A mechanism of reducing plant diversity in phyllostachys pubescens expansion:nitrogen and phosphorus

• 作 者: SONG Qing-ni QI Hong-yan LU Hui YANG Jun YANG Guang-yao YANG Qing-pei
• 机 构: Ministry of Education Key Laboratory for Earth System Modeling,Center for Earth System Science,Tsing
• 出 处: 第十三届中国竹业学术大会
• 发表日期: 2017年7期
• 关键词: Phyllostachys pubescens expansion plant diversity nutrient rhizosphere effects i

　　Question Bamboo(Phyllostachys pubescens)expansion had imposed great threats on plant diversity of adjacent forests in subtropical regions,however,little is known about the belowground mechanisms driving this ecological processes.Methods Using space-for-time substitution method,we sampled P.pubescens forest(PPF,originated from heavily bamboo expansion),bamboo broad-leaved mixed forest(BMF,moderately expansion)and evergreen broad-leaved forest(EBF)along the bamboo expansion.We investigated the growth vigor and abundance for P.pubescens and 8 tree species(5 arbor species: Castanopsis fargesii,Castanopsis sclerophylla,Symplocos laurina,Machilus pauho,Alniphyllum fortune,3 shrub species: Ardisia crenata,Loropetalum chinense,Camellia oleifera)in three forests,then we determined the contents of available N(NH4+-N,NO3--N)and Hedley available P(Resin-P,NaHCO3-Pi,NaHCO3-Po)from rhizosphere and non-rhizosphere soil for all species.And ultimately we compared their rhizosphere effects(RE,rhizosphere/non-rhizosphere ratio).Results(1)Along PPF to EBF,P.pubescens had more and more vigorous growth,but most trees(except S.laurina and C.oleifera)performed undesirably.(2)The RE of NH4+-N and available P for P.pubescens respectively increased by 94%and 37%,however,those of 5 arbor species(but S.laurina)decreased by 17%~30%and 19%~24%.(3)The content of NH4+-N,NO3--N and labile P of rhizosphere soil for tree species(except S.laurina)decreased by 39%~60%,31%~131%and 33%~49%,and C.sclerophylla,A.crenata and C.oleifera exhibitting the most susceptible response to bamboo expansion.Conclusions P.pubescens showed excellent growth and great REs on NH4+-N and labile P,in contrast most tree species did downward from PPF to EBF.These findings indicated that weakened REs on N and P could be a potential cause for the poor growth of trees and declined plant biodiversity during P.pubescens expansion into evergreen broadleaved forest.