4o8 The Ohio Naturalist. [Vol. Ill, No. 6, 



•doubtful if more than a very few of the phases of species distribu- 

 tion can be explained from the standpoint of any one factor alone. 

 It is not to be assumed that all the climatic factors of ecological 

 connection have been considered in these two articles, and neither 

 does it follow that any of the factors have been considered in all 

 their possible phases as related to ecology, but yet enough has 

 been considered to afford more or less of a basis for further work. 

 It is to be regretted that the edaphic conditions, such as soil 

 moisture, soil texture, etc., are not more completeh' worked out 

 for Ohio. They take a verj^ important part among the ecological 

 factors, and in many ca.ses are almo.st inseparably linked with 

 meteorological factors. 



For a concrete instance of some of the problems of plant ecol- 

 og}^, comparison may be made, for instance, between Ashtabula 

 and Cincinnati, although localities differing more widely ma}- be 

 found in the State. The two stations have the same average 

 range ( ioo° Fahr.) between the average minimum and maximum 

 temperatures, but Cincinnati is five degrees warmer in mean 

 annual temperature, thus having decidedly an advantage as to 

 the needs of many plants. The annual precipitation is the same 

 in both localities, but Ashtabula has sixty inches of snow to less 

 than twent}^ inches for Cincinnati. Now, perhaps for many 

 plants the protection offered by the extra forty inches of snow at 

 Ashtabula is a greater advantage than is the extra five degrees of 

 temperature at Cincinnati. Again, the monthly distribution of 

 the precipitation is another important factor — Cincinnati has a 

 maximum of 5.69 inches in March, while Ashtabula has a maxi- 

 mum of 6.95 inches in July, at about the middle of the growing 

 .season and just when needed for the majority of plants. Further- 

 more, Cincinnati has a very drying atmosphere (low relative 

 humidity) as compared with Ashtabula, but to counteract this the 

 higher wind velocity at Ashtabula indicates the ability of the air 

 to carry away more water. Cincinnati is farther south and would 

 thus be more directly under the sun's rays, but Ashtabula has 

 less cloudy weather and so perhaps gets more sunlight than does 

 Cincinnati. 



In problems like the above, where each climatic factor may 

 have some certain influence upon any j^articular species, a debit 

 and credit account might be imagined in which the factors are 

 balanced, and if something is known of the requirements of the 

 species, perhaps some light might be throwm upon the problems 

 of di.stribution or the possibilities open to introduced species. 



