江西武夷山珍稀濒危植物南方铁杉种群动态与空间分布

Population dynamics and spatial distribution of the rare and endangered plant Tsuga chinensis var. tchekiangensis in Wuyishan, Jiangxi Province

明晰江西武夷山国家级自然保护区内180年生的珍稀濒危植物南方铁杉(Tsuga chinensis var.tchekiangensis)的种群特征,并提出针对性的保护策略,对南方铁杉种群的就地保护具有现实意义。通过分析保护区内6.4 hm;动态监测固定样地的南方铁杉种群数据,编制了静态生命表,绘制了存活曲线、死亡率和消失率曲线、生存函数曲线,采用了时间序列模型对种群数量特征进行未来预测;同时,运用点格局分析Ripley′s K函数中的成对相关函数g(r)判断不同生长阶段的南方铁杉种群在不同尺度下的空间分布格局。结果表明:(1)南方铁杉种群的年龄结构呈“金字塔”型,属于衰退型种群;各龄级间的数量变化动态关系显示该种群在当前阶段呈增长型,但是种群的天然更新能力较差;(2)南方铁杉种群的存活曲线表现为Deevey-I型,种群个体在进入生理死亡阶段后产生一定的波动;(3)南方铁杉种群的生存率随龄级增加而逐渐下降,累积死亡率逐渐递增;死亡密度整体偏低,在第1-2龄级较高,总体波动幅度较小;危险率曲线总体呈现上升的趋势;(4)在经过不同龄级的时间后,南方铁杉幼龄树数量降低,中龄树和老龄树数量持平或增加;在未来的演替过程中,南方铁杉幼龄树的不足导致个体数出现波动;(5)总体上,南方铁杉幼龄树和中龄树在样地中主要呈聚集分布。老龄树在0-80 m的尺度下呈随机分布。种群所有个体g(r)值趋势与幼龄树类似,皆呈聚集分布。综上,要进一步加强保护南方铁杉以维持其种群数量,则需采取除灌、清理病腐木等良性干扰措施以改善林内南方铁杉幼苗生长环境,为该地区的南方铁杉种群续存创造有利的生境条件。

This paper aims to clarify the population dynamics and spatial distribution of the rare and endangered plant Tsuga chinensis var. tchekiangensis in Jiangxi Wuyishan National Nature Reserve, and attempt to put forward the targeted reservation strategies. It is of practical significance for the local conservation and the sustainable management of natural forests. Based on the first inventory of 6.4 hm~2 long-term plot in the Nature Reserve, population dynamics of T. chinensis var. tchekiangensis were analyzed through establishing static life table, depicting survival curve and mortality rate and vanish rate, and applying time sequence analysis. At the same time, function g(r) deduced by function K(r) of Ripley was used to determine the spatial distribution pattern of T. chinensis var. tchekiangensis population at different growth stages and scales. The results showed that(1) the age structure of T. chinensis var. tchekiangensis was a “pyramidal” type, belongs to a recession population. The dynamics of quantitative change among age class indicated that the population was growing at the present stage, but the renewal ability of T. chinensis var. tchekiangensis was poor comparatively.(2) The survival curve tended to be the type of Deevey-I. The numbers of population fluctuated slightly after the stage of physical death.(3) The survival rate of population gradually decreased with age raising, and the cumulative mortality rate was the opposite. As a whole, the mortality density was low, and the fluctuation range was small. The risk functional curve showed a monotonous upward trend.(4) After different age classes of time, the number of young trees decreased and the number of middle and old trees increased or unchanged. In future succession, the shortage of T. chinensis var. tchekiangensis young trees resulted in individual numbers to fluctuate.(5) T. chinensis var. tchekiangensis young and middle trees were mainly aggregated in plot totally. Old trees were randomly distributed at scales of 0—80 m. And g(r) values of all trees were similar to young trees. Therefore, to further strengthen the conservation of T. chinensis var. tchekiangensis for maintaining its population numbers, the benign interference measures can be implemented such as proper removal of shrubs or rotten woods to improve the growth environment of seedlings, which eventually create favorable habitat surroundings for the continuation of T. chinensis var. tchekiangensis populations in this area.