In this paper, the reproductive value and reproductive allocation of Tetraena mongolica were studied. The results showed that the curve of reproductive value ( Vx ) with increasing age tended to be low-high-low pattern. The change pattern of Vx in the age of 3～9,10～21, and older than 21 years was in the state of slow increase, rapid increase, and slow decrease respectively. The reproductive value was controlled by both the selective pressure of environment ( Kx ) and its own survival rate ( Lx ). The reproductive allocation value ( RA ) changed with the reproductive phase of T. Mongolica. RA decreased from the stage of flowering to frutiting. RA value increased with the age in the period of 4～21 years and decreased after 21 years. According to the relationship between reproductive age and reproductive allocation, the reproductive phase of the population could be divided into 4 stages:initial (less than 9 years old), increment (from 9～12 years old), peak (13～27 years old), and decline reproductive phase (older than 27 years old).%对四合木种群生殖值和生殖分配进行了研究，结果表明：四合木种群的生殖值从低龄组到高龄组，呈现出一种低→高→低的趋势。3～9 a生殖值缓慢增加，10～21 a生殖值迅速增高，19～21 a达到最大值，21a以后生殖值缓慢下降并渐渐平缓。在生境条件较差的群落中，四合木种群生殖值较高，这可能是其适应恶劣环境所采取的生殖对策。四合木的生殖值受环境因子的选择压力(kx)以及种群存活率(Lx)所控制。生殖分配(RA)与生殖阶段有关，从花期到果期，RA呈下降的趋势。四合木种群在4～21a之间，其RA随年龄增大逐渐递增，21 a以后，随年龄增大逐渐递减。根据其生殖年龄和生殖分配值大小，可将四合木种群的生殖期分为生殖起动期(＜9a)、生殖增长期(9～12a)、生殖高峰期(13～27a)和生殖衰退期(＞27a)
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