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CAS Workshop on Ecosystem Succession Theory and Practice of Ecological Restoration 在破落的山地上修复森林以保育香港的生物多样性 侯智恒1
苏国贤2 (1香港特别行政区，香港大学生态学及生物多样性学系；2香港特别行政区，嘉道理农场暨植物园） 摘要：自九十年代初开始，香港日益关注在破落的山地上修复森林以保育生物多样性。本文根据过往一些实地研究的结果，尝试总结在香港破落的山地上，森林天然更新的障碍。此外，本文就8个规模各异，分别由不同学者和单位于过去十年间所进行的种植试验作一次总结和评估，并比较这8个实验中57个乡土树种和灌木种的早期成活率和生长率。我们亦用了源自澳洲昆士兰省北部热带林区的「建构种方法」来评估这些乡土种的表现并作出归纳和分类。总结后的结果显示，苗木的表现在不同的种植地点有着很大的差异。但一般而言，多数拥有先锋种特性的树和灌木种较能适应无遮蔽及严重退化的土地，如鸭脚木，白楸及欓花椒，但亦有如乌般的先锋种表现较差。然而，有些属于树林演替后期才出现的树种，如华南青刚，竹叶青刚，韩氏蒲桃等亦能在无遮蔽的环境下生长，但其它种则普遍表现欠佳，如臀果木。这8个种植试验中，只有一个种植试验是以灌木为主，而初步的结果显示这些灌木种在极差的土壤条件和55度的斜坡上依然十分良好。这正好反映香港应检讨以种植树木为主的植林策略，应考虑仿照树林演替的自然过程，先种植灌木，然后才种植不同的树种，以增加物种的多样性和缩短成林所需的时间。本文最后亦建议了一些乡土建构种，以供修复香港的森林土地以保育生物多样性。 Forest restoration for biodiversity conservation on
degraded hillsides in Hong Kong, China Billy C.H.
Hau1 Ken K.Y.
So2 (1Department
of Ecology & Biodiversity, The University of Hong Kong, Pokfulam
Road, the Hong Kong SAR, China; 2Kadoorie Farm and
Botanic Garden, Lam Kam Road, Tai Po, N.T., the Hong Kong SAR,
China) Abstract:
The interest in restoring forest on degraded hillsides in Hong
Kong for biodiversity conservation has been growing since the
beginning of the last decade. Based on the results of previous field
researches, this paper attempts to generalise the barriers to
natural forest regeneration on Hong Kong’ degraded hillsides. In
addition, this paper reviews the results of 8 planting trials
conducted by different researchers on various scales in the last ten
years using a total of 57 native tree and shrub*[1]species
with respect to early survival and growth. The performances of these
seedlings were evaluated under the criteria of the Framework Species
Method of reforestation that was developed in North Queensland’s
Wet Tropics. Seedling performances are highly variable between
species and sites. In general, a higher number of the native tree
species showing early successional characters performed better on
the exposed and eroded hillsides, such as
Schefflera octophylla, Mallotus
paniculatus, and Zanthoxylum
avicennae. While other early successional species performed
badly, such as Sapium discolor. However, some late successional species also
performed very well on the exposed hillsides, e.g. Cyclobalanopsis neglecta, C.
edithiae, and Syzygium
hancei. Other late successional species performed very badly,
such as Pygeum topengii.
Only one of the 8 planting trials, also the latest one, used native
shrub species. The preliminary results indicated that shrubs were
doing very well even in very poor soil and on 55 degree cut slope
surfaces. This suggests that the focus on planting tree seedlings
for afforestation may have been misplaced in Hong Kong. The
succession pathway from shrubland1 to forest should be
given more consideration and the first step of forest restoration
projects may start with shrubs, followed by reinforcement with trees
at a later stage. A list of potential Framework Species for
restoring native, species-rich forest is prepared on the basis of
this review.
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