162 FORESTS, WOODS, AND TREES 
shallow soils, and is remarkably resistant to wind. It is, 
however, slow in growth under these circumstances, pro- 
ducing a remarkably tough wood. Cornish elm is suitable 
for planting in shelter belts near the sea, and may be 
introduced into broad-leaved woods in Wales, Ireland, and 
the west of Scotland. 
5. Dutch elm (Ulmus major). The origin of this tree is 
obscure. It is now widely spread in hedgerows in England 
from Cornwall to Yorkshire. It produces suckers freely, 
but the seed is absolutely unfertile. This elm grows fairly 
well in clay soil, and produces a soft wood, which is readily 
worked by the carpenter, and is used for purposes where 
strength is not required. 
6. Huntingdon elm (Ulmus vegeta). This elm is of 
hybrid origin, and is remarkably fast in growth. So far as 
I know, it has never been planted as a woodland tree; but 
it deserves a trial in plantations at low elevations, where, 
mixed with beech in small groups, it would probably 
develop a tall, straight, clean stem. Planted in the open, it 
tends to be wide-spreading in habit. 
Bireh.—The birch, being a light-demanding tree with 
very sparse foliage, does not improve the soil to any con- 
siderable degree ; and its production of timber per acre is 
meagre, Nevertheless its use in forestry is not un- 
important, as it is our hardiest tree, capable of growing in 
the poorest soils, and reproducing itself with the greatest 
ease. Natural woods of birch occur at higher elevation 
than those of any other species, ascending in some Highland 
glens to 2000 feet. In the Pennines, birch forms woods 
up to 1250 feet, and scrub as high as 1500 feet elevation. 
The ground vegetation in such wood or scrub differs little 
from that of the adjoining hill pasture or moorland ; and 
may consist of wiry grasses, heather, and bilberry, or be 
wet moor with peat plants. Birch thus occupies parts of 
the hill pasture and heather moor zones; and would doubt- 
less spread over much more extensive areas, but that it is 
kept down by grazing, as sheep destroy the seedling trees. 
