黄土高原子午岭辽东栎(Quercus liaotungensis)幼苗动态生命表及生存分析

Dynamic Life Table and Analysis on Survival of Quercus liaotungensis Seedlings in Mt. Ziwuling of the Loess Plateau

在子午岭马栏林区3种生境(辽东栎林、油松林、灌草丛)中通过野外播种,建立辽东栎(Quercus liaotungensis)幼苗同生群,根据3年观测数据,编制动态生命表,绘制存活曲线、死亡曲线、生存率函数曲线、死亡率函数曲线及危险率函数曲线,分析辽东栎幼苗同生群在不同生境的动态变化。结果显示:辽东栎幼苗存活曲线接近Deevey-Ⅱ型,但在幼苗生长的不同阶段有明显波动。在辽东栎林和油松林中,辽东栎幼苗生存率无显著差异,但均显著高于灌草丛中幼苗生存率。郁闭森林生境中,辽东栎当年生幼苗存活率较高,幼苗死亡高峰期出现在出苗后的第3年春季;灌草丛生境中,幼苗出苗后2个月内死亡率很高,第3年春季再次出现高死亡率。第3年的春旱是辽东栎幼苗生存的瓶颈期。

In the Malan forest region of the Mt.Ziwuling on the Loess Plateau,three kinds of communities,i.e.the Pinus tabulaeformis forests,Quercus liaotungensis forests and shrub grasslands,were selected as the experimental plots.The seeds of Q.liaotungensis were sowed to build the seedling cohorts in three habitats.According to the growth data gathered continuously in three years,the dynamic life tables,curves of cumulative survival rate,cumulative mortality rate and hazard rate are drawn in this paper.The results show that the survival curve of Q.liaotungensis trended to the Deevey-Ⅱ and fluctuated clearly at different stages.There was no significant difference in survival rate of Q.liaotungensis seedlings in P.tabulaeformis and Q.liaotungensis forests,but the survival rate was significantly higher than that in shrub grasslands.In dense forests,the survival rate of Q.liaotungensis seedlings was higher in the first year,and the highest mortality rate occurred in the third spring.In the shrub grasslands,the mortality rate of seedlings was high in the first two months,and the highest mortality rate of seedlings occurred in the third spring.Drought in the third spring is the key factor affecting the survival of Q.liaotungensis seedlings.