Warming mineralises young and old soil carbon equally

Conen, Franz; Leifeld, Jens; Seth, Barbara; Alewell, Christine

doi:10.5194/bg-3-515-2006

Cited by 116 publications

(78 citation statements)

References 28 publications

(41 reference statements)

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“…Some have found that the more labile SOM is more temperature sensitive (Liski et al, 1999;Giardina and Ryan, 2000), while others have found that the less labile SOM is more temperature sensitive (Bosatta and Ågren, 1999;Bol et al, 2003;Knorr et al, 2005;Fierer et al, 2005). Still other studies have found results indicating diff erent SOM fractions have the same temperature sensitivity (Fang et al, 2005;Conen et al, 2006).…”

mentioning

confidence: 81%

“…Apparent temperature responses can vary substantially when diff erent methods are used to assess temperature sensitivity and similar methods have found varying results between diff erent soils (e.g., Conen et al, 2006 andVanhala et al, 2007). Even aft er accounting for other factors ameliorating temperature controls on decomposition, such as substrate availability, soil moisture, and soil texture, there is signifi cant variation in decomposition responses to diff erences in temperature (e.g., Fissore et al, 2009;Gillabel et al, 2010).…”

mentioning

confidence: 99%

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The Role of Soil Characteristics on Temperature Sensitivity of Soil Organic Matter

Haddix

Plante

Conant

et al. 2011

Soil Science Soc of Amer J

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T emperature is an important factor controlling SOM turnover and understanding how temperature aff ects SOM decomposition will allow us to better predict how global climate change will aff ect SOM stocks. Understanding the temperature sensitivity of SOM decomposition is challenging because SOM is composed of many diff erent organic C compounds, with diff ering inherent kinetic properties (Davidson and Janssens, 2006). To simplify the process of modeling SOM decomposition, this range of compounds is usually classifi ed into a small number of discrete, kinetically defi ned pools with some portion of SOM being easily decomposable and the rest comprising one or more other pools decomposing more slowly.In most decomposition models, temperature eff ects are modeled as a decomposition rate multiplier for fi xed SOM pools (Lloyd and Taylor, 1994;Del Grosso et al., 2005), but some recent studies have hypothesized that temperature may actually alter the amount of substrate that would be considered easily decomposable (Zogg et al., 1997;Zak et al., 1999;Dalias et al., 2003;Rasmussen et al., 2006). Th e most broadly used terrestrial C models typically have a fi xed Q 10 of 1.5 to 2.0 or an Arrhenius-type function with the same respiration-temperature relationship to each of the diff erent SOM pools (Melillo et al., 1995;Burke et al., 2003;Friedlingstein et al., 2006 Th e uncertainty associated with how projected climate change will aff ect global C cycling could have a large impact on predictions of soil C stocks. Th e purpose of our study was to determine how various soil decomposition and chemistry characteristics relate to soil organic matter (SOM) temperature sensitivity. We accomplished this objective using long-term soil incubations at three temperatures (15, 25, and 35°C) and pyrolysis molecular beam mass spectrometry (py-MBMS) on 12 soils from 6 sites along a mean annual temperature (MAT) gradient (2-25.6°C). Th e Q 10 values calculated from the CO 2 respired during a long-term incubation using the Q 10-q method showed decomposition of the more resistant fraction to be more temperature sensitive with a Q 10-q of 1.95 ± 0.08 for the labile fraction and a Q 10-q of 3.33 ± 0.04 for the more resistant fraction. We compared the fi t of soil respiration data using a two-pool model (active and slow) with fi rst-order kinetics with a three-pool model and found that the two and three-pool models statistically fi t the data equally well. Th e three-pool model changed the size and rate constant for the more resistant pool. Th e size of the active pool in these soils, calculated using the two-pool model, increased with incubation temperature and ranged from 0.1 to 14.0% of initial soil organic C. Sites with an intermediate MAT and lowest C/N ratio had the largest active pool. Pyrolysis molecular beam mass spectrometry showed declines in carbohydrates with conversion from grassland to wheat cultivation and a greater amount of protected carbohydrates in allophanic soils which may have lead to diff erences found between the total...

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confidence: 81%

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confidence: 99%

The Role of Soil Characteristics on Temperature Sensitivity of Soil Organic Matter

Haddix

Plante

Conant

et al. 2011

Soil Science Soc of Amer J

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“…However, the evidence for the temperature sensitivity of organic matter decomposition correlated with biochemical recalcitrance is organic matter specific. For example, some studies were able to detect different Q 10 s for different substrates (Knorr et al 2005;Leifeld and Fuhrer 2005;Fierer et al 2006), whereas others were not able to do so or obtained inconsistent results (Fang et al 2005;Reichstein et al 2005b;Conen et al 2006). Conant et al (2011) recently suggested that the physico-chemical protection from decomposition of organic matter (OM) would affect the temperature response of SOM.…”

Section: Effect Of Grazing On Long-term Q 10mentioning

confidence: 99%

Variation of Q₁₀values in a fenced and a grazed grassland on the loess plateau, northwestern China

Zhang

Xu-dong

Wen

et al. 2015

Soil Science and Plant Nutrition

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Soil respiration (SR) and microbial respiration (MR), which were primarily regulated by soil temperature, can act as a feedback to climate change. Although many studies suggest that global warming will accelerate carbon dioxide (CO 2 ) emissions from soil, the magnitude of this feedback is unknown, mostly due to uncertainty in the temperature sensitivity (Q 10 , increaing ratio of SR and MR after a 10°C increase of temperature) of SR and MR. To investigate the seasonal variation of short-term Q 10 and estimate how grazing impacts temperature sensitivity of SR and MR, we measured SR and MR in a fenced and a grazed grassland on the loess plateau, northwestern China, during 2008China, during -2010. In this semiarid grassland ecosystem, soil temperature was the dominant factor controlling SR and MR during the experimental period. Short-term apparent Q 10 of SR and MR had a clearly seasonal variation, and was significantly and negatively related to soil temperature at 2-cm depth. However, no relationship was found between soil moisture (0-10 cm soil layer) and apparent Q 10 . By decreasing soil organic carbon and root biomass, grazing reduced the long-term Q 10 of SR and MR. In both the short term and the long term, Q 10 of MR was lower than that of SR, suggesting that autotrophic respiration is more sensitive than heterotrophic respiration to temperature. We emphasize the importance of using Q 10 when modeling trajectories of soil carbon stocks under climate change scenarios, and the seasonal variation of Q 10 should also be regarded as a parameter in the global carbon models.

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“…Recently, extensive debates have been done on temperature sensitivity focusing on the soil organic carbon quality, in which the temperature sensitivity of recalcitrant organic carbon was greater than (Conant et al, 2008a, b;Craine et al, 2010), equivalent to (Fang et al, 2005;Conen et al, 2006), or less than (Liski et al, 1999;Rey and Jarvis, 2006) that of labile organic carbon. However, most of the conclusions were drawn from soil incubation experiments from well-drained upland ecosystems and with less attention to wetland soils (Davidson and Janssens, 2006).…”

Section: Temperature Sensitivity and Its Variationmentioning

confidence: 99%

Ecosystem respiration and its components from a Carex meadow of Poyang Lake during the drawdown period

Yao

et al. 2015

Atmospheric Environment

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h i g h l i g h t sEcosystem respiration and its components were mainly controlled by temperature. Q 10 values varied widely with time and among ecosystem respiratory components. Summer flood duration could largely alter drawdown period carbon sink intensity. a r t i c l e i n f o a b s t r a c tLittle is known about the components of ecosystem respiration from a subtropical littoral wetland with dramatic annual inundation dynamics. In this study, we investigated ecosystem respiration and its components in a Poyang lake Carex meadow during the drawdown periods from May 2009 to June 2011. Both ecosystem respiration and its components showed clear temporal variation pattern, with temperature being the dominant control. Ecosystem respiration ranged from 98.01 to 1359.25 mg CO 2 m À2 h À1. Shoot and root respiration contributed approximately 36% and 26% to the ecosystem respiration, respectively, whereas microbial respiration accounted for 38% of the ecosystem respiration. The ratio of total soil respiration to ecosystem respiration varied from 0.45 to 0.90, depending on growing season stages. Their Q 10 values ranged from 1.72 to 2.51, with the maximum for shoot respiration and the minimum for microbial respiration. In addition, the Q 10 values varied with time and among ecosystem respiratory components and hence could not be treated as a constant. None of the respiration measurements was significantly related to soil moisture, suggesting that soil moisture was not a limiting environmental factor for respiratory activity during the drawdown periods in this meadow. The Carex meadow acted as strong carbon sink during the drawdown periods due to double growing seasons, but the previous summer flood duration could substantially alter carbon sink intensity in the following drawdown period. The total carbon sink of the littoral zone of Poyang Lake during drawdown periods was estimated to be 0.17e0.59 Tg C yr À1.

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Warming mineralises young and old soil carbon equally

Cited by 116 publications

References 28 publications

The Role of Soil Characteristics on Temperature Sensitivity of Soil Organic Matter

The Role of Soil Characteristics on Temperature Sensitivity of Soil Organic Matter

Variation of Q₁₀values in a fenced and a grazed grassland on the loess plateau, northwestern China

Ecosystem respiration and its components from a Carex meadow of Poyang Lake during the drawdown period

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Warming mineralises young and old soil carbon equally

Cited by 116 publications

References 28 publications

The Role of Soil Characteristics on Temperature Sensitivity of Soil Organic Matter

The Role of Soil Characteristics on Temperature Sensitivity of Soil Organic Matter

Variation of Q10values in a fenced and a grazed grassland on the loess plateau, northwestern China

Ecosystem respiration and its components from a Carex meadow of Poyang Lake during the drawdown period

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Variation of Q₁₀values in a fenced and a grazed grassland on the loess plateau, northwestern China