小麦水热、CO_2通量特征和能量平衡分析

目的]对河北栾城小麦水热、CO2通量特征和能量平衡进行分析。方法]基于栾城站利用涡度相关技术观测的2008年小麦水热、CO2通量数据及常规气象、生物量等数据,分析小麦水热、CO2通量特征和能量平衡闭合状况。结果]①潜热、感热、CO2通量表现出明显的日、季变化特征,潜热、感热通量日变化呈倒"U"型,CO2通量"U"型,且通量日峰值存在较大差异;②潜热、感热、CO2通量的强度变化与环境因子有较大关系:三者对光强、净辐射的反应较为敏感,相关系数分别达0.92、0.66、0.65及0.90、0.69、0.74,且晴天更好,对气温也较为敏感,潜热通量,特别是在降水后对土壤含水量反应较敏感;③小麦农田能量平衡闭合度为0.91,存在明显的不闭合现象,而且在不同月份、一天不同时段,闭合程度也不同,能量平衡不闭合的主要原因是测量误差和忽略热储量等。结论]该研究得到了小麦农田生态系统水热通量及CO2通量特征、传输机制及其影响因子,可为揭示作物冠层蒸散、光合与水分利用效率关系、能量分配等的机制提供科学依据。

Water,CO2 and Energy Exchange at Vegetation-air Interface

Objective] The aim was to analyze sensible and latent heat fluxes,CO2 fluxes and energy balance in wheat ecosystem in Luancheng in Hebei Province.Method] Based on data of latent heat,sensible heat,CO2 fluxes,routine meteorological and biomass in Luancheng in 2008,sensible and latent heat fluxes,CO2 fluxes and energy balance were explored.Result] The results showed that latent and sensible heat and CO2 fluxes were of obvious daily and seasonal changes;latent and sensible heat shaped an inverted U in daily change,and CO2 fluxes were of a U-shape;daily flux peak differed significantly.Furthermore,the change of latent heat,sensible heat and CO2 fluxes were closely related to environmental factors.Detailedly,the three were sensitive to light intensity and net radiation,and correlation coefficients were 0.92,0.66,0.65 and 0.90,0.69,0.74,respectively.Besides,the fluxes,sensitive to temperature,proved better in sunny day,especially for latent flux which is more sensitive to water in soils after precipitation.In addition,closure degree of energy balance in wheat fields was 0.91 and nonclosure,caused by measurement error and neglection of heat storage,was observed,too.Closure degree differed in months and time periods within a day.Conclusion] The research concluded water and heat fluxes,CO2 fluxes,transport mechanisms and concerning factors,providing scientific references for revealing mechanism of evaporation and dissipation of canopy,relationship between photosynthesis and use efficiency of water and energy distribution mechanism.