Temperature sensitivity of soil carbon fractions in boreal forest soil

Karhu, Kristiina; Fritze, Hannu; Hämäläinen, Kai; Vanhala, Pekka; Jungner, H.; Oinonen, M.; Sonninen, Eloni; Tuomi, Mikko; Spetz, Peter; Kitunen, Veikko; Liski, Jari

doi:10.1890/09-0478.1

Cited by 92 publications

(66 citation statements)

References 30 publications

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“…The temperature sensitivity of peat mineralization, as expressed by its Q 10 value, is a useful parameter for characterizing the intrinsic decomposability of SOM (Hogg et al, 1992;Biasi et al, 2005;Davidson and Janssens, 2006;Conant et al, 2008;Boddy et al, 2008;Karhu et al, 2010;Hilasvuori et al, 2013). In line with the biochemical and elemental evidence reviewed above, it was reported to increase with increasing resistance of peat soils against OM decomposition (Scanlon and Moore, 2000), soil depth and peat age (Hardie et al, 2011;Hilasvuori et al, 2013).…”

Section: Introductionmentioning

confidence: 87%

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

et al. 2018

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Abstract. Organic soils comprise a large yet fragile carbon (C) store in the global C cycle. Drainage, necessary for agriculture and forestry, triggers rapid decomposition of soil organic matter (SOM), typically increasing in the order forest < grassland < cropland. However, there is also large variation in decomposition due to differences in hydrological conditions, climate and specific management. Here we studied the role of SOM composition on peat decomposability in a variety of differently managed drained organic soils. We collected a total of 560 samples from 21 organic cropland, grassland and forest soils in Switzerland, monitored their CO 2 emission rates in lab incubation experiments over 6 months at two temperatures (10 and 20 • C) and related them to various soil characteristics, including bulk density, pH, soil organic carbon (SOC) content and elemental ratios (C / N, H / C and O / C). CO 2 release ranged from 6 to 195 mg CO 2 -C g −1 SOC at 10 • C and from 12 to 423 mg g −1 at 20 • C. This variation occurring under controlled conditions suggests that besides soil water regime, weather and management, SOM composition may be an underestimated factor that determines CO 2 fluxes measured in field experiments. However, correlations between the investigated chemical SOM characteristics and CO 2 emissions were weak. The latter also did not show a dependence on land-use type, although peat under forest was decomposed the least. High CO 2 emissions in some topsoils were probably related to the accrual of labile crop residues. A comparison with published CO 2 rates from incubated mineral soils indicated no difference in SOM decomposability between these soil classes, suggesting that accumulation of recent, labile plant materials that presumably account for most of the evolved CO 2 is not systematically different between mineral and organic soils. In our data set, temperature sensitivity of decomposition (Q 10 on average 2.57 ± 0.05) was the same for all land uses but lowest below 60 cm in croplands and grasslands. This, in turn, indicates a relative accumulation of recalcitrant peat in topsoils.

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Section: Introductionmentioning

confidence: 87%

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

et al. 2018

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“…The Q 10 values observed in this experiment were low (all less than 2.0, even when controlling for changes in soil moisture). Temperature sensitivities of ∼ 2 are more typical (Dutta et al, 2006;Schädel et al, 2016), although the temperature sensitivity of C release can change over time of incubation (Dutta et al, 2006) and vary between soil fractions cycling over different time horizons (Karhu et al, 2010;Schädel et al, 2014). Observed surface CO 2 fluxes at this CPCRW site exhibited a Q 10 of 5.1 ± 1.4 over a temperature range of 3.5-15 • C (C. Anderson, personal communication, 2016); however, these surface fluxes were measured over multiple months and include root respiration preventing any direct comparison.…”

Section: Temperature Vs Moisture Sensitivity For Cumulative Emissionsmentioning

confidence: 99%

“…Soils isolated during incubation may, for example, underestimate temperature sensitivity of respiration (Podrebarac et al, 2016) or exhibit lag effects . It should also be noted that our 100-day incubation was not long enough to observe slowly cycling soil fractions, which may vary in their response to experimental manipulation (Karhu et al, 2010). Nonetheless, the controlled environments of incubations provide an important way to elucidate the key mechanisms controlling GHG from high-latitude soils .…”

Section: Limitations and Weaknessesmentioning

confidence: 99%

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

2016

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Abstract. Rapid climatic changes, rising air temperatures, and increased fires are expected to drive permafrost degradation and alter soil carbon (C) cycling in many high-latitude ecosystems. How these soils will respond to changes in their temperature, moisture, and overlying vegetation is uncertain but critical to understand given the large soil C stocks in these regions. We used a laboratory experiment to examine how temperature and moisture control CO 2 and CH 4 emissions from mineral soils sampled from the bottom of the annual active layer, i.e., directly above permafrost, in an Alaskan boreal forest. Gas emissions from 30 cores, subjected to two temperatures and either field moisture conditions or experimental drought, were tracked over a 100-day incubation; we also measured a variety of physical and chemical characteristics of the cores. Gravimetric water content was 0.31 ± 0.12 (unitless) at the beginning of the incubation; cores at field moisture were unchanged at the end, but drought cores had declined to 0.06 ± 0.04. Daily CO 2 fluxes were positively correlated with incubation chamber temperature, core water content, and percent soil nitrogen. They also had a temperature sensitivity (Q 10 ) of 1.3 and 1.9 for the field moisture and drought treatments, respectively. Daily CH 4 emissions were most strongly correlated with percent nitrogen, but neither temperature nor water content was a significant first-order predictor of CH 4 fluxes. The cumulative production of C from CO 2 was over 6 orders of magnitude higher than that from CH 4 ; cumulative CO 2 was correlated with incubation temperature and moisture treatment, with drought cores producing 52-73 % lower C. Cumulative CH 4 production was unaffected by any treatment. These results suggest that deep active-layer soils may be sensitive to changes in soil moisture under aerobic conditions, a critical factor as discontinuous permafrost thaws in interior Alaska. Deep but unfrozen high-latitude soils have been shown to be strongly affected by long-term experimental warming, and these results provide insight into their future dynamics and feedback potential with future climate change.

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“…Previous studies have shown that Q 10 variations are closely related to soil temperature (Kirschbaum, 2006;Von Lutzow and Kogel-Knabner, 2009), substrate availability (Ågren and Wetterstedt, 2007;Gershenson et al, 2009), substrate quality (Von Lutzow and Kogel-Knabner, 2009;Sakurai et al, 2012), and the size and composition of a microbial population (Djukic et al, 2010;Karhu et al, 2010). Soil moisture is the most significant limiting factor for underground physiological processes in dry and semi-dry ecosystems (Balogh et al, 2011;Cable et al, 2011;Wang et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

“…However, this is an issue of considerable debate Kirschbaum, 2006), and the variations in Q 10 are the main source of controversy on this feedback intensity (Larionova et al, 2007;Karhu et al, 2010;Conant et al, 2011;Sakurai et al, 2012). Therefore, understanding the factors influencing Q 10 is important to accurately estimate C cycle and the feedback from the expected warmer climate.…”

Section: Introductionmentioning

confidence: 99%

Soil moisture influence on the interannual variation in temperature sensitivity of soil organic carbon mineralization in the Loess Plateau

et al. 2015

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Abstract. Temperature sensitivity of soil organic carbon (SOC) mineralization (i.e., Q 10 ) determines how strong the feedback from global warming may be on the atmospheric CO 2 concentration; thus, understanding the factors influencing the interannual variation in Q 10 is important for accurately estimating local soil carbon cycle. In situ SOC mineralization rate was measured using an automated CO 2 flux system (Li-8100) in long-term bare fallow soil in the Loess Plateau (35 • 12 N, 107 • 40 E) in Changwu, Shaanxi, China from 2008 to 2013. The results showed that the annual cumulative SOC mineralization ranged from 226 to 298 g C m −2 yr −1 , with a mean of 253 g C m −2 yr −1 and a coefficient of variation (CV) of 13 %, annual Q 10 ranged from 1.48 to 1.94, with a mean of 1.70 and a CV of 10 %, and annual soil moisture content ranged from 38.6 to 50.7 % soil water-filled pore space (WFPS), with a mean of 43.8 % WFPS and a CV of 11 %, which were mainly affected by the frequency and distribution of precipitation. Annual Q 10 showed a quadratic correlation with annual mean soil moisture content. In conclusion, understanding of the relationships between interannual variation in Q 10 , soil moisture, and precipitation are important to accurately estimate the local carbon cycle, especially under the changing climate.

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Temperature sensitivity of soil carbon fractions in boreal forest soil

Cited by 92 publications

References 30 publications

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

Peat decomposability in managed organic soils in relation to land use, organic matter composition and temperature

Temperature and moisture effects on greenhouse gas emissions from deep active-layer boreal soils

Soil moisture influence on the interannual variation in temperature sensitivity of soil organic carbon mineralization in the Loess Plateau

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