Dynamics of SOC_tree contents in bulk soil, LF and HF along stand basal area in poplar plantations.

<p>Solid line is regression for bulk soil, and dash line is regression for light fraction, and dot line is regression for heavy fraction.</p

Averages of SOC_crop contents in bulk soil, LF and HF in croplands and poplar plantations.

<p>The asterisk above the vertical bars indicates a significant difference between cropland and poplar plantation at <i>α = </i>0.05 level. The vertical error bars are standard errors of the means (<i>n</i> = 14).</p

Dynamics of soil <i>δ</i>¹³C in bulk soil, LF and HF along stand basal area in poplar plantations.

<p>Solid line is regression for bulk soil, and dash line is regression for light fraction.</p

Dynamics of soil <i>Δ_C</i> stocks in bulk soil, LF and HF along stand basal area in poplar plantation stands.

<p>Solid line is regression for the bulk soil, and dash line is regression for light fraction.</p

Averages of SOC concentration (a) and content (b) of bulk soil, LF and HF in croplands and poplar plantations.

<p>The asterisk above the bars indicates a significant difference between cropland and poplar plantation at <i>α = </i>0.05 level. The vertical error bars are standard errors of the means (<i>n</i> = 14).</p

Rapid Response of Hydrological Loss of DOC to Water Table Drawdown and Warming in Zoige Peatland: Results from a Mesocosm Experiment

<div><p>A large portion of the global carbon pool is stored in peatlands, which are sensitive to a changing environment conditions. The hydrological loss of dissolved organic carbon (DOC) is believed to play a key role in determining the carbon balance in peatlands. Zoige peatland, the largest peat store in China, is experiencing climatic warming and drying as well as experiencing severe artificial drainage. Using a fully crossed factorial design, we experimentally manipulated temperature and controlled the water tables in large mesocosms containing intact peat monoliths. Specifically, we determined the impact of warming and water table position on the hydrological loss of DOC, the exported amounts, concentrations and qualities of DOC, and the discharge volume in Zoige peatland. Our results revealed that of the water table position had a greater impact on DOC export than the warming treatment, which showed no interactive effects with the water table treatment. Both DOC concentration and discharge volume were significantly increased when water table drawdown, while only the DOC concentration was significantly promoted by warming treatment. Annual DOC export was increased by 69% and 102% when the water table, controlled at 0 cm, was experimentally lowered by −10 cm and −20 cm. Increases in colored and aromatic constituents of DOC (measured by Abs_{254 nm}, SUVA_{254 nm}, Abs_{400 nm}, and SUVA_{400 nm}) were observed under the lower water tables and at the higher peat temperature. Our results provide an indication of the potential impacts of climatic change and anthropogenic drainage on the carbon cycle and/or water storage in a peatland and simultaneously imply the likelihood of potential damage to downstream ecosystems. Furthermore, our results highlight the need for local protection and sustainable development, as well as suggest that more research is required to better understand the impacts of climatic change and artificial disturbances on peatland degradation.</p></div

Effects of water table levels and temperature treatments on Abs_{254 nm}, Abs_{400 nm}, SUVA_{254 nm}, and SUVA_{400 nm}.

<p>Data are means ± standard error. Same letter superscripts denote nonsignificant differences among the three water table levels from post hoc tests.</p

<i>P</i>-values of a two-way ANOVA and Levene's test for the effects of the water table level, temperature, and their interactions on the amount of annual DOC export, DOC concentration, absorbance and specific absorbance, and water discharge.

<p>*indicates a significant difference (<i>p</i><0.05, n = 18)</p><p>**indicates a highly significant difference (<i>p</i><0.01, n = 18).</p><p><i>P</i>-values of a two-way ANOVA and Levene's test for the effects of the water table level, temperature, and their interactions on the amount of annual DOC export, DOC concentration, absorbance and specific absorbance, and water discharge.</p

Effect of water table levels and temperature on DOC annual export.

<p>Data are means ± standard error. T0 and T1 correspond to ambient temperature and warming temperature, respectively, and W0, W1, and W2 indicate water table depths of 0 cm, −10 cm, and −20 cm, respectively.</p

Percent N remaining of leaf litter among different litter input quantity treatments during incubation in the control and N fertilization microcosms.

<p>Values are means (<i>n</i> = 5) ± SE. <i>CL1</i> soil + 1 g litter from control plots, <i>CL2</i> soil +2 g litter from control plots, <i>CL4</i> soil + 4 g litter from control plots, <i>NL1</i> soil + 1 g litter from N addition plots, <i>NL2</i> soil + 2 g litter from N addition plots, <i>NL4</i> soil + 4 g litter from N addition plots.</p