18 BULLETIN 299, U. S. DEPARTMENT OF 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 thsir 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. 
