26 SYLVICULTURE. 



The Climatic and Physical Effects of large compact blocks of 

 woodland consist in tending (1) to equalise the temperature 

 both of the soil and of the atmosphere, and to diminish extreme 

 differences in each of these during summer and winter ; (2) to 

 increase the relative humidity of the air, and also perhaps 

 slightly increase the total amount of dew, mist, and rainfall ; 

 (3) to absorb and retain moisture in the soil, and especially in 

 the upper layer of humus, thus helping to prevent floods, to 

 maintain the perennial flow of springs and brooks, and to act as 

 purifying filters in water- catchment areas ; (4) to protect the 

 surface-soil from erosion during heavy rainfall; and (5) to help 

 to purify the air from excess of carbon-dioxide. 



Their Economic Uses are (1) to provide work for part of the 

 rural population, and especially during winter, when other work 

 is scarce ; (2) to provide part of the timber now imported in 

 vast quantities for industrial purposes, and thus increase the 

 sum total of wages payable to workmen in our own country ; 

 (3) to give shelter to fields and farm live-stock ; and (4) to add 

 to the attractions of country life by increasing facilities for sport. 

 On the average every 100 to 150 acres of woodland provide 

 permanent work for one woodman ; but this gives no indication 

 of the total amount of employment of various kinds that large 

 woodlands worked on business principles would ensure to the 

 rural population in planting, tending, and felling timber-crops, 

 in preparing, extracting, transporting, and converting the timber, 

 and in distributing the converted timber and other woodland 

 produce. Under a great national scheme of afforestation many 

 million pounds sterling would in course of time be circulated 

 among our own rural population, in place of being paid to 

 foreign workmen as at present. Even 3,000,000 acres of well- 

 managed coniferous timber-crops worked with a rotation of 60 

 years would give an annual mature fall of 50,000 acres, besides 

 thinnings from younger woods, and would probably yield on the 

 average a total crop of about 100 tons weight of timber per acre, 



