any other kind could be seen as far
as the fire had reached.

In the Michigan Peninsula, northern Wisconsin and Minnesota, _P.
Banksiana_, a comparatively worthless tree, is replacing the valuable
red pine (_P. resinosa_), and in the Sierras _P. Murrayana_ and _P.
tuberculata_ are replacing the more valuable species by the same
process.

In this case, also, the worthless trees are the shortest lived. So we
see that nature is doing all that she can to remedy the evil. Man only
is reckless, and especially the American man. The Mexican will cut
large limbs off his trees for fuel, but will spare the tree. Even the
poor Indian, when at the starvation point, stripping the bark from the
yellow pine (_P. ponderosa_), for the mucilaginous matter being formed
into sap wood, will never take a strip wider than one third the
circumference of the tree, so that its growth may not be injured.

We often read that oaks are springing up in destroyed forests where
oaks had never grown before. The writers are no doubt sincere, but
they are careless. The only pine forests where oaks are not intermixed
are either in land so sandy that oaks cannot be made to grow on them
at all, or so far north that they are beyond their northern limit. In
the Green Mountains and in the New England forests, in the pine
forests in Pennsylvania, in the Adirondacks, in Wisconsin and
Michigan--except in sand--I have found oaks mixed with the pines and
spruces. In northwestern Minnesota and in northern Dakota the oaks are
near their northern limit, but even there the burr oak drags on a bare
existence among the pines and spruces. In the Black Hills, in Dakota,
poor, forlorn, scrubby burr oaks are scattered through the hills among
the yellow pines. In Colorado we find them as shrubs among the pines
and Douglas spruces. In New Mexico we find them scattered among the
pinons. In Arizona they grow like hazel bushes among the yellow pines.
On the Sierra Nevada the oak region crosses the pine region, and
scattering oaks reach far up into the mountains. Yet oaks will not
flourish between the one hundredth meridian and the eastern base of
the Sierras, owing to the aridity of the climate. I recently found
oaks scattered among the redwoods on both sides of the Coast Range
Mountains.

Darwin has truly said, "The oaks are driving the pines to the sands."
Wherever the oak is established--and we have seen that it is already
established whereever it can endure the soil and c