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Original Research ARTICLE Provisionally accepted The full-text will be published soon. Notify me

Front. Plant Sci. | doi: 10.3389/fpls.2019.00947

Functional Traits of Pinus ponderosa Coarse-Roots in Response to Slope Conditions

  • 1Rocky Mountain Research Station, United States Forest Service, United States
  • 2University of Insubria, Italy
  • 3Department of Biosciences and Territory, University of Molise, Italy

We excavated the root systems of Pinus ponderosa trees growing on a steeply-sloped, volcanic ash-influenced soil in the northern Rocky Mountains of the United States to assess their functional coarse-root traits and root system architecture. Trees, outplanted as one-year-old seedlings from a container nursery, were in their 32nd growing season on the site. We found that the trees had produced more roots, in terms of length and volume, in the downslope and windward quadrants than in their upslope and leeward quadrants, likely a response to mechanical forces toward improving stability. Moreover, we observed the development of three types of root cages (tight, enlarged, diffused) that likely reflect micro-site characteristics. As the cage type transitioned from tight to enlarged to diffused we noted a decrease in the overall volume of the roots associated with the cage and the taproot becoming a more prominent contributor to the overall volume of the cage. Finally, we noted the development of specialty roots, namely those with I-beam and T-beam shapes in cross section, in the downslope quadrant; these types of roots are known to better counteract compression mechanical forces. These observations improve our understanding of root plasticity and tree rooting response to environmental stimuli, which is becoming an increasingly critical topic as changes in climate increase the frequency and intensity of storms.

Keywords: I-beam, Root cage, Root system architecture, root topology, Functional root traits, T-beam, tree anchorage

Received: 12 Mar 2019; Accepted: 08 Jul 2019.

Edited by:

Christian Ammer, University of Göttingen, Germany

Reviewed by:

Veronica De Micco, University of Naples Federico II, Italy
Ivano Brunner, Swiss Federal Institute for Forest, Snow and Landscape Research (WSL), Switzerland  

Copyright: © 2019 Dumroese, Terzaghi, Chiatante, Scippa, Laserre and Montagnoli. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.

* Correspondence: Dr. Kasten Dumroese, Rocky Mountain Research Station, United States Forest Service, Fort Collins, United States,