Fig 1.
Research area and sample sites.
Maps of Shandong Province in China (A) and parts of Jining City in Shandong Province (B) were approved by the Ministry of Natural Resources of China and the approval numbers are GS (2020) No.4630. C and D are maps of the sample sites, made by ArcMap 10.8.1.
Fig 2.
SOC content in different habitats.
Error bars represent standard deviation of the mean (n = 5). DOC: dissolved organic carbon; LFOC: light fraction organic carbon; HFOC: heavy fraction organic carbon. Different lowercase letters indicate significant differences (p < 0.05).
Fig 3.
Soil properties in different habitats.
Error bars represent standard deviation of the mean (n = 5). TN: total nitrogen; NO3–-N: nitrate nitrogen; NH4+-N: ammonium nitrogen. Different lowercase letters indicate significant differences (p < 0.05).
Table 1.
ANOVA analysis of three forms of SOC.
Fig 4.
SOC comparison between different habitats in JWP and ZWP.
JWP: Shili Lake Ecological Wetland Park; ZWP: Shandong Zoucheng Taiping National Wetland Park; JS, JN and JH are the wetland, farmland and lakeside grassland in JWP, respectively. ZS, ZN and ZH are the wetland, farmland and lakeside grassland in ZWP, respectively. DOC: dissolved organic carbon; LFOC: light fraction organic carbon; HFOC: heavy fraction organic carbon. Error bars represent standard deviation of the mean (n = 5). Different lowercase letters indicate significant differences (p < 0.05).
Fig 5.
Soil properties in different habitats in JWP and ZWP.
JWP: Shili Lake Ecological Wetland Park; ZWP: Shandong Zoucheng Taiping National Wetland Park Error bars represent standard deviation of the mean (n = 5). CEC: soil cation exchange capacity; TC: total carbon; TN: total nitrogen; NO3–-N: nitrate nitrogen; NH4+-N: ammonium nitrogen. Other abbreviations as in Fig 4. Different lowercase letters indicate significant differences (p < 0.05).
Fig 6.
Spearman’s correlation analysis between SOC and various environmental factors in two wetland parks.
JWP: Shili Lake Ecological Wetland Park; ZWP: Shandong Zoucheng Taiping National Wetland Park. Blue means negative correlation. Red mean positive correlation. The darker the color, the greater the correlation. EC: electrical conductivity; BD: soil bulk density; SWC: soil water content; LFON: light fraction organic nitrogen; HFON: heavy fraction organic nitrogen. Other abbreviations as in Figs 4 and 5. *: p < 0.05; **: p < 0.01; ***: p < 0.001.
Table 2.
Stepwise multiple linear regression for SOC in JWP.
Table 3.
Stepwise multiple linear regression for SOC in ZWP.
Table 4.
Differences in SOC and environmental factors in JWP and ZWP.