| Mangrove forests are distributed in the inter-tidal region between the sea and theland in the tropical and subtropical regions providing a variety of ecosystem servicessuch as coastline protection from extreme events such as cyclones and tsunamis. Theproductivity and capacity of carbon sequestration of mangrove forests is very high. Somangrove forests have a huge amount of biomass carbon stock. Moreover, mangrovesoils can store lots of carbon because of long-term logging and anoxic environment.Mangrove soils organic carbon （SOC） content and storage are important in the globalcarbon cycle.This paper based on field survey and sampling, analysis the SOC content andstorage of mangrove soils in the different estuary position. Two sample sites areselected according to the distance that mangrove away from estuary, one was inestuary site and the another was far away from estuary. Then three soil profiles in eachplot （seaward, interior, landward） of each site are selected using a sampler constructedof PVC pipe respectively. Soil bulk density, moisture content and pH are measured tostudy their relationship with SOC content. The results are shown as following:In the mangrove near estuary, the SOC content is very high and increases withsoil depth until the peak value at60cm, then decreases. The SOC content （0-85cmdepths） ranges between16.5-59.5g·Kg-1,17.3-66.2g·Kg-1and9.1-28.0g·Kg-1,respectively in seaward, interior and landward sample plots. The average SOC contentof all samples decreases with the distance away from sea, the average SOC content ofseaward, interior, landward is as followed:36.76±3.04g·Kg-1,35.12±3.78g·Kg-1and17.20±1.56g·Kg-1.The trend of SOC storage varying with soil depth is consistent with its contentThe SOC storage （0-85cm depths） ranges between863.0-2624.0t·km-2,815.9-2681.2t·km-2and447.4-1543.0t·km-2, respectively in seaward, interior and landward samples.The total SOC storage （0-85cm depths） is29219.2t·km-2,24365.5t·km-2and14697.1 t·km-2respectively. The SOC storage is very high in the middle soil layer, the SOCstorage （60-85cm depths） accounts for40%or more of the whole profile in each plot.In the mangrove far away from estuary, the curve of SOC content varing withdepth is bimodal decreasing in all sample plots. The highest SOC content is at soilsurface and another higher value exists at the layer of40cm compared with adjacentlayers. The SOC content （0-60cm depths） ranges between11.8-38.3g·Kg-1,9.0-21.4g·Kg-1and8.4-21.5g·Kg-1, respectively in seaward, interior and landward sample plots.The average SOC content of all samples decreases with the distance away from sea,the average SOC content of seaward, interior, landward is in the order of:22.12±2.57g·Kg-1,14.83±1.01g·Kg-1and13.18±1.20g·Kg-1.The trend of SOC storage varing with soil depth is consistent with its content line.The total SOC storage （0-60cm depths） is10834.3t·km-2,8186.5t·km-2and6717.4t·km-2, respectively in seaward, interior and landward.The correlation between soil organic carbon content and soil bulk density is notsignificant; the relationship between soil moisture content and soil organic carboncontent is significantly negative in three of all samples, but there is no significantcorrelation with the others. More researches on the relationship between soil moistureand carbon content need to study. Among the three factors, soil pH has significantnegative relationship with soil organic carbon content in all sample plots. |
PDF Full Text Request