[目的]穗花杉是我国特有的珍稀濒危植物,具有较高的观赏价值和经济价值,是生物多样性的重要组成部分,分布较广但是数量稀少.旨在研究其种群年龄结构和数量动态变化并分析其产生原因,从而为其保育策略提供理论基础.[方法]在江西官山国家级自然保护区采用样地调查法,设立7个20 m×20 m的穗花杉样地(GS-01、GS-02、GS-03、GS-04、GS-05、GS-06、GS-07),对其物种组成、数量、胸径等数据进行调查分析.采用径级结构代替年龄结构的方法,探讨江西官山穗花杉种群的年龄结构,并绘制出静态生命表,得出种群存活曲线、死亡曲线、生存函数曲线和时间序列预测表.[结果](1)7个样地共有物种33科56属67种,构成群落的优势科是樟科Lauraceae、山茶科Theaceae、壳斗科Fagaceae,穗花杉在不同样地的不同冠层中的优势地位不同,如在乔木层中,GS-24样地穗花杉重要值最大(64.95),GS-28样地穗花杉重要值最小(4.24).(2)不同样地内的穗花杉种群年龄结构不同,GS-01、GS-02、GS-07样地的穗花杉种群年龄结构为增长型,GS-03、GS-04、GS-05、GS-06样地穗花杉年龄结构为稳定型.(3)随着龄级的增加,穗花杉的标准化存活率(lx)、龄级间存活数(Lx)、期望寿命(Ex)逐渐降低,龄级间死亡率(qx)、致死力(Kx)逐渐增加,标准化死亡数(dx)在第Ⅲ龄级最高,随后逐渐降低.(4)穗花杉种群存活曲线趋于Deevey-Ⅱ型.(5)根据4种生存函数的分析可以发现,穗花杉在幼苗时期发育状况比较平稳,到达中小径级后发育速率明显增加,而老年个体的发育速率则比较迟缓.(6)在经历了2、3、4个龄级时间后,随着时间推移,各个龄级时间之后的穗花杉种群个体数量均出现小幅度增加.[结论]研究穗花杉的存活现状以及原因,并对未来进行预测,这对于制定穗花杉相关的保护措施具有重要的意义.研究中江西官山穗花杉种群的年龄结构属于增长型,穗花杉的种群动态和时间序列预测总的来看表现为增长的趋势.总体来看江西官山穗花杉种群的生长状况较为良好,形成了较为稳定的群落结构,建议减少人类活动对这片区域的干扰,让穗花杉幼苗能保持增长的趋势,以不断补充穗花杉种群内衰老的个体.
[Objective]Amentotaxus argotaenia is a rare and endangered plant unique in China.With high ornamental and economic value,it is an important part of biodiversity.It is widely distributed but rare in quantity.This study aims to investigate the dynamic changes of its population age structure and quantity,analyze the causes,and provide a theoretical basis for its conservation strategy.[Method]Seven 20 m×20 m Amentotaxus argotaenia plots(GS-01,GS-02,GS-03,GS-04,GS-05,GS-06,GS-07)were set up in Guanshan National Nature Reserve,Jiangxi Province,and the data of species composition,quantity and DBH were investigated and analyzed.The age structure of the Amentotaxus argotaenia population was studied by using diameter class structure instead of age structure,the static life table was drawn,and the survival curve,death curve,survival function curve and time series prediction table were obtained.[Result](1)There were 33 families,56 genera and 67 species in the 7 plots,and the dominant families of the community were Lauraceae,Theaceae,and Fagaceae.Amentotaxus argotaenia had different dominant positions in different canopy layers,such as in the tree layer.The importance value of Amentotaxus argotaenia in GS-24 plot was the highest (64.95),and the importance value of Amentotaxus argotaenia in GS-28 plot was the lowest(4.24).(2)The age structure of Amentotaxus argotaenia population was different in different places. The age structure of Amentotaxus argotaenia population in GS-01,GS-02 and GS-07 plots was the growth type,while the age structure of Amentotaxus argotaenia in GS-03,GS-04,GS-05 and GS-06 plots was the stable type.(3)The standardized survival rate(lx),inter-age survival number(Lx)and life expectancy(Ex)decreased gradually with the increase of age classes,the inter-age mortality rate(qx)and lethal power(Kx)increased gradually,and the standardized death number(dx)was the highest in the third age class,and then gradually decreased.(4)The population survival curve tended to be Deevey-Ⅱ type.(5)According to the analysis of the four survival functions,it can be found that the development status of Amentotaxus argotaenia was relatively stable in the seedling stage,and the development rate increased significantly after reaching the middle and minor stage, while the development rate of the elderly individuals was relatively slow.(6)After 2,3 and 4 age classes,the individual numbers of Amentotaxus argotaenia species increased slightly with the passage of time.[Conclusion] Studying the survival status and causes of Amentotaxus argotaenia,as well as predicting the future development is of great significance for formulating its protection measures.In this study,the age structure of Amentotaxus argotaenia population in Guanshan,Jiangxi Province belonged to the growth type,and the population dynamics and time series prediction showed an increasing trend.In general,the population of Amentotaxus argotaenia in Guanshan of Jiangxi Province had a good growth condition and formed a stable community structure. It is necessary to reduce the interference of human activities in this area,consequently the seedlings of Amentotaxus argotaenia can maintain the growth trend,and constantly replenish the aging individuals in the population.