scholarly journals The direct and legacy effects of drying-rewetting cycles on active and relatively resistant soil carbon decomposition

2021 ◽  
Author(s):  
Shuai Zhang ◽  
Junjie Lin ◽  
Peng Wang ◽  
Biao Zhu
Keyword(s):  
Global Climate ◽  
Extended Period ◽  
Heavy Precipitation ◽  
Old Field ◽  
Minor Response ◽  
Carbon Decomposition ◽  
Legacy Effect ◽  
Bare Fallow ◽  
Co2 Release ◽  
Soc Decomposition

Global climate change is expected to increase the frequency of drought and heavy precipitation, which could create more frequent drying-rewetting cycles (DWC) in the soils. Although DWC effects on SOC decomposition has been widely studied, the effect of DWC and the subsequent legacy effect on the decomposition of different SOC pools is still unclear. We conducted a 128-d laboratory incubation to investigate the DWC effects by using soils from old-field for 15 years (OF, representing active SOC), bare-fallow for 15 years (BF), and bare-fallow for 23 years plus extra 815-d incubation (BF+, representing relatively resistant SOC). The experiment included nine 10-d DWC of three treatments: 1) constant-moisture at 60% WHC, 2) mild DWC with 10-d drying to 40% WHC and rewetting to 80% WHC, and 3) strong DWC with 10-d drying to 20% WHC and rewetting to 100% WHC. Following DWC period, there was a 10-d stabilization period (adjusting all treatments to 60% WHC), and then a 28-d extended incubation. During DWC period, the strong DWC had strong effect on CO2 release compared with the constant-moisture control, reducing the SOC decomposition from OF by 8% and BF by 10%, while increasing the SOC decomposition of BF+ by 16%. During extended period, both mild and strong DWC significantly increased SOC mineralization of OF, but decreased that of BF and BF+. This legacy effect compensated the changes in CO2 release during DWC period, resulting in the minor response of SOC decomposition of OF and BF+ to the DWC during the entire incubation.

scholarly journals The relative importance of decomposition and transport mechanisms in accounting for soil organic carbon profiles

2013 ◽  
Vol 10 (4) ◽  
pp. 2379-2392 ◽  
Author(s):  
B. Guenet ◽  
T. Eglin ◽  
N. Vasilyeva ◽  
P. Peylin ◽  
P. Ciais ◽  
...  
Keyword(s):  
Organic Matter ◽  
Organic Carbon ◽  
Soil Carbon ◽  
First Order ◽  
Carbon Decomposition ◽  
First Order Kinetics ◽  
Fresh Organic Matter ◽  
Deep Layers ◽  
Bare Fallow ◽  
Soc Decomposition

Abstract. Soil is the major terrestrial reservoir of carbon and a substantial part of this carbon is stored in deep layers, typically deeper than 50 cm below the surface. Several studies underlined the quantitative importance of this deep soil organic carbon (SOC) pool and models are needed to better understand this stock and its evolution under climate and land-uses changes. In this study, we tested and compared three simple theoretical models of vertical transport for SOC against SOC profiles measurements from a long-term bare fallow experiment carried out by the Central-Chernozem State Natural Biosphere Reserve in the Kursk Region of Russia. The transport schemes tested are diffusion, advection and both diffusion and advection. They are coupled to three different formulations of soil carbon decomposition kinetics. The first formulation is a first order kinetics widely used in global SOC decomposition models; the second one, so-called "priming" model, links SOC decomposition rate to the amount of fresh organic matter, representing the substrate interactions. The last one is also a first order kinetics, but SOC is split into two pools. Field data are from a set of three bare fallow plots where soil received no input during the past 20, 26 and 58 yr, respectively. Parameters of the models were optimised using a Bayesian method. The best results are obtained when SOC decomposition is assumed to be controlled by fresh organic matter (i.e., the priming model). In comparison to the first-order kinetic model, the priming model reduces the overestimation in the deep layers. We also observed that the transport scheme that improved the fit with the data depended on the soil carbon mineralisation formulation chosen. When soil carbon decomposition was modelled to depend on the fresh organic matter amount, the transport mechanism which improved best the fit to the SOC profile data was the model representing both advection and diffusion. Interestingly, the older the bare fallow is, the lesser the need for diffusion is, suggesting that stabilised carbon may not be transported within the profile by the same mechanisms than more labile carbon.

scholarly journals The relative importance of decomposition and transport mechanisms in accounting for C profiles

2012 ◽  
Vol 9 (10) ◽  
pp. 14145-14173 ◽  
Author(s):  
B. Guenet ◽  
T. Eglin ◽  
N. Vasilyeva ◽  
P. Peylin ◽  
P. Ciais ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Order Kinetic ◽  
Transport Mechanisms ◽  
First Order ◽  
Carbon Decomposition ◽  
Fresh Organic Matter ◽  
Deep Layers ◽  
Bare Fallow ◽  
Soc Decomposition

Abstract. Soil is the major terrestrial reservoirs of carbon, and a substantial part of this carbon is stored in deep layers, typically deeper than 50 cm below the surface. Several studies underlined the quantitative importance of this deep Soil Organic Carbon (SOC) pool and models are needed to better understand this stock and its evolution under climate and land-uses changes. In this study, we test and compare 3 simple theoretical models of vertical transport for SOC against SOC profiles measurements from a long-term bare fallow experiment carried out by the Central-Chernozem State Natural Biosphere Reserve named after V.V. Alekhin, in the Kursk Region of Russia. The transport schemes tested are diffusion, advection or both diffusion and advection. They are coupled to two different formulations of soil carbon decomposition kinetics. The first formulation is a first order kinetics widely used in global SOC decomposition models; the second one links SOC decomposition rate to the amount of fresh organic matter, representing a "priming effect". Field data are from a set of three bare fallow plots where soil received no input during the past 20, 26 and 58 yr respectively. Parameters of the models were optimized using a Bayesian method. The best results are obtained when SOC decomposition is assumed to be controlled by fresh organic matter. In comparison to the first-order kinetic model, the "priming" model reduces the underestimation of SOC decomposition in the top layers and the over estimation in the deep layers. We also observe that the transport scheme that improved the fit with the data depends on the soil carbon mineralization formulation chosen. When soil carbon decomposition is modelled to depend on the fresh organic matter amount, the transport mechanisms which improves best the fit to the SOC profile data is the model representing both advection and diffusion. Interestingly, the older the bare fallow is, the lesser the need for diffusion is. This suggests that stabilized carbon may not be transported within the profile by the same mechanisms than more labile carbon.

scholarly journals Co-variation of silicate, carbonate and sulfide weathering drives CO2 release with erosion

2021 ◽  
Vol 14 (4) ◽  
pp. 211-216
Author(s):  
Aaron Bufe ◽  
Niels Hovius ◽  
Robert Emberson ◽  
Jeremy K. C. Rugenstein ◽  
Albert Galy ◽  
...  
Keyword(s):  
Erosion Rate ◽  
Global Climate ◽  
Stream Water ◽  
Sulfide Oxidation ◽  
Silicate Weathering ◽  
Emission Rates ◽  
Mountain Ranges ◽  
Weathering Rates ◽  
Southern Taiwan ◽  
Co2 Release

AbstractGlobal climate is thought to be modulated by the supply of minerals to Earth’s surface. Whereas silicate weathering removes carbon dioxide (CO2) from the atmosphere, weathering of accessory carbonate and sulfide minerals is a geologically relevant source of CO2. Although these weathering pathways commonly operate side by side, we lack quantitative constraints on their co-variation across erosion rate gradients. Here we use stream-water chemistry across an erosion rate gradient of three orders of magnitude in shales and sandstones of southern Taiwan, and find that sulfide and carbonate weathering rates rise with increasing erosion, while silicate weathering rates remain steady. As a result, on timescales shorter than marine sulfide compensation (approximately 106–107 years), weathering in rapidly eroding terrain leads to net CO2 emission rates that are at least twice as fast as CO2 sequestration rates in slow-eroding terrain. We propose that these weathering reactions are linked and that sulfuric acid generated from sulfide oxidation boosts carbonate solubility, whereas silicate weathering kinetics remain unaffected, possibly due to efficient buffering of the pH. We expect that these patterns are broadly applicable to many Cenozoic mountain ranges that expose marine metasediments.

scholarly journals Carbon Costs of Indonesian Forested Land Conversion to Oil Palm Plantations

2019 ◽  
Vol 3 (3) ◽  
Author(s):  
Sri Walyoto
Keyword(s):  
Climate Change ◽  
Carbon Dioxide ◽  
Oil Palm ◽  
Global Climate ◽  
Secondary Data ◽  
Carbon Price ◽  
Forest Conversion ◽  
Carbon Costs ◽  
Carbon Dioxide Co2 ◽  
Co2 Release

This article analyzes the loss of carbon dioxide (CO2) released in the forest conversion to oil palm plantations. This research data gathered from the relevant secondary data and relate published reports. This research finds that a loss of release of carbon dioxide (CO2) per hectare of US $ 9,800 with a carbon price of USD2 of US $ 14,000 carbon price of USD3 and US $ 19,600 in carbon price of USD4. In addition, this conversion also has a significant impact on global warming (GWP) and global climate change. Keywords: oil palm plantation, CO2 release, GWP, climate change. 

scholarly journals Observed Changes of Rain-Season Precipitation in China from 1960 to 2018

2021 ◽  
Vol 18 (19) ◽  
pp. 10031
Author(s):  
Yanyu Zhang ◽  
Shuying Zang ◽  
Xiangjin Shen ◽  
Gaohua Fan
Keyword(s):  
Climate Change ◽  
Global Climate ◽  
Regional Climate ◽  
Precipitation Amount ◽  
Heavy Precipitation ◽  
Central China ◽  
The Tibetan Plateau ◽  
Natural Ecosystems ◽  
Daily Precipitation Data ◽  
Rain Season

Precipitation during the main rain season is important for natural ecosystems and human activities. In this study, according to daily precipitation data from 515 weather stations in China, we analyzed the spatiotemporal variation of rain-season (May–September) precipitation in China from 1960 to 2018. The results showed that rain-season precipitation decreased over China from 1960 to 2018. Rain-season heavy (25 ≤ p < 50 mm/day) and very heavy (p ≥ 50 mm/day) precipitation showed increasing trends, while rain-season moderate (10 ≤ p < 25 mm/day) and light (0.1 ≤ p < 10 mm/day) precipitation showed decreasing trends from 1960 to 2018. The temporal changes of precipitation indicated that rain-season light and moderate precipitation displayed downward trends in China from 1980 to 2010 and rain-season heavy and very heavy precipitation showed fluctuant variation from 1960 to 2018. Changes of rain-season precipitation showed clear regional differences. Northwest China and the Tibetan Plateau showed the largest positive trends of precipitation amount and days. In contrast, negative trends were found for almost all precipitation grades in North China Plain, Northeast China, and North Central China. Changes toward drier conditions in these regions probably had a severe impact on agricultural production. In East China, Southeast China and Southwest China, heavy and very heavy precipitation had increased while light and moderate precipitation had decreased. This result implied an increasing risk of flood and mudslides in these regions. The advance in understanding of precipitation change in China will contribute to exactly predict the regional climate change under the background of global climate change.

The effect of respiratory pattern on water loss in desiccation-resistant Drosophila melanogaster.

1998 ◽  
Vol 201 (21) ◽  
pp. 2953-2959 ◽  
Author(s):  
A E Williams ◽  
T J Bradley
Keyword(s):  
Drosophila Melanogaster ◽  
Water Loss ◽  
Loss Rate ◽  
Extended Period ◽  
Peak Height ◽  
Respiratory Pattern ◽  
Water Loss Rate ◽  
Selection For ◽  
Reduced Water ◽  
Co2 Release

We measured CO2 and H2O release from individual fruit flies from five populations of Drosophila melanogaster selected for resistance to desiccation (D flies). Our previous work found that these flies survive for an extended period in dry air, have an increase in the peak height and frequency of CO2 release, as measured by the standard error of a linear regression (SER) of CO2 release for the entire survival period, and have reduced water loss rates (VH2O) compared with their control or ancestor populations. In the present study, we examined the following respiratory characteristics: VCO2, VH2O, the SER of CO2 release and the ratio of VCO2 to VH2O in the D flies. Correlations between these characters were calculated in order to determine the effect of respiratory pattern on water loss. We found that, within the D flies, neither periodic release of CO2 nor an increased SER for CO2 release was associated with reduced water loss. In addition, an increased SER was positively correlated with both an increased water loss rate and a decreased survival time. Therefore, although selection for desiccation resistance leads to both an increased SER and a decreased rate of water loss in the D flies, the increased SER does not significantly reduce respiratory water loss.

scholarly journals Regional Perspective on Mechanisms for Tropical Precipitation Frequency and Intensity under Global Warming

2012 ◽  
Vol 25 (24) ◽  
pp. 8487-8501 ◽  
Author(s):  
Chao-An Chen ◽  
Chia Chou ◽  
Cheng-Ta Chen
Keyword(s):  
Global Warming ◽  
Climate Models ◽  
Global Climate ◽  
Longwave Radiation ◽  
Heavy Precipitation ◽  
Point Of View ◽  
Global Climate Models ◽  
Main Process ◽  
Precipitation Frequency ◽  
Horizontal Advection

Abstract From a global point of view, a shift toward more intense precipitation is often found in observations and global warming simulations. However, similar to changes in mean precipitation, these changes associated with precipitation characters, such as intensity and frequency, should vary with space. Based on the classification of the subregions for the tropics in Chou et al., changes in precipitation frequency and intensity and their association with changes in mean precipitation are analyzed on a regional basis in 10 coupled global climate models. Furthermore, mechanisms for these changes are also examined, via the thermodynamic and dynamic contributions. In general, the increase (decrease) of mean precipitation is mainly attributed to increases (decreases) in the frequency and intensity of almost all strengths of precipitation: that is, light to heavy precipitation. The thermodynamic contribution, which is associated with increased water vapor, is positive to both precipitation frequency and intensity, particularly for precipitation extremes, and varies little with space. On the other hand, the dynamic contribution, which is related to changes in the tropical circulation, is the main process for inducing the spatial variation of changes in precipitation frequency and intensity. Among mechanisms that induce the dynamic contribution, the rich-get-richer mechanism (the dynamic part), ocean feedback, and warm horizontal advection increase precipitation frequency and intensity, while the upped-ante mechanism, the deepening of convection, longwave radiation cooling, and cold horizontal advection tend to reduce precipitation frequency and intensity.

Utilization of fire brigade data in the impact analysis of extreme precipitation events over Berlin

2020 ◽  
Author(s):  
Alexander Pasternack ◽  
Ines Langer ◽  
Henning Rust ◽  
Uwe Ulbrich
Keyword(s):  
Impact Analysis ◽  
Global Climate ◽  
Urban Climate ◽  
Heavy Precipitation ◽  
High Temporal Resolution ◽  
Fire Brigade ◽  
Extreme Precipitation Events ◽  
Multiple Data Sets ◽  
The Impact ◽  
Precipitation Events

&lt;p&gt;Large cities and urban regions are highly sensitive to impacts caused by extreme events, e.g. heavy rainfall, since they cause fatalities and economic damages. Moreover, due to regional consequences of global climate change, problems caused by hazardous atmospheric events are expected to intensify in future. Thus adequate adaptation planning of urban infrastructure not only requires further research on potential impacts under changing precipitation patterns, but also practical feasibility for end users like insurances or fire brigades.&lt;/p&gt;&lt;p&gt;According to this we relate heavy precipitation events over Berlin to the available data on time and location of the respective fire brigade operations, within the research program &amp;#8220;Urban Climate Under Change&amp;#8221; ([UC]&lt;sup&gt;2&lt;/sup&gt;) funded by the BMBF. For this purpose multiple data sets like station, radar and model&amp;#160; based data with a high temporal resolution will be used. &amp;#160;Thus an improved assessment of the spatial and temporal evolution of severe precipitation events can be made, &amp;#160;which is consequently also of aid in the investigation of a connection to related impacts in the urban area.&lt;/p&gt;

Contribution of climatic changes in means and variability to temperature and precipitation extremes

2020 ◽  
Author(s):  
Karin van der Wiel ◽  
Richard Bintanja
Keyword(s):  
High Temperature ◽  
Extreme Events ◽  
Global Climate ◽  
Heavy Precipitation ◽  
Climatic Changes ◽  
Precipitation Extremes ◽  
Climate Extreme ◽  
The Mean ◽  
Mean Climate ◽  
Mean State

&lt;p&gt;Weather or climate extreme events disproportionately affect societies and ecosystems. Physical understanding of the impact of global climate change on the occurrence of such extreme events is therefore crucial. Here we separate changes in the occurrence of high-temperature and heavy-precipitation events in a part caused by climatic changes of the mean state and a part caused by climatic changes in variability. We extend the frequently used Probability Ratio (PR) framework, used to quantify changes in the occurrence of extreme events, such that it produces a 'PRmean' value for changes due to a change in mean climate and a 'PRvar' value for changes due to changes in climate variability. Large ensemble climate model simulations are used to quantify changes in extreme events in a 2C warmer world. It is found that the increased occurrence of high-temperature extremes is predominantly caused by the increase of mean temperatures, with a much smaller role for changes in variability (PRmean &gt;&gt; PRvar). The spatial differences are considerable, however, with the polar regions standing out as regions where changes in temperature variability do have a considerable limiting effect on extreme event occurrence. Changes in heavy-precipitation extremes are generally due to changes in both mean climate and variability (PRvar &amp;#8776; PRmean). Despite complex feedbacks in the global climate system, the ratio of PRmean to PRvar is largely independent of the event threshold and the climate scenario. These results help to quantify robustness of projected changes in climate extremes, given that projections of changes in the mean state are in many cases much better constrained than projections of changes in variability.&lt;/p&gt;

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