The Jersey City news. (Jersey City [N.J.]) 1889-1906, 1896-05-28
WHAT FORESTS Do.
State Biologists Report
Discusses a Very In
tefesting Subject.
RELATION OF TREES TO STREAMS
Grounds for Belief That Cutting
Forests Is Harmful to the
Watersheds of New Jersey.
ELATION OF TREES TO STREAMS
Grounds for Belief That Cutting

1t Is a very common belief among those
Interested in pure drinking water that
the presence of forests in the vicinity of
streams used for water supply for towns
is bad because of the decayed vegetation
which must get into the water and be-
cause trees absorb moisture which would
otherwise go into the streams. TIL re-
Gently published report of the State Geo.
lcgist has something to say upon this I'M
portant and extremely interesting subject,
the relation of forests to the flow of
streams and to the watershed. The most
Highland watersheds in New Jersey are
the ~headwaters of the Passaic, says that
branch of the report, and the principal
Importance to be attached to the proper
ton OF forest on the watershed Is that it
is indicative of absence of cultivation n
to a certain extent of population, conse-
quently there is less roiliness of the wa
ter and less liability to pollution where
the percentage of forest is large.
While, as a whole, the report goes on to
say, the Highland streams are of good
quality in their natural coalition and good
potable waters, 1t is nevertheless plainly
evident that those streams which have their
catchment in the northeastern glaciated
Highlands, carry much Tess sediment and
are purer and clearer than those in the
more highly cultivated southwestern
Highlands. This fact the State Geologist
thinks is partly due to the large percent
age of forest and less extent of cultivated
lands in that region. On the red sandstone
THE Hackensack catchment has about 60
per cent. of forest area, and it is due to
this fact hat the Hackensack carries
much less sediment than streams like the
Raritan on the deforested portion of the
Red Sandstone.
Since 1890 the State Geologist and his
able assistants have given much atten-
ton to the relation of forests to the flow
of streams. The question of The effect of
cutting OF the forests was forced on their
attention because they noticed through
out the State thai streams had
been unfavorably affected by the cutting
Off Of forests. The grounds for this belief
that streams had fallen to a lower stage
than formerly appeared in the fact that
the RancocaS and other branches of the
Delaware, the Rarbtan, etc, had formerly
but now 1T would be impossible. 1t was
claimed by these who had given the SUBJ
Jeet some attention that these rivers run
much lower than formerly and are more
subject to serious floods as witness that
OF the Raritan only a few months ago. It
was ALSO found that the extremely dry
spread expression Of these views, and the
cause assigned was almost Invariably the
cutting off of forests. Writers. on for
estTy and advocates of forest protection
were foremost in that opinion.
After a careful study, the report thinks
that a. correct comparison of evaporation
from forested and deforested watersheds
cannot be made without allowing for diff
terence in temperature, and without such
allowance in many cases forested water
sheds show a much larger evaporation
that those almost entirely deforested.
The more water that is drained out
from the soil the more can be absorbed
When the heavy rains come at the end of
tine thoughts. Humus in the forest forms
q great sponge, the report says, and Of
itself holds a large amount of water.
while 1t and the Inequalities caused by
tree roots. ETC., tend to prevent the water
moving over the surface and the roots of
the trees proved channels by which the
water percolates into the sub soil readily.
In this way the forest will easily absorb
a larger amount OF water than open lands.
A nigh state of cultivation also has a
tendency to increase the capacity Of the
ground to absorb water because of con-
slant loosening of the surface and the
T rsss PROVIDED for ready drainage. In
TO render floods less frequent; but the ef-
feet OF the drainage of the soil is that
the ground water absorbed is fed out
more rapidly to the streams during the
early months of a dry period than Is the
case in forests; consequently the ground
water is sooner exhausted and the dura-
tion Of the low stages Of the rivers during
protected droughts is thereby lengthened
Barren watersheds offer much less cana
city for absorption of rainfall. There is
no humus or other matter on the surface
to retain the rain and the ground becomes
hard and resists free percolation. The DIFF
ference, concludes the report. between
forested and deforested watersheds IS
very wen Illustrated by the Passaac and
'the small red sandstone watersheds ara
GOOD types or barren country.