132 FOREST PROTECTION 



Par. 10. Protection Against Heat. 



A. Heat Causes Harm Only: 



When it invites forest fires; 



When it fails to be balanced by the moisture in the air or soil (wood 

 lots in the prairies; old park trees); 



When it occurs suddenly, striking the trees in a state of non-pro- 

 tection (e. g., new plantations and trees isolated of a sudden). 



B. The Plants Protect Themselves Ordinarily Against Heat: 



By dropping leaves; 



By resinous cell contents; 



By closed stomata; 



By color and position of leaves; 



By coverings of cork, hair and that like. 



C. Remedies: 



1. In infant forests: 



(a) in nurseries: 



Secure irrigation; 



Provide lath screens or cloth screens; 

 Maintain a cover of mould on the soil; 

 Cviltivate so as to increase the porosity of soil; 

 Plant the seeds early in spring before the winter 



moisture has vanished; 

 Transplant early and transplant deeply. 



(b) in plantations: 



Use strong transplants; 



Adopt mound planting; 



Plant under cover; 



Adopt ball planting; 



Avoid loss of root fibres during act of out-planting; 



Cultivate. 



(c) in natural seed regenerations: 



Remove mother trees slowly; 



Remove trees reflecting heat unto young growth. 



(d) Generally: 



Maintain a dense cover overhead, and a good 

 layer of humus underneath. 



2. In pole forests and tree forests: 



Characteristic for damage (so-called sunscald) is: 



Bark scaling off; 



Sap wood turning brown; 



Discoloration and decay within a distinct sector of bole, 

 (a) Prevent sunscald by avoiding sudden changes of the 



influx of light; 



