竹阔界面土壤养分异质性对毛竹扩张的驱动机制

Phyllostachys edulis is a evergreen tree-like bamboo plant with strong guerrilla expansion ability. The expansion of Ph. edulis into its neighboring broad-leaved forests has exerted significant influence on the ecological values and biodiversity in nature reserves of subtropical China. Previous studies found a soil nutrient heterogeneity across bamboo-woodland interface where Ph. edulis encroaching broad-leaved forests, which suggests that soil nutrient heterogeneity could be a driving force for the expansion of Ph. edulis.. .To fully understand the mechanism of Ph. edulis expansion at the bamboo-woodland interface, a random block design experiment with nutrient addition of Nitrogen (N) and Phorsphorus (P) to creating homogeneity and heterogeneity habitats would be conducted in Jingganshan National Nature Reserve, on the basis of previous investigation on soil nutrients.. .Under such conditions, the expansion behaviors in Ph. edulis (including aboveground shoots and belowground rhizomes) will be recorded and the concentration of multiple nutrient components, such as C, N and P in the soils, microbes (in rhizospere and non-rizhospere) and different plant organs will be determined. The impacts of soil nutrients on the expansion behaviors and on the C:N:P stoichiometry (homeostasis) in Ph. edulis would be analysed, and the ecological linkages between the nutrient homeostasis in Ph. edulis and its expansion would be studied in detail...Our study could shed light on the intrinsic mechanism of Ph. edulis expansion under gradient nutrient environment, consequently, providing a theoretical reference for ecosystem management in distinctive and precious broad-leaved forests. The results of this study would contribute new knowledge to the ecological stoichiometry and interface ecology. These knowledge will be beneficial to bamboo management as well.

毛竹（Phyllostachys edulis）向邻近森林扩张，已影响到我国南方自然保护区常绿阔叶林的保护。前期研究发现在竹阔界面（竹林与阔叶林的接触面）两侧存在明显的土壤养分异质梯度,且很有可能就是毛竹扩张的一个重要驱动因子。针对土壤养分异质性对毛竹扩张的影响及其内在养分驱动机制，本项目以井冈山自然保护区典型竹阔界面为对象，采用均质与异质养分添加随机区组试验，开展对毛竹扩张行为（包括地上枝秆和地下鞭根）的监测和土壤（根际和非根际）养分计量的分析，研究土壤养分供应对毛竹扩张行为和毛竹体内化学计量比的影响规律，探讨毛竹扩张行为与体内化学计量平衡的内在关联性，揭示土壤养分异质性对毛竹扩张影响的潜在机制。研究成果不仅可为我国南方自然保护区生态系统管理提供科学依据，还可丰富生态化学计量学的内平衡理论和生长速率理论，为森林景观界面研究提供新的思路。此外，对毛竹林经营也有一定的启示作用。

竹子扩张（Bamboo expansion）严重影响了我国南方自然保护区常绿阔叶林，降低木森林生物多样性、改变土壤养分转化过程及有效性，在竹阔界面(竹林与阔叶林间的过度区)两侧呈现明显的土壤养分梯度。为了验证竹阔界面土壤养分异质性对毛竹扩张的驱动作用，本项目在江西井冈山、大岗山森林生态站开展竹阔界面样地调查、随机化区组施肥试验、养分生理整合分析，重点阐明了毛竹扩张过程、生态效应、土壤养分供应对毛竹扩张行为与体内化学计量的效应，揭示毛竹扩张的化学计量学机制。研究结果认为，毛竹是一种喜肥植物，克隆扩张是其种群扩增的一种生物学属性，不论周边土壤养分状况如何，它都会向外空间扩张，但土壤条件越好，种群扩张能力越强。在自然情况下，毛竹向“富养”阔叶林扩张时，通过克隆生理整合保证新竹养分化学计量平衡，有利于增加种群数量和空间拓展。可见竹阔界面养分导质性是毛竹种群水平空间拓展的驱动力之一。