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 on 

 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-basswood 

 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 



