不同土地利用类型对土壤可溶性有机碳的影响

Effects of land use type on soil dissolved organic carbon in a land reclamation area from lake

为了解土地利用类型对土壤有机质中易变组分的影响,选取湖泊围垦后形成的4种典型的土地利用类型（香樟林、水杉林、毛竹林和农田）作为试验地,研究了不同土地利用类型对土壤中可溶性有机碳,包括：冷水可溶性有机碳含量（cDOC,CW）、热水可溶性有机碳含量（cDOC,HW）和盐溶液可溶性有机碳含量（cDOC,Ca Cl2）的影响。结果表明：4种土地利用类型中土壤cDOC,HW、cDOC,CW和cDOC,Ca Cl2的含量随土层深度加深而降低。除香樟林外,不同土地利用类型cDOC,CW大小在0-10 cm和≥10-25 cm两个土层均表现为农田〉毛竹林〉水杉林,cDOC,HW和cDOC,Ca Cl2在毛竹林土壤中显著高于其他3种土地利用类型。在4种土地利用方式中,cDOC,HW与cDOC,Ca Cl2都与土壤有机碳、总氮含量以及土壤p H呈显著的相关性。而水杉林土壤的cDOC,HW与cDOC,Ca Cl2与土壤微生物生物量碳之间表现出了极显著的正相关性。总之,湖泊围垦后的不同土地利用类型伴随着不同的管理措施,导致了土壤理化因子和微生物性质的改变,从而在一定程度上影响了不同土地利用类型中积累的土壤可溶性有机碳的含量。

Since the late 1950s, land reclamation from lake has been a common human disturbance on lake ecosystems in China, and some shallow aquatic areas of lakes were converted into terrestrial soil with different land use types and managements. However, there is little known about the impact of different land use types on the soil carbon （C） cycle. We examined the influences of land use types on soil dissolved organic carbon （ DOC ） extracted from the cold-water （CDOC,cw） , hot-water （CDOC,HW） and CaCl2 solution （CDOC,CaCl2） , respectively. The results showed that the CDOC,HW was 2-6 times larger than CDOC,CW, and 4-9 times larger than CDOC,CaCl2. Under the four land use types, i.e. coniferous forest （MG）, evergreen broadleaf forest （CC）, moso bamboo forest （PE） and cropland （CL）, all CDOC,CW, CDOC,HW and CDOC,Cal2 decreased with the increase of the soil depth. The CDPC,CW under the different land use types exhibited the trends of CL 〉 PE 〉 MG in both 0-10 cm and ≥10-25cm soil depth, while the CDOC,HW and CDOC,CaCl2 under PE were larger than that under the other laud use types. The CDOC,CW and CDOC,CaCL2 under the four land use types showed significant correlations with the soil organic carbon （SOC） , total nitrogen （TN） and pH, and the C DOC,HW and C DOC,CaCl2 under the M G was significantly positive correlation with the soil microbial biomass carbon （BMBC）. However, CDOC,CW was only correlated with the SMBC at the land use type of CC. The results indicated that the soil DOC was affected by different soil pro erties induced from the different land use and management. The findings of this study are helpful to understand the impact of land use types reclaimed from lake on soil C cycle.