SYLVICULTURE. 



D. Density of stand. Every ruling species shows a particular 

 density of cover and a particular ramification during every stage 

 of its life, when grown in pure forests. 



I. Density of leaf cover overhead. 



a. The form of the crown of the individual depends on side- 

 shade, topshade, neighborly friction and quality of soil. 



b. Natural regeneration causes a greater density of cover than 

 artificial regeneration, certainly during the thicket and pole staj^e. 

 Other infiuencing factors are: quality of the soil, age of the forest, 

 inroads by snow break, wind fall, fire, deer, fungi, insects. 



c A dense canopy overhead produces clear boled timber and 

 allows of a heavy layer of humus on the ground. The method of 

 regeneration distinctly influences the value of the timber to be 

 formed. 



II. Number of trees per acre. 



Under normal conditions an acre of pure forest contains the 

 more specimens of equal height or diameter, the better the quahty 

 of the soil and the' better the climate; and the more specimens oi 

 the same age, the poorer these factors are. For example-Yellow 

 Pine Forests: 



Number of trees per acre. 

 Soil Boles 75' long. Diameter 12." Age 60 yrs. 



I quality... 320 240 380 



II quality... 240 215 460 



III quality... 190 190 540 



During .the pole stage and tree stage shade bearers exhibit per 

 acre of ground about 50% more trees than light demanders. 



The following curve illustrates the interdependence between age 

 and number of trees per acre: 



10,000 \ 

 .5,000 '. 

 Number 2,500 

 1.000 

 of 900 



800 * . 



trees 700 ■ . 



600 • . 



per 500 

 400 

 acre 300 ' • . ^ 



200 * • ♦ . . 



100 

 



10 20 30 40 50 CO 70 SO 90 100 120 130 140 150 160 170 180 

 Number of years old. 



