The Soil Carbon Sequestration Characteristics Of Pine Forest And Influence Factors Analysis In Shaanxi

This study took Pine forest in Shaanxi province as object, based on field investigation、data collection and laboratory experiments, with climate gradient as the main line, discussedthe effect of soil carbon sink of pine ecosystem and analysised the difference of soil organiccarbon accumulation of shaanxi province pine forest. The main research was soil organiccarbon content, soil organic carbon storage and the effect of soil organic carbon storage of thedifferent age of pine forest, the main conclusions showed as follows:（1）The results showed that soil organic carbon content of different forest age ofdifferent species and the same tree species were gradually decreased.North of Shaanxi: the soil average organic carbon content of junior forest, middle forest,near-mature forest, mature forest of Pinus tabulaeformis was6.464、8.694、13.451、9.348g·kg^-1, Soil organic carbon content of Pinus tabulaeformis firstly increasesed from juniorforest to near-mature forest then decreasesed in the process from near-mature forest forest tomature forest.South of Shaanxi: the soil average organic carbon content of middle forest, mature forestof Pinus massoniana was4.542、7.197g·kg^-1, soil organic carbon content of Pinusmassoniana increasesed in the process from middle forest to mature forest.The soil average organic carbon content of junior forest, near-mature forest, over-matureforest of Pinus tabulaeformis was8.676、9.157、6.232g·kg^-1, The soil organic carbon contentof Pinus tabulaeformis firstly increasesed then decreasesed in the process from junior forestto over-mature forest.The soil average organic carbon content of artificial junior forest, artificial over-matureforest, natural over-mature forest, natural middle forest of Pinus armandi was6.942、18.118、11.748、5.345g·kg^-1. The soil organic carbon content of artificial Pinus armandi increasesedin the process from junior forest to over-mature forest, the soil organic carbon content ofnatural Pinus armandi increasesed in the process from middle forest to over-mature forest.The central Shaanxi plain: The soil average organic carbon content of junior forest,middle forest, over-mature forest of Pinus tabulaeformis was12.637、11.957、13.602g·kg^-1, and it was no significant difference. The soil organic carbon content of Pinus tabulaeformisfirstly decreasesed then increasesed in the process from junior forest to over-mature forest.（2）The change of soil organic carbon density was consistent with the soil organiccarbon content, soil organic carbon density of different forest age of different species and Thesame tree species were firstly decreasesed then increasesed, and soil organic carbon densitywas mainly stored in the0-50cm soil layer and accounted for larger proportion in total soilorganic carbon reserves.North of Shaanxi: The soil organic carbon storage of Pinus tabulaeform firstlyincreasesed then decreasesed in the process from junior forest to mature forest, the maximumwas100.730t·hm^-2in near-mature forest, the soil organic carbon storage of mature forest was72.473t·hm^-2and it was higher than the junior forest that was68.090t·hm^-2, middle forestwas69.593t·hm^-2.South of Shaanxi: The soil organic carbon storage of Pinus massoniana increasesed inthe process from middle forest (44.761t·hm^-2) to over-mature forest (58.945t·hm^-2). Thesoil organic carbon storage of artificial Pinus armandi increasesed in the process from juniorforest(70.233t·hm^-2)to over-mature forest(167.284t·hm^-2),The soil organic carbon storageof natural Pinus armandi increasesed in the process from middle forest(50.269t·hm^-2)toover-mature forest(107.466t·hm^-2).The soil organic carbon storage of Pinus tabulaeformis was firstly increasesed thendecreasesed in the process from junior forest to over-mature forest. The maximum was87.340t·hm^-2in near-mature forest, the soil organic carbon storage of mature forest was54.617t·hm^-2and it is higher than the junior forest that was48.095t·hm^-2.Junior and over-mature forest stage,soil organic carbon storage of Pinus armandi arehigher than that pinus tabulaeformis; middle forest stage, soil organic carbon storage of pinustabulaeformis and Laris gmelini were higher than that Pinus massoniana; over-mature foreststage, soil organic carbon storage of artificial Pinus armandi are higher than that natural Pinusarmandi.The central Shaanxi plain: The soil organic carbon storage of Pinus tabulaeformis firstlydecreasesed then increasesed in the process from junior forest to over-mature forest. Themaximum was109.273t·hm^-2in over-mature forest, the second was98.353t·hm^-2in juniorforest, the minimum was90.830t·hm^-2in middle forest,The comparison of among soil organic carbon storage north and south and central ofShaanxi, The results showed that size order of soil organic carbon storage of different forestage was the central Shaanxi plain＞north of Shaanxi＞sorth of Shaanxi; it was significantdifference between the central Shaanxi plain and sorth of Shaanxi（P＜0.05）, others were no significant difference.（3）Correlation analysis showed that the relationship of soil organic carbon storage andtotal nitrogen、fine-root biomass、rainfall、altitude was a significant positive correlation（P＜0.05）, the relationship of soil organic carbon storage and average bulk density、temperaturewas a significant and very significant negative correlation（P＜0.01）.