Forest Soil Organic Carbon And Nitrogen Storage And Characteristics Of Spatial Distribution In Sichuan Basin

Carbon pool is important for change of global climate and environment which people living because it is the biggest carbon pool in terrestrial ecosystem.Forest soil is a special soil type and affected by forest litter horizon and activity of microorganism, therefore,the organic carbon and nitrogen storage are all more than other type soil.Soil organic carbon(SOC) and nitrogen density and storage of Forest land in Sichuan Basin and their characteristics of spatial distribution were studied based on data of 152 soil profiles,and some factors affected SOC and nitrogen storage such as climate and landform were analyzed.Finally,influence of temperature effect and wetness effect in soil formation on SOC and nitrogen storage were studied.The main results are as follows:(1) The average SOC density of forest soil was 35.492±21.099 kgC/m² with CV 59.45%,and the total SOC storage in forest land is 6.744×10¹⁵gC in whole basin.The SOC density in the Sub-alpine meadow-grassland soil was the highest with 118.477 kg C/m²,and the lowest value of SOC density was 3.145 kg C/m² for yellow soil under the grass-Masson pine vegetation.The SOC density had notably difference for soils under different vegetation types.(2) The temperature,rainfall and elevation were main factors that affect SOC storage,the relationship between average annual temperature and SOC density was a significant negative correlation,and annual average rainfall same to temperature.The relationship between elevation and the density of SOC was a significant positive correlation.Among the rainfall,temperature and landform factors,the temperature was a key factor.That region where the annual average rainfall was 400～800mm and annual average temperature was 0～4℃,was a high-value area of mean SOC density with 80 kgC/m².Where the temperature was 14～16℃and the precipitation was 1400～1600mm had low density of SOC with 20 kgC/m².The climate and landform controlled SOC storage in Sichuan Basin,and the model Y=6.719+ 0.005P-0.032T+0.010H can be used to predicted SOC density about forest soil.(3) The average nitrogen density of forest soil was 1.849±2.163 kgN/m² with CV 117.022%,and the total nitrogen storage in forest land is 3.513×10¹⁴ gN in whole basin. The nitrogen density in the Sub-alpine meadow-grassland soil was the highest with 6.02 kgN/m²,and the lowest value of SOC density was 0.68 kgN/m² for hilly area savanna red soil.(4) The temperature,rainfall and elevation were main factors that affect nitrogen storage,the relationship between average annual temperature and nitrogen density was a significant negative correlation,the relationship between annual average rainfall and nitrogen density was a weak negative correlation,and the relationship between elevation and the density of nitrogen was a significant positive correlation.Among the rainfall,temperature and landform factors,the temperature was a key factor.That region where the annual average rainfall was 600～900mm and annual average temperature was 2～4℃,was a high-value area of mean nitrogen density with 4.5 kgN/m².Where the temperature was 15～18℃had low density of nitrogen with 1.0～1.5 kgN/m².The climate and landform controlled nitrogen storage in Sichuan Basin,and the model Z=1.117+0.001P-0.057T+0.000H can be used to predicted nitrogen density about forest soil.(5) The relationship between temperature effect T in soil formation and SOC density,nitrogen were significant negative correlations;the relationship between wetness effect M in soil formation and SOC density,nitrogen density were significant positive correlations.The model between SOC density and T,M is Y=66.334+ 0.002T²+0.007M²-0.006TM-0.249T-0.570M and the model between nitrogen density and T,M is Z=18.511+0.009T²+0.002M²+0.006TM -0.763T-0.311M...