THE ECOLOGY OF THE UPPER GANGETIC PLAIN. 321 



Such a climax forest as has been sketched above is purely 

 hypothetical for the area, but all natural conditions seem to 

 warrant the assumption that it would develop. It would be 

 a typical deciduous monsoon forest, decidedly tropophytic, leaf- 

 less during some portion of the hot season. It would contain 

 few bulbous herbs, few epiphytes, abundants lianas, and would 

 have a great abundance and variety of grasses in the more open 

 places. The fine forests at the north side of the Upper Gangetic 

 Plain adjacent to the Himalayas, and in the more inaccessible parts 

 of the Vindhias to the south (Fig. 16) may be taken as a picture of 

 this hypothetical forest. 



Summary 



1. The area under discussion lies in a 10 mile radius about 

 Allahabad, and is representative of a large part of the Upper Gangetic 

 Plain. 



2. The vegetation is influenced and determined as much by 

 biotic as by climatic factors. 



3. The climatic factors, rainfall, insolation, temperature, humi- 

 dity, and air movements, are periodic in distribution, and produce 

 three distinct seasons : 



(a) Rainy season, from the middle of June to the end of 

 September, with high rainfull, low insolation, high tempe- 

 rature, and high humidity. . 



{b) Cold season, from the first of October to the end of Febru- 

 ary, with low rainlall, high insolation, low temperature, 

 and high humidity. 



(c) Hot season, from the first of March to the middle of June, 

 with low rainfall, high insolation, high temperature, low 

 humidity, and large air movement. 



4. The biotic factors are an agricultural population of about 530 

 er square mile, and associated domestic grazing animals of about 



4?0 per square mile. Cultivation, grazing, and cutting for food and 

 fuel have profoundly modified the original vegetation ; constantly 

 interfere with the normal development of the vegetation ; and cause 

 retrogression from the original climatic climax. White ants also prob- 

 ably exert marked influence on the vegetation. 



