Water content of leaves of Acer rubrum from 

 dififerent habitats and different levels' 



Lois Jotti.k 

 The aim of the investigation was to obtain definite figures 

 regarding the relative water content of leaves from trees growing 

 in varying habitats, as well as a comparison of the water con- 

 tent of upper and lower leaves from the same tree. 



Methods 



As three habitats, namely pineland aspen ,2 bog, and dry 

 aspen seemed to furnish the desired extremes for comparison, 

 as well as being characteristic of the region, trees were selected 

 from these habitats, and in addition from a fourth group com- 

 prised of trees growing in variable situations. The dry aspen 

 habitat was located on a very dry, sandy ridge, to some ex- 

 tent covered by typical aspen plants, but not a normal aspen 

 association due to the extreme lack of moisture and shade. 



Acer rubrum trees, used because the species was present in all 

 of the desired situations, were located permanently for all but 

 the variable group, leaves being taken from the same trees at 

 each collection. In as far as possible, selected trees were com- 

 parable in height and spread of branches. From these trees 

 leaves were collected in the early afternoon, when the maximum 

 amount of evaporation would be expected. 



Collections, made from the upper and lower portions of each 

 tree, consisted of typical, healthy leaves, cut off approximately 

 five millimeters from the point where the petiole joins the blade. 

 After cutting, leaves were put into tightly corked and properly 

 labeled bottles, and immediately upon return from the field 

 were weighed, then oven dried to a constant weight. The ex- 

 pression of water content was based on this dry weight of the 

 leaf. 



Data 



The resulting data clearly indicates that the water content 

 of leaves varies with the habitat, as leaves from trees in the bog 

 had the lowest water content, those from the dry aspen area 



^ Based upon work done under the direction of Dr. Frank C. Gates, during 

 July and August 1935, at the University of Michigan Biological Station. 



^ This association is fully described in: Gates, F. C., Aspen Association in 

 Northern Lower Michigan. Bot. Gaz. 90: 233-259. 1930. 



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