<正>以南京市区、近郊、远郊的6个典型城市森林群落枯落物层Cu、Pb、Cr、Zn、Cd等5种重金属元素为研究对象，运用ICP法测定其含量。结果表明：枯落物层中重金属元素平均含量大于其对应的南京市土壤背景值和地上部分含量，已分解层（Y层）重金属含量>未分解层（L层）重金属含量；南京城市森林枯落物层中重金属含量的空间分布格局为：市区和远郊较高，近郊相对低，不同群落类型的变异系数在17.91%～63.47%；枯落物层中5种重金属储量大小关系排序为：m（Zn）>m（Cr）>m（Pb）>m（Cu）>m（Cd），其中zn的储量达到0.9092kg/hm2。

The modified GD medium was suitable to the development of embryos in vitro of Pinus elliottii. The tip sprout carrying cotyledons as explants was more easily to build the regeneration system for P. elliottii. Axillary buds were induced from modified GD medium supplemented with 6-BA (3 mg/L) and NAA (0.05 rag/L). The differentiation frequency was very high, reaching to 73. 3%. The half MS medium supplemented with NAA (0.05 rag/L) could greatly promote the root induction of the regenerated plantlets in P. elliottii, in which the rate of induction was 60%. The 1/2 modified GD medium without hormone had the advantage for the root elongation.