Nature and impact of damage by wind, hail and snow in Australia's pine plantations

Summary

From Australia-wide surveys, forestry records and studies of major events of storm damage, a first comprehensive assessment is presented of the nature and incidence of damage caused by wind, snow and hail storms in Australian plantations of pines, mainly Pinus radiata. The main types of damage by wind and snow are the uprooting of trees, the tilting of saplings and trees and the bending or breakage of stems and branches. Wind may also abrade and strip the foliage or desiccate the crowns. The physical impact of hailstones damages the bark and cambium on limbs and the upper trunk, and detaches foliage and foliar shoots. This is sometimes followed by dieback of the crown and even death of trees, usually associated with infection by Diplodia pinea.

Meteorological records indicate that potentially damaging wind and hail storms have occurred in all Australian plantation areas, but damaging snow storms have been confined to the southeastern highlands.

During the 1970s, storms severely damaged at least 900 ha/yr (410 ha due to wind, 130 ha due to snow, and 350 ha due to hail). In the 1970s the annual damage was equal to about 7% of the annual harvest but only about 2/3 of it was salvaged. Because of the overall growth in the area of plantations, and the changes in the proportion of susceptible stands (mainly 20–30 m tall), damage in the 1960s was probably less than half that recorded in the 1970s, and damage in the 1990s could be three or four times as great as that in the 1970s.