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Soil Respiration And Its Factors Under Different Managements Types Of Chinese Fir Plantation

Posted on:2008-04-23Degree:MasterType:Thesis
Country:ChinaCandidate:J F ZhangFull Text:PDF
GTID:2143330332981850Subject:Ecology
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The soil is the most important carbon pool except ocean. The carbon pool amount in the global land soil is about 1300~2000PgC,2~3 times of the global land vegetation carbon pool and more than 2 times of the atmospheric carbon pool. The carbon in the forest soil accounts for 73% of the global soil organic carbon, soil is the important sink of atmospheric CO2. Just because of the enormous capacity of reservoir of the soil carbon, its small range's change may influence the discharge from soil carbon pool to atmosphere. A large amount of researches indicate, the influences of the soil organic carbon release is as important as the influences that industry discharges CO2 to the atmosphere, influences the global climatic change with the greenhouse effects, influences the nutrient supply of the vegetation of land too, and then produces deep influences on the distribution, composition, structure and function of the ecosystem of land; meanwhile, the greenhouse effects will promote the losses of the soil organic carbon conversely.Chinese fir is a kind of choiceness, quick-growing, native-growing tree in subtropical in China, because of the demand of timber and the devote of man-plant, Chinese fir plantation area is growing. Statistics of forest resource indicates, Chinese fir plantation area is 1239.1×104hm2, cumulation quantity is 47357.33×104m3,26.55% and 46.89% in China respectively. Chinese fir plantation becomes the most important one of forest types, and meanwhile, play a key role of global C balance.The object of this research is foster96, foster88,fallow plantation and grassland on National Key Wild Scientific Ecology Experiment Station of Hunan Hui-tong, measured index of soil respiration, soil microorganism respiration, soil temperature, soil moisture content, soil organic content and soil pH value. to explore the rules of soil respiration. The main results of study are:From July to next March, mean soil respiration on foster(96), foster(88),fallow and grassland are 1.076μmol.m-2.s-1, 0.838μmol.m-2.s-1,1.327μmol.m-2.s-1,2.358μmol.m-2.s-1 respectively. Mean soil respiration on foster(96) is greater than foster(88), and is 1.284 times of it; mean soil respiration on fallow is greater than foster(96), and is 1.233 times of it; mean soil respiration on fallow is greater than foster(88), and is 1.584 times of it; mean soil respiration on grassland is greater than foster(96), and is 2.191 times of it; mean soil respiration on grassland is greater than foster(88), and is 2.814 times of it; mean soil respiration on grassland is greater than fallow, and is 1.777 times of it. In a word, mean soil respiration out of forest is greater than in forest; mean soil respiration on fallow is greater than foster; the younger plantation has the large mean soil respiration.The daily changing of soil respiration on different months have the same vary rules approximately, namely represents single apex curve. The range of soil respiration daily changing is great on summer but small on winter.Soil respiration has obvious seasonal dynamic. Soil respiration velocity is descending from July to next January and increasing from next July to next March by monthly. The max soil mean respiration velocity presents on July and the least presents on next January, the soil mean respiration velocity on July is 9.26, 8.04, 8.14 and 5.92 times of on next January under foster96, foster88,fallow plantation and grassland respectively.Soil microorganism respiration and soil layer depth have the negative correlation, namely soil microorganism respiration velocity decreases when soil layer depth increases. Soil microorganism respiration velocity under different soil layer depth are all less than 1μmol.m-2s-1. on foster96, foster88, fallow plantation and grassland. Soil microorganism respiration velocity on foster88 plantation is less than on foster96 plantation and fallow plantation under each soil layer depth. The ratios of soil microorganism respiration in soil total respiration is small,27.12%, 26.67%,18.70% and 8.81% respectively on foster96, foster88,fallow plantation and grassland.On the rules fact of soil temperature seasonal changing, foster96, foster88,fallow plantation and grassland present consistency, summer>spring>autumn>winter. The highest grassland soil temperature presents on July,34.48℃, and the slowest presents on January,10.51℃; The highest foster(96) soil temperature presents on July,25.57℃, and the slowest presents on January, 5.89℃; The highest foster(88) soil temperature presents on July, 25.68℃, and the slowest presents on January,5.67℃; The highest fallow soil temperature presents on July, 27.84℃, and the slowest presents on January,7.69℃.Grassland has the highest monthly mean soil temperature, fallow is the second, foster(96) and foster(88) have the similar monthly soil temperature, and the lowest,too.Soil temperature and soil respiration is in close relation, the vary rules of them are consistency and the correlation is obvious, The correlation coefficient of grassland, foster(96), foster(88), fallow plantation are 0.987(P=0.000), 0.911(P=0.001), 0.976 (P=0.000) and 0.960(P=0.000) respectively.Q10 present the sensitivity of soil respiration to soil temperature, Q10:fallow>foster(96)>foster(88)> grassland,2.88,2.87,2.43,1.57 respectively.Foster(96) and foster(88) have the greater soil water content, and the value are similar in every month, fallow is the second, grassland has the lowest.The experiment live in the subtropical moist climate district and the soil moisture content is relatively high, the soil moisture content does not become the main restrict factor of soil respiration. The single factor analyze of soil moisture content and soil respiration on foster(96), foster(88),fallow plantation and grassland show that there are no remarkable correlation between them.The soil organic matter on foster(96), foster(88),fallow plantation and grassland is 3.13%, 2.53%, 2.79%, 2.47% respectively, soil mean respiration and soil organic matter vary trends are differ and the relativity is not remarkable from July to next March(P> 0.05).The soil pH value of foster(96), foster(88),fallow plantation and grassland is 5.62, 5.01,5.87, 8.65 respectively, soil mean respiration and the relativity is remarkable from July to next March (r=0.976, P=0.024).It indicates, Chinese fir plantation foster and intensive management will help to reserve soil C, and is significant to decrease soil CO2 efflux.
Keywords/Search Tags:Soil respiration, Microorganism respiration, Soil temperature, Soil water content, Soil organic matter
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