WATER RELATIONS OF FOREST TREES 375 



evaluate the effect of various phases of the water cycle on tree grov^th. 

 Although this paper has dealt almost exclusively with mature trees 

 rather than seedling material in their relation to water economy and its 

 effects on growth, it should not be forgotten that natural distributional 

 patterns are often governed by factors affecting seed germination (Moore, 

 1926) or seedhng tolerance as studied and discussed by Daubenmire (1943). 

 Knowledge of such Hmiting factors, although essential in any forest 

 management, does not necessarily prevent the cultivation of such trees. 

 For now many of our agricultural or horticultural crops would have to be 

 abandoned in many regions if natural regeneration was expected. 



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12-13. 



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