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Effects of soil data and simulation unit resolution on quantifying changes of soil organic carbon at regional scale with a biogeochemical process model.

Zhang L, Yu D, Shi X, Xu S, Xing S, Zhao Y - PLoS ONE (2014)

Bottom Line: Results project that from 1982 to 2000, total SOC change in the top layer (0-30 cm) of the 2.3 M ha of paddy soil in the Tai-Lake region was +1.48 Tg C, -3.99 Tg C and -15.38 Tg C based on P5, C5 and C14 databases, respectively.With the total SOC change as modeled with P5 inputs as the baseline, which is the advantages of using detailed, polygon-based soil dataset, the relative deviation of C5 and C14 were 368% and 1126%, respectively.The results also indicate that improving the framework of DNDC is essential in creating accurate models of the soil carbon cycle.

View Article: PubMed Central - PubMed

Affiliation: College of Resource and Environment, Fujian Agriculture and Forestry University, Fuzhou, China ; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.

ABSTRACT
Soil organic carbon (SOC) models were often applied to regions with high heterogeneity, but limited spatially differentiated soil information and simulation unit resolution. This study, carried out in the Tai-Lake region of China, defined the uncertainty derived from application of the DeNitrification-DeComposition (DNDC) biogeochemical model in an area with heterogeneous soil properties and different simulation units. Three different resolution soil attribute databases, a polygonal capture of mapping units at 1:50,000 (P5), a county-based database of 1:50,000 (C5) and county-based database of 1:14,000,000 (C14), were used as inputs for regional DNDC simulation. The P5 and C5 databases were combined with the 1:50,000 digital soil map, which is the most detailed soil database for the Tai-Lake region. The C14 database was combined with 1:14,000,000 digital soil map, which is a coarse database and is often used for modeling at a national or regional scale in China. The soil polygons of P5 database and county boundaries of C5 and C14 databases were used as basic simulation units. Results project that from 1982 to 2000, total SOC change in the top layer (0-30 cm) of the 2.3 M ha of paddy soil in the Tai-Lake region was +1.48 Tg C, -3.99 Tg C and -15.38 Tg C based on P5, C5 and C14 databases, respectively. With the total SOC change as modeled with P5 inputs as the baseline, which is the advantages of using detailed, polygon-based soil dataset, the relative deviation of C5 and C14 were 368% and 1126%, respectively. The comparison illustrates that DNDC simulation is strongly influenced by choice of fundamental geographic resolution as well as input soil attribute detail. The results also indicate that improving the framework of DNDC is essential in creating accurate models of the soil carbon cycle.

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Spatial distribution of validation points and simulated SOC values from different simulation methods for the Tai-Lake region for 2000 (a: P5, b: C5, and c: C14).
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pone-0088622-g004: Spatial distribution of validation points and simulated SOC values from different simulation methods for the Tai-Lake region for 2000 (a: P5, b: C5, and c: C14).

Mentions: Three maps of average SOC content for paddy soils at surface layers (0–15 cm) in the study area in 2000 were constructed on the basis of simulated data in different simulation methods (P5, C5, and C14) (Fig. 4). Also, corresponding SOC validation points were constructed from measurements of the surface layer (0–15 cm) of 1033 paddy soil samples taken in the study area in 2000. Fig. 4 demonstrates that the observed SOC in 2000 varied from 1.9 g kg−1 to 36 g kg−1. By comparison, Fig. 4 also illustrates that simulated SOC in 2000 varied from 5.1 g kg−1 to 34 g kg−1 in P5, from 11 g kg−1 to 24 g kg−1 in C5, and from 17 g kg−1 to 28 g kg−1 in C14; where 99.6%, 84.1% and 57.1% of simulated paddy soil samples in P5, C5 and C14 were within the ranges produced by the observed SOC data. Furthermore, the relative errors (E) of P5 and C5 were 6.4% and 5.0%, respectively; and within the range of 5%–10%, demonstrating that the DNDC model in P5 and C5 were acceptable for modeling SOC of paddy soils in the Tai-Lake region according to the evaluation criteria described earlier (Fig. 5a and b) [8], [44]. Moreover, the small values of MAE (4.0 g kg−1) and RMSE (5.0 g kg−1) in P5 and C5 also indicated that the modeled results were encouragingly consistent with observations in the Tai-Lake region (Fig. 5a and b). However, the E, MAE and RMSE of C14 reached −33%, 6.0 g kg−1 and 7.0 g kg−1, respectively, suggesting that the simulated results of C14 were not suitable for simulating paddy soils in the Tai-Lake region (Fig. 5c).


Effects of soil data and simulation unit resolution on quantifying changes of soil organic carbon at regional scale with a biogeochemical process model.

Zhang L, Yu D, Shi X, Xu S, Xing S, Zhao Y - PLoS ONE (2014)

Spatial distribution of validation points and simulated SOC values from different simulation methods for the Tai-Lake region for 2000 (a: P5, b: C5, and c: C14).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3921222&req=5

pone-0088622-g004: Spatial distribution of validation points and simulated SOC values from different simulation methods for the Tai-Lake region for 2000 (a: P5, b: C5, and c: C14).
Mentions: Three maps of average SOC content for paddy soils at surface layers (0–15 cm) in the study area in 2000 were constructed on the basis of simulated data in different simulation methods (P5, C5, and C14) (Fig. 4). Also, corresponding SOC validation points were constructed from measurements of the surface layer (0–15 cm) of 1033 paddy soil samples taken in the study area in 2000. Fig. 4 demonstrates that the observed SOC in 2000 varied from 1.9 g kg−1 to 36 g kg−1. By comparison, Fig. 4 also illustrates that simulated SOC in 2000 varied from 5.1 g kg−1 to 34 g kg−1 in P5, from 11 g kg−1 to 24 g kg−1 in C5, and from 17 g kg−1 to 28 g kg−1 in C14; where 99.6%, 84.1% and 57.1% of simulated paddy soil samples in P5, C5 and C14 were within the ranges produced by the observed SOC data. Furthermore, the relative errors (E) of P5 and C5 were 6.4% and 5.0%, respectively; and within the range of 5%–10%, demonstrating that the DNDC model in P5 and C5 were acceptable for modeling SOC of paddy soils in the Tai-Lake region according to the evaluation criteria described earlier (Fig. 5a and b) [8], [44]. Moreover, the small values of MAE (4.0 g kg−1) and RMSE (5.0 g kg−1) in P5 and C5 also indicated that the modeled results were encouragingly consistent with observations in the Tai-Lake region (Fig. 5a and b). However, the E, MAE and RMSE of C14 reached −33%, 6.0 g kg−1 and 7.0 g kg−1, respectively, suggesting that the simulated results of C14 were not suitable for simulating paddy soils in the Tai-Lake region (Fig. 5c).

Bottom Line: Results project that from 1982 to 2000, total SOC change in the top layer (0-30 cm) of the 2.3 M ha of paddy soil in the Tai-Lake region was +1.48 Tg C, -3.99 Tg C and -15.38 Tg C based on P5, C5 and C14 databases, respectively.With the total SOC change as modeled with P5 inputs as the baseline, which is the advantages of using detailed, polygon-based soil dataset, the relative deviation of C5 and C14 were 368% and 1126%, respectively.The results also indicate that improving the framework of DNDC is essential in creating accurate models of the soil carbon cycle.

View Article: PubMed Central - PubMed

Affiliation: College of Resource and Environment, Fujian Agriculture and Forestry University, Fuzhou, China ; State Key Laboratory of Soil and Sustainable Agriculture, Institute of Soil Science, Chinese Academy of Sciences, Nanjing, China.

ABSTRACT
Soil organic carbon (SOC) models were often applied to regions with high heterogeneity, but limited spatially differentiated soil information and simulation unit resolution. This study, carried out in the Tai-Lake region of China, defined the uncertainty derived from application of the DeNitrification-DeComposition (DNDC) biogeochemical model in an area with heterogeneous soil properties and different simulation units. Three different resolution soil attribute databases, a polygonal capture of mapping units at 1:50,000 (P5), a county-based database of 1:50,000 (C5) and county-based database of 1:14,000,000 (C14), were used as inputs for regional DNDC simulation. The P5 and C5 databases were combined with the 1:50,000 digital soil map, which is the most detailed soil database for the Tai-Lake region. The C14 database was combined with 1:14,000,000 digital soil map, which is a coarse database and is often used for modeling at a national or regional scale in China. The soil polygons of P5 database and county boundaries of C5 and C14 databases were used as basic simulation units. Results project that from 1982 to 2000, total SOC change in the top layer (0-30 cm) of the 2.3 M ha of paddy soil in the Tai-Lake region was +1.48 Tg C, -3.99 Tg C and -15.38 Tg C based on P5, C5 and C14 databases, respectively. With the total SOC change as modeled with P5 inputs as the baseline, which is the advantages of using detailed, polygon-based soil dataset, the relative deviation of C5 and C14 were 368% and 1126%, respectively. The comparison illustrates that DNDC simulation is strongly influenced by choice of fundamental geographic resolution as well as input soil attribute detail. The results also indicate that improving the framework of DNDC is essential in creating accurate models of the soil carbon cycle.

Show MeSH
Related in: MedlinePlus