Temperature Sensitivity of Soil Carbon Decomposition and Feedbacks to Climate Change

The Woods Hole Research Center, PO Box 296, Woods Hole, Massachusetts 02543, USA.
Nature (Impact Factor: 41.46). 04/2006; 440(7081):165-73. DOI: 10.1038/nature04514
Source: PubMed


Significantly more carbon is stored in the world's soils--including peatlands, wetlands and permafrost--than is present in the atmosphere. Disagreement exists, however, regarding the effects of climate change on global soil carbon stocks. If carbon stored belowground is transferred to the atmosphere by a warming-induced acceleration of its decomposition, a positive feedback to climate change would occur. Conversely, if increases of plant-derived carbon inputs to soils exceed increases in decomposition, the feedback would be negative. Despite much research, a consensus has not yet emerged on the temperature sensitivity of soil carbon decomposition. Unravelling the feedback effect is particularly difficult, because the diverse soil organic compounds exhibit a wide range of kinetic properties, which determine the intrinsic temperature sensitivity of their decomposition. Moreover, several environmental constraints obscure the intrinsic temperature sensitivity of substrate decomposition, causing lower observed 'apparent' temperature sensitivity, and these constraints may, themselves, be sensitive to climate.

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Available from: Ivan A. Janssens, Jun 11, 2015
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    • "R S is controlled by many factors. Soil temperature (ST) and soil moisture (SM) are the most notable abiotic factors associated with seasonal and inter-annual changes driving R S (Davidson et al., 1998; Wang et al., 2006). It is generally accepted that R S increases with increasing ST (Wang et al., 2010), and annual R S is closely related to average annual temperatures (Bahn et al., 2010). "
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    ABSTRACT: Moso bamboo forests represent an important forest type commonly found throughout subtropical China and are characterized by fast growing forests, and involves intensive management, such as reclamation, fertilization, and understory removal. However, effects of intensive management on soil respiration (RS) and net ecosystem production (NEP) remain unclear. In this study, RS was partitioned into root respiration (RR), litter respiration (RL), and soil organic matter derived respiration (RM) by litter removal and trenching approaches. One-year measurements of respiration rates, soil temperature, and soil moisture were conducted in an unmanaged and an intensively managed stand. Regardless of stand management, RS and source components increased exponentially with soil temperature and linearly with soil moisture. Temperature sensitivity (Q10) ranged from 1.6 to 2.5, with the highest value for RM, highlighting the importance of RM in regulating the response of RS to soil temperature change. Annual RS, RR, RL, and RM were 32.6, 10.7, 6.9, and 15.0t CO2 ha-1 a-1 for unmanaged stand, compared to 38.6, 12.5, 7.1, and 18.9t CO2 ha-1 a-1 for intensive managed stand, respectively, indicating that intensive management increased RS by RR and RM. Intensive management also increased NEP with 17.2t CO2 ha-1 a-1 for unmanaged stand and 20.4t CO2 ha-1 a-1 for intensive managed stand. This increase was mainly attributed to the increase in net primary production of bamboo forests under intensive management. However, the sustainability of intensive management needs further investigation due to the reduction of soil organic carbon content after intensive management. Forest management associated with the reduction in soil CO2 flux and increase in stand production should be developed for Moso bamboo forests.
    • "Yet, significant knowledge gaps remain with respect to CH 4 production potentials for specific storage conditions, including the detailed effect of slurry temperature. Generally, the temperature response of microbial activity below the optimum temperature can be described by the Arrhenius equation (Elsgaard and Jørgensen, 2002; Davidson and Janssens, 2006), i.e., rate = A exp (−E a /RT), where A is the frequency factor, E a is the activation energy (J mol −1 ), R is the gas constant (8.314 J mol − 1 K − 1 ) and T is temperature (K). "
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    ABSTRACT: Intensification of livestock production makes correct estimation of methanogenesis in liquidmanure increasingly important for inventories of CH4 emissions. Such inventories currently rely on fixed methane conversion factors as knowledge gaps remain with respect to detailed temperature responses of CH4 emissions fromliquid manure. Here, we describe the temperature response of CH4 production in liquid cattle slurry, pig slurry, and fresh and stored co-digested slurry from a thermophilic biogas plant. Subsamples of slurry were anoxically incubated at 20 temperatures from 5–52 °C in a temperature gradient incubator and CH4 production was measured by gas chromatographic analysis of headspace gas after a 17-h incubation period. Methane production potentials at 5–37 °C were described by the Arrhenius equation (modelling efficiencies, 79.2–98.1%), and the four materials showed a consistent activation energy (Ea) which averaged 81.0 kJ mol−1 (95% confidence interval, 74.9–87.1 kJ mol−1) corresponding to a temperature sensitivity (Q10) of 3.4. In contrast, the frequency factor (A) differed among the slurry materials (30.1 b ln A b 33.3; mean, 31.3) reflecting that origin, age and composition of the manure affect this parameter. The Ea estimate, based on individual slurry materials,was intermediate when compared to published values of 63 and 112.7 kJ mol−1 derived from composite data, but was similar to Ea estimated for CH4 production at microbial community level across aquatic ecosystems, wetlands and rice paddies (89.3 kJmol−1). This supports that the derived temperature sensitivity parameters may be applicable to dynamic modelling of CH4 emissions from livestock manure.
    Science of The Total Environment 01/2016; 539:78-84. DOI:10.1016/j.scitotenv.2015.07.145 · 4.10 Impact Factor
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    • "In contrast to N lab , gross rate of N rec mineralization increased with WFPS (Table 2). Under higher moisture, microbes become more active as indicated by higher respiration (Fig. 4) and in turn more efficiently decompose the recalcitrant SOM, which is more energy and moisture consumption than the labile SOM (Davidson and Janssens, 2006; Chavez-Vergara et al., 2014). Total gross NH 4 þ immobilization rate (I NH4-Nlab þ I NH4-Nrec ) varied with a similar pattern to total mineralization in response to changing moisture regimes, but was about 1.3 times higher than the later (Fig. 3). "
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    ABSTRACT: Future climate change is predicted to influence soil moisture regime, a key factor regulating soil nitrogen (N) cycling. To elucidate how soil moisture affects gross N transformation in a cultivated black soil, a 15N tracing study was conducted at 30%, 50% and 70% water-filled pore space (WFPS). While gross mineralization rate of recalcitrant organic N (Nrec) increased from 0.56 to 2.47 mg N kg−1 d−1, the rate of labile organic N mineralization declined from 4.23 to 2.41 mg N kg−1 d−1 with a WFPS increase from 30% to 70%. Similar to total mineralization, no distinct moisture effect was found on total immobilization of ammonium, which primarily entered the Nrec pool. Nitrate (NO3−) was mainly produced via autotrophic nitrification, which was significantly stimulated by increasing WFPS. Unexpectedly, heterotrophic nitrification was observed, with the highest rate of 1.06 mg N kg−1 d−1 at 30% WFPS, contributing 31.8% to total NO3− production, and decreased with WFPS. Dissimilatory nitrate reduction to ammonium (DNRA) increased from near zero (30% WFPS) to 0.26 mg N kg−1 d−1 (70% WFPS), amounting to 16.7–92.9% of NO3− consumption. A literature synthetic analysis from global multiple ecosystems showed that the rates of heterotrophic nitrification and DNRA in test soil were comparative to the forest and grassland ecosystems, and that heterotrophic nitrification was positively correlated with precipitation, soil organic carbon (SOC) and C/N, but negatively with pH and bulk density, while DNRA showed positive relationships with precipitation, clay, SOC, C/NO3− and WFPS. We suggested that low pH and bulk density and high SOC and C/N in test soil might favor heterotrophic nitrification, and that C and NO3− availability together with anaerobic condition were crucial for DNRA. Overall, our study highlights the role of moisture in regulating gross N turnover and the importance of heterotrophic nitrification for NO3− production under low moisture and DNRA for NO3− retention under high moisture in cropland.
    Soil Biology and Biochemistry 12/2015; 91:65-75. DOI:10.1016/j.soilbio.2015.08.026 · 3.93 Impact Factor
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