Height| Diameter ratio and tree stability relationships for four northern Rocky Mountain tree species

Ratios of tree height to diameter have been used to predict susceptibility to storm damage for many years. In this study, individual trees damaged by recent snow and wind events in western Montana were sampled in 1997 and 1998 to determine their height:diameter ratios in comparison to nearby undamaged trees. Four species were sampled: ponderosa pine (Pinus ponderosa), western larch (Larix occidentalis), interior Douglas-fir (Pseudotsuga menziesii var. glauca), and lodgepole pine (Pinus contorta var. latifolia). Ratios of 80:1 (both measures in equal units) provided a stability threshold for all four species. Trees with higher ratios were more prone to damage than trees with lower ratios. Height:diameter ratios from trees grown in spacing trials were used to examine spacings that avoided development of unstable trees. Wide spacings or early thinnings provide the best means of avoiding major losses to snow and wind damage. The growth and yield model Prognosis was unable to predict height:diameter ratios for developing stands. West. J. Appl. For.

[1]  Bernard L. Kovalchik,et al.  Forest habitat types of Montana. , 1977 .

[2]  S. Mitchell,et al.  Windthrow handbook for British Columbia forests. Research program working paper No. 9401 , 1994 .

[3]  F. Helles,et al.  Windthrow probability as a function of stand characteristics and shelter , 1986 .

[4]  J. Barrett,et al.  Growth and mortality of ponderosa pine poles thinned to various densities in the Blue Mountains of Oregon , 1995 .

[5]  J. Barrett,et al.  Thirty-five-year growth of thinned and unthinned ponderosa pine in the Methow Valley of northern Washington. , 1998 .

[6]  J. Barrett,et al.  Growth of ponderosa pine thinned to different stocking levels in central Oregon: 30-year results. , 1999 .

[7]  Ronald M. Lanner,et al.  On the insensitivity of height growth to spacing , 1985 .

[8]  Paul F. Hessburg,et al.  A structural classification for inland northwest forest vegetation. , 1996 .

[9]  Heli Peltola,et al.  Factors affecting snow damage of trees with particular reference to European conditions. , 1997 .

[10]  W. Dahms,et al.  Lodgepole pine development after early spacing in the Blue Mountains of Oregon , 1998 .

[11]  K. Milner.  Site Index and Height Growth Curves for Ponderosa Pine, Western Larch, Lodgepole Pine, and Douglas-Fir in Western Montana , 1992 .

[12]  Kenneth W. Seidel,et al.  A ponderosa pine-lodgepole pine spacing study in central Oregon : results after 20 years / , 1989 .

[13]  Bruce C. Larson,et al.  Forest Stand Dynamics , 1990 .

[14]  Nicholas L. Crookston,et al.  User's guide to the stand prognosis model / , 1982 .

[15]  P. Cochran,et al.  Growth and yield of western larch under controlled levels of stocking in the Blue Mountains of Oregon , 1999 .

[16]  K W Cremer,et al.  Effects of stocking and thinning on wind damage in [pine] plantations. , 1982 .

[17]  C. Oliver,et al.  Forest stand dynamics: updated edition. , 1996 .