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Kristiina Karhu - One of the best experts on this subject based on the ideXlab platform.
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Temperature Sensitivity patterns of carbon and nitrogen processes in decomposition of boreal organic soils quantification in different compounds and molecule sizes based on a multifactorial experiment
PLOS ONE, 2019Co-Authors: Ari Lauren, Kristiina Karhu, Mari Lappalainen, Anttijussi Kieloaho, Marjo PalviainenAbstract:Climate warming and organic matter decomposition are connected in a recursive manner; this recursion can be described by Temperature Sensitivity. We conducted a multifactorial laboratory experiment to quantify the Temperature Sensitivity of organic carbon (C) and nitrogen (N) decomposition processes of common boreal organic soils. We incubated 36 mor and 36 slightly decomposed Carex-Sphagnum peat samples in a constant moisture and ambient Temperature for 6 months. The experiment included three Temperature and two moisture levels and two food web manipulations (samples with and without fungivore enchytraeid worms). We determined the release of carbon dioxide (CO2) and dissolved organic carbon (DOC) in seven molecular size classes together with ammonium N and dissolved organic N in low molecular weight and high molecular weight fractions. The Temperature Sensitivity function Q10 was fit to the data. The C and N release rate was almost an order of magnitude higher in mor than in peat. Soil fauna increased the Temperature Sensitivity of C release. Soil fauna played a key role in N release; when fauna was absent in peat, the N release was ceased. The wide range of the studied C and N compounds and treatments (68 Q10 datasets) allowed us to recognize five different Temperature Sensitivity patterns. The most common pattern (37 out of 68) was a positive upwards Temperature response, which was observed for CO2 and DOC release. A negative downward pattern was observed for extractable organic nitrogen and microbial C. Sixteen Temperature Sensitivity patterns represented a mixed type, where the Q10function was not applicable, as this does not allow changing the sign storage change rate with increasing or decreasing Temperature. The mixed pattern was typically connected to intermediate decomposition products, where input and output fluxes with different Temperature sensitivities may simultaneously change the storage. Mixed type was typical for N processes. Our results provide useful parameterization for ecosystem models that describe the feedback loop between climate warming, organic matter decomposition, and productivity of N-limited vegetation.
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similar Temperature Sensitivity of soil mineral associated organic carbon regardless of age
Soil Biology & Biochemistry, 2019Co-Authors: Kristiina Karhu, Hannu Fritze, Emmi Hilasvuori, Marko Jarvenpaa, Laura Arppe, Bent T Christensen, Liisa Kulmala, M Oinonen, Juhamatti PitkanenAbstract:Abstract Most of the carbon (C) stored in temperate arable soils is present in organic matter (OM) intimately associated with soil minerals and with slow turnover rates. The Sensitivity of mineral-associated OM to changes in Temperature is crucial for reliable predictions of the response of soil C turnover to global warming and the associated flux of carbon dioxide (CO2) from the soil to the atmosphere. We studied the Temperature Sensitivity of C in 63 μm fractions rich in particulate organic matter (POM). The fractions were isolated by physical separation of two light-textured arable soils where the C4-plant silage maize had replaced C3-crops 25 years ago. Differences in 13C abundance allowed for calculation of the age of C in the soil-size fractions (old C, C3–C > 25 years; recent C, C4–C
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Temperature Sensitivity of soil respiration rates enhanced by microbial community response
Nature, 2014Co-Authors: Marc D Auffret, Jensarne Subke, Jennifer A J Dungait, Kristiina Karhu, Philip A Wookey, James I. Prosser, Brajesh K. Singh, D W Hopkins, Göran I. ÅgrenAbstract:Microbial community responses in soils from the Arctic to the Amazon often enhance the longer-term Temperature Sensitivity of respiration, particularly in soils with high carbon-to-nitrogen ratios and in soils from cold regions, suggesting that carbon stored in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted. Much of the large amount of carbon stored in soils is released into the atmosphere as carbon dioxide through soil microbial respiration. It is thought that a warming induced stimulation of soil microbial respiration rates could increase soil carbon dioxide emissions and hence induce a positive climate feedback effect, but the response of soil microbial communities to changing Temperatures remains uncertain. This paper investigates the role of microbial community level responses in controlling the Temperature Sensitivity of respiration in soils from the Arctic to the Amazon. The authors find that the microbial community level response enhances the longer-term Temperature Sensitivity of respiration more often than it reduces it. The strongest enhancing responses are observed in soils with high carbon-to-nitrogen ratios and in soils from cold climatic regions, suggesting that the substantial carbon stores in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted. Soils store about four times as much carbon as plant biomass1, and soil microbial respiration releases about 60 petagrams of carbon per year to the atmosphere as carbon dioxide2. Short-term experiments have shown that soil microbial respiration increases exponentially with Temperature3. This information has been incorporated into soil carbon and Earth-system models, which suggest that warming-induced increases in carbon dioxide release from soils represent an important positive feedback loop that could influence twenty-first-century climate change4. The magnitude of this feedback remains uncertain, however, not least because the response of soil microbial communities to changing Temperatures has the potential to either decrease5,6,7 or increase8,9 warming-induced carbon losses substantially. Here we collect soils from different ecosystems along a climate gradient from the Arctic to the Amazon and investigate how microbial community-level responses control the Temperature Sensitivity of soil respiration. We find that the microbial community-level response more often enhances than reduces the mid- to long-term (90 days) Temperature Sensitivity of respiration. Furthermore, the strongest enhancing responses were observed in soils with high carbon-to-nitrogen ratios and in soils from cold climatic regions. After 90 days, microbial community responses increased the Temperature Sensitivity of respiration in high-latitude soils by a factor of 1.4 compared to the instantaneous Temperature response. This suggests that the substantial carbon stores in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted.
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Temperature Sensitivity of soil respiration rates enhanced by microbial community response
Nature, 2014Co-Authors: Kristiina Karhu, Marc D Auffret, Jensarne Subke, Jennifer A J Dungait, Philip A Wookey, Göran I. Ågren, James I. Prosser, Brajesh K. Singh, D W Hopkins, Mariateresa SebastiaAbstract:Soils store about four times as much carbon as plant biomass, and soil microbial respiration releases about 60 petagrams of carbon per year to the atmosphere as carbon dioxide. Short-term experiments have shown that soil microbial respiration increases exponentially with Temperature. This information has been incorporated into soil carbon and Earth-system models, which suggest that warming-induced increases in carbon dioxide release from soils represent an important positive feedback loop that could influence twenty-first-century climate change. The magnitude of this feedback remains uncertain, however, not least because the response of soil microbial communities to changing Temperatures has the potential to either decrease or increase warming-induced carbon losses substantially. Here we collect soils from different ecosystems along a climate gradient from the Arctic to the Amazon and investigate how microbial community-level responses control the Temperature Sensitivity of soil respiration. We find that the microbial community-level response more often enhances than reduces the mid- to long-term (90 days) Temperature Sensitivity of respiration. Furthermore, the strongest enhancing responses were observed in soils with high carbon-to-nitrogen ratios and in soils from cold climatic regions. After 90 days, microbial community responses increased the Temperature Sensitivity of respiration in high-latitude soils by a factor of 1.4 compared to the instantaneous Temperature response. This suggests that the substantial carbon stores in Arctic and boreal soils could be more vulnerable to climate warming than currently predicted.
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Temperature Sensitivity of organic matter decomposition in two boreal forest soil profiles
Soil Biology & Biochemistry, 2010Co-Authors: Kristiina Karhu, Hannu Fritze, Mikko Tuomi, Pekka Vanhala, Peter Spetz, Veikko Kitunen, Jari LiskiAbstract:K. Karhu, H. Fritze, M. Tuomi, P. Vanhala, P. Spetz, & J. Liski, 'Temperature Sensitivity of organic matter decomposition in two boreal forest soil profiles', Soil Biology and Biochemistry, Vol. 42 (1): 72-82, first published online 23 October 2009. The version of record is available online at doi: http://dx.doi.org/10.1016/j.silbio.2009.10.002 © 2009 Elsevier Ltd. All rights reserved.
Weixin Cheng - One of the best experts on this subject based on the ideXlab platform.
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rhizosphere priming effect increases the Temperature Sensitivity of soil organic matter decomposition
Global Change Biology, 2011Co-Authors: Biao Zhu, Weixin ChengAbstract:The Temperature Sensitivity of soil organic matter (SOM) decomposition has been a crucial topic in global change research, yet remains highly uncertain. One of the contributing factors to this uncertainty is the lack of understanding about the role of rhizosphere priming effect (RPE) in shaping the Temperature Sensitivity. Using a novel continuous 13C-labeling method, we investigated the Temperature Sensitivity of RPE and its impact on the Temperature Sensitivity of SOM decomposition. We observed an overall positive RPE. The SOM decomposition rates in the planted treatments increased 17–163% above the unplanted treatments in three growth chamber experiments including two plant species, two growth stages, and two warming methods. More importantly, warming by 5 °C increased RPE up to threefold, hence, the overall Temperature Sensitivity of SOM decomposition was consistently enhanced (Q10 values increased 0.3–0.9) by the presence of active rhizosphere. In addition, the proportional contribution of SOM decomposition to total soil respiration was increased by soil warming, implying a higher Temperature Sensitivity of SOM decomposition than that of autotrophic respiration. Our results, for the first time, clearly demonstrated that root–soil interactions play a crucial role in shaping the Temperature Sensitivity of SOM decomposition. Caution is required for interpretation of any previously determined Temperature Sensitivity of SOM decomposition that omitted rhizosphere effects using either soil incubation or field root-exclusion. More attention should be paid to RPE in future experimental and modeling studies of SOM decomposition.
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effects of substrate availability on the Temperature Sensitivity of soil organic matter decomposition
Global Change Biology, 2009Co-Authors: Nicholas E Bader, Alexander Gershenson, Weixin ChengAbstract:Soil carbon is a major component in the global carbon cycle. Understanding the relationship between environmental changes and rates of soil respiration is critical for projecting changes in soil carbon fluxes in a changing climate. Although significant attention has been focused on the Temperature Sensitivity of soil organic matter decomposition, the factors that affect this Temperature Sensitivity are still debated. In this study, we examined the effects of substrate availability on the Temperature Sensitivity of soil respiration in several different kinds of soils. We found that increased substrate availability had a significant positive effect on Temperature Sensitivity, as measured by soil Q10 values, and that this effect was inversely proportional to original substrate availability. This observation can be explained if decomposition follows Michaelis‐ Menten kinetics. The simple Q10 model was most appropriate in soils with high substrate availability.
Noah Fierer - One of the best experts on this subject based on the ideXlab platform.
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widespread coupling between the rate and Temperature Sensitivity of organic matter decay
Nature Geoscience, 2010Co-Authors: Joseph M Craine, Noah Fierer, Kendra K MclauchlanAbstract:Soils comprise the largest terrestrial carbon store on the planet. Soil respiration measurements suggest that the more biogeochemically recalcitrant the soil organic matter, the greater the Temperature Sensitivity of soil respiration.
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landscape level variation in Temperature Sensitivity of soil organic carbon decomposition
Soil Biology & Biochemistry, 2010Co-Authors: Joseph M Craine, Rebecca Spurr, Kendra K Mclauchlan, Noah FiererAbstract:Abstract We examined landscape-level variation in Temperature Sensitivity of labile SOC across 71 sites at a central North American grassland. The observed range in activation energy of decomposition ( E a ), an index of Temperature Sensitivity, was as great at the landscape scale as has been observed at the continental scale. E a was lower for soils with more labile C, consistent with the ‘Carbon quality-Temperature’ hypothesis. Soil pH explained 67% of the variation in E a . Although there are strong environmental correlates with the E a of SOC decomposition at landscape scales, the amount of variation within landscapes could confound regional- to global-scale predictions of the response of soil C to warming.
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litter quality and the Temperature Sensitivity of decomposition
Ecology, 2005Co-Authors: Noah Fierer, Joseph M Craine, Kendra K Mclauchlan, Joshua P SchimelAbstract:The Temperature Sensitivity of litter decomposition will influence the rates of ecosystem carbon sequestration in a warmer world. A number of studies have shown that the Temperature Sensitivity of litter decomposition can vary depending on litter type and extent of decomposition. However, the underlying causes of this variation are not well understood. According to fundamental principles of enzyme kinetics, the Temperature sen- sitivity of microbial decomposition should be inversely related to litter carbon quality. We tested the accuracy of this hypothesis by adding ground plant shoot and root material to soils incubated under controlled conditions and measuring the Temperature sensitivities of decomposition at three time points throughout a 53-d incubation. As the overall quality of the litter organic C declined, litter decomposition became more sensitive to Temperature. This was true regardless of whether differences in C quality were due to inherent differences in litter chemistry or due to differences in the extent of decomposition. The same pattern was observed when specific C compounds of varying quality were added to soil, suggesting that substrate C quality has a significant and predictable influence on the Temperature Sensitivity of microbial decomposition.
Alexander Gershenson - One of the best experts on this subject based on the ideXlab platform.
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effects of substrate availability on the Temperature Sensitivity of soil organic matter decomposition
Global Change Biology, 2009Co-Authors: Nicholas E Bader, Alexander Gershenson, Weixin ChengAbstract:Soil carbon is a major component in the global carbon cycle. Understanding the relationship between environmental changes and rates of soil respiration is critical for projecting changes in soil carbon fluxes in a changing climate. Although significant attention has been focused on the Temperature Sensitivity of soil organic matter decomposition, the factors that affect this Temperature Sensitivity are still debated. In this study, we examined the effects of substrate availability on the Temperature Sensitivity of soil respiration in several different kinds of soils. We found that increased substrate availability had a significant positive effect on Temperature Sensitivity, as measured by soil Q10 values, and that this effect was inversely proportional to original substrate availability. This observation can be explained if decomposition follows Michaelis‐ Menten kinetics. The simple Q10 model was most appropriate in soils with high substrate availability.
Kendra K Mclauchlan - One of the best experts on this subject based on the ideXlab platform.
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widespread coupling between the rate and Temperature Sensitivity of organic matter decay
Nature Geoscience, 2010Co-Authors: Joseph M Craine, Noah Fierer, Kendra K MclauchlanAbstract:Soils comprise the largest terrestrial carbon store on the planet. Soil respiration measurements suggest that the more biogeochemically recalcitrant the soil organic matter, the greater the Temperature Sensitivity of soil respiration.
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landscape level variation in Temperature Sensitivity of soil organic carbon decomposition
Soil Biology & Biochemistry, 2010Co-Authors: Joseph M Craine, Rebecca Spurr, Kendra K Mclauchlan, Noah FiererAbstract:Abstract We examined landscape-level variation in Temperature Sensitivity of labile SOC across 71 sites at a central North American grassland. The observed range in activation energy of decomposition ( E a ), an index of Temperature Sensitivity, was as great at the landscape scale as has been observed at the continental scale. E a was lower for soils with more labile C, consistent with the ‘Carbon quality-Temperature’ hypothesis. Soil pH explained 67% of the variation in E a . Although there are strong environmental correlates with the E a of SOC decomposition at landscape scales, the amount of variation within landscapes could confound regional- to global-scale predictions of the response of soil C to warming.
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litter quality and the Temperature Sensitivity of decomposition
Ecology, 2005Co-Authors: Noah Fierer, Joseph M Craine, Kendra K Mclauchlan, Joshua P SchimelAbstract:The Temperature Sensitivity of litter decomposition will influence the rates of ecosystem carbon sequestration in a warmer world. A number of studies have shown that the Temperature Sensitivity of litter decomposition can vary depending on litter type and extent of decomposition. However, the underlying causes of this variation are not well understood. According to fundamental principles of enzyme kinetics, the Temperature sen- sitivity of microbial decomposition should be inversely related to litter carbon quality. We tested the accuracy of this hypothesis by adding ground plant shoot and root material to soils incubated under controlled conditions and measuring the Temperature sensitivities of decomposition at three time points throughout a 53-d incubation. As the overall quality of the litter organic C declined, litter decomposition became more sensitive to Temperature. This was true regardless of whether differences in C quality were due to inherent differences in litter chemistry or due to differences in the extent of decomposition. The same pattern was observed when specific C compounds of varying quality were added to soil, suggesting that substrate C quality has a significant and predictable influence on the Temperature Sensitivity of microbial decomposition.
