HARPER: VEGETATION OF THE PINUS TAEDA BELT 45 
frequent fires. South Carolina is probably above the average in 
calcium, phosphorus and iron, on account of the occurrence of 
those elements in the underlying strata. 
Another pretty good indication of soil fertility or the lack of it 
is the density of population, proportion of “improved land,’’ and 
the annual expenditure per acre for fertilizers.* In the table 
below these data are given for the portions of the belt under con- 
sideration in each state, and also for the whole of each state and 
the United States, as computed from the reports of the roth and 
13th censuses.t 
Inhabitants per Pons Jn of | Expenditure for 
square mi cre 
Areas ile mproved land | fertilizer pera 
1880 Ig10 1880 | 1910 1879 1909 
Pinus efi belt: 
Virbinia Aa ee 29.4 | 40.7 | 25.9 | 28.1 | $0.45 | $1.89 
No ap Cucaiian Sie NES HTN Tas 28:8 442.0 10.8). 279-2 41 | 2.67 
South Carouna 53355 ha. hae kw os 27.5 "|" 41.0 | 18.457 30.0 e713 AAT 
bide! Sern 
hE AE RNG eas cag See TR SO ss ay ci.2 33:0. 5228.3 25 | 0.70 
Mek th "Carolina CES aed apa Meo na Orie as 28.7: 1545.4. }° 20.82) 28.2 ‘531 £30 
South Carolina <3. vos 32.0.1 49-7. | 21.21 323 64 | 2.49 
Whole United States. 20. i. 60n005 es 16:05 | 3320.0: 4215.02 1 26.t | ‘TO | 0.247 
These statistics ought to make it plain enough that the soil of 
the Pinus Taeda belt is less fertile than the average of the states 
in which it lies, and that in this belt the soil fertility tends to 
decrease a little southward. The great increase in the use of 
fertilizers between 1880 and 1910 probably does not indicate soil 
exhaustion so much as that the greatly increased output of the 
nitrate, phosphate and potash mines in other parts of the world, 
together with the improvement of transportation facilities, makes 
it possible to cultivate with profit much poorer soils than formerly. 
Climate. As far as climate is concerned it will probably 
suffice for present purposes to give for one station in each state 
the mean temperature for January, July and the year, in degrees 
Fahrenheit, the average annual precipitation, in inches, and the 
* See Science II. 42: 500-503. Oct. 8, 1915. 
+ For some similar statistics for ae Abst ives states and their economic 
significance, with a map of the pine-barren region, see Journal of Geography 14: 
42-48. Oct. 1916. : 
