Simulation of dissolved organic carbon concentrations and fluxes in Chinese monsoon forest ecosystems using a modified TRIPLEX-DOC model

Shengwei Shi; Mingxia Yang; Yue Hou; Changhui Peng; Haibin Wu; Qiuan Zhu; Qiong Liang; Junfei Xie; Meng Wang

doi:10.1016/j.scitotenv.2019.134054

Simulation of dissolved organic carbon concentrations and fluxes in Chinese monsoon forest ecosystems using a modified TRIPLEX-DOC model

Sci Total Environ. 2019 Dec 20:697:134054. doi: 10.1016/j.scitotenv.2019.134054. Epub 2019 Aug 23.

Authors

Shengwei Shi¹, Mingxia Yang², Yue Hou², Changhui Peng³, Haibin Wu⁴, Qiuan Zhu⁵, Qiong Liang⁶, Junfei Xie⁷, Meng Wang⁸

Affiliations

¹ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China; Beijing University of Agriculture, Beijing 102206, China; Center for Ecological Forecasting and Global Change, College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China.
² Center for Ecological Forecasting and Global Change, College of Forestry, Northwest A&F University, Yangling, Shaanxi 712100, China.
³ State Key Laboratory of Soil Erosion and Dryland Farming on the Loess Plateau, Northwest A&F University, Yangling, Shaanxi 712100, China; Center of CEF/ESCER, Department of Biological Science, University of Quebec at Montreal, Montreal H3C 3P8, Canada. Electronic address: peng.changhui@uqam.ca.
⁴ Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Science, Beijing 100029, China; CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044, China; University of Chinese Academy of Sciences, Beijing 100049, China.
⁵ College of Hydrology and Water resources, Hohai University, Nanjing 210098, China.
⁶ Beijing University of Agriculture, Beijing 102206, China.
⁷ Beijing Institute of Landscape Architecture, Beijing 100102, China.
⁸ State Environmental Protection Key Laboratory of Wetland Ecology and Vegetation Restoration, Northeast Normal University, Changchun 130024, China.

PMID: 31476510
DOI: 10.1016/j.scitotenv.2019.134054

Abstract

Dissolved organic carbon (DOC) plays an important role in global and regional carbon cycles. However, the quantification of DOC in forest ecosystems remains uncertain. Here, the processed-based biogeochemical model TRIPLEX-DOC was modified by optimizing the function of soil organic carbon distribution with increasing depths, as well as DOC sorption-desorption efficiency. The model was validated by field measurements of DOC concentration and flux at five forest sites and Beijiang River basin in monsoon regions of China. Model validation indicated that seasonal patterns of DOC concentration across climatic zones were different, and these differences were captured by our model. Importantly, the modified model performed better than the original model. Indeed, model efficiency of the modified model increased from -0.78 to 0.19 for O horizon predictions, and from -0.46 to 0.42 for the mineral soils predictions. Likewise, DOC fluxes were better simulated by the modified model. At the site scale, the simulated DOC fluxes were strongly correlated with the observed values (R² = 0.97, EF = 0.91). At the regional scale, the DOC flux predicted in the Beijiang River basin was 16.44 kg C/ha, which was close to the observed value of 17 kg C/ha. Using sensitivity analysis, we showed that temperature, precipitation and temperature sensitivity of DOC decomposition (Q₁₀) were the most sensitive parameters when predicting DOC concentrations and fluxes in forest soils. We also found that both the percentage of DOC flux to forest net ecosystem productivity, and the retention of DOC by mineral soil were highly correlated with the amount of precipitation. Overall, our model validations indicated that the modified TRIPLEX-DOC model is a useful tool for simulating the dynamics of DOC concentrations and fluxes in forest ecosystems. We highlight that more accurate estimates of parameter Q₁₀ in deep mineral soils can reduce model uncertainty, when simulating DOC concentrations and fluxes in forest soils.

Keywords: DOC fluxes; Forest carbon cycle; Leaching; Precipitation; Soil organic carbon; TRIPLEX-DOC model.