大气污染对珠江三角洲村边林植被的影响

Vegetation Damage by Long-term Air Pollution at a Rural Site in the Pearl River Delta in South China

摘要:

在群落结构与组成分析的基础上,阐明了陶瓷工业污染对自然条件下生长的植被伤害状况、程度和原因,为类似地理气候区重度污染背景下退化生态系统的植被恢复提供参考。野外调查样地位于广东省佛山市南海区一村边半自然次生林内。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、泥竹,重要值依次为26.75、17.08、16.27和11.50,其它伴生种的重要值不足30。根据冠层叶可见症状、失绿和脱叶对植物受害进行综合评价,分死亡(受害程度100%,全部叶死亡脱落)、重度(60%-100%)、中度(25%-60%)、轻度(10%-25%)和健康(<10%)5个级别。隆缘桉和马尾松冠层叶完全脱落属于死亡类,泥竹、南岭黄檀属重度受害种类。尽管其它伴生树种有较低的重要值,但其中多数种类显示出较强耐受能力,这些种类包括鸭脚木、珊瑚树、酒饼叶、光叶山矾、白背叶、银柴、竹节树、山黄麻、构树、粗叶榕、潺槁树等。和乔木层比较,林下灌木和草本植物受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,在重度污染地区已经受到严重威胁,应该引起重视。另一方面,某些乡土树种在重度污染地区环境修复中显示出潜力和前景。

Abstract:

This study aims to characterize the damage or sensitivity of different plant species growing under long-term air pollution around ceramic industrial areas, on the basis of community survey, to provide implications for restoration of heavily polluted and degraded areas in similar condition. Field survey was carried out by ten quadrats 10m×10m in area for tree layer, and eight subquadrats 5m×5m for shrub and herb layers in a hilly land semi-natural secondary forest at a rural site in Nanhai city of Guangdong Province. The forest was dominated by exotic Eucalyptus exserta and Eucalyptus urophylla, followed by native tree species, Schefflera octophylla and Bambusa gibba, with the importance value (Ⅳ) of 26.75, 17.08, 16.27 and 11.50, respectively, while all other companion species accounted for less than 30%, Based on foliage loss and the extent of injured leaf tissues, plants were categorized into: (1) dead without any leaves attached, (2) severe damage with the injured degree ranging from 60% to 100%, (3) moderate damage, 25%-60%, (4) light damage, 10%-25%, and healthy with the injured degree less than 10%. Among all tree species, Eucalyptus exserta and Pinus massoniana were the most severely damaged species, of which all individuals were dead or with only a few dead branches without any leaves attached, and then followed by Bambusa gibba and Dalbergia balansae. Although the Ⅳ was much lower for the rest companion species, but most of them showed high capacities to cope with the pollution stress. These species include Schefflera octophylla, Viburnum odoratissimum, Desmos chinensis, Syplocos lancifolia, Broussonetia papyrfera, Mallotus apelta, Aporosa dioica, Carallia brachiata, Trema tomentosa, Ficus hirta and Litsea glutinosa. Compared with species in tree layer, damages of woody seedlings, herbs or lianas growing under the canopies were largely reduced. Results from this study demonstrate 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 forest restoration in hilly degraded lands and planted in a wide range of areas during 1970-80s, due to its fast growing aspect. The results also demonstrate the potentials and perspectives by developing native species as target plants for restoration of degraded area, which makes a stimulus 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.