scholarly journals REVIEW Soil carbon release responses to long-term versus short-term climatic warming in an arid ecosystem

2019 ◽  
Author(s):  
Anonymous
Keyword(s):  
Soil Carbon ◽  
Arid Ecosystem ◽  
Climatic Warming ◽  
Short Term ◽  
Carbon Release

scholarly journals Soil carbon release responses to long-term versus short-term climatic warming in an arid ecosystem

2019 ◽  
Author(s):  
Hongying Yu ◽  
Zhenzhu Xu ◽  
Guangsheng Zhou ◽  
Yao Shou
Keyword(s):  
Soil Temperature ◽  
Soil Carbon ◽  
Field Experiments ◽  
Arid Ecosystems ◽  
Organic Carbon Content ◽  
Climatic Warming ◽  
Short Term ◽  
Desert Steppes ◽  
Carbon Release

Abstract. Climate change severely impacts grassland carbon cycling, especially in arid ecosystems, such as desert steppes. However, little is known about the responses of soil respiration (Rs) to different warming magnitudes and watering pulses in situ in desert steppes. To examine their effects on Rs, we conducted long-term moderate warming, short-term acute warming and watering field experiments in a desert grassland of Northern China. While experimental warming significantly reduced Rs by 32.5 % and 40.8 % under long-term and moderate and short-term and acute warming regimes, respectively, watering pulses stimulated it substantially. Warming did not change the exponential relationship between Rs and soil temperature, whereas the relationship of Rs with soil water content (SWC) was well fitted to the Gompertz function. The soil features were not significantly affected by either long-term or short-term warming regimes, respectively; however, soil organic carbon content tended to decrease with long-term climatic warming. This indicates that soil carbon release responses strongly depend on the duration and magnitude of climatic warming, which may be driven by SWC and soil temperature. The results of this study highlight the great dependence of soil carbon emission on warming regimes of different durations and the important role of precipitation pulse during growing season in assessing the terrestrial ecosystem carbon balance and cycle.

scholarly journals Soil carbon release responses to long-term versus short-term climatic warming in an arid ecosystem

2020 ◽  
Vol 17 (3) ◽  
pp. 781-792 ◽  
Author(s):  
Hongying Yu ◽  
Zhenzhu Xu ◽  
Guangsheng Zhou ◽  
Yaohui Shi
Keyword(s):  
Soil Moisture ◽  
Soil Carbon ◽  
Field Experiments ◽  
Sigmoid Function ◽  
Desert Grassland ◽  
Climatic Warming ◽  
Short Term ◽  
Exponential Relationship ◽  
Carbon Release

Abstract. Climate change severely impacts the grassland carbon cycling by altering rates of litter decomposition and soil respiration (Rs), especially in arid areas. However, little is known about the Rs responses to different warming magnitudes and watering pulses in situ in desert steppes. To examine their effects on Rs, we conducted long-term moderate warming (4 years, ∼3 ∘C), short-term acute warming (1 year, ∼4 ∘C) and watering field experiments in a desert grassland of northern China. While experimental warming significantly reduced average Rs by 32.5 % and 40.8 % under long-term moderate and short-term acute warming regimes, respectively, watering pulses (fully irrigating the soil to field capacity) stimulated it substantially. This indicates that climatic warming constrains soil carbon release, which is controlled mainly by decreased soil moisture, consequently influencing soil carbon dynamics. Warming did not change the exponential relationship between Rs and soil temperature, whereas the relationship between Rs and soil moisture was better fitted to a sigmoid function. The belowground biomass, soil nutrition, and microbial biomass were not significantly affected by either long-term or short-term warming regimes, respectively. The results of this study highlight the great dependence of soil carbon emission on warming regimes of different durations and the important role of precipitation pulses during the growing season in assessing the terrestrial ecosystem carbon balance and cycle.

The influence of short-term and long-term warming on physical soil carbon pools

2020 ◽  
Author(s):  
Moritz Mohrlok ◽  
Victoria Martin ◽  
Niel Verbrigghe ◽  
Lucia Fuchslueger ◽  
Christopher Poeplau ◽  
...  
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Carbon Pool ◽  
Carbon Pools ◽  
Similar Response ◽  
Turnover Rates ◽  
Short Term ◽  
Microbial Decomposition ◽  
Carbon And Nitrogen

<p>Soils store more carbon than the atmosphere and total land plant biomass combined. Soil organic matter (SOM) can be classified into different physical pools characterized by their degree of protection and turnover rates. Usually, these pools are isolated by dividing soils in different water-stable aggregate size classes and, inside these classes, SOM fractions with differing densities and properties: Stable mineral-associated organic matter (MOM) and labile particulate organic matter (POM). Increasing temperatures are known to initially enhance microbial decomposition rates, releasing C from soils which could further accelerate climate change. The magnitude of this feedback depends on which C pool is affected the most by increased decomposition. Since MOM, thought to be the best protected carbon pool, holds most of the soil C, losses from this pool would potentially have the biggest impact on global climate. Experimental results are inconclusive so far, as most studies are based on short-term field warming (years rather than decades), leaving the ecosystem response to decades to century of warming uncertain.</p><p>We made use of a geothermal warming platform in Iceland (ForHot; https://forhot.is/) to compare the effect of short-term (STW, 5-8 years) and long-term (LTW, more than 50 years) warming on soil organic carbon and nitrogen (SOC, SON) and its carbon and nitrogen isotope composition (δ<sup>13</sup>C and δ<sup>15</sup>N) in soil aggregates of different sizes in a subarctic grassland. OM fractions were isolated via density fractionation and ultrasonication both in macro- and microaggregates: Inter-aggregate free POM (fPOM), POM occluded within aggregates (iPOM) and MOM.</p><p>MOM, containing most of the SOC and SON, showed a similar response to warming for both macro- and microaggregates. Compared to LTW plots, STW plots overall had higher C and N stocks. But warming reduced the carbon content more strongly in STW plot than in LTW plots. δ<sup>13</sup>C of MOM soil increased with temperature on the STW sites, indicating higher overall SOM turnover rates at higher temperatures, in line with the higher SOC losses. For LTW, δ<sup>13</sup>C decreased with warming except for the most extreme treatment (+16°C). Warming duration had no impact on iPOM-C. fPOM-C decreased in STW sites with increasing temperature, while it increased on the LTW sites.</p><p>Overall our results demonstrate warming-induced C losses from the MOM-C-pool, thought to be most stable soil carbon pool. Thus, warming stimulated microbes to decompose both labile fPOM and more stable MOM. After decades of warming, C losses are less pronounced compared to the short-term warmed plots, pointing to a replenishment of the carbon pools at higher temperatures in the long-term. This might be explained by adaptations of the primary productivity and/or substrate-limitation of microbial growth.</p><p> </p>

scholarly journals Abiotic and biotic drivers underly short- and long-term soil respiration responses to experimental warming in a dryland ecosystem

2020 ◽  
Author(s):  
Marina Dacal ◽  
Pablo García-Palacios ◽  
Sergio Asensio ◽  
Beatriz Gozalo ◽  
Victoria Ochoa ◽  
...  
Keyword(s):  
Soil Respiration ◽  
Soil Carbon ◽  
Temporal Dynamics ◽  
Climate Feedback ◽  
Experimental Warming ◽  
Short Term ◽  
Global Soil ◽  
Main Driver ◽  
Short And Long Term

AbstractSoil carbon losses to the atmosphere through soil respiration are expected to rise with ongoing temperature increases, but available evidence from mesic biomes suggests that such response disappears after a few years of experimental warming. However, there is lack of empirical basis for these temporal dynamics in soil respiration responses, and of the mechanisms underlying them, in drylands, which collectively form the largest biome on Earth and store 32% of the global soil organic carbon pool. We coupled data from a ten-year warming experiment in a biocrust-dominated dryland ecosystem with laboratory incubations to confront 0-2 years (short-term hereafter) vs. 8-10 years (long-term hereafter) soil respiration responses to warming. Our results showed that increased soil respiration rates with short-term warming observed in areas with high biocrust cover returned to control levels in the long-term. Warming-induced increases in soil temperature were the main driver of the short-term soil respiration responses, whereas long-term soil respiration responses to warming were primarily driven by thermal acclimation and warming-induced reductions in biocrust cover. Our results highlight the importance of evaluating short and long-term soil respiration responses to warming as a mean to reduce the uncertainty in predicting the soil carbon – climate feedback in drylands.

Dynamics of organic matter in soil as determined by variations in 13C/12C isotopic ratios and fractionation by ease of oxidation

Soil Research ◽  
1997 ◽  
Vol 35 (4) ◽  
pp. 881 ◽  
Author(s):  
A. Conteh ◽  
R. D. B. Lefroy ◽  
G. J. Blair
Keyword(s):  
Organic Matter ◽  
Soil Carbon ◽  
Plant Residue ◽  
Isotopic Ratios ◽  
Labile Carbon ◽  
Short Term ◽  
Native Soil ◽  
Adjacent Soil ◽  
Fertiliser Application

Management of organic matter in soils requires techniques that accurately monitor changes in soil organic matter over the short term and long term. This study was carried out in a glasshouse pot experiment to examine changes in soil carbon under the influence of long-term cropping, plant residue, and fertiliser application, using variations in 13C/12C isotopic ratios of organic materials and fractionation by ease of oxidation. The study examines the changes in carbon contents of adjacent soil samples with different cropping histories as affected by application of fertiliser and crop residue and the growth of wheat. Significant increases in soil carbon values were observed with residue application. The effects of the applied fertiliser on soil carbon levels depend on the presence or absence of wheat. A higher amount of labile carbon was found in the native soil than in cultivated soil.

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