种群密度过高产生的拥挤效应和食物资源不足是造成种群出生率和年度增长率下降的主要原因。
The effect of crowding and physiological stress and shortage of food resources were the main reasons for the decline of population natality and yearly increase rate.
构造了一个具有阶段结构的捕食—食饵模型，并研究了庇护所效应对于该系统平衡点的稳定性、平衡密度及其种群长期续存的影响。
This paper studied the effect of prey refuges on the stage-structured predator-prey model with two life stages-immature and mature, and with a mature prey using refuges.
人工种群植株不同密度间个体生长差异显著，尤其是人工二年生种群植株中、低密度区比高密度区个体生长得较大，体现了密度制约的效应。
Plants, especially in population of two years, have bigger bodies in low and middle densities than that in high densities in field. It's the effect of density dependence.
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