苦竹杉木混交林界面区竹子克隆分株抽枝展叶效率变化特征

Variations in Branching and Leaf Unfolding Efficiencies of Bamboo Clonal Ramets in the Interface Area of Pleioblastus amarus and Cunninghamia lanceolata Mixed Forest

植物抽枝展叶效率与环境关系密切。苦竹是分布广泛的笋材兼用竹种,揭示不同环境条件下苦竹的抽枝展叶特征及枝叶间资源投资权衡策略,可为苦竹林科学经营提供参考。以连续成片的苦竹—杉木扩张林分为对象,设置苦竹纯林(界面区、中心区)和混交林(界面区、中心区)4种样地,调查测定1-2 a立竹的枝叶功能性状指标,分析枝叶生物量异速生长关系。结果显示,竹杉混交促进了苦竹新竹竹冠生长,竹冠增长,枝盘数增多,生长空间扩大。界面区(苦竹林、混交林)有利于增强新竹枝叶生长能力,枝长、枝基径增大,叶片数量增多,叶面积和枝叶生物量明显增大,但2种界面区的立竹枝叶功能性状差异明显缩小;苦竹纯林和混交林界面区新竹具有较高的叶枝生物量比、叶面积比和出叶强度,在苦竹纯林和混交林分别形成以“利用”和“占据”为优先的抽枝展叶策略。2 a立竹显著提高了同化机构的资源分配优势,出叶强度和展叶效率大幅提高,整体形成以“利用”为主的展叶策略;试验林1-2 a立竹叶生物量与叶面积、比叶面积分别呈极显著的异速生长关系,枝干重与叶面积呈近等速生长关系。2 a立竹提高了叶面积—叶质量的相对生长速率和投资收益,克隆整合和混交生长未改变2 a立竹枝—叶大小的异速生长关系,但对1 a立竹存在显著影响。综上表明,在异质环境下,苦竹抽枝展叶特性存在明显的立竹年龄效应,新竹更为敏感。试验林界面区苦竹存在明显的克隆整合资源权衡关系,修饰立竹枝叶生长塑性,提高克隆分株的竞争力和适合度。

The efficiencies of plant branching and leaf unfolding are closely related to the environment.Pleioblastus amarus is a widely distributed dual-purpose bamboo species.The characteristics of branching and leaf unfolding and the strategy of resource allocation between branches and leaves under different environmental conditions were revealed,which can provide reference for scientific management of Pleioblastus amarus forest.A continuous and expansive bamboo(P.amarus)-fir(Cunninghamia lanceolata)mixed forest was studied,and four types of sample plots were set up in interfacial zones and central zones of both pure bamboo forest and mixed forest.The functional traits of branches and leaves of 1-2 y/o bamboo were investigated and determined,and the allometric relationships between the biomasses of branches and leaves were analyzed.The results showed that mixing promoted the growth of new bamboo crown,the increase of branch number and the expansion of growth space.The interfacial zones were beneficial to enhancing the growth capability of branches and leaves of new bamboo,with the increases of branch length,branch base diameter,the number of leaves,the leaf area and the biomass of branches and leaves.But the difference of functional traits of bamboo branches and leaves in the two interfacial zones was significantly reduced.In the interfacial zones of both pure bamboo forest and mixed forest,new bamboo had higher leaf-branch biomass ratio,leaf area ratio and leaf sprouting intensity,and the strategies of branching and leaf unfolding in pure bamboo forest and mixed forest were prioritized with“utilization”and“occupation”,respectively.2 y/o bamboo significantly improved the resource allocation advantage of assimilation tissues,greatly improved leaf sprouting intensity and leaf unfolding efficiency,and generally adopted a“utilization”-oriented leaf unfolding strategy.There was a very significant allometric growth relationship between leaf biomass and leaf area or specific leaf area of 1-2 y/o bamboo,and there was a nearly isokinetic growth relationship between branch weight and leaf area.2 y/o bamboo increased the relative growth rate of leaf area-leaf mass and investment benefit.Clonal integration and mixed growth did not change the allometric growth relationship of branch-leaf size of 2 y/o bamboo,but had a significant effect on that of 1 y/o bamboo.In conclusion,there was apparently an age-dependent effect in branching and leaf unfolding of P.amarus in heterogeneous environment,and new bamboo was more sensitive.There was a significant resource trade-off relationship with clonal integration in the interface area of the experimental forest,which modified the growth plasticity of branches and leaves,and improved the competitiveness and adaptability of clonal ramets.