256 THE PROTECTION OF WOODLANDS. 



are the least hardy against frost; while the most hardy are 

 softwoods, Hornbeam, Pines, and Colorado Douglas Fir. 

 Alder, Birch, and Hornbeam flush their leaves earlier than 

 the less hardy Oak, &c. ; and Silver Fir side-shoots are often 

 killed, while the leading - shoot escapes, as the terminal bud 

 is the last to develop. Larch is sensitive just when the buds 

 are opening, but hardy after the leaves expand. 



Damage from late frosts in nurseries can best be prevented 

 by selecting sites with a N. or N.W. aspect, or protected on 

 E. and S. by old woods, and preferably broad - leaved ; and 

 young seedlings and transplants are best protected by a hori- 

 zontal framework of thin laths about 1 in. broad set 1 in. apart. 

 In planting land exposed to frost, any existing protection, such 

 as heather, &c., should be made use of as long as required ; or 

 hardy quick-growing trees like Birch, Larch, Pine, and White 

 Alder can be planted as nurses to protect less hardy kinds 

 and if practicable they should be planted a year or two in 

 advance ; but they should be cut out in the weedings and 

 early thinnings when they have served their purpose and are 

 no longer needed to protect the other kinds of trees intended 

 to form the timber-crop. When soil and seedlings are lifted 

 in nurseries by hard winter frost, only the soil sets when the 

 thaw comes, so that the roots are more or less exposed and have 

 to be banked up, and the young plants are sometimes lifted 

 so high that they fall over and soon die unless replanted, as is 

 often the case (except with deep-rooting seedlings like Oak, 

 Chestnut, and Pine). Drill-sown beds suffer less than broad- 

 sown, and the danger of lifting is decreased by putting sawdust, 

 moss, or loose earth between the drills. Broad-leaved saplings 

 badly frost-bitten can be cut back to shoot from the stool, and 

 blanks in Conifer plantations should be beaten up with hardy 

 quick-growing trees (Birch, Aspen, Pine). 



Frost-shakes or Frost-cracks are longitudinal fissures on the 

 lower part of the stem, and especially of 50- to 70-year-old Oak, 



