| Global climate change has become a major issue with common concern of multi-disciplinary from all around of the world. As the huge carbon storage of the soil carbon pool, it has great significance for the global carbon cycle.v Soil respiration, which represents the huge CO2efflux from the soil surface, has a significant influence to the change of the CO2concentration. A large number of studies, which mostly concentrated to the strenth, the temporal dynamics, and the impact factors, has been carried out in the world. But few studies have been reported about the spatial variability of the soil respiration, especially at small scales. Bus this is very important for the accurate estimate of the global carbon cycle.A masson pine sample has been established in the Three Gorges Reservoir Area where has a highly sensitive to the ecological environment. The autotrophic respiration and heterotrophic respiration are seperated with a root-excised method. For a deep understanding of the spatial characteristics of soil respiration at a small scale within the study area, both traditional statistics and geostatistics are used. The main results were as follows:(1) Soil respiration showed significant seasonal dynamics, and the temporal coeffeicient of variation(CV) was41%. The controlling factor of soil respiration was soil temperature, but not soil moisture. The heterotrophic respiration has a similar temporal dynamics of soil temperature, and has a certain correlation with soil moisture. But there is no significant correlation between autotrophic respiration with neither soil temperature nor soil moisture.(2) Soil respiration in the study area has a moderate variation with a coefficient of variation between32.6%and46.3%. Microorganism respiration has the biggest CV, root respiration has the smallest one, and the litter respiration has a intermediate CV. Enviroment factors have diffirent CVs respectivily.(3) The semivariograms of soil respiration rate could well be descrybed by spherical model(springand summer) or exponential model(autumnand winter). The R2values are high, and the (Co/(Co+C)) values are low, except in spring.(4) The autocorrelation range of soil respiration stabled at about100m. The values of Moran’s1reduced with the increase of the lag diatance with fluctuations. (5) The ratio of anisotropic showed a typically seasonal dynamic. Variations in the direction of45°are higher than that in the direction of135°in spring and summer, but the result is opposite in autumn and winter. From spring to winter, the variations in the direction of45°get lower and lower, but that in the direction of135°get higher and higher.(6) Fractal dimensions in the isotropic in four seasons are close. In anisotropic, the fractal dimension in the direction of135°is higher than the ones in other directions in four seasons.(7) The isoline map of soil respiration rates produced with the Kriging interpolation method showed a spatial pattern of plaque or wtrip with significant local differences. The spatial patterns of SOM, available N and fine root biomass are similar to the ones of soil respiration.(8) The correlation analysis showed significant correlations between soil respiration and fine root biomass, total porosity of the surface soil, and a highly significant correlation between soil respiration and soil available N content. Geostatistical analysis revealed more correlations between soil respiration and the environmental factors, such as SOM, soil available P content, and so on.(9) The CVs are used to estimate the reasonable sampling points. The results showed that the sampling points in this study are inadequate within10%error, but are enough within20%error. |
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