【作者】 李忠和；

【导师】 汤洁；

【作者基本信息】 吉林大学 ， 环境科学， 2014， 博士

【摘要】 中国陆地生态系统的多样性，地形地貌的复杂性及地理区位的特殊性为研究陆地碳循环提供了得天独厚的天然实验室。从我国土壤背景、有机碳水平和碳库来看，我国农田有机碳水平显著低于欧美发达国家，说明我国仍是土壤有机碳（SOC）密度较低的国家，土壤有着巨大的固碳潜力。吉林西部位于全球变化研究中国东北样带内，为世界三大盐碱土区之一，气候变化、土地冻融交替显著，是土壤碳循环研究的典型地区。有关不同开发年限水稻土的固碳容量等碳变化主要是通过模型估算得到，那么，对全年不同开发年限典型时期水稻土壤各剖面的基本理化性质、土壤酶活性、土壤微生物菌群与土壤相关碳指标的响应变化关系研究，就显得尤为重要，这也是本文研究的主要内容。本研究以野外监测、实验室测试和数据分析为主要技术支持，以吉林西部典型盐碱稻田土壤（pH>8）为研究对象，对自然条件下全年四个时期（消融期、生长期、冻结前、冻结期)、不同开发年限、不同水稻土壤剖面的4种基本理化指标、土壤微生物菌群数量、4种碳指标、4种酶活性等大量实验数据指标进行机理趋势性分析的基础上，采用SPSS法和SIMCA-P软件进行重点指标间相关性分析，得到以下几方面结论。一、在四个时期中，未开发盐碱土壤的容重、碱化度、电导率均最高；生长期土壤容重、碱化度是4个时期中最小的，电导率在消融期最大，容重、碱化度、电导率在土壤剖面变化中，大多耕层较大，基本趋势是随剖面加深先升高再降低，即犁底层>耕层>淋溶层>母质层。实验数据分析说明有机碳含量较低的未开发年限其容重、电导率、碱化度等均较高。二、对于4种土壤碳指标含量，在不同开发年限4个时期中基本呈现出随土壤纵向剖面的加深而降低，个别出现先升高再降低的趋势。不同开发年限总碳（TC）含量大小变化为：25年>35年>8年>55年>15年>未开发；四个时期TC含量大小变化为：冻结前期>生长期>消融期>生长期。对有机碳（SOC）含量大小变化，不同开发年限：35年>8年>25年>55年>15年>未开发；四个时期SOC总量大小变化为：生长期>冻结期>冻结前>期>消融期。不同开发年限DOC含量大小变化：8年>55年>15年>35年>25年>未开发，四个时期DOC总量大小变化：冻结期>消融期>生长期>冻结前期。不同开发年限SMBC含量大小变化：8年>15年>35年>55年>25>年未开发，四个时期SMBC总量大小变化为：冻结前期>消融期>生长期>冻结期。总碳（TC）与可溶性有机碳（DOC）相关性不显著。三、不同开发年限土壤纤维素酶活性主要呈现出以下顺序：35年>25年>55.年>15年>8年>未开发，消融期和生长期酶活性变化大，四个时期纤维素酶活性：消融期>冻结前期>生长期>冻结期；纤维素酶活性与可溶性有机碳（DOC）均保持较高水平的正相关性（0.01水平显著）。不同开发年限土壤淀粉酶活性：35年>8年>55年>25年>15年>未开发；四个时期土壤淀粉酶活性表现为：冻结期>消融期>生长期>冻结前期，在消融期和生长期，淀粉酶与可溶性有机碳（DOC）呈现正相关性（0.01水平显著），在消融期，与有机碳（SOC）呈现负相关性（0.01水平显著），在冻结期和生长期，与有机碳（SOC）呈现正相关性（0.01水平显著）。不同开发年限土壤蔗糖酶活性：15年>35年>55年>25年>8年>未开发，从四个时期看：冻结期>消融期>生长期>冻结前期；蔗糖酶与土壤总碳（TC）呈现正相关性（0.01水平显著），与土壤可溶性有机碳（DOC）在消融期呈现负相关性（0.01水平显著），在其它时期呈现正相关性（0.01水平显著），在4种土壤酶中蔗糖酶活性最大，正相关显著水平最好，可以选作特征酶。不同开发年限土壤纤二糖酶活性：未开发>15年>35年>8年>25年>55年。从四个时期看：冻结前期>消融期>生长期>冻结期，4个时期中未开发盐碱地纤二糖酶活性均是最高的；纤二糖酶与总碳（TC）在冻结期呈现负相关性（0.01水平显著），在其它时期相关性不显著；与有机碳（SOC）在冻结前期呈现正相关性（0.01水平显著），在其它时期相关性不显著；与可溶性有机碳（DOC）在冻结前期呈现正相关性（0.01水平显著），在冻结期和消融期呈现负相关性（0.01水平显著），在生长期相关性不显著；与微生物量碳（SMBC）呈现正相关性（0.01水平显著）。土壤4种酶活性在趋势上呈现纵向剖面逐渐升高和逐渐降低及先升高后降低三种趋势。四、在培养土壤微生物菌群数量上：细菌>放线菌>真菌，在纵向土壤剖面上土壤三种菌呈现逐渐递减趋势。4个时期中微生物菌数：消融期>生长期>冻结前期>冻结期。4个时期中：总碳（TC）与微生物菌数无明显相关性，有机碳（SOC）与微生物菌数基本呈现正相关性（0.05水平显著），可溶性有机碳（DOC）与微生物菌数基本呈现负相关性（0.01水平显著），微生物量碳（SMBC）与土壤微生物菌数呈现正相关性（0.01水平显著）。4个时期土壤4种碳指标对土壤微生物菌群的相关性为：SMBC>DOC>SOC>TC。该研究成果在理论上为科学认识与评价我国北方典型盐碱稻田区自然条件下土壤碳变化提供技术参数，在实践上为实现土壤碳变化管理措施提供数据支持。更多还原

【Abstract】 China is in the special geographic location with various terrestrial ecosystem andcomplex topography, which provides a natural laboratory for the study of terrestrialcarbon cycle. In terms of national backgrounds of soil organic carbon level andcarbon pool, soil organic carbon level in China is significantly lower than that of thedeveloped countries in Europe and America. It explains that soil organiccarbon density in China is still low, and the soil has a great potential for carbonsequestration. Due to the significance of climate change and land alternate freezingand thawing, western Jilin as one of the three saline soil areas of the world is a typicalarea for soil carbon cycle research, which is located in Northeast China Transect inthe global change research. Carbon sequestration capacity of paddy soil with differentreclamation years is mainly obtained by model estimation. It is particularly importantto make a deep analysis of influencing factors on carbon sequestration of paddy soilby exploring the response relationship between the related soil carbon fractions andthe factors like the basic physicochemical properties of Paddy soil, soil enzymeactivity and soil microbes in different soil profiles with different reclamation years ina whole year. Base on field monitoring, laboratory tests and data analysis, this paperselects typical saline paddy soil(pH>8) in western Jilin Province as the researchobjects, and make the correlation analysis of the different experimental indexesincluding four kinds of basic physicochemical index, soil microflora, four kinds ofcarbon index and four kinds of enzyme activity from different reclamation years indifferent soil profiles during four periods in a whole year(that is Ex-freezing period,Freezing period, Ablation period, Growth period).The con clusions of this study are asfollows:1. In every period, the bulk density, alkalinity and conductivity ofSaline soaked soil with0reclamation years are the highest; Soil bulk density andalkalinity in Growth period is the smallest of the four periods; Ablation period has themaximum conductivity; Bulk density, alkalinity and conductivity change in the soil profile, and the basic trend is first increased and then decreased with the increasingdepth, Plough layer> Topsoil> Leaching layer>parent material.2. The four kinds of soil carbon content with different reclamation years in fourperiods have a decreasing trend with the increasing depth in general, but theindividuals first increase and then decrease. Soil total carbon content in differentreclamation years:25years>35years>8years>55years>15years>0year. Soil totalcarbon content in the four periods: ablation period>growth period> meltperiod> freezing period. Soil organic carbon content in different reclamation years:35years>8years>25years>55years>15years>0year. DOC content in differentreclamation years:8years>55years>15years>35years>25years>0year.DOC content in the four periods: freezing period> melt period> growthperiod>.ablation period. SMBC content in different reclamation years:8years>15years>35years>55years>25years>0year. SMBC content in thefour periods:.ablation period> melt period> growth period> freezing period.3. The cellulose activity in different development period main show up that35years>25years>55years>15years>8years>0year. Enzyme activities of ablationand growth period have great variation. Soil cellulose and soluble organic carbonwas maintained in high level positive correlation (significant level of0.01), nosignificant correlation with soil organic carbon. The cellulose activity in thefour periods: melt period>ablation period>growth period>freezing period. Theamylase activity in different development period show up that35years>8years>55years>25years>15years>0year. Soil amylase activity show up that freezingperiod>ablation period>growth period>ablation period. Soil enzyme and soildissolved organic carbon, organic carbon showed a significant level of0.01positiveand negative correlation. The inverters activity in soil:15years>35years>55years>25years>8years>0year. The inverters activity in the four periods: freezingperiod>melt period> growth period>.ablation period. Soil inverters and soil totalcarbon, dissolved organic carbon, inorganic carbon has positive and negativecorrelation (significant level of0.01); in the4largest enzyme activity of soil enzymein significant positive correlation, the best level, can be selected as characteristic enzyme. In different development periods, fiber disaccharidase activity:0year>15years>35years>8years>25years>55years. The fiber disaccharidase activity in thefour periods: ablation period>melt period> growth period>freezing period. soilenzyme and fiber two of total carbon, organic carbon, dissolved organic carbonpresent, microbial biomass carbon (a significant level of0.01) of positive andnegative correlation; no significant correlation with soil inorganic carbon. Theactivities of four enzymes showed increasing and decreasing soil longitudinal sectionand increase firstly and then decrease two trends in the trend.4. In the aspect of the bacteria cultivation: bacteria> actinomycetes>fungi; Soilbacteria had a decreasing trend in the vertical soil profile. The amount of themicroflora of the4periods: the melting period> the growth period> the early stage offreezing period> the freezing period. Different periods: There was no significantcorrelation between total soil carbon and soil bacteria quantity, soil organic carbonand soil bacteria showed significantly positive correlation of0.05, soil dissolvedorganic carbon and bacterial number showed significantly negative correlation of0.01,soil microbial biomass carbon and soil microflora showed significantly positivecorrelation of0.01.The four soil carbon indicators and soil microflora in the differentperiods has the relation of: SMBC> DOC> SOC> TC。In theory, the results of research provide technical parameters and typicalexamples for us to correctly realize and assess the soil carbon cycle under naturalconditions in northern China.更多还原