子午岭60年辽东栎林种子质量与森林更新

Seed quality and forest regeneration of a 60-year Quercus liaotungensis forest in the Ziwuling region,northwestern China.

辽东栎是我国暖温带落叶阔叶林地带的优势乔木树种之一。通过26年的定位监测,对子午岭辽东栎林种子质量消减、种子萌发与环境条件、实生苗时空分布动态以及对其森林更新的影响等方面进行了初步探讨。结果表明:辽东栎林在子午岭半阳坡、半阴坡和阴坡3种类型中,平均完好种子占种子总数的26.65%;霉变种子占18.72%;动物取食虫蛀种子在阴坡远高于半阴坡和半阳坡,占到种子总数的26.32%;已发芽的种子占其总数的28.31%,且半阴坡>半阳坡>阴坡。每年均有大量种子生产,但在生境与动物的共同作用下,种子数量和质量受到很大影响,多达73.35%的种子失去生命力,直接影响实生苗的形成;地表覆盖物虽能促进种子的快速发芽,但对成苗却是一个物理障碍,影响是负作用的,主要影响因子是地表覆盖物的厚度和含水量;在辽东栎林下虽有一定的实生幼苗分布,但数量极少,平均密度仅为140~120株/hm2,且不同立地条件差异显著,严重影响森林的天然更新。

Quercus liaotungensis is one of the dominant tree species in broadleaved deciduous forests of China.The authors conducted a 26-year monitoring to study seed quality declining,the relationship between seed germination and environmental condition,the dynamics of spatio-temporal distribution of seedlings,and their effects on forest regeneration in the Ziwuling region of northwestern China.Results showed that on the three types of slope aspects（semi-sunny,semi-shady,shady）,the number of seeds eaten and infested by animals on the shady slope was far more than those on the semi-sunny and semi-shady slopes,but numbers of germinating seeds followed semi-sunny 〉 semi-shady 〉shady.On average,sound seeds,decayed seeds,seeds eaten and infested by animals,and germinating seeds accounted for 26.65%,18.72%,26.32% and 28.31%,respectively.Although a large amount of seeds can be produced from Q.liaotungensis trees,their quantity and quality were seriously affected by animals and other environmental variables. About 73.35% of total number of seeds lost vitality,which significantly affected the establishment of seedlings.The results also indicated that application of ground mulch could promote rapid germination of seeds,but as a physical barrier,it had negative effects on seedling establishment mainly due to its thickness and water content.Establishment of the oak seedlings in the understory layer in the study area was very limited,with average density of 140～210 plants/hm^2,and appeared significantly different under different site conditions.Because of this,natural forest regeneration was severely affected.