Plant and Soil

, Volume 333, Issue 1–2, pp 93–103 | Cite as

Use of near-infrared reflectance spectroscopy to predict species composition in tree fine-root mixtures

  • Pifeng LeiEmail author
  • Jürgen Bauhus
Regular Article


Assessment of belowground interactions in mixed forests has been largely constrained by the ability to distinguish fine roots of different species. Here, we explored near infrared reflectance spectroscopy (NIRS) to predict the proportion of woody fine roots in mixed samples and analyzed whether the prediction quality of NIRS models is related to the complexity of the fine-root mixture. For model calibration and validation purposes, 11 series of artificial mixed species samples containing known amounts of fine roots of up to four temperate tree species and non-woody plants were prepared. Three types of models with different calibration/validation approaches were developed and tested against external independent data for additional validation. With these models the proportion of each species in root mixtures was predicted accurately with low standard error of prediction (RMSECV/RMSEP <6.5%) and high coefficient of determination (r2 > 0.93) for all fine-root mixtures. In addition, NIRS models also provided satisfactory estimates for samples with low (<15%) or no content of particular components. The predictive power of the NIRS models did not decrease substantially with increasing complexity of the root samples. The approach presented here is a promising alternative to hand sorting of fine roots, which may be influenced substantially by operator variation, and it will facilitate investigating belowground interactions between woody species.


Fine roots Belowground diversity Near-infrared reflectance spectroscopy (NIRS) NIRS model Species proportions 



We are grateful to Julia Sohn, Adam Benneter, Grit Techel and Zhanying Gu for assistance with sample collection. Renate Nitschke and Marie-Cecile Gruselle provided indispensable help on NIRS model development. Many thanks to Michael-Scherer-Lorenzen and Ernst Detlev Schulze for the permission to use the BIOTREE experiment. Pifeng Lei was supported by the German Academic Exchange Service (DAAD). Helpful comments of two reviewers substantially improved the manuscript.


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Copyright information

© Springer Science+Business Media B.V. 2010

Authors and Affiliations

  1. 1.Institute of SilvicultureUniversity of FreiburgFreiburg i. Br.Germany
  2. 2.Faculty of Life Science and TechnologyCentral South University of Forestry and TechnologyChangshaPeople’s Republic of China

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