| Carbon recycling of soil is a key process of the flow of matter and energy in terrestrial ecosystems. As a very important part of the carbon cycle, atmospheric CO2 assimilation process of soil microbes is a biochemical process which is mainly controlled by the soil autotrophic microbes with carbon assimilation ability. Among the study of assimilation process conducted by the soil autotrophic microbes with carbon assimilation ability, more attention have been paied in the farmland ecosystem. However, Autotrophic organisms which is widely varied in different ecosystems, participating in the process of CO2 assimilation in different environmental conditions such as natural wetland, the vast grassland and woodland habitat, have very strong environment adaptiveness. Therefore, from the view of the material and energy flow of the whole biosphere, the CO2 function of autotrophic microbe assimilation of and assimilation of carbon conversion in different ecosystems is of great significance to improve the carbon cycle theory.The experiment was carried out to quantify the transformation and the distribution of labeled C in soil organic carbon polls(14C-SOC), activated carbon pool, different size aggregates and humus after 45 d. The main results were summarized as follows:1) Showing that soil autotrophic organisms have considerable CO2 assimilation ability, after 45d labeling, The 14C-SOC content of the eight tested soil ranged from 17.45 to 109.79 mg-kg’1, which represent an annual, global rate of about 0.85 to 9.3 Pg. The content of 14C-SOC and Carbon assimilation rate from high to low is wetland soil> rice soil> meadow soil> forest land soil.2) The distribution of labeled C in activated carbon pool is different. After 45d cultivation, The content of 14C-DOC、14C-MBC in paddy soil ranges from 2.37 to 6.06 mg·kg-1、3.41 to 24.07 mg-kg-1, respectively. The averge content of 14C-DOC、14C-MBC in paddy soil were higher than that of upland soils. The content of 14C-DOC、 14C-MBC in Wetland soil is highest among the all tested soils, which ranges from 7.41 mg·kg-1 to 56.87 mg·kg-1。3) The distribution of labeled incorporated into different particle size of aggregate is of great significance according to different soil types. The assimilated carbon is mainly stored in the< 53μm aggregates. But as to P1 and P5 soils, The 14C content in >250 μm aggregates is the highest, being 88.86 mg·kg-1,62.00 mg·kg-1, respectively. And autotrophic microbe assimilation carbon in wetland soil is mainly stored in 53-250 μm aggregates.4) The distribution of carbon assimilated by autotrophic microbes in the humus composition also shows a significant difference, alongwith the different soil type. The content of 14C in the humus compositions follows the order which is 14C-Hu>14C-FA>14C-HA. The content of 14C-Hu in Wetland soil is the highest than any others soil type, which is 134.37 mg·kg-1. The content in Paddy soil ranged from 47.38 to 47.38 mg·kg-1. The grassland soil and soil were 18.15 mg·kg-1 10.51 mg·kg-1, respectively. |
PDF Full Text Request