Assessment Of Soil Carbon Components And Soil Carbon Reservoir Of Three Forest Types In Central Shandong Province

Soil carbon reserves in forest ecosystems have an important impact on the global carbon sink,and quantifying soil carbon reserves based on soil carbon components has profound significance for a deep understanding of soil carbon sink capacity.In this study,three types of typical forest in Shandong（coniferous forest、broad leaved forest and theropencedrymion）analyzed the content difference of organic carbon and carbon components between different density and forest forest,constructed the depth distribution model of soil carbon density of different forest types,and clarified the rules of soil organic carbon accumulation and change in different forest types.Based on the investigation of different forest characteristic factors,the evaluation model of soil carbon reserves in the study area was constructed to predict the soil carbon reserves of different forest types,so as to provide technical support for the assessment of forest soil carbon reserves in the future.The main study results are presented as follows:1.There are large differences in soil organic carbon content among the three forest types.The total organic carbon content of soil in each forest ranged between 48.35 and 56.36 g·kg^-1,and the total organic carbon content was the largest in theropencedrymion,followed by coniferous forest and the smallest in broad leaved forest.The content of soil organic carbon in each forest type was the largest in the humus layer（about 70%）,and gradually decreased downward.2.The soil carbon component content showed significant vertical distribution differences in the soil layer.The difference between easily oxidized organic carbon and dissolved organic carbon in the humus layer was not significant,the difference between recalcitrant organic carbon stands was significant,and the content of recalcitrant organic carbon in broad leaved forest was significantly higher than the other two forests.Each stand showed that the soil dissolved organic carbon content was significantly lower than the easily oxidized organic carbon content and the recalcitrant organic carbon content.The contribution rate of easily oxidized organic carbon to the total organic carbon increased with the soil depth,while the opposite was true between recalcitrant organic carbon and dissolved organic carbon.3.Forest density and age group are the key factors affecting the soil organic carbon reserves of each forest type.With the increase of forest density,the total organic carbon content in coniferous forest decreased first and then increased,and the broad leaved forest and theropencedrymion showed a trend of increasing the first and then decreasing.The total organic carbon of the soil was largest in the middle-aged forest and smallest in the mature forest.The influence of soil organic carbon content in forest litter is similar in different stands.4.The assessment model of forest soil carbon reserves was constructed based on different types of forest characteristics.The optimal depth distribution function of soil organic carbon density is a negative exponential function,and the basic expression of the depth distribution model of soil carbon density in different forest types in the study area is y=A₁*exp（-x/t₁）+y₀.Soil carbon reserves was significantly related to the forest age group and density,the evaluation model was:y=4533-2376*x₁-0.6519*x₂+0.0002846*x₂²+368*x₁².In conclusion,forest soil carbon reserves and carbon components vary significantly among different types of stands,and show significant differences in the vertical distribution of soil layers.Forest density and forest age can be used as predictors of forest soil carbon reserves,which lays a theoretical basis for the remote sensing assessment of large-scale forest soil carbon reserves in the future.