不同封育年限高寒草甸植被/土壤碳密度及净生态系统CO2交换量的比较

封育是推广范围最广的草地恢复措施之一. 为研究不同封育年限高寒草甸植被、土壤碳密度变化, 对1 a、6 a和16 a不同封育年限样地监测结果进行分析.结果表明: 不同封育年限高寒草甸植被现存碳密度表现出封育16 a>封育1 a>封育6 a, 分别为1 522.57 gC·m^-2、1 323.12 gC·m^-2和1 148.17 gC·m^-2, 但不同封育年限之间植被现存碳密度差异不显著(P>0.05). 土壤碳密度垂直分布明显, 0~5 cm和5~10 cm土层有机碳密度较高, 随土层深度增加土壤有机碳密度明显下降, 土壤容重上升;不同封育年限之间0~40 cm层次土壤碳密度和土壤容重差异性均不显著, 但仍可表现出土壤碳密度封育1 a>封育6 a>封育16 a, 分别为28 636.32 gC·m^-2、26 570.92 gC·m^-2和26 060.71 gC·m^-2;同时, 土壤容重随封育时间延长而下降. 对7月下旬到10月上旬净生态系统CO₂交换率(NEE)监测来看, 封育1 a植被土壤碳吸收速率显著高于封育16 a(P<0.05);而排放率与封育16 a样地接近, 差异不显著(P>0.05).

A Comparison of the Vegetation/Soil Carbon Density and Net Ecosystem CO2 Exchange of Alpine Meadow with Different Enclosure Durations

Exclusion is one of the most promoted measures in grassland restoration. At present, it is necessary to study the vegetation-soil carbon density of alpine meadow with different enclosures. Based on monitoring 1-year, 6-year and 16-year grazing exclusion plots, it is found that: 1) the existing vegetation carbon density of alpine meadow with different enclosure durations is in the order of 16-year grazing exclusion plot (1 522.57 gC·m^-2) > 1-year grazing exclusion plot (1 323.12 gC·m^-2) > 6-year grazing exclusion plot (1 148.17 gC·m^-2), with a density variation statistically insignificant (P>0.05);2) the soil carbon density has a significant vertical distribution, with relatively high organic carbon density at 0~5 cm and 5~10 cm depths, soil organic carbon density greatly reducing downwards and soil bulk density increasing with depth. Moreover, the differences in soil organic contents and in soil bulk density are not statistically significant (P>0.05) between different enclosure ages, but the soil carbon density at 0 40 cm depth has the order of 1-year grazing exclusion plot (28 636.32 gC·m^-2) > 6-year grazing exclusion plot (26 570.92 gC·m^-2)> 16-year grazing exclusion plot (26 060.71 gC·m^-2). The soil bulk density reduces with enclosure age;3) by monitoring the net ecosystem CO₂ exchange (NEE) from lately July to early October, it is found that the soil carbon uptake rate of 1-year grazing exclusion plot is significantly higher than that of 16-year grazing exclusion plot (P<0.05), but their release rates are almost the same, with a difference statistically insignificant (P>0.05).