| 摘要: |
| 【目的】对寒温带兴安落叶松林生态系统生长季碳通量及其主要环境因子进行观测研究，探明兴安落叶松林生态系统生长季碳、水、热交换特征和变异规律及其相互作用关系，为兴安落叶松生态系统碳源/汇的评估提供基础数据。【方法】在内蒙古大兴安岭地区林龄为100～120年的兴安落叶松原始林内建立观测点，采用涡度相关通量观测技术，进行生长季兴安落叶松 大气之间的CO2通量、潜热通量和感热通量以及降雨量、土壤含水率、土壤温度、气温、光合有效辐射等主要环境因子的连续观测，并进行了兴安落叶松林CO2通量与光合有效辐射、土壤温度和土壤含水率的相关性分析。【结果】兴安落叶松林CO2通量有明显的日变化规律，从06:00开始为碳吸收，12:30-13:30达到峰值，随后逐渐下降；从约18:00开始，CO2通量值从负值转变为正值，开始进行碳释放，一直持续到次日凌晨06:00；在生长季白天表现为碳汇，夜间为CO2排放；6、7和8月份CO2通量平均日变化分别为－0.64，－0.88和－0.46 mg/(m2·s)，固碳、碳释放最大值均出现在7月份，分别为－1.09和0.19 mg/(m2·s)。兴安落叶松林潜热通量、感热通量日变化特征表现为昼夜主要吸收H2O和热，变化范围分别为－100～500 W/m2和－100～400W/m2。CO2通量与光合有效辐射呈指数相关 (6月R2=0.467，7月R2=0.759，8月R2=0.623)，光合有效辐射越强碳汇能力越大；与土壤温度呈指数相关 (6月Rv=0.381,7月R2=0.425，8月R2=0.442)，CO2通量随着土壤温度的升高而显著增加；与土壤含水率呈线性相关，在7月份相关性较高(R2=0.487)，但总体相关性相对较低。【结论】兴安落叶松林生态系统CO2通量、潜热通量和感热通量月均日变化具有明显的特征，不同月份间通量变化存在一定的差异，但变化趋势和规律基本一致。CO2通量主要受光合有效辐射及土壤温度和含水率的影响，光合有效辐射越强生态系统碳汇能力越大，土壤温度和含水率越高，CO2通量越大；且与光合有效副射和土壤温度的相关性较高。 |
| 关键词: 兴安落叶松林 CO2通量 环境因子 涡度相关技术 |
| DOI： |
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| 基金项目:林业公益性行业科研专项（201304308）；中国科学院战略性先导科技专项（XDA05050601-01）；内蒙古农业大学科技创新团队项目（ndpytd2013-4） |
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| Carbon flux and its impact factors of Larix gmelinii forest ecosystem during growing season |
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LI Xiao-mei,ZHANG Qiu-liang
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| Abstract: |
| 【Objective】This study investigated the carbon fluxes and main environmental factors for Larix gmelinii forest ecosystem in growing season at cold temperature zone.The exchange characteristics of carbon,water and heat and their variation regular and interactions were also analyzed to provide scientific data for carbon source/sink assessment.【Method】 The observation point was established in 100－120 years old Larix gmelinii virgin forest in Daxing’an Mountain,Inner Mongolia.Then an eddy covariance system was used to continuously observe latent heat flux,sensible heat flux,and CO2flux of between Larix gmelinii and atmosphere during growing season and main environmental factors including rainfall,soil water content,soil temperature,atmospheric temperature and photosynthetically active radiation.At last,the correlation between CO2 flux,photosynthetically active radiation,soil temperature,and soil water content was analyzed.【Result】CO2 flux in Larix gmelinii forest had obviously diurnal change.The forest began to absorb carbon from 06:00 am,reached the uptake peak during 12:30-13:30 pm,then gradually declined.From 18:00 pm,the flux values changed from negative to positive,indicating the start of carbon release till 06:00 am of next day.In growing season,carbon absorption occurred in day,while carbon release happened at night.The average diurnal variations of June,July,and August were －0.64,－0.88 and －0.46 mg/(m2·s),respectively.The maximum carbon sequestration and release values of －1.09 and 0.19 mg/(m2·s)appeared in July.The diurnal variation characteristics of latent heat flux and sensible heat flux were absorbing H2O and heat with ranges of －100-500 W/m2 and －100-400 W/m2,respectively.CO2 flux and photosynthetic active radiation had exponential correlation (June R2=0.467,July R2=0.759,and August R2=0.623),and it had exponential correlation with soil temperature (June R2=0.381,July R2=0.425,and August R2=0.442).CO2 flux also had linear correlation with soil water,with the highest coefficient in July (R2=0.487).【Conclusion】Monthly averaged diurnal variations of CO2 flux,latent heat flux and sensible heat flux were significant.The fluxes were different in different months,but the changing trends were consistent.CO2 flux was mainly influenced by photosynthetic active radiation,temperature and humidity.The carbon flux increased significantly as the increase of photosynthetic active radiation and soil temperature. |
| Key words: Larix gmelinii forest CO2 flux environmental factor eddy covariance |
