| Vegetation restoration and reconstruction is an effective important measure that could control soil and water loss and improve ecological environment.its carbon sequestration benefits is the important basis to measure regional ecological effect.Under the background in the returning farmland to forest (grass),this paper adopts the method that combining the space time, field investigation and indoor experiment,the typical sample area of artificial and natural vegetation restoration in loess plateau for sampling and determination could be analyzed, discussed the dynamic characteristic of soil organic carbon and inorganic carbon in the process of vegetation restoration and reconstruction, evaluating the development relation between vegetation restoration and soil carbon sequestration effect, illustrating the direct and indirect factors that affects soil organic and inorganic carbon fixation, aim to a comprehensive understanding and the understanding the soil carbon sequestration effect of vegetation restoration in loess plateau, giving a guidance on the loess plateau vegetation restoration and provide a scientific reference for reconstruction work. The main conclusions are as follows:With the increasing of the recovery year, artificial locust forest soil organic carbon (SOC) fixed effect decreases firstly and increases secondly, the surface is more greater than the lower, and lower level affected by vegetation is not obvious;0-100 cm soil inorganic carbon (SIC) pool reserves is 4.5-7.4 times of organic carbon. Soil inorganic carbon fixed effect does not change significantly with the year changing, at 12.65～15.46 g·kg-1 fluctuation change. Surface SIC content is the lowest, and increases with soil depth, artificial afforestation can change carbonate deposition layer distribution position of soil profile; Soil inorganic carbon storage is 81.9～88.2% of the total soil layer, illustrating that soil inorganic carbon stock makes contribution to the total carbon storage capacity that accounts for most.2.With the processing of natural vegetation restoration succession, the 0-100 cm soil organic carbon all storage change tendency is to reduce first (<35 a) and increase second (>60 a),the last is stable change, its value is 5.93～8.95 kg·m-2,the main enrichment at 0-20 cm; the profile inorganic carbon storage capacity of 0-100 cm is 3.0～4.6 times of organic carbon.0-100 cm soil inorganic carbon sequestration ability is on the decline in total, ability to store inorganic carbon of 0-10cm is the lowest, decalcified phenomenon is obvious. With the increase of fixed number of year,0-20 cm soil layer SIC sequestration ability drop, does not change significantly below 20 cm, can also change the profile distribution of calcium deposition layer; With the fixed number of year.3.With the artificial vegetation restoration, the correlation of soil properties on SOC content as follows:soil root biomass>soil pH>soil bulk density>soil water content, and soil water content and soil pH value have primarily a direct effect on SOC content, indeed, root biomass have negative direct and indirect effect on SOC content,and soil bulk density to the negative straight of SOC content is equal to the negative indirect effect, the each character determination coefficient showed that the soil pH, soil bulk density are the dominant factors which act on SOC content.The correlation of soil properties to SIC content as follows:soil sand content>soil clay content>soil water content, the soil clay and sand are the main factors that affect the formation and transformation of SIC content. Short time of artificial vegetation recovery, the level of the SIC content is mainly decided by soil parent material.4.With natural vegetation restoration, the correlation of soil properties on SOC content as follows:root biomass>soil bulk density>soil electrical conductivity>soil moisture content, soil root biomass and soil moisture content have upright direct and indirect to SOC content, soil bulk density all have negative direct and indirect on SOC content, decision coefficient showed that the soil bulk density, root biomass and soil moisture are the leading factors which affect SOC content, the soil electrical conductivity is the limit factor of the formation of SOC content. Correlations between soil properties and SIC content as follows:soil root biomass>soil bulk density>soil moisture content> soil silt content. The root biomass, soil bulk density, and silt have negative direct and indirect effect on SOC content, soil moisture content makes direct and indirect positive contribution for SIC content.Soil bulk density, root biomass are the leading factors that decide the change of SIC content, shows that the soil characteristics have some influence on SIC content under the natural vegetation restoration.In the process of vegetation restoration, through the path analysis of SOC, SIC content, this research found that the residual size coefficient is larger, shows that there are still some important factors have not been taken into consideration, (such as precipitation, temperature, evaporation, leaching conditions, terrain, etc.), need to strengthen the study of soil carbon pool, action mechanism.5. Under different vegetation restoration model the SIC pool fixed above SOC pool. The carbon sequestration rate (0.036g·kg-1·a-1) of natural vegetation is higher than that of artificial vegetation (0.022g·kg-1·a-1), recovery year make significant impact on soil carbon levels. Vegetation restoration can affect soil properties, at the same time in the process of vegetation restoration, the formation and turnover of SOC SIC content will be affected by other soil properties, there is a certain interaction between different soil properties. Under different vegetation restoration, there is significant negative correlations between SOC pool, and SIC pool, shows that there may be certain transformation relationship between them, which needs to further to study. |
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