Trees and Shrubs* 
19 
greatly reduced the population. On the first 
cry of independence, a number of slaves obtain¬ 
ed their liberty by fighting under the standard 
of the new republic. Its wide-spreading culti¬ 
vation was neglected; the forest trees, so luxu¬ 
riant within the tropics, had again, in a great 
measure, usurped dominion over that region, 
which its inhabitants, after a century of constant 
and painful labor, had reclaimed. During the 
growing prosperity of the valley of Aragua, 
the numerous streams which fed the lake, had 
been arrested and employed in innumerable irri¬ 
gations, and their beds were found dry for 
«iore than six months in a year. At the last 
epoch to which we have alluded, 1822 , the 
streams being no longer so diverted, flowed 
without interruption. Thus, then, the progress 
and continuance of agricultural industry in the 
valley of Aragua, when the process of clearing 
was carried farther and farther, and when culti¬ 
vation in every variety was advancing, the level 
of the water gradually subsided. More lately, 
on the contrary, during a period of misfortune, 
when the clearing was no longer continued, 
and the cultivated lands have fallen back into 
their primitive wildness, the waters having 
ceased to fall, and are now very speedily assum¬ 
ing a rising movement. 
The same facts are corroborated by numerous 
other instances. “ In laying low the forests/' 
says Humboldt, “ which cover the tops and the 
flanks of the mountains, mankind, in all cli¬ 
mates, are, at one and the same time, entailing 
two great calamities upon succeeding genera¬ 
tions—a scarcity both of wood and of water.” 
The truth of this remark we find verified by 
examining the history of all the civilized coun¬ 
tries of the globe. The influence of forest sce¬ 
nery in increasing the moisture of the atmos¬ 
phere, and in preventing a climate from being 
so hot in summer, and so cold in winter, as it 
would otherwise be, is well understood, and need 
only be mentioned. 
The utility of studying the influence of trees 
in an uncultivated country is, to afford useful 
hints with reference to the planting or thinning 
of them in countries which are civilized. That 
which is applicable on a grand scale, where 
forests cover many thousand acres, must operate 
more or less in the same manner where they 
extend only to a few acres; and, consequently, 
this influence must be kept in view in the for¬ 
mation of plantations both useful and orna¬ 
mental. If forests, in their primitive state, sup¬ 
ply food to birds and insects, or afford shelter 
to larger animals or reptiles, in a civilized coun¬ 
try birds and insects, larger animals and reptiles, 
may be expected to abound more or less wher¬ 
ever there are trees and shrubs to supply them 
with food and shelter. Hence the advantage of 
knowing what trees and shrubs are obnoxious 
to particular insects, and what inseets attack 
trees and shrubs generally. The total destruc¬ 
tion of herbaceous plants in dense forests ena¬ 
bles us to know, that, where we wish the grass 
or other herbage under trees to thrive, we must 
plant or leave the trees thinly; and the influ¬ 
ence from the decay of leaves, branches, and 
trees, in adding to the soil teaches us how bar¬ 
ren soil may be improved by trees; and this 
natural effect has been imitated by trenching 
down entire plantations of Scotch pine, grown 
on extremely poor soils, in some parts of Scot¬ 
land. Undrained woods are known to retain 
the water which falls on them much longer 
than open groves or plains; and, as increased 
exhalation and evaporation must be going on 
from such woods during the period of retention, 
an increased moisture must be thus produced in 
the atmosphere, and the circumstance may de¬ 
mand consideration in planting extensive shrub¬ 
beries near dwellings ; and, more especially, in 
jplanting such as art intended, by frequent dig- 
iging, always to present a surface of naked loose 
jsoil. The influence of trees in modifying both 
ithe temperature and moisture of the atmosphere 
im civilized countries and in artificial scenery, is 
jgenerally known; and this knowledge should 
’not be lost sight of in the disposition of trees 
land shrubs about houses, more especially in low 
Situations. There is great reason to believe that 
I many residences in this country and particularly 
in England, naturally healthy, are rendered un- 
I healthy by the superabundance of trees and 
jshrubbery, and by the quantity of loosened earth 
!in their immediate vicinities. The insects which 
ioften infest the rooms of our houses, are also 
very much increased by the proximity of wood. 
From trees and shrubs in a wild state we can 
only truly learn their primitive natures; be¬ 
cause plants, like animals, begin to change their 
habits as soon as they are taken into cultivation. 
The fact that this change takes place ought to 
be borne in mind, when we wish to improve a 
tree by placing it in a different soil or situation 
from that in which it is found in its natural state. 
There are certain soils and situations, however, 
in which plants are found in a wild state, that 
can hardly be improved by art; these are peat 
bogs or swamps, such as are found in many 
parts of our country, and Alpine situations. 
So various and so important are the uses of 
trees and shrubs to man that to say much on the 
subject here would go beyond our circumscribed 
limits. In spring, when they put forth their 
young buds ; in summer, when they exhibit their 
fully-expanded leaves; in autumn, when robes of 
every variety of hue are hung upon their branch¬ 
es ; in winter, when the glory of summer is 
‘ trodden under foot, presenting around a scene 
