The appearance of the root system in plan and in west elevation and a projection 

 of the live tree crown perimeter are shown in figure 1 . Several interesting facts are 

 readily apparent: 



1. The arrangement and extent of main laterals are uneven. 



2 . The root system extends horizontally further than the radial spread of the 

 tree's crown. 



3. Most lateral roots and their rootlets are located within 18 inches of the 

 ground surface; only the main taproot and the sinker roots penetrate to greater depths. 



4. Some of these lateral roots extend considerable distances from the trunic (53 

 feet straight line) and can be within an inch or two of the mineral soil surface . 



5. The horizontal area designated by joining the adjacent live ends of lateral 

 roots is larger (5.4 times) than the projection of green crown. 



6. More of the root system is on the downhill side than on the upliill side, an 

 observation recorded by others (Berndt and Gibbons 1958; Busgen and Munch 1929; 

 McMinn 1955^). 



7. Most of the sinker roots lie close to the stem. 



8. The taproot forks at a depth of about 25 inches. 



Figure 1 could not show that the proximity of other trees apparently did not affect 

 the direction of the main laterals of the study tree. 



Table 1 records the numbers of rootlets by their diameter and their distance 

 from the main trunk. From this table and from root measurements the following facts 

 can be noted: 



1. More than 73 percent of primary and secondary laterals were located in 18 

 inches (between 6 and 24 inches beneath the ground surface) of soil. 



2. More than 92 percent of primary and secondary laterals were found in the 

 first 24 inches of mineral soil. 



3. Nearly 85 percent of the secondary roots were in the 0.10- to 0.25-inch 

 diameter class, and 98 percent were 1 inch or smaller in diameter. 



^ McMinn, R. G. Studies on the root systems of healthy and pole blight affected 

 white pine ( Pinus monticola Dougl.). Canada Dept. Agr. Sci. Serv. Interim (unpub.) 

 Rpt. , 31 pp. , illus. 1955. 



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