洞庭湖湿地土壤碳、氮、磷及其与土壤物理性状的关系

Soil C,N and P contents and their relationships with soil physical properties in wetlands of Dongting Lake floodplain

以洞庭湖3类典型湿地的8个土壤剖面为代表,研究了土壤碳、氮、磷,微生物量碳、氮、磷和土壤物理性状的分布特征.结果表明,土壤表层有机碳含量为19.63～50.20g·kg-1,微生物量碳为424.63～1597.36mg·kg-1,微生物量碳占有机碳的比例为3.17%～4.82%;土壤表层全氮1.85～4.45g·kg-1,微生物量氮57.90～259.47mg·kg-1,微生物量氮占全氮的比例3.13%～6.42%;土壤表层微生物量磷含量顺序为:湖草洲滩地(200.99mg·kg-1)>垦殖水田(163.27mg·kg-1)>芦苇洲滩地(24.16mg·kg-1),微生物量磷占全磷的比例为1.09%～11.20%;土壤表层容重0.65～1.04g·cm-3;土壤表层粘粒(<0.001mm)26.24%～39.48%.土壤表层有机碳、全氮、微生物量氮、微生物量磷的含量,湖草洲滩地>垦殖水田>芦苇洲滩地.土壤表层微生物量碳,垦殖水田和湖草洲滩地接近,而大于芦苇湿地;土壤表层容重,芦苇洲滩地>垦殖水田>湖草洲滩地;土壤表层<0.01mm、<0.001mm粘粒,湖草洲滩地、芦苇洲滩地>垦殖水田.湿地土壤剖面中有机碳、微生物量碳、全氮、微生物量氮、微生物量磷、容重以及微生物量碳占有机碳的比例、微生物量氮占全氮的比例、微生物量磷占全磷的比例均随深度的增加而降低,至一定深度稳定,而土壤全磷在剖面上下的差异很小.湿地土壤微生物量碳、氮、磷之间呈极显著的正相关关系;土壤容重与有机碳、全氮、微生物量碳、氮、磷之间呈极显著指数负相关关系.湿地土壤<0.001mm粘粒与有机碳、全氮、微生物量碳、氮、磷含量呈极显著对数正相关关系.

Eight representative soil profiles were installed on three types of wetland （two profiles on Garet spp.-dominated floodplain, four on Phragmites-dominated floodplain, and two on paddy soil） in Dongting Lake floodplain of China in 2004, and their C, N and P contents, microbial biomass C, N and P, 〈 0.001 mm clay particles, and bulk density were measured. The results indicated the spatial distribution of soil C and N and soil microbial biomass C, N, and P were very similar in the profiles （0- 100 cm） of three types of wetland, being decreased gradually with depth, except for soil TP which was constant in the profiles. The percentages of soil microbial biomass C, N and P to soil organic C, total nitrogen and total phosphorus decreased gradually with depth. In top layer （0- 10 cm）, the contents of soil organic C and microbial biomass C and the percentage of soil microbial biomass C to organic C were 19.63 - 50.20 g·kg^-1, 424.63 - 1 597.36 mg· kg^-1, and 3.17 % - 4.82 %, respectively, the contents of soil total N and microbial biomass N and the percentage of soil microbial biomass N to total N were 1.85-4.45 g·kg^-1,57.90 - 259.47 mg·kg^-1, and 3.13 % - 6.42 %, respectively, and the content of soil microbial biomass P and the percentage of soil microbial biomass P to soil total P was 24.16-200.99 mg·kg^-1 and 1.09% - 11.20 %, respectively. The bulk density of soil top layer （0-10 cm） was 0.65-1.04 g·cm^-3, and the content of 〈 0.001 mm clay particles was 26.24% -39.48%. The contents of soil organic C and N and microbial biomass N and P in 0- 10 cm layer were the highest in Cares： spp.-dominated floodplain, followed by paddy soil, and Phragmites-dominated floodplain. Also in 0 - 10 cm layer, the soil microbial biomass C in Caret spp.- dominated floodplain and paddy soil was higher than that in Phragmites-dominated floodplain, while the soil bulk density in Phragmites-dominated floodplain was higher than that in paddy soil, and much higher than that in Caret spp.-dominated floodplain. The amount of soil 〈 0.001 mm clay particles in Caret spp.-dominated floodplain and Phragmites-dominated floodplain was higher than that in paddy soil. In these three types of wetland, soil organic C and N and microbial biomass C, N and P had a significant logarithm correlation （ P 〈 0. 01 ） with 〈 0. 001 mm clay particles, and a significant index correlation （P 〈 0. O1 ） with bulk density.