Abstract Soil active organic carbon responds quickly to soil disturbances and is a sensitive indicator of early changes in soil organic carbon (SOC). In order to identify the differences in the distribution of dissolved organic carbon (DOC), light fraction organic carbon (LFOC), SOC and their changes as affected by vegetation degradation degree along water gradient in wetland, we analyzed DOC, LFOC, and SOC in the 0–100 cm soil layer under four vegetation degradation degrees: non-degradation (ND), lightly degradation (LD), moderately degradation (MD) and heavily degradation (HD). The results showed that soil DOC, LFOC and SOC in the 0–100 cm layer of ND wetland was significantly higher than the other three degradation levels. DOC, LFOC and SOC contents decreased with increasing soil depth under the four degradation degrees and the contents of soil DOC, LFOC and SOC were mainly concentrated in the soil surface (0–20 cm). The DOC, LFOC, and SOC contents in the 0–20 cm layer under all four degradation levels showed obvious seasonal changes, while the DOC, LFOC, and SOC contents in the 20–100 cm layer showed little fluctuation over the plant growing season. There was a significant positive correlation between soil DOC and SOC, and between LFOC and SOC, with correlation coefficients of 0.948 and 0.911, respectively. There was also a very significant correlation between DOC and LFOC(R2 = 0.904). Soil DOC and LFOC in the 0–100 cm layer under the four degree of degradation were linearly correlated with SOC. While there was a linear correlation between DOC and LFOC in the non-degradation wetland soils, DOC and LFOC in the three degradation soils correlated exponentially correlated with SOC.

中文翻译：

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沿水梯度植被退化导致嘎海湿地土壤活性有机碳流失

摘要 土壤活性有机碳对土壤扰动反应迅速，是土壤有机碳（SOC）早期变化的敏感指标。为了识别湿地中溶解有机碳（DOC）、轻质有机碳（LFOC）、SOC分布的差异以及受植被退化程度影响的湿地水梯度变化，我们对DOC、LFOC和SOC进行了分析。 0-100 cm 土层在四种植被退化程度下：未退化（ND）、轻度退化（LD）、中度退化（MD）和严重退化（HD）。结果表明，ND湿地0-100 cm层土壤DOC、LFOC和SOC显着高于其他三种降解水平。文件，LFOC 和 SOC 含量在四种退化程度下随着土壤深度的增加而降低，土壤 DOC、LFOC 和 SOC 的含量主要集中在土壤表面（0-20 cm）。4种降解水平下0~20 cm层DOC、LFOC、SOC含量均呈现明显的季节性变化，而20~100 cm层DOC、LFOC、SOC含量在植物生长季节变化不大。土壤DOC与SOC、LFOC与SOC呈显着正相关，相关系数分别为0.948和0.911。DOC 和 LFOC 之间也有非常显着的相关性（R2 = 0.904）。4种退化程度下0-100 cm层土壤DOC和LFOC与SOC呈线性相关。