连香树（Cercidiphyllum japonicum Sieb. et Zucc.）为国家二级保护植物，种群数量与规模已非常有限。在全面踏查湖北后河、湖南壶瓶山、湖北木林子和安徽老山共4个连香树分布地的基础上，对选定区域内的连香树进行每木调查，记录株高、胸径等指标，采用高度级和径级代替年龄的方法分析种群年龄结构；对全部连香树植株进行定位，并绘制分布点图，利用Programita软件对各种群进行点格局分析。结果表明，4个种群中，后河种群的年龄结构连续且呈明显的纺锤型，种群处于衰退之中，而其它3个种群无完整的年龄结构，已完全衰退。后河种群在16m以下尺度呈随机分布，16m以上各尺度下均为集群分布。其它种群在个别尺度下呈集群分布，绝大多数尺度下呈随机分布。分析认为，生境异质性是导致后河种群在大尺度上呈集群分布的主要原因，而环境条件相似、种子均匀散布等原因造就了后河种群在小尺度上的随机分布。其它3个种群衰退程度加剧，使得连香树由集群分布向随机分布过度，其成因可能是萌发对于环境要求的极端苛刻、有限的林窗、种间竞争以及生境条件的恶化等。最后对连香树的保护工作提出建议。
Cercidiphyllum japonicum Sieb. et Zucc. was listed as one of national protected plants at second category in Chinese Plant Red Book because of its population in extremely low quantity and small size. In the four selected populations from the geographic distribution areas occupied by the species of Houhe, Hubei; Hupingshan, Hunan; Mulinzi, Hubei and Laoshan, Anhui, each individual tree of C. japonicum was surveyed to get the data such as height and diameter at breast height. The age structure of every population was clarified by height class and diameter class instead of age class, and then the point maps were drawn based on the orientation data obtained from location instruments. Finally, the point pattern analysis was performed using Programita software. The results showed that the age structure of Houhe population presented the type of obviously uninterrupted spindle, which has meant a tendency of the population toward declining, whereas the other three populations didn't show uninterrupted age structures, indicating that they had declined. The Houhe population has the spatial distribution pattern of randomly distributing at scales ＜16m, but of clumped at scales ＞16m, while the other three populations tended to be randomly distributed at most of scales ＜100m. The analysis demonstrated that heterogeneous habitat in Houhe population might possibly result in formation of clumped distribution at bigger scales, while the similar environment and random seed dispersal could be responsible for random distribution at smaller scales. The reasons for decline and random distribution of the other three populations was due mainly to rigorous germination condition the species requires, few gap appearance, interspecific competition, habitat deterioration and so on. Some suggestions were also made for conservation of the species C. japonicum.