| 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. |
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