FROZEN PLANT-ORGANS. 503 



a. During the Formation of Woods. 



i. Drain wet places and all swamps in the forest before 

 restocking. 



Moisture is not always favourable to frost, for Wollny 

 states that dry humus has a low specific heat and is a bad 

 conductor, while wet humus has a high specific heat and is a 

 good conductor. In accordance with this principle, cranberry 

 swamps in Carolina are irrigated during the blossoming 

 period, when frost is feared ; also, in Northern India, vegetable 

 gardens and sugar-cane crops are irrigated in order to obviate 

 danger from frost. In sphagnum peat-bogs, a thin layer of 

 peat is left at the base of the bog, when the peat is cut, in 

 order to reproduce the peat, and unless this is kept wet, frost 

 and drought kill the peat. 



ii. Abandon attempts to grow frost-tender species in the 

 open. Such species as beech and silver-fir should not be 

 grown in bad frost localities, and, in any case, should be 

 protected by planting beforehand, or simultaneously with 

 them as nurses, fast-growing hardy trees, such as Scots pine, 

 larch, birch, or white alder. 



iii. Natural regeneration under a shelterwood and keeping 

 seeding-cuttings dark should be preferred, especially on easterly 

 or southerly aspects. Low, branching shelter-trees should be 

 pruned to promote air-circulation. 



iv. Strong transplants should be used, plants with balls of 

 earth and mound-planting being preferable for frost localities. 

 On wet ground, ridge-planting may be adopted. 



v. Protective belts, 30 to 40 feet wide, of spruce, or Scots 

 pine, may be established along the easterly boundaries of 

 a wood. 



vi. Where areas to be restocked are covered with a dense 

 growth of grass or herbage, this should be removed before 

 planting or sowing is attempted. 



vii. Transplants should be lifted from the nursery early 

 in the planting season and heeled-in in shady places near the 

 area to be planted, in order to delay their sprouting. Silver- 

 fir planted out late in the spring suffers less from May frosts 

 than spruce planted out early or in the previous autumn, 

 because its buds open later. 



