苦竹-杉木混交林界面区克隆分株秆形和地上生物量分配的适应策略

苦竹(Pleioblastus amarus)是优质笋材兼用竹种,分布广。为探究界面区苦竹分株秆形及地上构件生物量分配格局的变化特征,解析苦竹对异质生境适应机制,该研究选取了相邻的苦竹林和苦竹-杉木(Cunninghamia lanceolata)混交林两种林分类型,分别测定了苦竹林和混交林中心区及界面区不同龄级立竹秆形和秆、枝、叶的生物量,分析立竹秆形及地上构件生物量积累、分配、异速生长关系的差异。结果表明:(1)界面区1 a立竹生物量积累及分配差异增大,其中苦竹林界面区各构件相对生物量和叶生物量分配比例提高,而混交林界面区各构件相对生物量和叶生物量分配比例降低; 2 a立竹生物量积累及分配比例的差异缩小,界面区两边2 a立竹各构件相对生物量和生物量分配比例均无明显差异。(2)界面区立竹秆形特征及1 a立竹各构件生物量异速生长关系均无明显变化,而苦竹林界面区2 a立竹秆的增长速率提高,枝、叶的增长速率降低。综上认为,苦竹通过权衡资源分配关系,明显改变界面区立竹秆形及生物量分配格局,以提高克隆分株对异质环境的适合度。

Adaptive strategies for culm form and aboveground biomass allocation of clonal ramets in interface area of mixed forest with Pleioblastus amarus-Cunninghamia lanceolata

Pleioblastus amarus, a bamboo species with wide distribution, can be utilized for its high quality shoot and timber. In order to explore the change characteristics of the culm form and the biomass distribution pattern of aboveground components in the interface area of P. amarus and to understand how the bamboo species adapt to heterogeneous habitats, pure stand of P. amarus, Cunninghamia lanceolata and mixed forest with P. amarus and C. lanceolata were selected to investigate culm form, culm, branch and leaf biomass of 1-2 year-old P. amarus in the central and boundary zone of the pure forest and mixed forests, and the differences culm shape and aboveground module biomass accumulation, allocation and allometric grouth relationship were analyzed. The results were as follows:(1)The differences of biomass accumulation and allocation of one-year old P. amarus in the interface area increased. Furthermore, the relative biomass of module and leaf biomass allocation under the interface area of P. amarus forest increased, while the relative biomass of module and leaf biomass allocation under the mixed forest interface decreased. However, the differences of biomass accumulation and allocation of two-year old bamboos decreased, and there was no significant difference on relative biomass of module and biomass allocation of two-year old bamboos on the two sides of the interface area.(2)Culm shape characteristics and the allometric growth relationship of module biomass of the one-year old bamboo changed slightly, while allometric growth rate of culm biomass of two-year old bamboo in the interface area of P. amarus stand increased, and those of the branches and leaves decreased. All the above results indicate that the culm shape and biomass allocation pattern of P. amarus obviously change under the interface area by balancing the relationship of resource allocation to enhance suitability and fitness to heterogeneous environment.