猴耳环天然更新特性

Natural Regeneration Characteristics of Archidendron clypearia

为研究药用植物猴耳环(Archidendron clypearia)的天然更新特性,2015年7月和2016年7月对广东省广州市、惠州市和深圳市主要森林公园、自然保护区和生态公益林内天然分布的42株母树进行了天然更新状况调查,并采用熵值法对更新效果进行评价。结果表明:(1)母树的上下和左右冠幅十分接近,但97.6%的母树存在偏冠现象,尤以向坡下偏冠更为明显,上坡方向树冠宽度约为下坡的1/2;偏冠是影响种子散布范围的主要原因之一;(2)与母树的距离与不同方向对种子雨量影响显著,但两者对苗木的数量和径高生长没有显著影响;(3)林冠下≤1 a的苗木占总数的87.8%,且林下无5年及以上的幼树,预示猴耳环依靠天然更新维持种群增长困难较大;(4)用信息熵理论导出的更新指数来评价与母树不同距离的更新效果显示,与母树距离越远更新效果越差;距母树0~3 m范围内更新效果最好;(5)猴耳环具有诸多"极小种群野生植物"的特征,亟需对其资源分布现状及生物生态学特性开展进一步的深入调查和研究。

In order to study characteristics of natural regeneration about medicinal plants-Archidendron clypearia,we investigated the seed production,dispersal,and recruitment and growth of seedlings of 42 A. clypearia seed trees naturally distributed in forest parks,nature reserves and ecological public welfare forests in July,2015 and 2016 in Guangzhou,Huizhou,and Shenzhen,Guangdong Province of China. The mean crown width in the left/right direction was very close to that in the up/down direction,however,97. 6% of the seed trees had inclined crowns that were more frequent on down-ward than the other directions,resulting the mean length of the upward crowns was about 1/2 of that of the down-ward ones. Inclined crowns of seed trees appeared to be,among others,one of the main factors affecting seed dispersal. The numbers of seeds and seedlings were significantly correlated with the distance to the base of seed trees,while the diameter at ground level and height of seedlings were not significantly varied among the different distances. All the studied parameters,except the number of seeds dropped,were not significantly different among all sub-plots（ 1. 0 m ×1. 0 m） in the four directions. The newly emerged seedlings（ 1-2 weeks old） and one year old seedlings accounted for 87. 8% of the total of seedlings,and none of five years old seedling was found under seed tree canopies,implying that it is hard for A. clypearia to maintain its population growth by natural regeneration. Theoverall result of natural regeneration of the species inversely correlated with the distance to the base of seed trees evaluated by a regeneration index derived from Entropy method,with the best regeneration result recorded in areas within 3. 0 m away from the seed trees. A. clypearia appears to have more characteristics in common with those of the plant species with extremely small populations. Research needs in biological and ecological sciences should be a priority for the species in the near future.