尕海湿地植被退化过程中植被-土壤系统有机碳储量变化特征

青藏高原湿地作为陆地生态系统的重要组成部分,在全球碳循环中发挥着重要作用.以青藏高原东缘尕海湿地植被不同退化程度样地(未退化CK、轻度退化SD、中度退化MD及重度退化HD)为研究对象,通过分析地上植物、凋落物、根系和土壤有机碳,研究湿地植被退化过程中植被-土壤系统有机碳储量变化特征.结果表明: 除HD外,不同退化程度湿地地上植被碳储量为99.58～205.64 g·m^-2,根系(0～40 cm)碳储量为56.96～754.37 g·m^-2,地上、根系碳储量随退化程度的加剧显著下降,土壤容重随退化程度加剧呈先增加后减少趋势,植被退化湿地各层土壤容重均大于对照样地,而凋落物碳储量为17.29～35.69 g·m^-2,CK和MD均显著高于SD;不同退化程度湿地土壤0～40 cm碳储量为7265.06～9604.30 g·m^-2,且MD＞CK＞SD＞HD,土壤有机碳储量CK和MD显著高于SD、 HD;植被-土壤系统的碳储量为7265.06～10389.94 g·m^-2,各样地大小顺序为CK＞MD＞SD＞HD,有机碳主要储存于土壤中,占湿地总碳贮量的90%以上,说明适度干扰有利于发挥高寒湿地生态系统的碳汇功能.

Variations of organic carbon storage in vegetation-soil systems during vegetation degradation in the Gahai wetland,China

Qinghai-Tibet Plateau wetland, an important component of terrestrial ecosystem, plays an essential role in global carbon cycling. To understand the variation of organic carbon storage in vegetation-soil system during vegetation degradation in the Gahai wetland we examined aboveground litter, root biomass and soil organic carbon content in different degradation stages (CK: no degradation, SD: light degradation, MD: moderate degradation, HD: heavy degradation). The results showed that except for HD, carbon storage of aboveground biomass was 99.58-205.64 g·m^-2 and that of root biomass (0-40 cm) was 56.96-754.37 g·m^-2. The carbon stocks of aboveground and roots decreased significantly with degradation. Soil bulk density increased first and then decreased with degradation. Soil bulk density of each layer under degraded wetland was greater than that of the control. The carbon storage of litter was 17.29-35.69 g·m^-2, which was significantly higher in CK than in MD and HD. The carbon storage in the soil (0-40 cm) was 7265.06-9604.30 g·m^-2, with the order of MD＞CK＞SD＞HD. The carbon storage in CK and MD as significantly higher than that in SD and HD. The total carbon storage in the vegetation-soil system was 7265.06-10389.94 g·m^-2 under different degradation stages. The largest was in CK, followed by MD, SD, and HD. Organic carbon was mostly stored in soil, which accounted for over 90% of the storage. Moderate interference might benefit carbon sequestration of the alpine wetland ecosystems.