【作者】 张中杰；

【导师】 杨学春； 朱波；

【作者基本信息】 西南农业大学 ， 环境工程， 2004， 硕士

【摘要】 试验设置在川中丘陵区紫色土农业生态站，土壤为钙质紫色土，紫色土旱地生态系统温室气体通量排放的研究对整个陆地生态系统的碳循环研究提供理论依据。农田生态系统是人类活动最活跃的部分，农田生态系统碳通量研究对全球碳循环研究有重要意义。 利用静态箱/气相色谱法定点、监测川中丘陵区旱地生态系统温室气体排放的季节变化与日变化规律，研究不同气候环境条件下川中丘陵区旱地生态系统的温室气体变化规律，揭示影响川中丘陵区早地生态系统温室气体通量排放的主要环境因子。 通过野外观测与采样分析，查明川中丘陵区旱地生态系统温室气体的日变化与季节变化特征，明确环境因子对各温室气体的影响作用。研究了川中丘陵区早地生态系统温室气体的通量排放及相关过程。试验分为四个处理：按常规施肥，种作物的常规处理，主要测定植株、根系和土壤呼吸作用；箱内无作物空白处理，主要测定作物根系和土壤呼吸作用；裸地，主要测定在没有作物时土壤的呼吸作用；箱内有作物的无氮处理，主要测定作物在不施氮肥的状况下作物对温室气体排放的影响。结果表明，川中丘陵区早地生态系统的CH₄、CO₂和N₂O的通量排放呈现出不同的季节变化与日变化进程，CH₄的季节通量以吸收为主，总体上表现为汇的功能；CO₂和N₂O的季节通量过程以排放为主，表现为源的功能。在不同的作物生长季节，温室气体的季节排放规律出现不同的变化趋势，在小麦的生长季节中，温室气体的季节排放规律与小麦植株的生长呈现明显的相关性；在玉米的生长季节，其季节排放规律和作物的生长性无必然联系。日变化趋势大致相同。通过同种作物的不同试验处理，温室气体的通量排放差异性显著，总体上通量排放表现为，常规处理＞空白处理＞裸地处理。 在小麦的整个生长季中，常规、无氮、空白、裸地等实验处理的CO₂、N₂O和CH₄的通量排放具有显著差异。CO₂通量排放表现为常规＞空白＞裸地，且作物的不同生长季CO₂通量排放具有一定的差异。其中常规处理季节平均通量排放为329.67 mg·m^-2·h^-1，空白处理季节平均通量排放为175.65 mg·m^-2·h^-1，裸地处理季节平均通量排放为89.25mg·m^-2·h^-1，无氮处理季节平均通量排放为359.32mg·m^-2·h^-1。在小麦生长季中，N₂O通量排放呈递增趋势，N₂O通量排放表现为常规＞空白＞裸地，常规处理季节平均通量排放为0.02751mg·m^-2·h^-1，空白处理季节平均通量排放为0.0036 mg·m^-2·h^-1，裸地处理季节平均通量排放为-0.015mg·m^-2·h^-1。CH₄通量排放在旱地小麦生态系统中缺乏CH₄产生的厌氧环境，排放无规律。 川中丘陵区早地玉米CO₂通量排放表现为排放，但是季节变化规律不明显，总体上排放差异性不大，没有形成排放峰值与谷值。在整个季节变化中，常规试验处理的平均通量排放为313.32 mg·m^-2·h^-1，裸地处理的平均通量排放为344.90 mg·m^-2·h^-1，无氮处理的平均通量排放为408.15 mg·m^-2·h^-1。同样出现了无氮处理通量排放的异常现象。川中丘陵区旱地玉米N₂O通量排放表现为排放，季节变化规律明显。由于试验处理差异，整个玉米生长季所获得的温室气体排放无植株呼吸的贡献。旱地玉米CH₄通量排放的季节变化波动大，无明显规律，西南农业大学硕士学位论文摘要但通量排放特点表现为吸收。 早地小麦在不同生长季日变化CO:排放通量具有一定的差异。日最高排放值在每日一3:00一5:00时出现，通量排放为拔节期242.76 mg·m，·h一’;扬花期70一25 mg·m一，·h一’。最低出现在凌晨3:00一6:00，排放通量为拔节期l一2.74 mg·m一，·h一’;扬花期379.73 mg·m一，·h一’。 观测期间，对影响川中丘陵区旱地生态系统温室气体通量排放的相关因子进行分析中发现，温度和植株生长状况与co:通量排放呈显著性相关（r，>0 .80），可以确定影响coZ通量排放的主导因子是温度和植株生长状况。N20的通量排放和温度、湿度及植株生长状况的相关不显著〔产<0 .1)，表明影响N20通量排放的因素较复杂，要确定其主导影响因子在川中丘陵区早地生态系统中还需继续观测研究。 在不同的试验设计中，研究表明，常规处理的co:排放通量主要受土壤微生物对有机质的分解（即抑氧呼吸，RH），植物根系呼吸（自氧呼吸，RAR）和地上植物部分的呼吸作用（RAs）三者的共同作用。与空白处理及裸地处理对比发现，植株呼吸作用是川中丘陵区早地生态系统CO:排放的主要贡献者，占整个排放的46.7%。 在对早地NZO排放通量的分析中发现，表明NZo通量排放和植株、根系及土壤生物有着一定的联系。但是由于其排放通量都比较低，很难定性它们之间的排放机制。有待进一步深入研究植物排放及传输机理后才能彻底解决这一问题。更多还原

【Abstract】 Purple soil agro-ecosystem research center (Chinese Academy of Sciences) is situated in upriver Yangtze and southwest SiChuan hilly region. Calcium purple soil is the main soil type of that region. Research on greenhouse gas emission of dry land purple soil ecosystem has significant meaning to carbon fluxes of land ecosystem. Agro-ecosystem is the most active part of human activities, therefore, research on carbon fluxes of agro-ecosystem is essential to the study of global carbon fluxes.Using static chamber and gas chromatographic techniques, both seasonal and daily change rules of greenhouse gas emission from dry land ecosystem of mid-SiChuan hilly area were carefully monitored. Furthermore, variation characteristics of greenhouse gas emission under different climate condition were studied. Environmental factors which are responsible for greenhouse gas emission were also proposed.By means of field investigation and sample analysis, both daily and seasonal variation characteristics of greenhouse gas emission from dry land ecosystem were inquired, and environmental factors’ influence on various greenhouse gases was clarified. In this study, we concerned on emission fluxes and related process of greenhouse gas in dry land ecosystem of mid-SiChuan hilly area. There were four treatment schemes involved in this experiment. Scheme one, crops were fertilized and treated as conventional, respiration effects of plant, root system and soil were determined respectively. Scheme two, the control (without plant in the static chamber), respiration effects of root system and soil were determined. The third scheme was plain field, and respiration effects of soil without plant were investigated. The fourth scheme involved plants in the chamber, but without nitrogen input, by which crops’ influences on greenhouse gas emission were achieved. Results showed that emission fluxes of methane, carbon dioxide, and N2O in these area presented different seasonal change and daily change. The seasonal fluxes of methane was proved to be mainly absorbing, which could be regarded as a sink on the whole. While the seasonal fluxes of CO2 and N2O were mainly emission, which could be viewed as a source. Seasonal emission rules of greenhouse gas also showed different change trend at different season of plant growth. During the growth period of wheat, seasonal emission character of greenhouse gas showed evident correlation with the growth of wheat. Whereas during the growth season of corn, its seasonal emission character of greenhouse gas had no evident relationship with the growth of corn. However, daily variation trends were basically the same. Result indicated that emission fluxes of greenhouse gas significantly varied from each other. Generally, the emission fluxes followed the order of conventional treatment>the control>plain field treatment.Through the whole growth period of wheat, emission fluxes of CO2, N2O, and CH4 varied significantly from treatment to treatment. Emission fluxes of CO2 followed the sequence of conventional treatment>the control>plain field treatment, and different growth period could also influence the emission fluxes. The average seasonal emission fluxes of conventional treatment was 329.67 mg m-2h-1, and the average seasonal emission fluxes of the control was 175.65 mg m-2h-1 while the average seasonal emission fluxes of plain field was 89.25mg m-2 h-1, and that of non-nitrogen treatment was 359.32mg m-2 h-1 During the growth period of wheat, emission fluxes of N2O fit the trend of increase by degrees, and followed the order of conventional treatment>the control>plain field treatment. The average seasonal emission fluxes of conventional treatment was 0.0275lmg m-2 h-1, and that of the control and plain field were 0.0036 mg m-2 h-1 -0.015mg m-2h-1 respectively. As for emission fluxes of CH4 its character was irregular because dry land ecosystem lack anaerobic environment, which was essential for the forming of CH4.Carbon dioxide emission fluxes of corn in mid-SiChuan hilly area was proved to be emissi更多还原