黄土高原苜蓿碳储量年际变化及固碳机制的研究

This project researched on inter-annual dynamic variations of carbon storage and sequestration mechanism of alfalfa has important significance to carbon budget, carbon management decision and evaluation of alfalfa grassland carbon sink enhancement measures. Heterogeneity of environment in the Loess Plateau and inter-annual dynamic variations results in differences in alfalfa carbon accumulation and carbon sequestration mechanism. The specific environment effects in the Loess Plateau on the key driving factors of alfalfa carbon storage and the corresponding contribution remain still remain to be studied. This project will take alfalfa growing 1 to 15 years as the research object. Based on the instruments of ACE soil carbon flux monitoring system, the Eco-Watch ecological network monitoring system, CL-340 photosynthesis system, MINI-PAM photosynthesis yield analyzer and other apparatus, combined with long-term continuous test data and laboratory analysis, the aboveground and underground biomass carbon storage, litter storage, soil carbon storage (including soil microbial biomass), soil respiration, photosynthesis and relevant influence environment factors of carbon storage of alfalfa from 1 to 15 years will be studied in the lanzhou Scientific Observation and Experiment Field Station of Ministry of Agriculture for Ecological System in Loess Plateau Areas (Gansu Lanzhou). The more tests will be completed in order to know inter-annual dynamic variations of carbon storage and sequestration mechanism of alfalfa. The relevance between different growing year alfalfa carbon sequestration and biological characteristics and environmental factors will to be evaluated. The results will provide more support for the accurate assessment of alfalfa grassland carbon source/sink and carbon sequestration potentials.

苜蓿草地碳储量及固碳机制的研究对苜蓿碳收支评估、碳管理决策以及苜蓿草地碳减排增汇措施的实施具有重要意义。黄土高原环境和苜蓿生长年际变化的异质性，导致苜蓿草地碳积累过程及固碳机制的差异，黄土高原特定环境对影响苜蓿碳储量的关键驱动因子和相应贡献有待科学上给予阐明。该项目以生长1年至15年的苜蓿为研究对象，采用ACE 土壤碳通量监测系统、Eco-Watch 生态网络监测系统、CL-340光合测定仪和超便携式调制叶绿素荧光仪MINI-PAM等仪器，结合长期连续的试验数据与实验室分析，研究苜蓿生物量碳储量、土壤碳储量（包括土壤微生物量）、土壤呼吸、光合作用及其与环境因子之间的联动过程。以期阐明苜蓿碳储量的年际变化规律和固碳效应，揭示不同生长年限苜蓿的固碳机制，评价不同生长年限苜蓿固碳与环境因子之间的联动关系。研究结果为准确地评估苜蓿草地的碳源/汇及其固碳潜力提供科学依据。

草地碳储量及碳增汇的研究是近年来研究的热点。该项目依据研究内容和研究目标，结合长期连续的试验数据与实验室分析，对黄土高原不同生长年限的苜蓿地上生物量碳储量、地下生物量碳储量、土壤碳储量（包括土壤微生物量及土壤有机碳及其组分变化特征）、土壤呼吸、苜蓿光合作用及其与环境因子之间的联动过程进行了一系列的分析研究。研究确定了苜蓿生物量碳含量系数为0.30，分析了1年龄至17年龄不同生长年限苜蓿地上生物量碳储量、地下生物量碳储量（1.5m）变化趋势及差异显著性（p<0.05）。测定了不同种植年限的苜蓿在1m土层的微生物量碳含量、不同生长年限不同生育期苜蓿土壤有机碳和其组分变化特征、土壤呼吸速率日变化、月变化和年变化的规律及不同生长年限苜蓿的植物学特性等。研究结果对揭示不同生长年限苜蓿的固碳机制和准确地评估苜蓿草地的碳源/汇及其固碳潜力提供了科学依据。