Publication Title: Determination of ash and nitrogen concentration of decomposing woody roots by near infrared reflectance spectroscopy [Abstract]
Year: 2001 Status: Published Publication Type: Abstract
H. J. Andrews Publication Number: 3137
Citation: Chen, Hua; Harmon, Mark E. 2001. Determination of ash and nitrogen concentration of decomposing woody roots by near infrared reflectance spectroscopy [Abstract]. In: The Ecological Society of America 86th annual meeting: Keeping all the parts: preserving, restoring and sustaining complex ecosystems; Madison, WI. Washington, DC: The Ecological Society of America: 69.
Online PDF: http://andrewsforest.oregonstate.edu/pubs/pdf/pub3137.pdf
Abstract: Near infrared reflectance spectroscopy (NIRS) has been successfully used to measure ash, N, and carbon-fraction of leaf litter. However, it is not clear whether this technique will work for woody detritus litter such as woody roots. We evaluated the accuracy of NIRS predictions of ash and N concentrations of decomposing woody roots from a time series experiment and a chronosequence study and determined the effects of species, root size, degree of decomposition, tissues type, and site on NIRS predictions. The time series experiment included 11 coniferous and 7 deciduous tree species. After 4 years of decomposition the determination coefficients (R2) of ash and N concentration of the woody root samples were 0.98 and 0.97, respectively. Analysis of calibration and validation using different data groups based on species, root sizes, and sites did not significantly improve the predictive accuracy of ash and N concentrations. The ages of root samples from the chronosequence study ranged from 1 to 45 years old. The values of R2 of ash concentration for these samples ranged from 0.94 to 0.95, while the R2 value of N calibration of root samples was 0.90. The predictive accuracy of ash concentration using all three-site samples for calibrations was much lower than for each site separately, although for N concentration predictions pooling sites had little effect. Our study indicate that NIRS can successfully determine ash and N concentration of woody roots as long as the samples have been grouped appropriately to reduce their heterogeneity.
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