| Research on the relationship between vegetation restoration and soil organic carbon has always been a focus of research in areas such as ecology and soil science in the Loess Plateau.According to the decomposition rate of soil organic carbon,it was divided into three carbon pools,active organic carbon pool,slow organic carbon pool,and passive organic carbon pool.We selected nine typical areas at different longitudes in the forest vegetation area of the Loess Plateau,collected plant and soil samples from the area.We conducted basic index determination and indoor cultivation experiments,conducted statistics and analysis based on the results,and comprehensively study the plant-soil-microbe eco-stoichiometry and the distribution characteristics of soil active carbon pool,slow carbon pool,passive carbon pool.The conclusion of the study is as follows:(1)The distribution of soil organic carbon and total nitrogen content is spatially consistent,and both show a decreasing trend with the increase of longitude,and the total phosphorus content has less variation with the increase of longitude.Changes in soil eco-stoichiometry are less affected by longitude,and as the increase of longitude in the Loess Plateau,the difference is small.The ecological stoichiometry is greatly affected by environmental factors(elevation,annual average rainfall,annual average temperature,and so on).And rain and heat conditions will affect the formation and changes of soil nutrients.(2)Geographical longitude has a greater impact on activated organic carbon,while the effects of slow organic carbon and passive organic carbon are smaller.In the different longitude regions of the Loess Plateau,the total organic carbon content of the 0-20 cm and 20-40 cm soil layers is 11.40?72.77 and 6.24?45.80 g/kg,and the content of active organic carbon is 0.11-1.00 g/kg,0.02?0.36 g/kg,accounting for 0.3?4.9%,0.1?2.5% of the total organic carbon content,turnover time is 2?5 d,1?9 d;slow organic carbon content is 5.86?56.9 g/kg,4.31?33.73 g/kg,accounting for 43.9?88.0%,46.6?95.5% of the total organic carbon content,turnover time is 0.3?3.6 a,0.7?3.5 a;passive organic carbon content is 2.08?16.23 g/kg,0.60?11.84 g/kg,accounting for 11.4?55.3% and 3.7?37.9% of the total organic carbon content.The decomposition regular of organic carbon in the two soil layers is similar,both of which have a fast decomposition rate in the early stage,slow decomposition afterwards,and a stable stage in the later stage.(3)The carbon,nitrogen,and phosphorus content and ecological stoichiometry of plants(leaves,stems,and roots)vary with longitude,and the regular is not significant.The change rule of organic carbon content was leaf> stem> root,and the range of organic carbon content in leaves,stems,and roots was 363.58?465.97 g/kg,335.8?454.43 g/kg,306.96?424.82 g/kg,nitrogen content ranges from 4.15?32.18 g/kg,2.86?15.68 g/kg,1.01?13.15 g/kg,phosphorus content range It is 0.51?7.40 g/kg,0.34?4.37 g/kg,0.26?5.20 g/kg.The range of carbon,nitrogen ratio of leaves,stems,and roots is 14.98?101.73,24.22?102.02,15.07?157.41,and the ratio of carbon,phosphorus,leaves,stems,and roots is 52.24?988.95,99.49?1263.39,72.24?900.39.(4)With the increase of longitude,the soil microbial carbon and nitrogen content are first reduced and then increased and then decreased,and the phosphorus content is first reduced and then increased;the soil microbial ecological stoichiometry(C: N,C: P,N: P)changes are not obvious.The range of microbial biomass carbon in 0?20cm and 20?40cm is 80.50?921.94 mg/kg and 43.01?503.03 mg/kg respectively;the range of microbial biomass nitrogen in the two soil layers is 6.26?130.85 mg/kg,4.11?57.47 mg/kg,the value of 0?20 cm is higher than that of 20?40 cm soil layer.The range of microbial biomass phosphorus in the two soil layers is 1.33?21.91 mg/kg,0.78?8.85 mg/kg,and the content of microbial biomass phosphorus in 0?20 cm is higher than that in 20?40 cm.The range of C:N value of microbial biomass is 6.14?139.84,2.40?18.53,the range of C:P value is 6.14?139.84,20.84?372.85,and the range of N:P value is 2.61?21.39,1.48?48.54,respectively.the microbial biomass C:N,C:P,N:P fluctuate greatly with the change of longitude,the regular is not significant. |
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