INTRODUCTION 



The study of vegetation or of plant communities is concerned with 

 the ecology or interrelationships of plants and animals to one an- 

 other and to the environment; and also with their composition 

 and structure, genesis, chorology, history, dynamics and classifica- 

 tion. In this viewpoint the community is the focus and ecology is 

 one kind of approach. 



The individual plant requires not only light to provide energy 

 for photosynthesis, but a suitable temperature, carbon dioxide, 

 water, certain minerals, and chlorophyll. Photosynthesis, as is true 

 also of all other functions of the plant, is dependent upon a num- 

 ber of external and internal conditions. Neighboring plants may 

 reduce the light intensity so much that a seedling pine may not 

 be able to grow, or fundamental damage may be caused by leaf- 

 destroying insects. The individual plant in order to live must 

 establish successful relations with its physical environment as well 

 as with other plants and animals. 



In nature plants usually grow in groups, not as isolated individ- 



