豫西北地区暖性灌草丛类草地生态系统固碳特征

草地中灌木数量动态变化是影响草地生态系统碳收支的重要因素,灌木层的碳储量是草地生态系统碳库中最不确定的组分之一。暖性灌草丛在豫西北丘陵山地广泛分布,属区域典型植被类型。为揭示暖性灌草丛类草地生态系统固碳特征,对豫西北地区7个样地的灌木层、草本层与土壤碳密度进行了调查,并对生态系统碳密度进行了计算。结果表明,植被与土壤平均有机碳密度分别为2360.07和4610.47 g C·m^-2,其中灌木层植被碳密度(981.63 g C·m^-2)低于草本层(1387.44 g C·m^-2),但差异不显著(P>0.05)。植被碳密度主要由根系所贡献,占整个植被碳密度的93.04%,其中灌木层根系所占比例为41.51%,略小于草本层。生态系统中土壤碳密度占有较大比例,约占整个生态系统碳密度的62.80%。对不同样地而言,由于各自所处生境不同,其生态系统固碳特征存在一定区域差异。各样地的植被碳密度大小顺序依次为P₁>P₅>P₂>P₄>P₆>P₇>P₃,但差异并不显著(P>0.05);土壤碳密度大小顺序依次为P₁>P₂>P₆>P₅>P₄>P₃>P₇,其中P₁与P₄、P₃、P₇存在显著差异(P<0.05);生态系统碳密度大小顺序依次为:P₁>P₂>P₆>P₅>P₄>P₇>P₃,其中P₁与P₄、P₃、P₇差异显著(P<0.05)。

Carbon sequestration characteristics of a warm shrub tussock grassland ecosystem in northwestern Henan

Dynamics of shrub populations are important factors affecting the carbon budget of natural grassland ecosystems. Shrub biomass and the soil carbon stock beneath shrubs are among the most uncertain components in grassland ecosystem carbon accounting. Warm shrub tussock is widely distributed in hilly areas in northwestern Henan and comprises a ‘typical' (i.e. reference) regional vegetation type. To elucidate the carbon sequestration characteristics of a warm shrub tussock grassland ecosystem, the carbon density of above ground shrub and herb biomass, and the associated soil carbon density were measured in seven plots of different areas in northwestern Henan, and ecosystem carbon density was calculated. The mean vegetation and mean soil organic carbon densities were 2360.07 and 4610.47 g C·m^-2, respectively. The vegetation carbon density for shrub vegetation was 981.63 g C·m^-2, while that of the herb layer was 1387.44 g C·m^-2. The carbon density was mainly contributed by the roots, which accounted for 93.04% of the total vegetation biomass. For shrubs, the root biomass was 41.51%, of total biomass; for herbs it was slightly more. The soil carbon density accounted for 62.80% of the total ecosystem carbon density. Across the seven plots measured, there were differences in the characteristics of ecosystem carbon sequestration. For vegetation carbon density, the plots ranked: P₁>P₅>P₂>P₄>P₆>P₇>P₃, but the difference was not significant (P>0.05). For soil carbon density the ranking was P₁>P₂>P₆>P₅>P₄>P₃>P₇, with significant differences between P₁ and P₄, P₃, and P₇ (P<0.05). The ranking for ecosystem carbon density was P₁>P₂>P₆>P₅>P₄>P₇>P₃, with P₁ being significantly different from P₄, P₃ and P₇ (P<0.05).