312 
TREES OF SOUTHERN EUROPE. 
a partial compensation for the loss of the native forest. It is 
true that these trees, planted as most of them are, at such dis¬ 
tances as to admit of cultivation, or to the growth ol grass 
among them, are hut an inadequate substitute for the thick 
and shady wood; but they perform to a certain extent the 
same offices of absorption and transpiration, they shade the 
surface of the ground, they serve to break the force of the 
wind, and on many a steep declivity, many a bleak and barren 
hillside, the chestnut binds the soil together with its roots, and 
prevents tons of earth and gravel from washing down upon 
the fields and the gardens. Fruit trees are not wanting, cer¬ 
tainly, north of the Alps. The apple, the pear, and the prune 
are important in the economy both of man and of nature, but 
they are far less numerous in Switzerland and Northern 
France than are the trees I have mentioned, in Southern 
Europe, both because they are in general less remunerative, 
and because the climate, in higher latitudes, does not permit 
the free introduction of shade trees into grounds occupied for 
agricultural purposes.* 
The multitude of species, intermixed as they are, in their 
spontaneous growth, gives the American forest landscape a 
variety of aspect not often seen in the woods of Europe, and 
* The walnut, the chestnut, the apple, and the pear are common to 
the border between the countries I have mentioned, but the range of the 
other trees is bounded by the Alps, and by a well-defined and sharply 
drawn line to the west of those mountains. I cannot give statistical details 
as to the number of any of the trees in question, or as to the area they 
would cover if brought together in a given country. From some peculi¬ 
arity in the sky of Europe, cultivated plants will thrive, in Northern Italy, 
in Southern France, and even in Switzerland, under a depth of shade 
where no crop, not even grass, worth harvesting, would grow in the 
United States with an equally high summer temperature. Hence the 
cultivation of all these trees is practicable in Europe to a greater extent 
than would be supposed reconcilable with the interests of agriculture. 
Some idea of the importance of the olive orchards may be formed from 
the fact that Sicily alone, an island scarcely exceeding 10,000 square miles 
in area, of which one third at least is absolutely barren, has exported to 
the single port of Marseilles more than 2,000,000 pounds weight of olive 
oii per year, for the last twenty years. 
