CONDITIONS OF DEVELOPMENT. 61 



amount of transpiration to be performed by the foliage, and again with most species we must place 

 this transpiration movement into relation with available soil moisture, in order to determine what 

 the requirements and the most suitable habitat of the species are" (B. E. Fernow). Hence we find 

 that east of the Mississippi River the Longleaf Pine occurs in greatest frequency along the isotherm 

 of 6(P F. ranging to the 34° north latitude, while west of the Mississippi it follows a line between 

 the isotherms of 03° and 64° F. and is scarcely found north of the thirty-second parallel of north 

 latitude. Within this area of its distribution it is exposed to wide variation of temperature and 

 moisture conditions. 



Under the intluence of the vapor-laden breezes from the Mexican Gulf and an evenly distributed 

 rainfall ranging from 42 to 03 inches during the year, the Longleaf Pine appears of the same thrift 

 and vigor of growth in tlie interior of Alabama under 34° to 3.3^ north latitude, with the ther- 

 mometer falling as low as 4^ F. ( — 10° (J.) and a range of temperature of !)3o (at Tuscaloosa), as it 

 is found in the subtropical belt of the coast with a maximum temperature of 105° F. (40° C.) and a 

 range of temperature of 94"; west of the Mississippi River, beyond longitude 97° and above 

 latitude 32°, although the temperature reaches rarely a minimum of 15°, the diminished humidity 

 of the atmosphere and lesser rainfall, particularly during tbe warmer season, account for its 

 absence. There can be no doubt that the greater exposure to the violence of the sudden gusts of 

 dry and cold wind known in Texas as "dry northers" exercises also no small inlluence in limiting 

 the Longleaf Pine. 



ASSOCIATED SPECIES. 



The Longleaf Pine is eminently a gregarious tree, covering areas of wide extent, to the almost 

 complete exclusion of any other species. In the fiat woods of the coastal plain, particularly near 

 its northern limit on the Atlantic Slope, it is not infrequently associated with the Loblolly Pine; 

 farther south and along the Gulf Coast to the Mississippi River, more or less frequently with this 

 tree and tbe Cuban Pine. In the upper part of the maritime pine belt it not rarely occurs together 

 with the Shortleaf Pine and the Loblolly Pine intermixed with the deciduous trees of the uplands, 

 viz, the P>lack Oak, Spanish Oak, Black-jack, Bitternut, Morkcinut llickm-ies, and Black Gum. 



It will be apparent, from what has been said regarding the demands for light, that the asso- 

 ciated species must be either slower growers or later comers, if the Longleaf Pine is to survive iu 

 the mixture. As has been pointed out elsewhere, with the culling of the Longleaf Pine from the 

 mixed growths it must soon cease to play a part in them, since its renewal under the shade of 

 the remaining associates is impossible. 



ENEMIES. 



The greatest danger threatening the existence of the forests of Longleaf Pine must be ascribed 

 to the agency of man, since their destruction is caused chiefly by the reckless manner in which 

 they are depleted without heed to recuperation. The right of ownership has been generally 

 acquired on such low terms that since no value has been attached to the laud without the 

 timber, despoliation has been carried on with no other object than the quickest return of 

 momentary profits. 



EXPLOITATIOX. 



Such management could not but entail tremendous waste, a large percentage of the body of 

 the trees felled being left on the ground to rot or to serve as fuel for the conflagrations which scour 

 these woods almost every year. Infinitely greater than the injuries inflicted upon the forest by 

 the logger and by getting out cross-ties and hewn square timber, which consist chiefly in the 

 accumulation of combustible waste, are those caused by the production of naval stores. When 

 the fact is considered that the production of the 40,000 barrels of spirits of turpentine, which on 

 an average during the latter half of this decade annuallj' reached the market of Mobile alone, 

 implies the devastation of about 70,000 acres of virgin forest, the destruction caused by this 

 industry appears iu its full enormity. Under the management of the turpentine orchards 

 l)revailing at present, trees of such small size are tapped that they are unable to resist the force 

 of the winds, and in a few years are inevitably prostrated, while the larger trees, weakened by the 

 severe gashes on almost every side, become largely wind shaken, and the timber after a longer 

 lai)se of time loses much iu value. 



