HEIGHT GROWTH. 29 



TABLE I. Height growth of White Pine planted in lawn at Ann Arbor, Mich., ly years, in inches. 



NOTE. Trees Nos. 1 to 6 stood in shallow soil on gravel subsoil ; Nos. 7 and 8 in deep loam. 



From this table it appears that these eight trees grew on an average hardly more than 6 

 inches during the first six years, more than three times as fast during the next six years, and 

 reached a maximum rate of over 27 inches per year during the third period of six years, the 

 decline beginning after the twentieth year and the rate decreasing until it has fallen to about 15 

 inches near the thirtieth year. 



To show how, under less favorable conditions, the progress of self-sown trees is very nearly 

 the same, the following measurements may serve, from which it appears that natural seedlings on 

 pastures, standing more or less crowded, reach at ten years a height of 10 feet; at the age of 

 twenty years about 25 feet, and trees thirty-five to forty years of age, with diameters of 6 to 9 

 inches, attained and even passed the height of GO feet, showing an average growth for that period 

 of 15 to 18 inches per year : 



TABLE II. Measurements of self-sown White Pine on pasture. 

 (Furnished by Mr. J. E. Hobbs, of North Berwick, Me. ; altitude, 250 feet.) 



NOTES TO TABLE II. 



No. 1. From old pasture after one year's tillage; 5 feet from No. 6; bore cones. 



No. 2. With Nos. 1 and 3, and from similar trees. 



No. 3. Old pasture, soil shallow, gravelly loam on compact subsoil of sand; pine mixed with Hemlock, Oak, and Maple. 



No. 4. Level ground, soil heavy loam, somewhat shaded. 



No. 5. From old pasture after one year's tillage; 5 feet from No. 6; bore cones. 



N,,. 0. From old pasture after one year's tillage ; 5 feet from No. 1 ; bore cones. 



No. 7. From old pasture after one year's tillage; 5 feet from No. ; bore cones; distant from neighbors 8, 34, and 19 inches. 



No. 8. From old pasture after one year s tillage; 5 feet from No. 6; bore cones; touched another 4-inch diameter. 



