i9i 7] GA NO— ECOLOGY OF FLORIDA 371 



t 



at the end of the spring drought, does the percentage of moisture 

 in the first 3 inches of soil fall lower than the wilting coefficient, 

 and then but slightly. The maximum amount is reached in late 

 January and early February, while a summer maximum is reached 

 in July, coinciding with the two periods of rainfall. The curve 

 of the range of the soil moisture agrees quite closely with that of 

 the average daily evaporation, which in this association therefore 

 has a direct relation to the soil moisture and the consequent 

 humidity of the atmosphere at the surface of the soil where 

 evaporation is actively occurring. 



Considering the edaphic character of the flatwoods in expla- 

 nation of its position as determined by the evaporation averages, 

 the order of succession for upland forests as observed seems to 

 have a definite relation to the obtained rate of evaporation. 

 This tends to confirm the observation that in the coastal region 

 studied the present pines are pioneers making a temporary forest, 

 which, owing to present geological, topographical, and soil condi- 

 tions, may make but slow progress toward the ultimate climax, at 

 least over large areas. When once started, however, the climate 

 favors a rapid mesophytic, advance. 



To the lectures and teaching of Dr. H. C. Cowles I am indebted 

 for my interest in this subject and for my point of view; to 

 Dr. G. D. Fuller for instructions concerning field work with 

 e vaporimeters ; and to Dr. J. M. Greenman for aid in identification 

 of various plants. Also I acknowledge the assistance of Professor 

 Jerome McNeill of Tallahassee, Florida, in the field work and 

 in securing the evaporation and soil moisture readings over an 

 extended time. 



Richmond, Ind. 



LITERATURE CITED 



J 



Circ. Bur. 



Soils, U.S. Dept. Agric. 

 2. Briggs, L. T., and Shan 



determination. U.S. Dept. Agric, Bur. Plant Ind. Bull. no. 230. 191 2. 

 Climatological Service Reports, District no. 2, South Atlantic and ea 

 Gulf states. U.S. Dept. Weather Bur. Service, 1912-1914. 



