Coarse root system characteristics and toppling of clonal and seedling trees of Pinus radiata on Canterbury Plains.

Authors: M. Gautam, D. J. Mead, C. Frampton, S. X. Chang
Publication: New Zealand Journal of Forestry, Volume N.Z.J.For. 1999, Issue N.Z.J.For. 44(1) 1999, pp 15-18, May 1999
Publisher: New Zealand Institute of Forestry

---

Abstract:
Qualitative characteristics of coarse root components, i.e., core distortion, lateral root distribution and dominance of vertical roots, and the relationship between tree root characteristics and toppling were studied using Mason's root core, Menzies' lateral root, and modified Menzies' vertical root scoring methods on three planting material types. Two of the planting material types were clonal tissue cultured plantlets (clone 3, Set 11/8, and clone 4, Set 38/9) and the other seedling (a GF 14 seedlot of "850" selections) trees of Pinus radiata D. Don. The trees were grown with either lucerne, ryegrass/clover or no understorey in the Lincoln University agroforestry experiment on the Canterbury Plains.
Understorey competition had no significant effect on any of the coarse root characteristics studied. Core distortion was least severe with clone 3 trees compared with clone 4 and seedling trees. Clonal trees had more straight and dominant vertical roots whereas seedling trees had more forked and weakly developed vertical roots. The toppled trees frequently had moderately distorted root cores and weakly developed vertical roots,- however, analysis using the cumulative logit model showed that tree stability was significantly related to planting material type but, within each planting material type, was not related to core distortion or dominance of vertical root. Therefore, in addition to coarse root characteristics, other factors specific to each of the planting material types not tested in this study have affected the tendency of the trees to topple.

---