THE ASHES: THEIR CHARACTERISTICS AND MANAGEMENT. 13 
18. F. dipetala Near foothill streams and in gulches; in dryish or 
slightly moist rocky and gravelly soils; in clumps 
mingled with other chaparral species; inner coast 
ranges and foothills of the Sierra Nevada in Cali- 
fornia. 
OCCURRENCE OF IMPORTANT SPECIES AND THEIR ASSOCIATES. 
Ash, with its wide geographic distribution and many different 
forms and species, naturally occurs on a great variety of sites and in 
many forest types, but usually forms only a small percentage of the 
trees of any stand. Exceptions to this are the occurrence of green 
ash as a principal tree on limited areas of overflow river bottoms of 
the Mississippi and its tributaries, but usually in comparatively young 
stands less than 100 years old; of white ash as a principal tree (very 
rarely) on small areas of second-growth upland hardwood stands oh 
fairly moist soil; and of black ash as occasionally a principal tree in 
virgin swamp forests of the Lake States. In old-growth virgin 
stands white and green ash never form more than a small percentage 
of the merchantable stand, which is mainly of longer-lived, more 
persistent trees, such as the oaks, birch, beech, sugar maple, yellow 
poplar, hemlock, white pine, and spruce, red gum, and cypress. Any 
agency removing the old growth, such as lumbering, often gives 
white and green ash a chance to become, by their good natural re- 
production, relatively more important in the second growth. 
WHITE ASH. 
White ash occurs on comparatively well-drained sites along small 
streams, in swales and coves, and on moist north and east slopes, 
usually where the soil is both moist and permeable. It will grow even 
in comparatively wet places, provided there is good underdrainage. 
It occurs in three distinct forest types or associations of trees, in all 
of which hardwoods predominate: (1) birch-beech-maple-bass wood 
type; (2) mixed oaks and chestnut type; (3) yellow poplar type. In 
places these types often merge into each other. White ash occurs 
most frequently in the birch-beech-maple-basswood and the yellow 
poplar types, where it attains good development and is usually a 
dominant forest tree. In the mixed oaks and chestnut type it is 
usually subordinate. 
The birch-beech-maple-basswood type is the common northern 
hardwood forest, which extends south into the Appalachian Moun- 
tains at constantly higher elevations to northern Georgia and Ala- 
bama. The hardwoods of this type include yellow and black birch, 
beech, hard and soft maples, basswood, white ash, white elm, bitter- 
nut hickory, and black cherry; and in the southern Appalachians, 
cucumber, yellow buckeye, chestnut, and oaks. Coniferous species 
