18 BULLETIN 299, U. S. DEPARTMENT OP AGRICULTURE. 



soil comparatively moist during a considerable part of the growing 

 season. It is exacting in regard to mineral food in the soil and is 

 somewhat exhausting to it. It does well on rich, loose, limy, or 

 marly soils, and some species even on dry limestone soils. It does 

 not do well on binding or argillaceous soils or on dry sand. On 

 porous soils which offer no hindrance to the developing root system 

 it is as a rule less exacting in regard to surface moisture and fertility 

 than it is on stiff impermeable soils. Ash is adapted, some species 

 more than others, for growing in swamps provided the soil is not 

 acid and there is no turf, but it prefers a rich, moist soil which has a 

 rapid renewal of the water through either surface or subterranean 

 drainage. 



Although all species of ash thrive best on moist, well-drained, 

 fertile, porous soils, yet the different species vary in their ability to 

 grow on very wet or on dry soils. The important wet-soil species, 

 in the order of their relative capacity for growing on wet sites, are 

 water, black, pumpkin, and green ash, while the species which will 

 endure dryness of soil (east of the Mississippi) are, in the order of 

 relative capacity, blue, Biltmore, and white ash. West of the Mis- 

 sissippi the green ash forms in the fertile prairie and plain States 

 (where red and green ashes run together) are very enduring under 

 dry conditions, as are also the southwestern species of the green ash 

 group. 



LIGHT. 



Ash is a light-demanding tree, except for the first few years, during 

 which it does best where the soil is shaded. In youth it is more 

 tolerant than oak and reproduces itself well under a comparatively 

 dense forest cover, because this provides, usually, suitable soil- 

 moisture conditions. The seedlings here show great persistence and 

 tenacity and are able to survive for some time. As an underwood 

 in broken forests seedlings thrive well. After the pole stage, how- 

 ever, ash becomes very light-demanding and space-demanding, espe- 

 cially in pure stands, which is a natural result of its wide-spreading, 

 soil-exhausting root system. The relative intolerance of ash is less 

 apparent because it is most often found on moist fertile soils where trees 

 of all kinds have their greatest tolerance. The effects of even slight 

 shading or crowding on the side is at once apparent in long, clear, 

 thin, spindly boles and small crowns. Ash often shows, however, 

 excellent persistence under unfavorable light conditions, although 

 making no substantial growth, and is quick to recuperate and respond 

 to increase in light. The extreme sensitiveness of ash in this respect 

 is one of the things which commend it for forest management. 



Blue, black, and white ash are the most tolerant and persistent 

 under adverse light conditions, and green and pumpkin ash the 

 least so. 



