liJt) Journal op the Mitchell Society [3Iarch 



6. Cliiiiquapin oak — small shagbark hickory — post oak — red cedar type, 

 quality 4. This covers a large portion of the limestone barrens of Tennessee 

 and Alabama. It passes especially at lower altitudes and outside of the moun- 

 tains into pure red cedar (cedar barren). 



7. Sweet gum — swamp southern red oak (Quercus pagoda) — spotted oak — 

 black gum — Acer tridens — green ash — Celtis laevigata type, quality 2. This 

 occurs along alluvials of larger streams at the southern end of Appalachians at 

 altitudes of 2,000 feet or less. (Appendix 18.) 



8. Sweet gum — white oak — black gum — shagbark hickory — sycamore type, 

 quality 2. This occurs on alluvials, chiefly of smaller streams at altitudes below 

 3000 feet in northern Georgia and below 1000 feet in the mountains of Virginia. 



9. Eiver birch — sycamore — red maple — black willow type, quality 3. This is 

 a riparian type and occurs on alluvials of smaller streams at altitudes below 

 2500 feet at the southern end of Appalachians, and in Maryland below 800 feet. 



APPENDIX 



(1) In Augusta County, Virginia, the Carolinian zone ascends to 1,100 feet; 

 in the French Broad basin, and southward to approximately 2,600 feet on sunny 

 slopes. See also Kearney, Science 12:831. 1900. 



(2) See also Warming, Ecology, 359. 



(3) Among the most important of these natural causes may be mentioned 

 insects. White pine and black pine have been practically exterminated over 

 wide areas from Pennsylvania southward since 1870 by the southern pine beetle, 

 Dendroctomis frontalis (see Hopkins' reports). Chestnut has ceased to exist in 

 great portions of Alabama, Georgia and the Carolinas, largely as a result of the 

 two-line chestnut borer and the root fungus. (See "Chestnut in Tennessee," 

 page 11.) Within the past decade the composition of stands in which the 

 hickories form a significant element has been seriously modified, especially in 

 northern Illinois and the adjacent region, by an insect (Scolytus quadrispinosus). 

 Two decades ago there was a similar modification in the composition of oak, 

 hickory, and rosemary pine stands in Piedmont Carolina, through the dying out 

 of the southern red oak and black oak, there being in many places a displace- 

 ment of the natural equilibrium which cannot be restored for many years. How 

 large a part drought, an extended period of which terminated about this time, 

 and insects relatively contributed to this condition is a subject of conjecture. 



(4) Dominant is employed in the sense of exceeding all other in height, its 

 significance in an extensive forest literature (see Standard Dictionary). Con- 

 trolling species is used to designate such as are numerically preponderant. 



(5) The basis for division is approximately the same as that Avhich has been 

 used in the work of appraising hardAvood timber lands for purchase for eastern 

 National Forests; i. e., an interval of 16 feet in the length of the merchantable 

 stem (a standard saw-log length) or 25 feet as the difference in the height of the 

 crown of the dominant trees, since approximately one-third of the total height 

 of a tree with a deliquescent form is in the crown and tAvo-thirds in the stem. 



