permits fullest use of the environment and maximum production 

 on a sustained basis. 



The composition and population of the climax are determined 

 by all factors of the mature ecosystem, not by any one factor. 

 These factors are the properties of each species, biotic interrela- 

 tions, floristic and faunistic availability, chances of dispersion, 

 interaction, soils, climate, and possibly special factors such as 

 fire, wind, snow, and salt spray. 



Climax vegetation may be considered, according to Whit- 

 taker, 2°^ as a pattern of populations corresponding to the pattern 

 of environmental gradients. The relationships among the popula- 

 tions change with alterations in these gradients. The vegetation 

 pattern is more or less diverse in accordance with the diversity of 

 the environmental complex, and the composition of the climax 

 type is meaningful only in relation to its particular spatial posi- 

 tion on the environmental gradient. There is convergence or 

 succession to similar structural-functional population patterns in 

 similar environments, yet this is partly independent of the original 

 environmental conditions and the course of development. There 

 is a homogeneity between stands on similar sites, and any varia- 





Figure 5-8. A vigorous 

 clump of Bouteloua gracilis. 

 August, San Antonio, Texas. 

 (U.S.D.A. Soil Conservation 

 Service.) 



