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Irrigation, fertilization and initial substrate quality effects on decomposing Loblolly pine litter chemistry

Informally Refereed

Abstract

Changes in carbon chemistry (i.e., carbon compound classes such as aromatics, phenolics, etc.) of loblolly pine (Pinus taeda L.) litter were examined during three years of decomposition under factorial combinations of irrigation and fertilization treatments. Cross polarization magic angle spinning 13C nuclear magnetic resonance revealed that total carbon and nutrient concentrations correlated strongly with carbohydrate and 0-alkyl carbon concentrations but did not relate well with concentrations of lignin, aromatic and phenolic carbon, or with lignin-related decomposition indices. The best correlations to carbon and nutrient concentrations occurred with the C/N (R2 = 0.86, P > 0.0001) and alkyl/O-alkyl (R2 = 0.75, P > 0.0001) decomposition indices. In all situations, the carbon chemistry of the decomposing litter followed the general pattern of accumulation of alkyl and carbonyl carbon with a loss of 0-alkyl and methoxy carbon. Only small variations in the aromatic and phenolic carbon concentrations were detected. Since lignin is composed primarily of aromatic and phenolic carbons, the observation that there were only small changes in the aromatic and phenolic carbons of the litter is consistent with the general stability of lignin in these ecosystems. Trends in carbon chemistry during decomposition suggested that ertilization accelerated the decomposition process by about 100% as compared with the control plots. Irrigation also accelerated the decomposition process but to a lower extent (about 62% greater than control plots). Initial litter quality, as defined by the litter C/N, did not have a significant effect on the carbon chemistry of the decomposing litter. This study demonstrated that the decomposition mechanisms were not altered by the treatments but there were important changes in the relative chemistry of the decomposing litter which impacted the rate of decomposition.

Keywords

CPMAS 13C NMR, litter decomposition, Loblolly pine

Citation

Sanchez, Felipe G. 2004. Irrigation, fertilization and initial substrate quality effects on decomposing Loblolly pine litter chemistry. Plant and Soil (2004) 270: 113-122
https://www.fs.usda.gov/research/treesearch/21164