NATURAL AREAS AND REGIONS 



441 



swamps which are filled with water 

 during flood seasons. 



CLIMATE 



Difference in latitude, combined with 

 higher altitudes in the north, give a 

 gradation in temperature from one end 

 of the state to the other; but the range 

 of temperature, either regional or 

 seasonal, is not very great. The mean 

 for the state as a whole is G3°. The 

 winter mean in the north is 41°; the 

 summer mean in the south is 81°. The 

 rainfall throughout the state, except 

 in the immediate vicinity of the coast 

 where it is somewhat greater, is about 

 52 in. per year. In general the greatest 

 rainfall occurs in summer in regions of 

 pine forest, and in winter in regions of 

 hardwood forest. The distribution of 

 vegetation within the state seems to 

 correspond much more closely to soil 

 than to climate, however. 



SOIL 



Throughout the greater part of the 

 coastal plain the predominating soil 

 type is sandy loam, usually somewhat 

 intermixed with clay or loam. A con- 

 siderable part of this region is under- 

 laid by limestone, but the surface soil 

 is often sandy. The black belt (prairie) 

 has rich soil, formed by the weather- 

 ing of soft limestone, which extends 

 in a band about thirty mi. wide 

 nearly across the state just south of 

 the central part. North of the black 

 belt, the remainder of the coastal plain 

 is mingled clay and sandy loam, gener- 

 ally deficient in lime. 



In the hilly country to the north, the 

 soil is less sandy. The soil here has 

 mostly been formed by the weathering 

 of the hard rocks of the region. As 

 streams cut through and expose to 

 weathering agencies the different layers 

 of rock, the soil even of a limited area 

 is necessarily very variable. A brief 

 account of the soils of separate sub- 

 divisions will be found in the second 

 part of this report. 



Coniferous forests, principally of long- 

 leaf and shortleaf pine, occur throughout 



the state wherever the soil ia poorest. 

 Pine forests (especially those of Iohr- 

 leaf pine) are subject to fires which, 

 feeding on fallen needles, do.stroy other 

 vegetation but apparently do not injure 

 the pines. The fires destroy the humus 

 in the soil and keep the soil poor in 

 nitrogen. Regions protected from fire 

 by ravines or forks of .streams, even 

 though in a pine forest territory u.sually 

 develop patches of hardwooil forest. 



ORIGINAL BIOTA (m. 8. J.) (a. II. H.) 



1. Vegelalional regions 



Alabama can be divided, very roughly, 

 into a northern deciduous forest and a 

 southern coniferous forest area. In- 

 cluded within the coniferous forest area 

 is a prairie belt, corresponding to the 

 black belt already referred to under 

 the heading "Soil." This division into 

 vegetational regions is somewhat in- 

 definite, though, for a certain proportion 

 of one forest type occurs in the territory 

 of the other; and between the two, and 

 in certain local areas elsewhere, the two 

 types of forest grow mixed together. 

 Besides these principal forest types, 

 which themselves can be further sub- 

 divided (as in the second part of this 

 paper), are various other les.ser vegeta- 

 tional regions, locally distributed and 

 dependent on local conditions. Animal 

 distribution is influenced by the various 

 factors which affect plant distribution, 

 and by plant distribution itself. 



a. Deciduous forest. The deciduous 

 forest of Alabama is primarily oak. 

 White oak,' post oak, red oak, black 

 oak, black-jack oak, chestnut oak, and 

 Spanish oak are most common of the 

 many oaks. Other trees characteristic 

 of deciduous forest are tulip po|)lar, 

 sweet gum, chestnut, beech, hickory, 

 and dogwood. Even in the deciduous 

 forest areas, though, shortleaf pine is 

 often more abundant than any otlu-r 



one tree. 



Animals. iMammals: Virginia opos- 

 sum {Didclphis virginiana), common, 



» Scientific names of trecearc given in the second 



part of this paper. 



