稳定碳同位素示踪农林生态转换系统中土壤有机质的迁移和赋存规律

为了探讨土壤有机质在降解过程中的迁移、赋存规律,利用C₃植物与C₄植物明显的δ¹³C值差异,选取贵州茂兰保护区内农林生态系统发生转换生长的地域,分析土壤的不同粒径组分和比重组分中土壤有机质的δ¹³C值.结果表明,粗砂中的土壤有机质年代最新,细粉中的土壤有机质年代最老,有机质在降解过程中,在土壤各粒径组分中的迁移次序是:粗砂＜细砂＜粗粉＜粘土＜细粉;土壤重组分中的有机质年代较老,以降解充分、稳定的有机无机复合体为主,相对

The Dynamics Rules of Soil Organic Matter of Turnover Ecosystems Traced by Stable Carbon Isotopes

On the basis of different photosynthetic pathway, there's obvious difference in delta 13 C values between C3 plants and C4 plants. Use this characteristic, the delta 13C values in different size and density fractions of two profile soil samples either in farm land and forest lands near Maolan Karst virgin forest was analyzed, there plant C3 plants previously and plant C4 plants now. Results showed that the delta 13C values of different size fractions in forest soil aere delta 13Ccoarse sand < delta 13Cfine sand < delta 13Ccoarse silt < delta 13Cclay < delta 13Cfine silt, and the delta 13C values of different size fractions in farmland soil were delta 13Ccoarse sand > delta 13Cfine sand > delta 13Ccoarse silt > delta 13Cclay > delta 13Cfine silt, it indicated that the soil organic matter was fresh in coarse sand and oldest in fine silt. The delta 13C values of different density fractions in forest soil were delta 13Clight < delta 13Cheavy, and the delta 13C values of different density fractions in farmland soil were delta 13Clight > delta 13Cheavy, it also indicated that the soil organic matter was fresh in light fractions and old in heavy fractions.