薇甘菊对香港郊野公园植物群落危害的分析

从薇甘菊(Mikania micrantha)对不同类型群落的危害,群落中各植物种类受薇甘菊危害的程度,以及薇甘菊与群落中主要乔木和灌木的种间联结性等方面,对香港郊野公园植物群落受薇甘菊危害状况进行了分析。研究样地所在的植被受薇甘菊的危害严重,草灌丛中薇甘菊的平均覆盖率高达80%,灌木群落中薇甘菊的平均覆盖率为60%左右,常绿阔叶林中的薇甘菊覆盖率平均约为30%。对香港郊野公园受薇甘菊危害的植物种类分析表明:受薇甘菊危害最大的主要是乔木和灌木,草本和藤本的受害比例和受害程度相对较小。受薇甘菊危害的乔木有30种,占群落中乔木的62.50%;受薇甘菊危害的灌木有29种,占群落中灌木的70.73%;受薇甘菊危害的草本植物有10种,占群落中草本植物的33.33%。通过无样方法采用2×2列联表的χ2检验对薇甘菊与群落中主要乔木和灌木的种间联结性分析表明:与薇甘菊呈正联结的乔木有12种,占主要乔木(28种)的42.86%,这些种大多是阳生性乔木;与薇甘菊呈负联结的乔木有16种,占主要乔木的57.16%。与薇甘菊呈正联结的灌木有11种,占主要灌木(19种)的57.89%,多是阳生性灌木;与薇甘菊呈负联结的灌木有8种,占主要灌木的42.11%,这些种大多数也是阳生性灌木,仅九节是耐阴性灌木。

The damage of Mikania micrantha to plant communities in the Country Park of Hong Kong

The damage of Mikania micrantha to different plant communities, to every plant species in communities and interspecific associations between M. micrantha and trees or shrubs in the communities were analyzed. The vegetation in study site was damaged seriously by M. micrantha. The average coverage of M. micrantha in herbaceous, shrub community and evergreen broadleaved forest was above 80%, 60%, and 30%. Shrubs and trees were damaged hardest by M. micrantha in ratio and degrees of damage, while herbs and liana were damaged slightly. A total of 30 species of trees accounting for 62.5% of those in plots were damaged by M. micrantha. In comparison, 29 species of shrubs accounting for 70.73% of those in plots were damaged and 10 species of herbs accounting for 33.33%. The results indicated that 12 species of trees, which accounted for 42.86% of the main trees (28 species) and most of which were heliophytes, showed positive association with M. micrantha. Of which, Leucaena glauca, Celtis austro-sinensis showed significant positive association. Sixteen species of trees, which accounted for 57.66% of the main trees, showed negative association. Cratoxylon cochinchinensis showed significant negative association with M. micrantha, while Liquidambar formasana, Viburnum odoratissimum and Machilus kwangtungensis showed significant negative association with M. micrantha. Eleven species of shrubs, which accounted for 57.89% of the main shrubs (19 species) and most of which were heliophytes, showed positive association with M. micrantha. Nine species of Lantana camara, Vitex negundo var. cannabifolia and Vitex negundo showed significant positive association with M. micrantha. Eight species of shrubs, which accounted for 42.11% of the main shrubs, showed negative association with M. micrantha. Most of them were heliophytes except Psychotria rubra that was shade-tolerant shrub. Four species, Litsea rotundifolia var. oblongifolia, Alchornea trewioides, Ilex asprella and Psychotria rubra, showed significant negative association with M. micrantha.