WIND AND FROST. 255 



woods may be comparatively little injured. The extent of the 

 damage done varies with the kind, age, and density of the crop ; 

 and heavily-thinned woods are more likely to be thrown than 

 those in close-canopy, when the tree-crowns afford each other a 

 slight support. The best means of preventing damage have 

 already been indicated in Part II. (see pp. 120 to 123). Wind- 

 fall and broken trees should be extracted as soon as possible, to 

 prevent insect attacks; and to shorten the time of the land 

 lying unproductive, roads and rides should be prepared for 

 immediate extraction of timber. In natural regenerations, 

 where the roots of standards have torn up great masses of 

 soil, the butts should be sawn through and the stumps tilted 

 back into their former position, if possible, to save the seed- 

 lings. Conifer windfall timber will get soon attacked by insects 

 unless barked ; and weevils will breed enormously, and hinder 

 replanting for 3 or 4 years, unless the stumps can be grubbed up. 

 Frost may do damage in spring (late frost), autumn (early 

 frost), or winter (winter frost). In any frost-bitten part of a 

 plant, water expands beyond the cells and into the intercellular 

 spaces, the cell-tissue loses its tension, and the affected parts 

 wither and die. Late frosts in spring are often very destruc- 

 tive in nurseries, seedlings being killed and transplants losing 

 their young shoots, and in young plantations many deaths are 

 caused, especially in damp, low-lying, sheltered spots (frost-holes), 

 where there is no current of air to carry away the cold layers. 

 Early frosts in autumn nip young shoots before they harden 

 properly, but seldom kill the plant outright, though often 

 causing leaf - shedding in young Conifers (like that in Pine 

 due to the fungus Lophodermium pinastri). Winter frosts 

 lift the soil and the plants in nurseries, especially when a 

 stiff soil is wet, and in young plantations, and make frost- 

 cracks in trees. Among broad - leaved trees Ash, Chestnut, 

 Beech, Eobinia, and Sessile Oak, and among Conifers, Silver 

 Fir, Pacific Douglas Fir, Menzies Spruce, and Maritime Pine 



