| Black carbon is a special product, which is formed after biomass or fossil fuels burn imperfectly. Because of the highly aromatic structure, the black carbon has high thermal stability,biological and chemical inertness, Black carbon still exists in sediments after a long slow circulation of soil organic carbon library, In order to understand the distribution of black carbon in forest after burned, experiments which based on different fire time, different fire frequency and different fire intensity are processed in 8 villages 3 towns Jianyang Fujian Province. And we took three samples ( top, half and foot) in each region and recorded the stand growth and environmental factors such as elevation , aspect in each region. We consulted the basic situation before burning of each region, after admeasuring ang analysising, reached the result as follows:1. Effect of burning to the distribution of black carbon in soilIn the acquisition of forest soils, We diacovered that in 0 10 cm layer below surface, the mass fraction of organic carbon and black carbon reached more than 40%, in 10 20 cm layer ,this is 30%. Finally we concluded that soil organic carbon and black carbon are mainly concentrated in the topsoil and the sub-topsoil.2. Effect of different fire time to the distribution of black carbon in soilIn the acquisition of forest soils, the mass fraction of black carbon in the sample are 9.00 g·kg-1, 7.76 g·kg-1and 7.76 g·kg-1 when the fire time are 1990,1995 and 2000. In 2004, this is 5.27 g·kg-1, and 2008, this is 9.43 g·kg-1. So we can conclude that the mass fraction of black carbon in the sample was decreasing from 1990 to 2000, and increasing from 2000 to 2008 after the forest was burned3. Effect of different fire intensity to the distribution of black carbon in soilIn the acquisition of forest soils, when fire time is 1995, the mass fraction of black carbon is bigger when fire area is smaller, but when fire time is 2000, 2004 and 2008, the mass fraction of black carbon is bigger when fire area is bigger. 4. Effect of different fire frequency to the distribution of black carbon in soilThe black carbon mass fraction is 9.82 g·kg-1 when the fire was repeated. This is 5.85 g·kg-1 when the fire was once. This demonstrated that the mass fraction of black carbon increased after repeated burning.5. Effect of environmental factors to the distribution of black carbon in soilThe average mass fraction of black carbon in 150-200m, 200-250m, 250-300m and 300-350m are 5.24 g·kg-1, 6.80 g·kg-1, 7.98 g·kg-1 and 4.34 g·kg-1. When the samples slope is 40-50°, the mass fraction of black carbon is twice to three times of when samples slope is 10-40°. After burning, the mass fraction of black carbon is 7.51 g·kg-1, 5.55 g·kg-1, 6.67 g·kg-1and 6.77 g·kg-1 in east, south, west and north position. The mass fraction of black carbon are 5.84 g·kg-1, 6.46 g·kg-1 and 7.51 g·kg-1 in top, half and foot of the mountain.6. The correlation between soil black carbon and every factorThe mass fraction of soil black carbon and fire area, fire frequency, fire occurrence time, samples elevation,samples slope, samples aspect are positively correlated. In which, fire frequency and samples slope are significantly correlated, the correlation coefficients are 0.36 and 0.39. The mass fraction of soil black carbon and fi samples aspect are negativly correlated, and the correlation coefficient is -0.02.7. The contribution of soil black carbon on forest soil total organic carbonThe acquisition of the soil burned all the black carbon quality score in 0 10 cm, 10 20 cm and 20 30 cm layer respectively for the average 9.57 g kg-1 , 6.42 g kg-1 and 3.97 g kg-1 , burned back carbon mass fraction of soil organic carbon quality score of proportion, 0 10 cm, 10 20 cm and 20 30 cm layer respectively for 37%, 36% and 29%, Had not happened in fire black carbon quality score in 0 10 cm, 10 20 cm and 20 30 cm layers of average respectively, 5.64 g kg-1 ,4.67 g kg-1 and 2.92 g kg-1,not fire to black carbon mass fraction of soil organic carbon quality score of proportion ,0 10 cm, 10 20 cm and 20 30 cm layer respectively for 39% , 37% and 33%. Results showed that whether or not fire on soil black carbon mass fraction of soil organic carbon has a little influence on the mass fraction of proportion. |
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