. This study is aimed at investigating the axial load transfer of continuous-flight piles in frozen soils under long-term loads. A primary objective is to examine the effects of soil temperature, water content, and soil salinity on the resistance and the failure mode of continuous-flight piles in frozen soils. A series of axial load tests of model continuous-flight piles with a shaft diameter of 89 mm were carried out in the lab. Results show that primary and secondary creeps were observed during the constant load tests. The cylindrical shear mode and individual bearing mode were observed and inferred from the measured data. The adfreeze shear resistance and the individual plate bearing resistance under constant loads were estimated and verified using data from the literature. The adfreeze resistance increased with the applied load, and the plate bearing resistance increased as the normalized pile displacement rate increased. The mobilized adfreeze and plate bearing resistances suggest a potential increased load capacity of the continuous-flight pile compared to conventional smooth piles of similar diameter.

Nitrogen release from different polymer‐coated urea fertilizers in soil is affected by soil properties

AbstractThe use of urea as nitrogen (N) fertilizer in agriculture needs to consider environmental, economic and resource conservation aspects because of low N‐use efficiency (NUE). Polymer‐coated urea (PCU) offers an effective way to improve the NUE of urea and to reduce its environmental trade‐offs. However, we lack information on the impact of climate and soil properties on N release from PCU. Therefore, this study was performed to quantify the effects of soil texture, moisture and temperature on the release kinetics of N from PCU. We designed a test system for soil incubation experiments and investigated three fertilizers with different release patterns, five topsoils, three moisture levels and two temperatures over 48 days. We analysed the concentrations of inorganic N ( and ) in the soil and estimated N release rates using the unified Richards model. Soil texture did not change the N release patterns, but release rates varied significantly among the investigated soils. Changes in soil moisture for a given soil had no effect on N release from PCU and urea when fertilizers were incorporated into the soil at conditions supportive of crop growth. Lowering soil temperatures, however, decreased N release rates from PCU by 16%–49% but only in silt loam and not in sandy loam. We conclude that PCU improves the N residence time in soil, but predictions on N release from PCU must be adapted to the prevailing environmental conditions and cannot be generalized across differently textured soils.

Moisture, temperature and respiration of two soil classes under pasture and tropical dry forest in the semiarid Brazilian region

Soil respiration (Rs), or soil CO2 efflux, is the largest carbon flux from ecosystems to the atmosphere; it is an order of magnitude greater than that released by human activity, and is a key process in CO2 atmospheric accumulation and climate change. Due to its importance, many studies have investigated respiration in different ecosystems, with studies in tropical dry areas being more scarce. We measured the effects of soil temperature and moisture on respiration from Regosols and Luvisols under pasture and native deciduous forests in the Brazilian Northeast semiarid region. Respiration had a direct relationship with soil moisture and an inverse relationship with temperature in both soil classes and land covers. Respiration was higher under the forest than under the pasture (9.0 and 4.8 Mg C ha−1 y−1) in both wet and dry seasons, probably due to higher biomass incorporation and higher root respiration, but it did not differ between soil classes. These respirations corresponded to high proportions of the soil C contents in the 0–10 cm superficial layer (46.2% in Caatinga and 36.7% in pasture). In the Brazilian semiarid region, soil respiration was controlled by soil moisture (positively) and temperature (negatively), both of which were affected by land-use changes.

Amendments of waste ochre from former coal mines can potentially be used to increase soil carbon persistence

There is an increasingly urgent need to remove CO2 from the atmosphere. Increasing C storage in soils has been discussed as a possible method of achieving this. Regardless of whether increasing soil C would result in reduced atmospheric C or not, increasing the amount of organic carbon (OC) stored as organic matter in soils is widely regarded as leading to agronomic benefits such as increased water retention and resistance to erosion. Fe oxides adsorb OC in soil, protecting it from degradation. In this study we investigated the use of waste ochre (Fe oxy-hydroxide) that precipitates from the drainage of former coal mines as a soil amendment to increase C storage in soils via reduced C lability. In preliminary batch experiments, ochres reduced the release of OC from soils into solution. In plant growth experiments with wheat (var. Skyfall, RAGT) 5 wt% amendments of ochre to soils significantly reduced the concentration of hot water extractable OC by approximately 16% and OC lost from the soils in leachate by approximately 43%. Above ground plant biomass was significantly reduced by approximately 50% in the amended soils. There was no evidence for increased uptake of potentially toxic elements in the plants from the ochre-amended soils compared to the study controls but Olsen P extractable phosphate was decreased by the ochre amendments. In subsequent experiments with agronomically realistic additions of KH2PO4 there was no difference in plant biomass between the study controls and the ochre-treated soils suggesting that reduced plant growth was due to reduced P availability; C lability was still significantly reduced. Furthermore, the ochre amendments helped retain th added phosphate in the soil. These results indicate that Fe oxide amendments to soil may be a viable way of changing soil chemistry in order to increase the amount of OC retained in soils. Further experiments investigating the impacts of the ochre amendments on greenhouse gas emissions and soil biology are required followed by field trials where the impact of more variable soil moisture and temperature effects can be assessed and crops grown to harvest. A full Life Cycle Analysis could then be performed. Given the relatively limited quantities of former coal mine ochres available in the UK and the carbon footprint of transporting materials prior to adding them to soils, similar experiments to those reported here, taking into account chemical and mineralogical variations, are warranted to determine the global stock pile of Fe-rich wastes that could potentially be used to reduce C lability in soils.

Effect of Soil Temperature on Reproduction of Root-knot Nematodes in Flue-cured Tobacco with Homozygous Rk1 and/or Rk2 Resistance Genes.

Most commercial flue-cured tobacco cultivars contain the Rk1 resistance gene, which provides resistance to races 1 and 3 of Meloidogyne incognita and race 1 of M. arenaria. A number of cultivars now possess a second root-knot resistance gene, Rk2. High soil temperatures have been associated with a breakdown of root-knot resistance genes in a number of crops. Three greenhouse trials were performed from 2014 to 2015 investigate the effect of high soil temperature on the efficacy of Rk1 and/or Rk2 genes in reducing parasitism by a population of M. incognita race 3. Trials were arranged in randomized complete block design in open-top growth chambers set at 25°, 30°, and 35°C. Plants were inoculated with 3,000 eggs and data were collected 35 days post-inoculation. Galling, numbers of egg masses and eggs, and reproductive index were compared across cultivar entries. Nematode reproduction was reduced at 25°C and 30°C on entries possessing Rk1 and Rk1Rk2 compared to the susceptible entry and the entry possessing only Rk2. However, there were often no significant differences in reproduction at 35°C between entries with Rk1 and/or Rk2 compared to the susceptible control, indicating an increase of root-knot nematode parasitism on resistant entries at higher temperatures. Although seasonal differences in nematode reproduction were observed among experiments, relative differences among tobacco genotypes remained generally consistent.

Land‒atmosphere coupling effects of soil temperature and moisture on extreme precipitation in the arid regions of Northwest China

With global warming and more frequent extreme precipitation events in recent years, the phenomenon of warming and humidification in the arid regions of Northwest China (ANWC) has attracted increasing attention. We assessed the coupling effects of soil temperature and moisture on extreme precipitation in the ANWC by using daily precipitation data from CN05.1 and monthly data on soil temperature, soil moisture, and energy from ERA5-land, 1961–2018. After logical partitioning by K-means clustering, the primary influencing routes in each partition were investigated using two indices of extreme precipitation, indicated by precipitation on very wet days (R95P) and the number of extreme precipitation days (R10day). We found that 1) Local extreme precipitation has had a steadily growing impact on overall precipitation. In summer, this impact is primarily driven by an increase in the quantity of extreme precipitation, but in winter, it is primarily driven by an increase in the intensity of single precipitation. 2) The Tianshan Mountains (TM) and Qilian Mountains (QM) are the key locations for the coupling of soil temperature and moisture with the extreme precipitation index. Both locations exhibit a positive coupling state for soil temperature with extreme precipitation with positive coupling in the TM but negative coupling in the QM for soil moisture with extreme precipitation. 3) In the coupling of soil temperature and moisture with energy, the relevant significant regions are almost all over the ANWC throughout the year and all seasons, and the coupling high-value areas are concentrated around the basin. 4) In the TM–Hami Basin (HB)–QM, the coupling between energy and the extreme precipitation index is also stronger. The specific coupling paths have been changing with seasonal and regional changes.

Experimental Study on the Dynamic Characteristics of Frozen Silty Clay and Its Influencing Factors

Frozen soils are widely distributed in the seismically active regions of northwest China. Under the background of global warming, the study of the dynamic characteristics of frozen soil is very significant for the sustainable development of engineering in cold regions. In this study, the silty clay in the Lanzhou area of northwest China is selected to investigate the dynamic characteristics and its influence factors by dynamic triaxial tests. Various influence factors were considered, including confining pressure, soil temperature, soil water content and loading frequency. The dynamic elastic modulus ratio and reference dynamic strain amplitude increase as confining pressure and soil temperature decrease, and they also increase as soil water content and loading frequency increase. With an increase in confining pressure, soil water content, loading frequency, and a decrease in soil temperature, the damping ratio decreases but the maximum dynamic elastic modulus increases. With an increase in dynamic strain amplitude, the dynamic elastic modulus ratio has a decreasing trend, while the damping ratio has an increasing trend. It was found that the dynamic behaviors are most sensitive to the soil temperature. In addition, the comprehensive influence effect of soil water content, confining pressure, soil temperature, and loading frequency on the maximum dynamic elastic modulus, maximum damping ratio, and reference dynamic strain amplitude of frozen silty clay are analyzed, and the quantitative relationships between them are established. The results can provide evidence for seismic design and safe operation and maintenance of infrastructure in cold regions.

Impact of soil temperature, pH and carbon dioxide on the population and efficiency of fluorescent pseudomonad in the rhizosphere soil of Pokkali rice

The present study was aimed at the evaluation of soil temperature, pH and carbon dioxide evolution on the number and efficiency of fluorescent pseudomonads around the root system of Pokkali rice at Vytilla in Ernakulam district of Kerala. Two plots (40 m2) comprising control (without application of Pseudomonas fluorescens) and P. fluorescens treated plants were used for the field experiment. The isolates of fluorescent Pseudomonads or Pseudomonas fluorescence were counted and their efficiency was assessed for IAA, ammonia, HCN and siderophore production. Simultaneously, soil temperature, pH, and carbon dioxide evolution were also recorded. A total of 6 fluorescent pseudomonads (VPJU, VPJL, VPAU1, VPAU2, VPAU3 and VPAU4) were found during the crop period. All the isolates produced IAA and ammonia with varying degrees of intensity. Three isolates (VPAU1, VPAU3 and VPAU4) produced HCN, and no microbial isolates produced siderophore. The effect of soil temperature, pH, EC and carbon dioxide evolution was correlated with the number of fluorescent pseudomonads in the soil. The bacteria were significantly afflicted by pH and EC, whereas soil temperature and CO2 evolution did not show any effect on the number of fluorescent pseudomonads. There was no significant influence of soil temperature, pH, EC and carbon dioxide evolution on indole acetic acid production, ammonia, and HCN production. Inoculated Pseudomonas fluorescence did not survive in Pokkali rice fields. However, further studies are needed for at least three seasons in Pokkali soils to confirm the results of the present study.

Pores distribution influences the soil microorganism's response to changes in temperature and moisture

Microorganisms are an essential fraction of soil organic matter, which presence and activity depend directly on soil physical conditions. This study aimed to address the effect of soil temperature and moisture under contrasting macroporosity conditions on soil biological properties. Soil physical-chemical characterization implicated the collection of composite samples and undisturbed surface soil samples (0 to 10 cm). Also, samples of undisturbed surface soil were extracted in 40 polyvinyl chloride cylinders of 18 cm diameter and 20 cm height for the arrangement of soil mesocosm as the experimental units of a completely randomized experiment with a 2x2x3 factorial arrangement. The experiment duration was 21 days, and the soil biological properties measured were microbial biomass (MB) and soil respiration (SR). Macroporosity showed a significant effect on MB, which indicates that aeration pore influences the number of microorganisms in the soil; for the SR, the macroporosity had a not significant effect. The temperature at the ranges established in the experiment did not significantly affect MB, whereas a highly significant effect of temperature over SR was observed. A highly significant effect of soil moisture was observed on MB and SR. Macroporosity, moisture, and temperature are determining factors in the presence of soil microorganisms, both directly and through the interaction between them. Herein the microorganisms have a wide range of thermal adaptation, and the effect of soil temperature can boost soil microorganisms. In turn, it was observed that the microorganisms present are significantly sensitive to the moisture deficit in soil.

Major threats caused by climate change to grapevine

The main worrying feature of climate change is its rapid evolution, in extent and variation, becoming less and less predictable. In this paper, we have reviewed the available literature and elaborated original data to outline how climate change will affect the grapevine cultivation and wine quality. We start by discussing which features of climate change will impact grapevine production most. The effects of heatwaves, air and soil temperature, extreme rainfall events, atmospheric evaporative demand, wildfires, and smoke are addressed. An increased frequency and intensity of heat waves since 2010 is shown in four grapevine production areas of Northern Italy. The focus then shifts to the impacts of the predicted increase in temperature and drought on frost risks, grapevine phenology, yield, berry quality and water needs as well as vine and vineyard carbon budgets. Climate change will challenge the achievement of current yields and wine quality as well as the ability of vineyards to sequester atmospheric carbon, but such effects will likely depend on the characteristics of the growing environments and on the varieties present. Climate change-related threats to grapevine call for a rapid implementation of adaptation strategies

A competitive study of a geothermal heat pump equiped with an intermediate economizer for R134a and R513A working fluids

At temperatures below 60?C, the best way to use geothermal sources for heating is to use heat pumps. A heat pump can provide air conditioning for a residential, commercial, etc., all year round by heating in winter and cooling in summer using a low temperature source. Also, a heat pump can be used for water distillation through evaporation. The ground source heat pump with a high COP and low temperature thermal energy sources is one of the best technologies for using RES. In the present study, the effects of changing ambient temperature and soil temperature on a heat pump?s overall COP and energy efficiency are investigated using a simulated geothermal heat pump with an economizer. The system?s thermodynamic simulation is first performed in the engineering equation solver software for R134a and R513a working fluids. The exergy destruction of different components for both working fluids was calculated and displayed as a figure. The COP of the heat pump for R134a working fluid is equal to 3.916, equal to 3.729 for R513a working fluid, which indicates that R134a fluid has about 5% better performance. The COP of the system for R134a working fluid is equal to 3.662, which is equal to 3.504 for R513a working fluid, which indicates that R134a fluid has about 4.5% better performance.

Soil Temperature Prediction Based on 1D-CNN-MLP Neural Network Model

Highlights To predict soil temperature, a new deep learning model called 1D-CNN-MLP is proposed, which has higher accuracy or faster convergence compared with MLP or LSTM. Convolutional neural network part in the model could extract and calculate transmission of soil temperature. Using the non-sequential data of several soil temperature layers combined with the model, we can predict other temperature layers. The model can greatly reduce the difficulty and cost of soil temperature measurement. Abstract. Soil temperature plays an important role in agriculture. In order to achieve cost reduction in the sensor arrangement when monitoring soil temperature, a novel model called 1D-CNN-MLP (One dimensional convolutional neural network-Multilayer perceptron) was proposed for soil temperature prediction. Meteorological data and soil temperature data on different soil layers collected for the 2018~2021 period from a weather station in Yangling, China, were used for calculation in our work. Our model was evaluated using statistical measures of MSE (Mean Square error). The model parameters with high operation efficiency and high accuracy are obtained, and the training result records much lower error than MLP (multilayer perceptron) and faster convergence than LSTM (long short-term memory) with an MSE of 0.288 x 10&-3. The 1D-CNN (One-dimensional convolutional neural network) part of the model is used to reveal and extrapolate the law of how soil temperature propagates in different soil layers. In the case where only three layers of soil temperature data are known, the characteristic temperature layer depths of 10 cm, 15 cm, and 40 cm, are selected to place sensors and obtain the best prediction effect of soil temperature at different depths of 5 to 160 cm with a RMSE (Root mean squared error) of 1.988?. The model may help users with improved and economical soil temperature prediction and control, thus boosting crop yield. Ultimately, we found the model has a relatively poor performance in the accuracy of deep soil temperature prediction when only three layers of soil temperature data are known, and it is suggested that the model can be further optimized in terms of kernel parameter setting, data composition, and the variation law of deep soil temperature. Keywords: 1D-CNN, MLP, Soil temperature prediction.

Application and Evaluation of the Gravel Parameterization Scheme in WRF‐CLM4 Model

AbstractAs the gravel is a vital component of soil that affects the soil hydrothermal condition, its application can help improve the numerical simulations. In this study, a soil data set containing gravel content suitable to the Weather Research and Forecasting Model‐Community Land Model version 4 (WRF‐CLM4) is firstly established, and a gravel parameterization scheme is coupled to the WRF‐CLM4. On this basis, numerical simulations are conducted over the Tibetan Plateau, whose results are further compared with the global atmospheric Re‐Analysis released by the China Meteorological Administration (CRA‐40) for evaluation. The results show that the new scheme can improve the simulation effect of soil temperature to a certain extent. The correlation coefficient (R) with the CRA‐40 data for soil temperature is enhanced in the shallow soil layer in the new scheme. Besides, the root mean square errors (RMSEs) of soil temperature are significantly reduced in shallow soil layer. Comparatively, the new scheme has a better simulation effect for soil moisture. The values of R increase significantly for soil moisture in the shallow soil layer. The RMSEs for soil moisture in both shallow and deep layers are greatly reduced. Regional‐averages over the three areas and time series show that gravel has large impact on soil temperature and moisture compared with the old scheme. Overall, the values of R and RMSEs for soil temperature and moisture in the new scheme have been greatly improved, while their trends in the shallow layer are closer to the comparison data.

Carbon Dioxide Efflux of Bare Soil as a Function of Soil Temperature and Moisture Content under Weather Conditions of Warm, Temperate, Dry Climate Zone

It is difficult to estimate the contribution of individual sources to the total CO2 efflux from soil with vegetation. Long-term experiments with bare soil will provide useful conclusions. In this study, we aimed to mathematize the effect of soil temperature and soil moisture content on bare soil CO2 efflux in a four-season semiarid region to assess the adequacy of different models and to enable future predictions by seasons. We proved that the exponential model adequately described the relationship between the CO2 efflux and the soil temperature. The model calculations showed no significant relationship in the case of an additional quadratic exponential function, while, in the case of the linear model, the homoscedasticity criteria were not met, and the accuracy of the estimation was found to be dependent on the level of CO2 efflux. When the soil moisture content with either an exponential function or power was added to the exponential formula, the models did not provide more accurate results. Our findings confirm that the best-fitting models are dependent on the local environmental conditions, and there are areas in which the moisture content does not significantly affect the CO2 efflux of bare soil. Using trends in historical hourly temperature data in the exponential model, the CO2 emission was estimated to be in the range 772–898 g m−2 y−1 in 2050 in the location we used. Trends in climate change are expected to have considerable effects on the processes that govern the CO2 emissions of soil.