吕梁山南端白皮松幼林种群结构的研究

在吕梁山南端乔家湾、黑虎沟、郭家洼3个地段分别设置了3个样地，用样方法对白皮松幼林种群进行了调查，并做样方272个。分析了白皮松的群落学特征、径级结构及其密度变化规律；绘制了存活曲线和死亡曲线，从多角度研究了白皮松幼林种群的动态变化规律。结果表明：乔家湾白皮松幼林种群生长最好，基本接近于增长型种群。存活曲线表现为5－7．5cm径级后存活曲线显著下降，该种群的变化趋势接近Deevey I型。死亡曲线在7．5－10cm径级之间存在一个死亡高峰。黑虎沟和郭家洼的种群属于下降型种群，幼年个体补充不足严重影响着该种群的生存和发展。

Study on younger forest population structure of Pinus bungeana in the Luliang Mountains

In the south of Mts Luliang,3 stands were set up at Qiaojiawan,Heihugou and Guojiawa respectively. The younger forest population of Pinus bungeana were investigated by the sampling method. 272 plots were finished. The community feature, size-class structure, the regulation of changing density were analyzed and the survival curve,the death curve and the life table were worked out. The changing dynamic regulation of the younger forest population of Pinus bungeana was studied from many views. The results showed that the younger forest population.of Pinus bungeana at Qiaojiawan grew best,and was close to the expanding population basically. The survival curve dropped obviously after 5-7. 5 cm size-class. The population had a peak of mortality between 7. 5-10 cm,and the survival curve tended to be the type Deevey I . The populations at Heihugou and Guojiawa belonged to diminishing population. The shortage of younger individuals limited seriously the survival and development of the population.