不同密度侧柏人工林碳储量变化及其机理初探

以徐州侧柏Platycladus orientalis（Linn）Franco人工林为研究对象,运用生物量转化方程及土壤调查数据探讨了1 679、2 250和3 074株.hm-2的3种密度对生态系统碳储量的影响及其机理。结果表明,①乔木层、土壤层和生态系统的碳储量均随林分密度的增加而明显减少,灌草层碳储量在低林分密度最大,而枯落物层碳储量在中林分密度最大。低林分密度生态系统的碳储量是94.11 t.hm-2,分别是中密度和高密度生态系统的碳储量1.19倍和1.28倍,而这种差异主要是由乔木层和土壤层碳储量差异引起的。②林分密度对细根生物量的影响不显著（P〉0.05）,而细根形态随林分密度的增加表现为低级根中1、2级根直径变粗,根长先变长后变短,比根长变短（P〈0.05）;而高级根中的5级根直径显著变细,根长和比根长变长（P〉0.05）。③林分密度对细根生物量的影响与乔木层、土壤层和生态系统碳储量的变化规律具有较高的一致性,均为低密度下最大,高密度下最小。因此,细根生物量可能是导致系统碳储量变化的主要因素之一。

Carbon storage changes and its mechanism of different densities in Platycladus orientalis plantation

To research Xuzhou Platycladus orientalis plantation, apply biomass transformative equation and soil survey data to study the Platycladus with 3 different stand densities, respectively 1 679, 2 250 and 3 074 trees/hm2 , in terms of its impact on the carbon amount of the ecosystem and related mechanism. The results indicated that （1）the carbon storage of tree layer, soil layer and ecosystem obviously decrease with the increase of stand density, while the carbon storage of the shrub and herb is the maximum under low density, and that of the litter layers is the maximum under medium density. The carbon amount of low-stand density ecosystem is 94.11 t / hm2, respectively 1.19 times and 1.28 times as much as that of medium and high-density ecosystems. Yet, this difference is mainly caused by the different carbon storage of tree layer and soil layer; （2）the impact of stand density on fine root biomass is not so obvious （P〉0.05）, while with the increase of stand density, the 1st root order and 2nd root order become wider in diameter, successively longer and shorter in root length, and shorter in specific root length （P〈0.05）; while 5th root order obviously becomes narrower in diameter, and longer in root length and specific root length （P〉0.05）; （3） the impact of stand density on fine root biomass is highly consistent with the varying pattern of carbon storage of tree layer, soil layer and ecosystem. They are of the maximum under low density and minimum under high density. So fine root biomass may be one of the main factor that cause the changes of carbon storage of ecosystem.