The record-union., 1899-09-14
TREES AND RAINFALL.

O%@AS~N
lows:
Il have noticed that writers in your
valuable paper have taken the position
that the natural growth Of trees has
tendency to produce rain. / have
been living here in Colusa County over
thirty years Since the beginning Of
1873 have kept a very careful account
of the rainfall here. The average fall
for twenty years up to 1898 was 25.3s
inches. For the last ten years it was
2S.34 inches, and for five years 81. 19.
Now does it not seem reasonable that
with this knowledge. should we. begin
to figure how to take care of more
rain2 In 1898 we had 9.75 inches and
in 1899 1884. Can you give your read
ers some reason for this? / have often
read that a country after being settled
up for a number OF years has more
regular weather. do not suppose that
in any country have fruit trees been
put out so plentifully, or as fast as
here. Why should one then, when in
these days we seek a cause for every
thing, not come to the conclusion that
the increase in these trees has in
creased the rainfall?"
Whether the conclusion of our corre-
Epondent is sound or not it has been
settled by observation. which brooks no
denial. that there is intimate relation
between rainfall and tree growth To
what extent the increase of orchard
tree growth augments rainfall it is
difficult to say, but that forest growth
promotes it and aids to its better
distribution is undeniable. We do not
need to seek for reasons since it is
a demonstrated fact. and with that we
have been repeatedly set forth in these
columns so frequently that it. is un-
necessary to repeat many of them.
But it is at all times useful to give
the reasons why destruction Of forest
growth decreases the right distribution
of rainfall lessons the volume of the
fall. and endangers the lands below the
water sheds. In brief. tree growth con-
serves humidity of the atmosphere and
the soil, equally and regularly by nat
ural processes. One of these involves
evaporation, another the checking of
the currents of the atmosphere laden
with moisture, and others induce wide
and even distribution of deposition of
moisture
Vegetation in any form is the natural
cover and protector of the soil. In for
ests its greatest energy is manifest.
Remove these and we disturb the nice
balance nature provides for the dis
tribution Of her benefcence. Hence in
treeless regions the storm waters reach
the earth unimpeded. wash off the soil,
gully and scour it out. choke the rivu-
let's and convert creeks into torrents,
and rivers fed by these suddenly rise
and flood the country they should
drain.
But rainfall ina timbered country is
most largely absorbed. not only by the
foliage to a certain degree. but by the
vegetation protected soil. But where
the earth is bare and unprotected there
is least absorption and greatest run
off of the water. instead of a gradual
and extended feeding of the streams
and saturation of the earthly surface.
Again in a treeless land the layers of
hot, cold, moist and dry atmosphere
can superimpose themselves. as DR..
Manson showed recently in his paper
on effects Of deforestization. In such
cases when condensation takes place
which means precipitation-the latter
is sudden, violent and destructive.
Tree growth less induces rain than it
serves to modify rainfall and adapt it
to the needs Of the SOIL Thus In tropi-
cal regions the rainfall is very heavy
and long continued. But such regions
are richly covered with Vegetation and
the result is that the running ofe of
the waters is checked by absorption.
Thus retained the water is slowly fed
to the natural channels for its depart
ure to the sea, and large quantity is
again taken up by evaporation, not only
from the soil but from the foliage
which is fed through the tree trunks
by methods familiar to every school
boy.
DR.. Manson shows in his late mono
graph that in many forests In Cali
fornia it takes more than five inches
of rainfall in the autumn to give an
appreciable Increase of run off, prov
ing that the forest has checked the
rate Of run off. aided the soil storage
Of water, and preserved the springs,
streams and artesian supply. In our
northern counties, says the same scien-
tist, where the timber is heavy and
widespread the channels OF the streams
are far less in capacity than in the
more southern counties. where there is
much less timber. But in these northern
counties where the rainfall is from 5O
to go inches annually. the streams
carry the waters, their flood capacity
being equal to the demand upon them;
while in the treeless regions the soil
has small storage capacity and the
waters exceed the flood ability of the
natural drainways-the streams and
rivers, and hence we have disastrous
floods in one place and slow and harm
less run offs in the other.
Recurring TO the inducement of rain
by forests, it is to be said that as for
ests affect temperature in any given
section. and that has to do with the
moisture bearing character of the at
mosphere, it is reasonable to say that
forests have tendency to induce rain