Influence of Shade on Plantations. 



i8i 



was kept of those trees which had a stone as close as 6 to 8 inches 

 from the stem, whether the stone had been placed there by the 

 planter or not. Although the amount of data is not large, it is 

 sufficient to indicate that an exposed stone close to a planted tree 

 was a strong adverse influence in this dr)^ season. The data on 

 this factor are given in Table III. 



Table III. 



Stotie Influence in a Plantation of Three-Year White Pine 

 Transplants- 



Low High 

 Shade. Shade. 



None, 



Medium, 



Heavy, 



None, 

 I to 3 hrs. 

 3 to 4!/^ hrs. 

 Over 4^2 hrs 

 None, 

 I to 3 hrs. 

 3 to 4H hrs. 

 Over 41/2 hrs 

 None, 

 I to 3 hrs. 

 3 to 45/2 hrs. 

 Over 4^ hrs. 



167 



99 



In the open, the stones apparently caused the death of 14 trees 

 out of every 100 which had them. The influence of the stones 

 is much less marked, however, when some shade is present, and 

 is less than the influence of root competition. Radiation from 

 the sun-heated stones undoubtedly caused increased transpiration 

 from the needles of the planted trees, and may have tended to dry 

 out the soil underneath. Whatever the means, a stone was a 

 greater danger to a tree than root competition in the absence of 

 shade; but was distinctly less dangerous than root competition 

 when shade was present, although still a danger. 



A total of 29 trees were found which had contended with both 

 root competition and the influence of nearby stones. Of these, 

 5 were without shade — 2 alive and 3 dead ; while of the 24 with 

 some shade, 14 (58%) were alive. The numbers involved are 

 too small to justify comment other than that the percentages of 



