摘要
防护林林下植被对水源涵养、土壤保育和提升生态服务功能具有重要意义。以珠江流域中上游广西都安县5种典型珠江防护林(桉树、任豆、马尾松人工纯林,马尾松+荷木人工混交林和青冈栎天然林)为研究对象,应用半球影像技术获取林分冠层结构(林冠开阔度CO和叶面积指数LAI)和林下光环境指标(林下直射光、林下散射光和林下总光照),并分析两组指标之间的关系及其对林下植被特征的影响。结果表明:1)马尾松+荷木混交林较人工纯林更有利于林下灌木层植被多样性的维持。2)各林分冠层结构与林下光照指标极显著相关(P<0.001),冠层结构对林下散射光的影响比对林下直射光大。3)CO和林下光环境指标与灌木层物种丰富度(S)和多样性指数(H)呈极显著负相关(P<0.001),较高的林下光照不利于林下灌木层植被多样性的维持。冠层结构是影响林下灌木层植物多样性和更新的关键因素,而灌木层和草本层种间竞争可能是影响物种多样性的另外一个重要因素。人工纯林改造和结构调整中,对乔木层可通过适当补植伴生树种,增加林下郁闭度,促进灌木层物种发育;对草本层可适度降低单优草本优势度,为灌木和幼苗更新提供空间。
Understory vegetation of shelterbelt forest is important for water conservation, soil re- tention and ecosystem service enhancement. Five types of sheherbehs along the middle and upper reaches of Pearl River in Du＇ an, Guangxi were observed, including Eucalyptus robusta forest, Zenia insignis forest, Pinus massoniarta forest, Pinus massoniana ＋ Schima superba mixed forest and Cyclobalanopsis glauca forest, to study the effect of canopy structure and understory light on vascular species composition and regeneration. We used DMC-LX5 and external Nikon FC-E8 fisheye lens to record canopy openness （CO）, leaf area index （LAI）, transmitted direct solar ra- diation, transmitted diffuse solar radiation and transmitted total solar radiation, and investigated relations among the indexes and their effects on the understory vegetation. The results showed that： 1 ） P. massoniana ＋ S. superba mixed forest was more conducive to maintaining shrub layer diversity than other pure forests; 2） The canopy structure indexes （CO and LAI） were signifi- cantly correlated with understory light indicators （P〈0.001）, and canopy structure had a greater effect on transmitted diffuse solar radiation than on transmitted direct solar radiation; 3） CO and understory light were significantly negatively correlated to shrub layer species richness （S） and Shannon index （H） （P〈0.001）, suggesting that higher light in understory did not facilitate themaintenance of the shrub layer diversity. We concluded that canopy structure was a key factor affecting the shrub diversity and regeneration, and the interspecific competition between shrub layer and herb layer might be another important factor. To improve ecosystem services of the for- ests, we recommend planting associated tree species to increase canopy density, promoting the development of shrub layer species. For herb layer improvement, single dominant herb species should be moderately reduced in coverage to provide space for other species＇ regeneration.
出处
《生态学杂志》
CAS
CSCD
北大核心
2016年第12期3148-3156,共9页
Chinese Journal of Ecology
基金
广西林业科技项目(桂林科字〔2012〕第7号)
广西科技重大专项(桂科攻14124004-3-11)
广西科技重大专项第五课题(桂财教〔2012〕22号)资助
林业公益性行业科研专项(201204101-11)
关键词
珠江防护林
林下植被
冠层结构
光环境特征
物种多样性
Pearl River shelterbelt forest
understory vegetation
canopy structure
light envi-ronment
species diversity.
