20 TRANSACTIONS OF ROYAL SCOTTISH ARBORICULTURAL SOCIETY. 
late frosts than others; and although old trees do not prevent 
this altogether, yet the shelter afforded by the crowns lessens 
the danger considerably. Again, if the parent trees are allowed 
to stand too long, they have a deteriorating effect on the young 
seedlings, by checking their growth or causing them to grow up 
weak and crooked. 
On ground stocked with light-demanding species, the old trees, 
and especially oak, may be dispensed with early. 
The removal and cutting of old standards on a regenerated 
area is always a matter of difficulty, as a certain amount of 
damage cannot be avoided. But if the trees have been carefully 
selected, and only those with narrow crowns left, the damage is 
not so serious as one would expect. Young trees quickly replace 
a broken leader, and if the crop is thick a few are never missed. 
In removing the trees, it is a wise policy only to use a janker, 
as the logs can then be lifted and taken out easily with little 
damage, because the tramping and moving about of men and 
horses necessary for loading on an ordinary cart often causes 
more damage than the fall of the trees. 
As regards coniferous woods, the two principal factors which 
determine the success or failure of natural regeneration are the 
surface-weeds, and the annual fall of dead needles. As to 
the former, much depends on the leaf-canopy. Shade-bearing, 
heavily-foliaged trees, such as spruce or silver fir, check under- 
growth much more effectually than the majority of pines, which 
allow more light to penetrate through their crowns. But a great 
deal also depends on the density of the crop. As the majority 
of Scots pine-woods are too open, undergrowth of a varied 
character is then always to be found. Open woods are un- 
doubtedly more pleasing to the eye than close canopy with 
comparatively bare poles; and the prospect of a quick return 
from early thinnings may induce over-thinning, present require- 
ments being considered before future advantages. 
In over-thinned woods the thick undergrowth not only retards 
the germination of seed, but also uses up a great deal of plant- 
food otherwise available for the growth of the crop. In woods 
covered with weeds, seedlings may often be found wherever the 
mineral soil has been laid bare, ¢.g., as where wood has been 
dragged. Hardwood seedlings, being stronger and more robust 
than those of conifers, are able to push their radicle through the 
roots of the grass to the soil beneath; but seedlings of conifers 
