南亚热带不同林龄人工针阔混交林物种多样性研究

为系统评价南亚热带不同林龄人工针阔混交林生物多样性的状况，在广东省佛山市云勇林场选择立地条件相近的针阔混交林，对乔木层、灌木层和草本层的生物多样性进行了比较。针阔混交林分为3个林龄段，其中针阔混交林Ⅰ为10-11a生，针阔混交林Ⅱ为7-9a生，针阔混交林Ⅲ为3-5a生。生物多样性用物种丰富度指数（S）、Shannon-Wiener指数（H′）、Simpson优势度指数（D）和Pielou 均匀度指数（E）衡量。结果表明：随着林龄的增大，针阔混交林乔木层和灌木层植物种数先减小再增大，草本层则先增大再减小。针阔混交林乔木层重要值最大的科均为杉科，其重要值随林龄的增大呈现出先升高后降低的趋势，表明杉木在演替过程中不断衰退，逐渐被阔叶树种所取代。不同林龄针阔混交林乔木层主要以樟科、金缕梅科、山茶科、大戟科、芸香科和木兰科占优。在乔木层，重要值较高的造林树种包括米老排、阴香、山杜英、藜蒴、香樟、火力楠、楝叶吴茱萸，这些树种适宜于本地区杉木林改造；重要值较高的自然更新乔木物种为鸭脚木、山苍子、山麻黄和银柴。在灌木层，重要值较高的物种因林分而异，藜蒴、鸭脚木、山苍子、山黄麻等乔木树种的幼苗具有较高的重要值，表明部分造林树种能够实现自我更新，群落处于正向演替过程中。草本层以蔓生莠竹、弓果黍、蕨、乌毛蕨和假臭草等为主。随林龄的增加，乔木层S呈上升的趋势，而H′、D和E表现为先降低后升高；灌木层S表现为先降低后升高，而H′、D和E呈现出下降的趋势；草本层所有指数则表现为先升高后下降。多样性指数的变化也反映出林分改造促进了群落的演替。

Study of Species Diversity of Conifer broadleaved Mixed Plantation of Different Age in Southern Subtropical Region

Plant diversity of conifer-broadleaf mixed forest （CBMF ）of different age was studied in Yu-nyong Forest Farm of Foshan,Guangdong.Three CBMF in similar site conditions were 10 to 1 1 ,7 to 9 and 3 to 5 years old,respectively.The species abundance index （S）,Shannon-Wiener index （H′）,Simpson index （D）and Pielou index （E）were chosen to compare the diversity of tree,shrub and herbaceous layer of the three CBMF.The results were as following：along with the increasing age of CBMF,species number decreased first and then in-creased in tree and shrub layer,but the contrary change was found in herbaceous layer.The important value （IV） of Taxodiaceae was highest than other families in tree layer,but declined at 10 to 1 1 years old,indicating Cunning-hamia lanceolata declined and was replaced by other broadleaf species.The families of Lauraceae,Hamamelidace-ae,Theaceae,Euphorbiaceae,Rutaceae and Magnoliaceae dominated in tree layer of CBMF.These species,in-cluding Mytilaria laosensis,Cinnamomum burmannii,Elaeocarpus sylvestris,Castanopsis fissa,Cinnamomum cam-phora,Michelia macclurei and Evodia meliaefolia,had higher IV,indicating that they were appropriate in forest transformation in this region.Schefflera octophylla,Litsea cubeba,Trema tomentosa and Aporosa chinensis were nat-ural regeneration species which had higher IV.Species of higher IV in shrub layer were different in three CBMF. The seedlings of Castanopsis fissa,Schefflera octophylla,Litsea cubeba and Trema tomentosa dominated in shrub lay-er in CBMF suggested that species in tree layer could regeneration and the community were in positive succession. Microstegium fasciculatum,Cyrtococcum patens,Pteridium aquilinum,Blechnum orientale and Praxelis clematidea were the major species in herbaceous layer.Along with forest age increasing,the S index increased,and the H′,D and E index decreased first and then increased in tree layer;the S index decreased first and then increased,while the H′,D and E index of shrub layer decreased in shrub la