根茎型木本克隆植物准噶尔无叶豆的种群数量动态

POPULATION QUANTITATIVE DYNAMICS OF THE RHIZOMATOUS WOODY CLONAL PLANT EREMOSPARTON SONGORICUM IN CHINA'S GURBANTUGGUT DESERT

根据根茎型木本克隆植物的特征,不以种群的分株数量代表种群大小,而尝试以不同茎级的根茎长度代表种群大小,运用种群静态生命表、存活曲线、生殖力表和Leslie矩阵模型,研究了准噶尔无叶豆(Eremosparton songoricum)的两个种群——A种群(46°31.09′N,88°33.06′E,紧邻乌伦古湖)和B种群(46°28.07′N,88°33.07′E,位于沙漠腹地)的种群数量动态。结果表明:种群存活表现为Deevey-I型。A种群在中龄阶段受到的人为干扰较大,死亡率出现高峰,种群的净增长率(R0)、内禀增长率(rm)和周限增长率(λ)较低,表现为衰退型种群,Leslie矩阵模型的模拟结果表明,15a内种群呈现下降趋势;B种群所受到的压力主要是干旱贫瘠的荒漠环境所导致的系统压力,种群的R0、rm和λ值适中,表现为缓慢增长型种群,Leslie矩阵模型的模拟结果表明,15a内种群呈现先下降、再上升的趋势。此外,研究结果验证了Leslie矩阵模型可以扩展应用到根茎型木本克隆植物这类特殊生活型植物的种群数量动态研究上。

Aims Our objective was to analyze population quantitative dynamics of the rhizomatous woody clonal plant Eremosparton songoricum,a rare dwarf shrub of mobile or semi-fixed sand dunes of central Asian desert. Methods We investigated rhizome structure along three transects at the edge of two dune populations of E. songoricum （riverside population A at 46°31.09 N,88°33.06 E; hinterland population B at 46°28.07 N,88°33.07 E） in Gurbantuggut Desert in Xinjiang,China. We used rhizome length as the unit of the populations instead of ramets. Based on rhizome structure, we constructed static life tables, survival curves, fecundity schedules and Leslie matrix modes for the two populations and predicted their dynamics in the next 15 years. Important findings The survival curves of the two E. songoricum populations were the Deevey Type I and mortality rates were low at the early stage. For population A, the net reproductive rate （R0）, the intrinsic rate （rm） and the finite rate （ 2 ） were low, indicating that the size of population A would decline; this agreed with the prediction of the Leslie matrix model. For population B, Ro, rm, and λ were moderate, indicating that the size of population B would slowly increase in the future. This result was generally consistent with the prediction of the Leslie matrix model, which showed that population B would first decrease and then increase in the next 15 years.