桉树林和针阔混交林对植物多样性的影响比较

为了系统评价桉树林和针阔混交林对生物多样性的影响，采用立地条件控制及空间代替时间法，对南亚热带桉树林（2代和1代）和针阔混交林（10～11 a生和5～7 a生）乔木层、灌木层和草本层生物多样性进行了比较。结果表明，针阔混交林Ⅰ（10～11 a生）有68种植物，隶属38科62属，桉树林Ⅱ（桉树2代）有41种，隶属26科39属，针阔混交林Ⅲ（5～7 a生）有53种植物，隶属30科48属，桉树林Ⅳ（桉树1代）有55种植物，隶属33科51属。针阔混交林乔木层重要值较大的科为杉科、樟科、金缕梅科、大戟科、山茶科、木兰科和楝科，灌木层为五加科和大戟科，草本层以禾本科、鳞始蕨科和乌毛蕨科为主。桉树林乔木层重要值较大的科为桃金娘科、芸香科、樟科、大戟科和漆树科，灌木层为冬青科、樟科、大戟科和芸香科，草本层以禾本科和里白科为主。4种试验林间乔木层、灌木层和草本层物种丰富度指数（S）、Shannon-Wiener指数（H’）、Simpson优势度指数（D）、Pielou均匀度指数（E）差异不显著（P > 0.05）。针阔混交林Ⅰ乔木层和灌木层H’指数、D指数及E指数显著高于草本层（P < 0.05），桉树林Ⅱ乔木层、灌木层和草本层间H’指数、D指数及E指数均存在显著差异（P < 0.05）。针阔混交林乔木层均匀度指数（E）均大于桉树林。与针阔混交林Ⅲ相比，针阔混交林Ⅰ乔木层物种S，H’，D及E指数呈上升趋势，而灌木层和草本层呈下降趋势。与1代桉树林Ⅳ相比，2代桉树林Ⅱ灌木层和草本层S，H’和D指数呈下降趋势。研究结果为桉树人工林物种多样性保护和可持续经营提供科学依据。

Effects of Eucalypt Plantation and Conifer-Broadleaved Forest on Plant Biodiversity

A comparative study was conducted on the plant biodiversity of tree layer, shrub and herb layers in eucalypt plantation (the second-generation and the first-generation) and conifer-broadleaved forest (10-11 years old and 5-7 years old) in southern subtropical region to understand the effects of eucalypt plantation and conifer-broadleaved forest on the plant biodiversity by using the methods of site condition control and space instead of time. The present results showed that there were 68 species belonging to 38 families and 62 genera in conifer-broadleaved forest (10-11 years old), and 41 species belonging to 26 families and 39 genera in eucalypt plantationⅡ (the second-generation of eucalypt), 53 kinds of plants, belonging to 30 families and 48 genera in conifer-broadleaved forest Ⅲ (5-7 years old), and 55 species belonging to 33 families genera 51 in eucalypt plantation Ⅳ(the first-generation of eucalypt). The large important values of families of tree layer were Taxodiaceae, Lauraeeae, Hamamelidaeeae, Euphorbiaceae, Theaceae, Magnoliaceae and Meliaceae, those of shrubs were Araliacea, Euphorbiaceae, and those of herb layer were Graminaceous, Lindsaeaceae and Blechnacea in conifer-broadleaved forest. The large important values of families of tree layer were Myrtaceae, Rutaceae, Lauraeeae, Euphorbiaceae, Anacardiaceae, and those of shrubs were Aquifoliaceae, Lauraeeae, Euphorbiaceae, Rutaceae, and those of herb layer were Graminaceous and Gleicheniaceae in eucalypt plantation. The species richness (S), Shannon-Wiener index (H’), Simpson dominance index (D), Pielou evenness index (E) of tree layer, shrub layer and herb layer were not significant (P > 0.05) among four kinds of experimental forests. The index of H’, D and E of tree layer and shrub were significantly higher than those of herb layer (P < 0.05), the index of H’, D and E were significantly different (P < 0.05) among tree layer, shrub and herb layer in eucalypt plantationⅡ. The evenness index (E) of conifer-broadleaved forest was greater than that of eucalyptus forest. The index of S, H’, D and E of tree layer in conifer-broadleaved forestⅠincreased, while those of the shrub and herb layers decreased compared with the conifer-broadleaved forestⅢ. The indexes of S, H’ and D of shrub and herb layer in eucalypt plantationⅡ(the second-generation of eucalypt) declined in varying degrees compared with the eucalypt plantation Ⅳ(the first-generation of eucalypt). The results provided a scientific basis for species diversity conservation and sustainable management of eucalypt plantation.