CHAPTER XXIV. 1 



THE RECOGNITION OF CHARACTER OF SOILS FROM THEIR 

 NATIVE VEGETATION ; MISSISSIPPI. 



Climatic and Soil-Conditions. Next to climatic conditions, 

 chief among which are temperature and moisture, the physical 

 and chemical nature of the soil and subsoil is the most potent 

 factor in determining the natural vegetation of any region. 

 The limitations we observe in the adaptation of cultivated lands 

 to certain crops, even with artificial help, must be much more 

 strongly pronounced when no such aid is given, and the strug- 

 gle for the survival of the fittest is continued, subject only to 

 seasonal variations, for thousands of years. It is obvious that 

 within the limits of the regional flora, the natural vegetation of 

 any tract represents the best adaptation of plants to soils, in 

 the results of long periods of the struggle for existence be- 

 tween competing species; the survivors being those best 

 adapted to the entire environment. 



In countries uninhabited by man the chief conditions outside 

 of the direct influence of climate and soil that may materially 

 affect the results of the competition are connected with the 

 animal creation ; and within the latter, insects are probably the 

 most influential, beneficially in the part they play in the fertil- 

 ization of flowers, injuriously in their role as parasites. Since 

 in the absence of man, the effects of fire would ordinarily be 

 conditioned upon the occurrence of thunderstorms, its effects 

 would then properly come under the head of climatic influences. 

 But while these and some other disturbing factors must not 

 be forgotten in considering the relations of soils to the 

 natural vegetation borne by them, the common consensus of 

 mankind has long recognized the intimate connection existing 

 between the two, and has everywhere made it the basis of at 

 least a general estimate of the agricultural value of the land 

 concerned. 



1 The special object of this chapter as a whole has seemed to the writer to r& 

 quire a repetition of much that is already said in the preceding chapters. 



487 



