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CAS Workshop on Ecosystem Succession Theory and Practice of Ecological Restoration 大气酸污染背景下华南珠江三角洲地区村边林植被受害证据及启示* 温达志
刘世忠
旷远文
张倩媚 （中国科学院华南植物研究所，广州
510650） 摘要：酸污染已经成为华南珠江三角洲地区的一个主要环境问题。以检测大气污染物排放种类、通过物理和化学方法监测大气污染物浓度为基础的大气监测和质量评估无论在地方还是国家层次上都日趋完善，并积累了丰富的数据，并且为政府部门决策是否控制或限制某种污染物的排放提供了指南。然而，大气监测结果并不能直接给出或推断被测定污染物对植被的影响。本研究的目的是阐明酸污染对植被的伤害状况和程度，从而为类似地理区域的重度污染区的植被恢复提供参考。野外调查样地位于广东省南海市一村边半自然次生林内，乔木层共设10个10m×10m
的样方，下木草本层设有8个5m×5m
的亚样方。结果表明，该森林以隆缘桉和尾叶桉占优势，其次是乡土树种鸭脚木，重要值指数依次为30.8,19.7和19.1。其它伴生种的重要值指数不足30。在所有的乔木种中，以隆缘桉受害最为严重，表现为所有径级的个体整株死亡，其次为尾叶桉。根据冠层枝叶损失量和可见伤害面积划分为重度（受害部分超过75%）、中度（受害部分介于25%-75%）和轻度伤害（受害部分小于25%），尾叶桉约10%、75%和15%的个体依次属于这3个等级。尽管其它伴生树种有较低的重要值指数，但其中多数种类显示出较强的耐受污染的能力。这些种类包括鸭脚木、光叶山矾、白背叶、黄荆、银柴、竹节树、山黄麻、钩树和粗叶榕等。和乔木层比较，林下灌木和草本植物受酸污染的伤害大大降低。桉树类树种因其速生、快速郁闭的特点被认为是华南荒山、退化丘陵地区植被恢复的重要种类，并且在许多地区的植被恢复中发挥了重要作用，本简报结果表明大气污染已经对我省部分地区外来引进桉树种类构成严重威胁，应该引起高度重视。另一方面，某些乡土树种作为重度污染地区环境修复显示出极大潜力，污染胁迫下以植物功能过程为基础及它们之间的交互作用的研究亟待加强。 Vegetation damage by ambient levels of air pollution at a rural
site in the pearl river delta of south China: evidence from a field
survey[1] Wen Dazhi Liu Shizhong Kuang Yuanwen Zhang Qianmei (South
China Institution of Botany, Chinese Academy of Sciences, Guangzhou
510650, China) Abstracts: Acid pollution is a major environmental problem in the Pearl River Delta areas of subtropical China. Much progress has been achieved in air monitoring and quality assessment at regional and national level based on emission inventories and measurements of ambient air concentrations taken by physical and chemical methods, which make it possible to control whether limit the emission of certain pollutants by decision-makers. These monitoring results, however, do not permit direct conclusions on the effects of the measured pollutant concentrations on vegetations. The purpose of this study is to characterize the damage or sensitivity of plants induced by acid pollution and provide implications for restoration of heavily polluted and degraded areas with similar geolocation. Field survey was carried out in a hilly land semi-natural secondary forest at a rural site in Nanhai city of Guangdong province, by ten quadrates 10m×10m in area for the tree layer, and eight subquadrates 5m×5m for the shrub and herb layers. The results showed that the forest was dominated by exotic species, Eucalyptus exserta and Eucalyptus urophylla, followed by the native tree species, Schefflera octophylla, indicated by the important value index(IVI) of 30.8, 19.7 and 19.1, respectively. Other companion species accounted for less than 30 in IVI. Among all tree species, Eucalyptus exserta was the most severely damaged, in which all individuals among all DBH ranges were dead with dead branches without any leaves attached, and then followed by Eucalyptus urophylla. Among this species, approximately 10%, 75% and 15% individuals were categorized as severe damage with leaf loss or visible injury part exceeding 75%, and moderate with injured degree ranging from 25% to 75%, and light damage less than 25%, respectively. Although the IVI was low for the rest companion species, but most of them showed high capacities to cope with the acid pollution. These species include Schefflera octophylla, Syplocos lancifolia, Mallotus apelta, Vitex negundo, Aporosa dioica, Carallia brachiata, and Ficus hirta. Compared with the tree layer, damages on woody seedlings, herbs or lianas growing under the canopies were largely reduced. Results form this study demonstrated that attention and concern should be made on those introduced Eucalyptus species in heavily polluted area, which had ever been considered as one of the important species for restoration of hilly degraded lands and planted in a wide range of areas during 1970-80s, due to its fast growing aspect. The results also implied that the potentials and perspectives by developing native species as target plants for restoration of degraded area, and make a stimuli for scientists to initiate studies as a base for advancing our ability to describe the functional aspects of native species and process-based interactions with pollution stress. Key words: acid pollution; forest damage; the Pearl River Delta area; South China
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