香港乡土树种幼苗在次生林下生长的研究

SURVIVAL AND GROWTH OF NATIVE TREE SEEDLINGS IN SECONDARY FOREST OF HONG KONG

摘要:

通过苗木移植试验,测定了21种香港乡土树种在次生林下的成活率及生长状况。结果表明,大多数种类的幼苗具有一定的耐荫性,可在林下生长；只有极少数种类表现出极耐荫或极不耐荫,导致林下先锋树种幼苗死亡率高的主要原因是荫蔽或因荫蔽而生长不良受病虫害致死。在香港次生林演替中占优势的种类通常具有生长快、稍耐荫,或生长稍慢但耐胁迫等特点。这是对香港退化土地长期适应的结果。鸟播植物在香港次生林中占有重要地位,建议加强鸟播树种生态学特性的研究及其在植树造林中应用。结合本实验结果,对一些现代植物群落演替假说进行了简要的讨论。

Abstract:

The seedling survival and growth of 21 native tree species were studied by transplanting into two natural forest sites and an open site for approximately 22 months during June-August ]989 and April-October 1991. The results showed that the seedlings of most species had some tolerance to shading and could survive in forests. Only a few species showed extreme tolerance or intolerance to shade. The seedlings of most pioneer species died directly from shading or insect damage and pathogens in forests. The extremely shadeintolerant species in the study were Pinus massoniana, Sapium discolor, and Trema tomentosa.These species with a typical syndrome of pioneer characters do not play an important role in secondary succession in Hong Kong. The major components in current secondary forest,such as Machilus chekiangensis and Gordonia axillaris, have mixed and intermediate characters,which may be an adaptation to the soil degradation caused by centuries of fire and erosion.Bird-dispersed species play an important role in secondary forest of Hong Kong. Research and application of the bird-dispersed woody flora must be enhanced. Some hypotheses on the current floristic succession are briefly discussed.