毛竹林地下碳分配对氮磷添加响应机制研究

氮磷是限制毛竹林生长的关键元素，但氮磷如何调控毛竹林地下碳分配（陆地生态系统最重要且了解最少的碳通量之一）还缺乏相应关注。基于“氮磷添加改变根系生长环境和根特性，改变土壤自养呼吸和异养呼吸，进而驱动地下碳分配过程变化”的科学假设，本项目以四川长宁竹林生态系统国家定位观测研究站为依托，研究毛竹林地下碳分配对氮磷添加的响应。通过氮磷添加试验，研究毛竹林地下生产力（细根，粗根和竹鞭）、凋落物归还量、自养呼吸、异养呼吸及其相关的土壤温度、湿度、土壤有机碳含量等，旨在：（1）阐明毛竹林地下生产力对氮磷添加的响应；（2）阐明毛竹林自养呼吸和异养呼吸对氮磷添加的响应；（3）通过对比直接测量法和碳平衡法估算地下碳分配，揭示氮磷添加对毛竹林地下碳分配的影响机理。本项目的实施对深入理解毛竹林地下碳分配调控机理，对阐明毛竹林地下碳分配在全球碳循环的作用具有重要意义，也为毛竹林的经营管理提供理论依据。

Nitrogen (N) and phosphorus (P) are key elements for constraining the growth of Moso bamboo forests (Phyllostachys heterocycla (Carr.) Mitford cv. Pubescens). However, there is little concern about how N and P affecting total belowground carbon allocation (TBCA, one of the most important but least understood carbon fluxes in terrestrial ecosystems). Based on the scientific assumption that ‘N and P addition change root growth environment and root characteristics, and alter soil autotrophic and heterotrophic respiration, further drive the change of TBCA processes’, relying on National Observation and Research Station of Bamboo Ecosystem in Changning, Sichuan Province, this project will study the effects of N and P addition on TBCA in Moso bamboo forests. Through N and P addition experiment, this project will analyze the belowground production (including fine and coarse root, bamboo rhizome), litterfall return amount, autotrophic respiration, heterotrophic respiration and related soil temperature and moisture, soil organic carbon content, etc. in moso bamboo forests. This project aims to (1) illustrate the response characteristics of belowground production to N and P addition; (2) clarify the response characteristics of autotrophic and heterotrophic respiration to N and P addition; (3) reveal the response mechanism of TBCA to N and P addition through comparing the direct measurement of TBCA and mass balance based TBCA in Moso bamboo forests. Implementing this project will help to further understand the driving mechanism of TBCA in Moso bamboo forests, and illustrate its significance in global carbon cycling, and provide theoretic evidence of the management of Moso bamboo forests.