DAMAGE CAUSED BY LOW OR HIGH TEMPERATURE. 17 



earlier melting of the snow and the quickening of active 

 vegetation in spring, but also through the dying off, or at 

 any rate the sickliness and wilting of weakly plants in 

 the direction in which the warmth is reflected. 

 (d) The time of the occurrence of abnormal heat is also of con- 

 sequence. It is particularly injurious in the month of 

 May, after the operations of sowing and planting have 

 been completed, as it hinders the seed from germinating, 

 and causes the death of the slender, shallow-rooting seed- 

 lings and of young transplants that have not had time to 

 establish their root-systems in their new home. 



12. Protective Measures against Damage from Heat and Drought. 



The injurious effects of heat and drought can be prevented by 

 adopting measures to retain, so far as possible, the natural degree 

 of soil-moisture, and the atmospheric precipitations reaching the 

 soil, or as can only be practically applied on a comparatively 

 small scale, and to a limited extent by maintaining a due supply 

 of soil-moisture by watering or irrigation. 



The natural freshness and moisture of the soil can be retained 

 by taking measures to prevent, or at any rate minimise, direct in- 

 solation of the soil or plant, or direct exposure to winds. Of the 

 measures practically adaptable to serve these ends, the most im- 

 portant is the avoidance of any exposure or laying bare of the 

 soil, as, e.g., a preference for natural reproduction under parent or 

 protective standards, which should consist rather of the smaller 

 girth-classes of trees than of big stems with large crowns inter- 

 Icepting the atmospheric precipitations to any great degree. Under 

 jlarge old Beech the natural growth of seedlings is comparatively 

 [slight, weakly in development, and often succumbs quickly in warm 

 (summers. In localities where protection is especially necessary, 

 Isuch as stony, limy soil, or dry southern exposures, it is better to 

 maintain closed canopy as far as possible, and only extract a 

 limited number of mature stems here and there annually. Where 

 natural reproduction has taken place on dry soil, a speedy clearance 

 jof the standards is necessary as soon as the young crop has been 

 'formed, in order that the latter may have the full benefit of the 

 [atmospheric precipitations (rainfall, dew), whilst any spontaneous 

 jgrowth of seedlings, even although unsuitable for forming part of 



B 



