论文部分内容阅读
Decomposition of stumps in successive rotation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) plantations was studied using a chronosequence approach. The results showed that decomposition rate constant of Chi- nese fir stump was 0.02695 as calculated from Olson’s model. The N content of stump increased during the first two-year decomposition. When the dead stump C/N ratio was 463.2 ± 27.3, the stumps started to release N. The pattern of P release was similar to that for N. However, K content of stumps showed a consistent declining trend over time during the whole decomposition. 13C nuclear magnetic resonance spec- troscopy with cross polarization and magic-angle spinning (13C CPMAS-NMR) was used to analyse organic carbon (C) components in decomposing stumps. The 13C CPMAS-NMR spectra of stumps displayed that stump was dominated by cellulose and hemicellulose. The spectra also showed the ac- cumulation of intensity in alkyl C, aromatic C, and carboxyl C spectral regions, which was expected as the labile cellulose and hemicellulose components in O-alkyl C spectral region were selectively decomposed first.
Decomposition of stumps in successive rotation of Chinese fir (Cunninghamia lanceolata (Lamb.) Hook.) Plantations was studied using a chronosequence approach. The results showed that decomposition rate constant of Chi- nese fir stump was 0.02695 as calculated from Olson’s model. The N When the dead stump C / N ratio was 463.2 ± 27.3, the stumps started to release N. The pattern of P release was similar to that for N. However, K content of stumps 13C nuclear magnetic resonance spec- troscopy with cross polarization and magic-angle spinning (13C CPMAS-NMR) was used to analyze organic carbon (C) components in decomposing stumps. The 13C CPMAS -NMR spectra of stumps displayed that stump was dominated by cellulose and hemicellulose. The spectra also showed the ac- cumulation of intensity in alkyl C, aromatic C, and carboxyl C region regions, whi ch was expected as the labile cellulose and hemicellulose components in O-alkyl C spectral region were preferentially decomposed.