树种组成对成都绕城高速路域不同人工林群落物种多样性的影响

Effects of tree species composition on species diversity of different plantation communities in Chengdu ring expressway

【目的】探究乔木树种组成及林分因子对不同路域人工林群落物种多样性的影响,为成都路域人工林营造与管理提供参考。【方法】采用典型样地法对成都绕城高速路域现种植的5种不同树种组成人工林群落(Ⅰ,加杨纯林;Ⅱ,樟树、加杨混交林;Ⅲ,樟树纯林;Ⅳ,樟树、巨桉混交林;Ⅴ,巨桉纯林)的林分因子及林下植被物种多样性进行全面调查。【结果】(1)研究区共记录林下植物190种,隶属于71科131属。林下记录到植物科属种数量均为草本层多于灌木层,其中樟树纯林记录到的林下物种数最多。(2)构树(Broussonetia papyrifera)和葎草(Humulus scandens)重要值占比大,分别占据不同人工林群落灌木层与草本层的优势地位。(3)樟树纯林的灌木物种丰富度指数(D)显著高于其他群落(P<0.05);草本层的Shannon-Wiener指数(H)、Simpson指数(H')和D指数大小变化趋势一致,表现为群落Ⅲ>Ⅳ>Ⅰ>Ⅱ>Ⅴ,其中樟树纯林的H指数显著高于樟树、巨桉混交林外其他群落(P<0.05)。(4)乔木层平均冠幅与灌木层的D指数和H指数、草本层的H指数、H'指数、D指数、Pielou均匀度指数(Jsw)均呈显著正相关(P<0.01),与灌木层的H'指数和Jsw指数均呈显著负相关(P<0.01);乔木层平均枝下高与灌木层的H指数、H'指数、D指数、Jsw指数均呈显著正相关(P<0.01)。【结论】乔木层的树种组成、平均枝下高和平均冠幅显著影响路域人工林群落的物种多样性,因此,选择合适树种并定期修枝管理,有利于路域人工林乔灌草群落结构的形成和林下植被物种多样性维持。

[Objective]The study aims to explore the effects of tree species composition and other stand factors on species diversity of plantation communities in different road areas,and provide reference for the construction and management of plantation communities in Chengdu.[Methods]By using the typical plot method,the stand factors and understory vegetation species diversity of 5 different tree species in the plantation community(Ⅰ,poplar pure forest.Ⅱ,camphor and poplar mixed forest.Ⅲ,pure camphor for-est.Ⅳ,mixed forest of camphor and eucalyptus.Ⅴ,eucalyptus grandis forest)of Chengdu Ring Expre-ssway were investigated.[Results](1)A total of 190 species of understory plants belonging to 71 families and 131 genera were recorded in the study area.The number of species of plant families recorded under the forest was more in the herbaceous layer than in the shrub layer,among which the number of understory species recorded in the pure camphor forest was the highest.(2)The important values of Broussonetia pa-pyrifera and Humulus scandens dominated the shrub layer and herb layer of different plantation communi-ties,respectively.(3)The shrub species richness index(D)of pure camphor forest was significantly higher than that of the other communities(P<0.05);the Shannon-Wiener index H,Simpson index(H')and D index size of the herbaceous layer had the same trend of change,showingⅢ>Ⅳ>Ⅰ>Ⅱ>Ⅴ,of which H of pure camphor forest was significantly higher than that of the other communities,except mixed forest of camphor and eucalyptus(P<0.05).(4)The average crown width in the tree layer was significantly positively correlated with D index and H index in shrub layer,H index,H'index,D index,and Pielou uniformity index(Jsw)in herbaceous layer(P<0.01),and negatively correlated with H'index and Jsw index in shrub layer(P<0.01).The average height under branches in the tree layer was signifi-cantly positively correlated with H index,H'index,D index,and Jsw index in shrub layer(P<0.01).[Conclusion]The tree species composition,average undershoot height,and average crown width of the tree layer significantly affect the species diversity of plantation communities in the road area,and the selec-tion of appropriate tree species and regular pruning management would be conducive to the formation of good tree and shrub community structure and the maintenance of understory vegetation species diversity in road plantations.