<正>在调查南京牛首山森林公园的南京椴天然次生林典型群落样地基础上。分析了该群落的植物区系特点、群落组成及其特征、群落的层次结构特征以及演替趋势。研究表明，该群落的植物区系特征具有一定的热带性质，温带区系成分占相当的比例。群落中木本植物占绝对优势：层次分明，有乔木、灌木和草本3个层次。南京椴林在演替过程中能够保持落叶阔叶林的稳定结构。但有人工毛竹林种群侵入该群落。若不及时清除，将最终对南京椴林的顺行演替产生威胁。

The floor characteristics of heating radiant are analyzed. The results show that multi-ply solid wood parquet flooring is an excellent material of heating radiant. The effects of storing heart energy and radiation are very good. The surface temperature of the floor is uniform. The gradients of temperature along vertical direction are small. The radiant energy is about 50 % the total energy. The dimensional stability of the floor is also good.