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ij (Reprinted from Ecology, Vol. Ill, No. i, January, 1922. | 



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INFLUENCE OF CERTAIN SOIL FACTORS ON THE GROWTH 

 OF TREE SEEDLINGS AND WHEAT ^ 



Barrington Moore 



Contents 



Climate and Soils 65 



Experiment 66 



Results 69 



Influence of Humus 69 



Rate of Growth in Height 69 



Growth of Roots and Green Weight 73 



Influence of Humus on Wheat 76 



Influence of Alkalinity 76 



Heavy Application of Burnt Lime 76 



Light Application of Burnt Lime 80 



Summary 8 1 



Climate and Soils 



The influence of climate upon plants and animals under natural conditions 

 has received more attention than the influence of soil. Climate exerts the 

 major control ; without heat, moisture, and light the most fertile soil is useless. 

 In the mountains of our West climate is so closely related to altitude that dif- 

 ferent climatic zones occur within short distances and give the impression that 

 climate alone influences distribution. In general — of course there are excep- 

 tions — those who have studied the environment of western American plants 

 and animals have devoted most attention to climate, while those who have 

 studied in the eastern United States and Europe have considered the influence 

 of geological formation and soil as well as of climate. 



Progress in studies of the relation of soil to natural vegetation has been 

 slow, partly owing to the complexity of the problem, and partly because of 

 insistence on -the control exerted by physical properties of the soil to the 

 exclusion of its other properties. But there are signs of change. Fernald's 

 work (2) on the distribution of Pinus Banksiana and Thuja occidentalis has 

 done much to emphasize the importance of geological formation. Hessel- 

 man's (4) investigations in Swedish forests have thrown much light on the 

 importance of nitrogen in forest humus and on the influence of various kinds 

 of humus and methods of treatment upon the composition- and reproduction 

 of the forest. His discoveries are of the utmost value and will stimulate 

 work on soil factors. 



1 Presented before the Ecological Society of America at its meeting in Chicago 

 on December 28, 1920. 



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