土壤有机碳及其活性组分能够敏感地反映土壤碳库的变化。调查采集杭州湾自然滩涂湿地土壤样品(0~10 cm、10~20 cm、20~30 cm),比较分析芦苇、互花米草、海三棱藨草、裸滩的土壤有机碳(SOC)、水溶性有机碳(DOC)、易氧化碳(ROC)和轻组有机质(LFOM)的变化。结果表明:(1)0~30 cm各土层,芦苇、互花米草、海三棱藨草和裸滩的SOC平均含量依次为3.87~5.08 g kg ~(-1),6.46~6.78 g kg ~(-1),4.33~4.48 g kg ~(-1)和4.99~5.25 g kg ~(-1),互花米草SOC含量高于相同土层的其他类型;(2)互花米草DOC和LFOM平均含量分别为90.69~98.90 mg kg ~(-1),2.35~2.95 g kg ~(-1),高于相同土层的海三棱藨草、芦苇和裸滩,而裸滩ROC含量(2.06~2.22 g kg ~(-1))却高于相同土层的其他三种类型;(3)芦苇、互花米草和海三棱藨草DOC占土壤有机碳的分配比例无显著性差异,而相同土层的DOC占土壤有机碳的分配比例大小依次为裸滩>海三棱藨草>芦苇>互花米草;(4) SOC和DOC、ROC、LFOM、全氮(TN)、土壤含水量、pH之间均存在极显著关系(p<0.01),各指标与pH之间均表现为负相关性。研究表明互花米草的入侵增强了滩涂湿地的固碳能力,有机碳活性组分能够反映有机碳库的变化。
英文摘要:
Soil organic carbon and its labile components are sensitive indicators of changes in soil carbon pool. Therefore, the study on soil organic carbon and its labile components is of great significance to the research of global climate change. A field survey was carried out of tidal flats and natural wetlands in Hangzhou Bay with samples of soils at 0~10 cm, 10~20 cm, 20~30 cm in depth collected for analysis of changes in soil organic carbon (SOC), soil dissolved organic carbon (DOC), soil readily oxidizable carbon (ROC) and light fraction organic matter (LFOM) in bare mudflat and mudflats under Phragmites australis, Spartina alterniflora and Scirpus mariqueter, and relationships between various fractions of organic carbon and soil physico-chemical properties. Results indicate that (1) the mean SOC content in soils of the three soil layers was 3.87~5.08 g kg ~(-1), 6.46~6.78 g kg ~(-1), 4.33~4.48 g kg ~(-1) and 4.99~5.25 g kg ~(-1) in mudflat under Phragmites australis, Spartina alterniflora, and Scirpus mariqueter, and bare mudflat; the mudflat under Spartina alterniflora was the highest and followed by bare mudflat in mean SOC content; soil TN and SOC varied in a similar trend, regardless of vegetation; (2) The mudflat under Spartina alterniflora was the highest in mean DOC and LFOM content, being 90.69~98.90 mg kg ~(-1) and 2.35~2.95 g kg ~(-1) respectively, while the bare mudflat the lowest, however, the bare mudflat was the highest in mean ROC content, being 2.06~2.22 g kg ~(-1); (3) No significant difference was observed between the mudflats under Phragmites australis, Spartina alterniflora, and Scirpus mariqueter in DOC/SOC ratio, but in ROC/SOC ratio, a decreasing order was found of bare mudflat > mudflat under Scirpus mariqueter > mudflat under Phragmites australis > mudflat under Spartina alterniflora; (4) SOC was significantly and positively related to DOC, ROC and LFOM; Besides, SOC was also significantly and positively related to TN and soil moisture content; but all the SOC fractions were negatively related to soil pH (p<0.01). All the findings indicate that the invasion of Spartina alterniflora is not so bad because the plants help enhance wetlands' carbon sequestration capacity, and the labile fractions of organic carbon are good indicators of changes in soil organic carbon pool in wetlands.