Fort Collins, Colorado 80521. June ... Southwest Forest and Range Experiment Station. ..... ments taken at one point in time and at relatively shallow depths.
DISSERTATION
LOGGING EFFECTS ON SOIL MOISTURE LOSSES
Submitted by Robert Ruhl Ziemer Department of Earth Resources
In partial fulfillment of the requirements for the Degree of Doctor of Philosophy Colorado State University Fort
Collins,
Colorado
June, 1978
COLORADO
STATE
UNIVERSITY
June, 1978
WE HEREBY RECOMMEND THAT THE DISSERTATION PREPARED UNDER OUR ON
SUPERVISION SOIL
MENTS
FOR
BY
MOISTURE THE
ROBERT
LOSSES
DEGREE
OF
RUHL
BE
ZIEMER
ACCEPTED
DOCTOR
OF
AS
ENTITLED
FULFILLING
PHILOSOPHY.
Committee on Graduate Work
Adviser
ii
LOGGING IN
EFFECTS PART
REQUIRE-
ABSTRACT OF DISSERTATION LOGGING
The an
depletion
isolated
EFFECTS
of
mature
soil
sugar
moisture
pine
and
California Sierra Nevada was 2
weeks
for
measured
5
SOIL
MOISTURE
within
the
an
LOSSES
surface
adjacent
uncut
15
feet
forest
by
in
the
measured by the neutron method every
consecutive
periodically
ON
summers.
Soil moisture recharge was
the
winters.
during
intervening
Groundwater
fluctuations within the surface 50 feet were continuously recorded during the
the
soil
same
period.
surface, eventually recharging the entire soil profile to
"field
capacity".
portion
of
deplete
moisture
the
early winter. rainfall, to
During
the
recharge
soil.
was
at
from
the
drier
"field
period,
although
capacity",
soil
below
the
the
the
trees
wetting
top
continued front
to
into
Groundwater levels began to rise within days after
whereas
progress Soil
Each fall, a wetting front progressed from
weeks
through
moisture
or
the
months
were
unsaturated
depletion
by
the
zone
required above
isolated
for the
tree
the
wetting
water
table.
was
maximum
front
at
a
depth of 8 to 13 feet and extended about 15 feet away from the tree. The influence of the tree on soil moisture depletion extended to a depth of about 18 feet and to a distance of about 40 feet. An excellent linear relationship was found between the quantity of soil moisture depleted by the tree at the end of the summer and distance
from
the
tree.
The
isolated
tree
iii
used
between
2200
and
2600
cubic feet more soil moisture than a bare portion of the plot outside
of
the influence
of the
tree.
Robert Ruhl Ziemer Department of Earth Resources Colorado State University Fort Collins, Colorado 80521 June, 1978
ACKNOWLEDGEMENT
This
research, Study PSW 1603-5, was undertaken as an integral
part of the Lower Conifer Project, U. S. Forest Service, Pacific Southwest Forest and Range Experiment Station. received Water
additional
funding
Resources,
forestry
from
were
the
State
of
California,
Department
of
During the 15 years since I began this study, many
students
California
by
Until 1967, the study
the
Berkeley
introduced
to
the
campus joys
of
of
the
University
outdoor
research
of as
seasonal
employees or as work-study students collecting field or laboratory data
or
attempting
to
make
sense
out
of
the
mounds
of
computer
output.
The number of men and women who worked on various aspects of this study
are, unfortunately,
too numerous to acknowledge individually, but
their assistance is greatly appreciated. Some Agee's
individuals,
special
recognition.
Jim
field work and perceptiveness was outstanding during his 2
years
with
soil
analysis
years
the
of
quired ment
however, require
was
devotion
for
with
research
study,
data this
Hutch Wood's assistance with the laboratory
indispensable. to
developing
analysis study,
cannot
in
some
Bob Thomas' contribution the
multiple
be
overstated.
small
computer
way, induced
many
programs
Perhaps each
and
re-
their
to
involve-
follow
a
career.
The
resident
staff
at
the
Challenge
Experimental
Forest
were
invaluable for their daily observations, particularly Ross Cole, who carried 18
on
months
the
field
while I
was
work
and
attending
kept
in
classes
telephone at
CSU.
communication
for
the
Gina
Enrique, Melinda Hamen,
and
Diane
Haase
were
very
under-
standing and provided excellent clerical assistance during the heat of
out
manuscript
preparation.
And
finally, Ray Rice must be commended for his patience through-
the
lengthy
gestation
which
I
required
vi
before
completing
this
work.
TABLE OF CONTENTS
Page
Chapter
I.
II.
INTRODUCTION . . . . . . . . . . . . . . . . . . . . l
l
Historical Perspective . . . . . . . . . . . . . . . The Soil Moisture Study . . . . . . . . . . . . . .
1 6
THE STUDY AREA. . . . . . . . . . . . . . . . . . . . .
9
Location . . . . . . . . . . . . . . . . . . . . . . Geomorphology . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Soils Climate . . . . . . . . . . . . . . . . . . . . .
Vegetation III.
. . . . . . . . . . . . . . . . . . . . .
LOCATION AND INSTRUMENTATION OF SOIL MOISTURE SAMPLING SITES . . . . . . . . . . . . ... . . . . . . . . . .
9 9 11 11 13
15
Plot Description and Instrumentation . . . . . . . . Tree Growth . . . . . . . . . . . . . . . . . . . . Soil Analysis . . . . . . . . . . . . . . . . . . . Description . . . . . . . . . . . . . . . . . . Texture . . . . . . . . . . . . . . . . . . . . Water retention . . . . . . . . . . . . . . . . Soil Moisture Measurement . . . . . . . . . . . . . . Access tube installation . . . . . . . . . . . . . Calibration . . . . . . . . . . . . . . . . . . Field measurement . . . . . . . . . . . . . . .
15 16 22 25 25 28 30 30 38 38 40
SOIL WATER REGIME . . . . . . . . . . . . . . . . . . .
42
Plot
IV.
1
Selection . . . . . . . . . . . . . . . . . . .
Soil Moisture at Recharge . . . . . . . . . . . . . Depletion Trends . . . . . . . . . . . . . . . . . . Partially cut condition . . . . . . . . . . . . Isolated tree condition . . . . . . . . . . . . . . . . . . . . Bare condition Total Summer Soil Moisture Depletion . . . . . . . . Surface 5 feet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 to 10 feet . . . . . . . . . . . . . . . . . 10 to 15 feet Total 15-foot profile . . . . . . . . . . . . . Depletion During Fall Recharge . . . . . . . . . . . Groundwater Variation . . . . . . . . . . . . . . . Recession . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Rise
vii
59 62 62 65 67 69 69 74 76 77 89 101 102 110
Page
Chapter
................
115
LITERATURE CITED. . . . . . . . . . . . . . . . . . . . . .
121
APPENDIX
126
V.
SUMMARY AND CONCLUSIONS
. . . . . . . . . . . . . . . . . . . . . . . . . .
viii
LIST
OF
TABLES
Table
Page
1.
Climatological
2.
Distribution of basal area by species and size class in the study plots . . . . . . . . . . . . . . . . . . . . . 17
3
Typical profile characteristics of the Challenge Soil Series . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
4.
Physical and chemical analyses of the Challenge Soil Series collected by the California Cooperative Soil Vegetation Survey at the series classification plot. . . . . 29
5.
Physical characteristics of the soil plots. . . . . . . . . . . . . . . . .
l
Summary, Challenge Ranger Station . . . . . . 12
in the study ...........
37
6. Average soil moisture by 5-foot depth classes at the end of each summer depletion season in study plot L1 . . . . 70 7.
Average soil moisture within the surface 15 feet of soil at the end of each summer depletion period in study tree plot Ll for each of the six concentric distances from the study tree from 1965 through 1969. . . . . . 78
8.
Average soil moisture within the surface 15 feet of soil at the end of each summer depletion period in study tree plot Ll for each of the six concentric distances from the study tree relative to soil moisture 40 to 60 feet from the study tree from 1965 through 1969 . . . . . . . . . . . . . . . . . . . . . . . . . . . . 79
9.
Average soil moisture within the surface 15 feet of soil at the end of each summer depletion period in study tree plot Ll for each of the six concentric distances from the study tree relative to soil moisture in the plot after the tree was cut in 1969 . . . . . . . . 82
10.
Volume of soil moisture depleted within 40 feet of the study tree in excess of that depleted 40 to 60 feet from the study tree when adjusted for equal. soil moisture in the plot after the tree was cut. . . . . . . . . 88
11.
Changes in soil moisture in the uncut control plots C1 and C2 during the fall recharge period . . . . . . . . . . . 91
ix
Page
Table
12 .
Daily precipitation during 1964-65, Challenge Ranger Station............ . ... .. .. . . . .
127
13 .
Daily precipitaiton during 1965-66, Challenge Ranger Station.........................
128
14 .
Daily precipitation during 1966-67, Challenge Ranger Station.........................
129
Daily precipitation during 1967-68, Challenge Ranger Station.........................
130
15 . 16. 17 .
Daily precipitation during 1968-69, Challenge S t a t i o n . . . . . . . . . . . . . . . . . ...
Ranger . .. .
Daily precipitation during 1969-70, Challenge Ranger Station.........................
X
131 132
LIST
OF
FIGURES
Figure
Page
1.
Location of study plots within the Challenge Experimental Forest, California . . . . . . . . . . . . . . . . . 10
2.
Spatial distribution of trees and neutron access tubes in plot L1. . . . . . . . . . . . . . . . .
3.
Spatial distribution of trees and neutron access tubes in the uncut control. plots. . . . . . . .
l
. . .
18
. . . . . 20
4.
Concentric distance classes and location of neutron access tubes around the study tree in plot L1 . . . . . . . 21
5.
Annual growth of the sugar pine study tree and of a ponderosa pine from a nearby uncut stand. . . . . . . . . . 24
6.
Distribution of sand, silt, and clay in tree plot L 1 . . . . . . . . . . . .
7.
8.
the .
31
Distribution of sand, silt, and clay in the uncut control plot Cl . . . . . . . . . . . . . . . . . . . . .
32
l
l
Distribution of sand, silt, and clay in the uncut control plot C2 . . . . . . . . . . . . . . . . . . . . 33 l
9.
study . . .
. . .
l
l
Soil moisture retention in the study tree plot Ll . . . . . 34 Soil moisture retention in the uncut control plot Cl. . . .
35
11. S o i l moisture retention in the uncut control plot C2. . . .
36
10.
12.
13.
14.
15.
Isopleths of soil moisture in the the partially cut study plot L1 on a) August 16, b) September 14, and c) October 19, 1965 . . . . . . . . . . . . . . . . . . .
43
Isopleths of soil moisture in the partially cut study plot Ll on a) November 30, 1965, b) January 17, and c) February 11, 1996. . . . . . . . . . . . . . . .
44
Isopleths
of
soil
moisture
in
the partially
cut
study
plot L1 on a) May 6, b) May 19, and c) June 9, 1966 . . .
45
Isopleths of soil moisture in the partially cut study plot L1 on a) June 30, b) July 15, and c) August 12 , 1966. . . . . . . . . . . . . . . . . . . . . . . . . . . .
46
Figure --
16.
17.
18.
19
l
Page
Isopleths of soil moisture in the partially cut study plot Ll on a) August 29, b) September 6, and c) October 25, 1966.. . . . . . . . . . . . . . . . . . . . . .
47
Isopleths of soil moisture in the isolated tree study plot Ll on a) January 19, b) March 2, and c) June 22, 1967.. . . . . . . . . . . . . . . . . . . . . . . .
48
Isopleths of soil moisture in the isolated tree study plot Ll on a) July 18, b) August 16, and c) September 7, 1967...... . . . . . . .. . . . .
49
Isopleths of soil moisture in the isolated tree study plot Ll on a) September 26, b) October 13, and c) October 30, 1967 . . . . . . . . . . . . . . . . . . . .
50
l
20.
21 .
22
l
23.
24.
25.
26.
27.
28.
Isopleths of soil moisture in the isolated tree study plot Ll on a) January 22, b) March 4, and c) May 2, 1968 . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
51
Isopleths of soil moisture in the isolated tree study plot Ll on a) May 29, b) June 7, and c) June 26, 1968. . .
52
Isopleths of soil moisture in the isolated tree study plot Ll on a) August 12, b) August 28, and c) September ll, 1968 . . . . . . . . . . . . . . . . . . . .
53
Isopleths of soil moisture in the isolated tree study plot Ll on a) September 25, b) October 9, and c) October 23, 1968 . . . . . . . . . . . . . . . . . . . . .
54
Isopleths of soil moisture in the isolated tree study plot Ll on a) January 7, 1969 and in the bare study plot Ll on b) March 27, and c) May 5, 1969 . . . . . . . .
55
Isopleths of soil moisture in the bare study plot Ll on a) June 16, b) July 2, and c) July 25, 1969 . . .
56
l
Isopleths of soil moisture in the bare study plot Ll on a) August 13, b) September 17, and c) October 2, 1969 . . . . . . . . . . . . . . . . . . . . . . . .
57
Isopleths of soil moisture in the bare study plot Ll on a) October 29, b) November 20, 1969, and c) February 25, 1970 . . . . . . . . . . . . . . . . . . . . .
58
Average soil moisture at the end of each summer depletion season between the depths of a) O-5 feet, b) 5-10 feet and c) 1 0 - 1 5
feet for
different distances
from the study tree and for the uncut plots. . . . . . . . xii
71
Figure
29.
30.
Page
Relative soil moisture in the study tree plot at the end of each summer depletion period for each of five concentric distances from the study tree from Table 9 . . . . . . . . . . . . . . . . . . . . . . . . . .
83
Relationship between distance from the study tree and relative soil moisture at the end of the 1965, 1966, 1967, and 1968 depletion seasons from Table 9 . . . . . .
31.
Profiles
of
soil
moisture
content
with
depth
at
each
of the six access tubes in the uncut control plots during the 1964-65 f a l l recharge period . . . . . . . 32.
. .
92
Profiles of soil moisture content with depth at each of the six access tubes in the uncut control plots during the 1965-66 fall recharge period . . . . . . . . . l
33.
85
93
Profiles of soil moisture content with depth at each of the six access tubes in the uncut control plots during the 1967-68 fall recharge period . . . . . . . . 94 l
34.
Profiles of soil moisture content with depth at each of the six access tubes in the uncut control plots during the 1968-69 f a l l recharge period . . . . . . . .
35.
.
. 95
Fluctuations in depth to water table during water year 1966 in plots 5, 7, and 16 . . . . . . . . . . . . . 103 l
36.
37.
Fluctuations in depth to water year 1967 in plots 5, 7, and 16 Fluctuations
in
depth
to
water
Fluctuations
in
depth
to
l
table
year 1968 in plots 5, 7, and 16 38.
table during water . . . . . . . . . . . 104 l
during
water
. . . . . . . . . . . . . . 105
water
table
during
water
year 1969 in plots 5, 7, and 16 . . . . . . . . . . . . . .. 106 39.
Fluctuations
in
depth
to
water
table
during
a
portion
of water year 1970 in plots 5 and 7 . . . . . . .
107
40.
Relationships between precipitation, water table depths in plots 5, 7, and 16, and average end of season soil moisture in the uncut control plots. . . . . . . . . 108
41. .
Time lag in the initiation of water table rise in plots 5, 7, and 16 relative to precipitation during fall 1965............. . . . . . . . . . . l
xiii
112
Page
Figure
42.
Time lag in the initiation of water table rise in plots 5, 7, and 16 relative to precipitation during fall 1966............. .. . . . . . . . . . . .
xiv
113
CHAPTER I
Historical Not begin An
Perspective until
to
the
middle
experiment
additional
with
200
of the
years
the
seventeenth
agricultural
passed
before
century
aspects
the
of
did soil
importance
of
investigators moisture.
soil
moisture
in forested areas was recognized as a regulator of tree growth. By the 1800's,
field
trees
on
the
first
to
report
less
soil
The
studies
soil
difference
moisture
that
moisture
beech
than
was
forest
deeper the
plantation
than
15
plantation
moisture
under
open
greatest
In 1892, Charmow a
were
regime. and
the
contained
all
late
the
influence
of
(1899) was among the
forests
during
during
document
Ebermayer
pine
areas
to
four
considerably
seasons
of
the
year.
summer.
measured soil moisture to a depth of a meter in in
the
meters.
He
increased forest
underway
Ukrainian
steppe
found soil
(Wyssotzky,
stands
from
where
moisture
the
decreased
1932).
Wyssotzky
to
and
1892
water
1899
as
table the
studied
reported
was
age
of
soil
that
the
roots of the trees extracted soil moisture0 to a depth of about 16 meters.
He
further
showed
seasonal
isopleths
of
soil
depth and time for the 7-year duration of his study.
moisture
with
Later, he studied
the seasonal changes in soil moisture for a 2-year period, from 1928 to 1930. Wyssotzky's studies stood alone, but have been largely unrecognized,
as
the
most
elaborate
and
extensive
soil
moisture
storage
and depletion work in forests until the advent of neutron soil moisture meter in the mid-1950's.
2
The early studies required an enormous effort to obtain the gravimetric
soil
moisture
samples
at
these
deeper
depths.
In
addition,
since a new hole must be dug or drilled for each sample, the site is eventually of
rendered
numerous
bandoned
holes
his
adversely By
useless left
7-year
influencing
for
by
further
previous
study
sampling.
study
in
1899
because
the
site
and
his
trenching, Fricke
(1904)
and thereby isolated a quadrat
because
of
Wyssotzky
previous
the
influence
eventually
sample
removal
the
concluded basic
driest that
cause
months
decreased
for
of
severed
the
of soil.
the
root
increased
roots
of
surrounding
From
competition
(1926)
made
significance and spatial By
studying
land,
detailed
Aaltonen
species
quality
of
soil.
as
the
the
border
the
growing
the
above-ground
and
the
the
soil.
trees
then
there
are
are
was
rather
the
than
the
light. advance
stands
was
which
highest
approached.
necessary
portion
competition
moisture
Fricke
in
understanding
the
a
is
and
reproduction
definite directly
space
in
Fin-
arrangement
dependent
upon
the
He found that in an opening in any forest, the
center
space
He
each
soil thinning,
major
forest
that
of
in
of
concluded
members
seedlings
next
experiments,
areas
distribution of soil moisture in the forest.
charts
between
the
the
his
for
following
previously popular concept of increased Aaltonen
trees
He found two to three times
year.
growth
was
data.
more soil moisture in the trenched areas than within untrenched during
a-
of
existing
for
each
trees
is
between
demonstrated
oratory experiment with corn.
this
and The
become poorer
tree.
the
site,
smaller
the
larger
This space arrangement of
mainly
determined
them
for
very
clearly
Unfortunately,
progressively
water
by
and
by
Aaltonen
their
roots
nutrients
in
means made
of no
a
labsoil
3
moisture analysis to support his theory, nor did he verify his laboratory
experiments The
soil
work
in of
the
field
Conrad
and
moisture, carried
(1934)
to
attempt
a
out
with
trees.
Veihmeyer
with
similar
(1929)
sorghum
study
with
on
root
plants
in
forest
trees
development
California, in
and
led
Lunt
Connecticut.
Lunt "recognized that the California type of climate, characterized by little for
or
no
soil
rainfall
moisture
during
studies.
the
growing
season,
Nevertheless,
is
the
ideal
condition"
he "felt that such a study
would be of value in humid New England in spite of its frequent summer showers".
Thus,
having
in his area, Lunt
recognized
measured
the
the
drawbacks
distribution
of
imposed soil
by
the
moisture
climate
under
iso-
lated trees by digging a trench from the base of the tree out into the open.
Soil moisture was determined
collected
from
the
walls
from four trees --two was 4 feet.
pines
was
found
of the tree. ture
content
interception
the and
trench two
at
several
oaks.
depths
and
distances
The maximum depth measured
In one study he measured soil moisture to a distance of
41 feet from an oak. content
of
gravimetrically from soil samples
In
nearly
immediately
all
beneath
cases, the the
crown
lowest and
soil
close
moisture
to
the
base
Lunt recognized that three factors influenced the moisof by
the the
soil
in
crown, and
his
climate,
absorption
namely,
by
the
surface roots.
He
evaporation, felt
further extensive experimentation was necessary to properly evaluate the
interaction
of
these
factors.
Lunt's
figures
also
show
that
mois-
ture was being depleted below a depth of 4 feet, but he did not specifically
acknowledge
this
observation
in
the
text.
During the 1930's the literature began to proliferate with studies related
to
soil
moisture
under
forest
stands.
The conclusions of various
4
authors
were
soil-water extremely soil of
often
relationships, unlike complex
texture
and
and
trees, both
conditions
depth, within
(1935)
as and
limited
ual
papers
in
in
both
well
to
was
their
as
becoming
obvious
agricultural time
and
climate,
that
forest
counterpart,
space.
Not
variable,
but
were
only the
was
response
species, to these variable growing
considerably.
Several
generalize
authors, such
about
the
as
Hayes
rooting
and
depth
of
tree rooting characteristics are so interrelated with
soil texture, and
are
It
between
attempted
However,
climate,
variable
differed
Stoeckeler trees.
contradictory.
usefulness.
related
to
tree
moisture By
regime
1955, there
root
systems
that
such
were alone
well
classifications over
(Karisumi
400
and
individ-
Tsutsumi,
1958).
A bibliography containing more than 800 papers related to soil
moisture
under
of
literature
forests seems
had to
been
compiled
repeatedly
by
Ziemer
demonstrate
that
by
1973.
soil
The bulk
moisture
de-
pletion by trees continues below the depth of measurement unless the roots For
are
restricted
by
truly
impervious
and
continuous
soil
layers.
example, McClurkin (1958) in Mississippi and Gaiser (1952) in Ohio
found that all available soil moisture was used throughout the 40- to 42-inch measurement depth.
McClurkin had earlier assumed the roots
would be restricted by a heavy clay layer, but later concluded that the clay "had not seriously impeded root penetration".
Lull and Axley
(1958) measured soil moisture to a depth of 12 feet in the New Jersey pine
barrens
occurring
and
below
concluded their
that
deepest
depletion
by
the
trees
was
probably
measurement.
Hendrickson (1942) was among the first to propose that soil moisture
studies
could
be
used
to
determine
water
use
by
forest
vegetation.
A study using this approach was made by Rowe and Coleman (1951) in
5
woodland-chaparral
and
ponderosa
pine
in
California.
Annual evapo-
transpiration was calculated by summing soil moisture losses between storms. the
This
rooting
approach
depth
of
required the
soil
vegetation
moisture and
an
measurements
adequate
throughout
measurement
of
the
variation of soil moisture within the forest stand.
spatial
Very
few
authors
have
understand the spatial
followed
Lunt's
early
work
in
an
effort
variation of soil moisture around trees.
to
Notable
exceptions have been Giulimondi (1960), Douglass (1960), and Ziemer Giulimondi
(1964). tances The
from
a
moisture
(1960) measured soil moisture at increasing dis-
Eucalyptus
lost
3
meters
shelterbelt from
the
into
an
adjacent
shelterbelt
was
cultivated
nearly
twice
field. that
lost at a distance of 5 meters, 3 times that at 9 meters, and 13 times that at 17 and 25 meters.
Unfortunately,
his soil moisture measure-
ments were only made at a depth of 30 to 35 cm. Douglass
(1960) measured soil moisture at the end of the two grow-
ing seasons following thinning a 16-year-old in
South
Carolina.
loblolly
pine plantation
Soil samples of the surface 4 feet were taken at
2-foot intervals along a line between trees spaced about 20 feet apart. Soil
moisture
to the trees. depth.
In
was
highest
midway
No
mention
was
their
between
made
of
the soil
trees
and
moisture
lowest
adjacent
distribution
with
climate, some of the differences observed by Giuli-
mondi and Douglass may have been due to a combination of rainfall interception
by
the
tree
canopy
and
soil
As Lunt had pointed out earlier, the
moisture
ideal
depletion
climate
to
by
study
the
roots.
soil
mois-
ture depletion by forests is in an area with little summer rainfall such
as
California.
6
In the subalpine zone of the Sierra Nevada in California, Ziemer (1964)
measured
the
pattern
of
soil
long transects running from unlogged
moisture
storage
to
a
depth
of
4
feet
depletion
a-
red fir forests into openings
which had been cut 1, 5, 10 and 12 years earlier. measured
and
using
the
relatively
Soil moisture was new
neutron
meter
technique. This method allowed identical locations to be repeatedly remeasured throughout the summer depletion season, a distinct advantage over the earlier gravimetric technique.
Ziemer found soil moisture
content
center
progressively
increased
end of the summer, whereas
toward
in
early
the
of
the
opening
at
the
spring, soil moisture was nearly
equal throughout the plot. The trees depleted soil moisture 30 to 40 feet the
into
the
opening.
As
differences
between
soil
new
tree
moisture
seedlings in
the
occupied forest
the
and
opening,
opening
became
smaller.
Those differences would become negligible 15 years after
cutting.
Because of the cobbly
nature of the morainal soils, Ziemer
was unable to measure soil moisture depletion below the rooting depth of the trees. Thus, through problems, and
a
combination
of
climate,
soil,
and
study
design
we still do not h a v e an adequate understanding of the timing
pattern
of
soil
moisture
depletion
by
individual
trees
throughout
their rooting depth.
The Soil Moisture Study The purpose of this study was to measure the quantity, timing, and pattern of soil moisture storage and depletion throughout the rooting depth
of
an
isolated
mature
sugar
pine
tree.
7
To be successful in such a study, it attempt tered
to by
conduct
eliminate
past
problems
researchers
this
mentation,
the
These
study.
2)
and
climate,
ments
meter
were
in
made
the
is
cation.
Consequently,
ments
taken
Prior
one
can
to
mid-1950's,
been
to
identify
repeatedly
an
idealized
be
grouped
and
encoun-
site
in
which
under
1)
instru-
the
nearly
development
of
all
moisture
soil
the
to
neutron
soil
measure-
Gravimetric sampling is very time
when collecting deep soil samples.
destructive, one
at
have
select
gravimetrically,
sampling
necessary
soil, and 4) saturated groundwater flow.
3)
particularily
consuming,
to
problems
1) Instrumentation. moisture
which
was
can
not
repeatedly
return
to
Since the
the
same
lo-
most early studies represented a few measure-
point
in
time
and
at
relatively
shallow
depths.
The neutron meter was selected for use in this study because with an initial installation of the access tubes soil moisture measurements can
then
be
made
rapidly
and
repeatedly
at
the
same
location
throughout
the depth of the access tube.
This is a necessary condition to in situ
measurements
soil
of
the
2) Climate.
timing
of
moisture
depletion
and
recharge.
Lunt and others discussed the problems associated
with measuring the influence of vegetation on soil moisture depletion in
areas
Following
where such
continued rainfall,
it
summer is
rainfall difficult,
partially if
not
recharges impossible,
the to
soil. sep-
arate the components of interception losses, surface runoff, variable infiltration, tion U.
of S.
the and
and redistribution of the infiltrated water from deplesoil
moisture
particularly
in
by the
the
vegetation.
central
Sierra
The
climate
Nevada
of
in
the
western
California is
ideally suited for soil moisture depletion studies because a rainl.ess period extends from spring through autumn.
8
3) Soil. rocky
and
Forest
are
soils
often
in
underlain
the by
It
is
out
to
understand
soil of
rooting
depth
moisture. the
soil
pletion
necessary
bedrock
which
measure
the ability
shallow
soil
of
is
and
easily
moisture
the tree
through-
to
extract
is
desirable
to
ease
interpretation
of
the
moisture
de-
patterns.
fringe
of
to
typically
In addition, horizontal as well as vertical uniformity
4) Saturated Groundwater.
will
are
fractured
penetrated by roots. the
west
is
present
have soil
a
readily
water
use
treme
case
(1964)
and Urie
of
fluctuations forests. error.
within
the
rooting
available by
the
shallow
for
depth
of
the trees,
supply
of
soil
will
be
greatly
tree
water
(1966)
If a water table or its capillary
tables,
moisture
and
such
attempted
to
vegetation
any
complicated.
investigators,
example, have
the
In the ex-
as
use
estimates
Heikurainen diurnal
of groundwater levels to estimate evapotranspiration by
This
process
requires
many
assumptions
that
are
subject
to
In areas where the saturated groundwater is at an intermediate
depth, the magnitude of the contribution of the water table to evapotranspiration
is
completely
unknown
and
in
many
correctly ignored or assumed to be negligible. able
to
select
sites, free
well-drained
from
be
free
from
surface
ponding
during
has
It
thus,
the
is,
influence
been
of
The
ideal
site
rainfall
which
would
table and subsurface lateral saturated flow. also
studies
in-
prefera
water
should result
in non-uniform soil moisture recharge. Therefore, a
forest&d
table
in
study a
a
substantial site
region
on
having
a
effort deep
long
and
was
initially
uniform
rainless
soil
summers.
expended with
no
to
select
groundwater
CHAPTER 11
THE
STUDY
AREA
Location The
study
site
is
located
on
the
Challenge
Experimental
Forest
in Sections 33 and 34, T.19N., R.7E., M.D.M. at an elevation of 2,600 feet
in
the
north
Sierra
Nevada.
The Experimental Forest is located
40 miles northeast of Marysville, California at latitude 39o 29' N., longitude 121o 14' W. (Fig. 1).
Geomorphology The block,
Sierra
the
Nevada
eastern
geomorphic
margin
of
The
western
flank
or
dip
120
to
feet
per
mile
neath
180 the
alluvial
fill
which
slope
the
developed
uplifted
of
toward
of
province
this the
along
large
west,
a
a
of
faults.
block
slopes
from
eventually
passes
be-
Valley.
The
parent
this province are metamorphosed sediments and volcanics Carboniferous the
The
rock
of probable
area
rocks
are
tilted was
in
upper
metavolcanics
block
of
eroded
the to
a
Jurassic
time.
of
Jurassic
to
Sierra
Nevada
near
tableland
and
then
The rocks of the Triassic the
age.
Challenge
deeply
incised
Experi-
mental
Forest
major
drainages-- Feather River to the north and Yuba River to the
south.
of
age, together with granitic rocks which intruded into
metamorphosed
Challenge
tilted
series
fault
and
Sacramento
on
into
11 Soils The sists
soil is
of
deep
and
metamorphosed name
given
ed.
During
of the very
Challenge deep
basic
igneous
metamorphism
The Challenge series con-
well-drained
andesite, commonly
to
series.
called
rocks
the
soils
greenstone.
that
original
forest
have
been
developed
from
Greenstone
is the
hydrothermally
alter-
ferromagnesian
minerals
were
largely changed into chlorite, which gives the resulting parent material
rock
granular,
medium
non-cobbly Challenge
a
to
very
The
strongly
are
Experimental series
producing
color.
acid, moderately
types
Challenge
timber
green
medium
massive,
The
a
site
important
fine
acid,
recognized. Forest
is
covers
about
of
Challenge
series
textured
clayey
has
surface
subsoils.
reddish soils
brown, and
Both cobbly
red,
and
The soil in many portions of the
estimated 50
to
be
thousand
the
deep
forest
1969,
the
mean
50
to
acres
soils.
and
100
feet
deep.
is
the
highest
Economically,
it
is
temperature
at
soil.
Climate __L___.-From
1965
through
annual
maximum
the Challenge Experimental Forest was 69oF and the mean minimum temperature was 43oF; mean
maximum
extremes of 104oF and 11oF
temperatures
ranged
were
recorded.
90oF in July to
from
Monthly
51oF in December.
Monthly mean minimum temperatures ranged from 56oF in July to 32oF in January measured
(Table only
1).
Prior
to
September
1965,
air
temperature
was
intermittently.
Precipitation occurs predominantly in winter with about 90 percent of
the
April.
annual The
total
entire
falling soil
in
moisture
the
6
months
profile
is
from
November
usually
through
recharged
to
"field
13
capacity"
by
January
or
February.
Soil moisture depletion starts in
spring, usually in April or May. 2
inches
of
intensity
rain
falling
convectional
The
from
summers
June
through
thunderstorms.
are
dry
with
less
September--mainly
Thus, soil
moisture
than
from
high
depletion
continues through the summer season without significant recharge until
late
from
October
1939
or
through
November.
1969.
Precipitation
Average
annual
was
rainfall
measured is
68
at
Challenge
inches,
ranged from 94.13 to 37.20 inches in the 30 years of record.
but
has
Snow
is
rare-- only 3 or 4 days occur annually with measurable snow depth. A summary
of
monthly
temperatures
the study is found in Table 1. years
is
found
in
the
and
precipitation
Daily
Appendix,
for
precipitation
Tables
12
through
the
for
6
each
years of
of
the
6
17.
VegetationThe study site is located forest
vegetation
in
the
area
in
consists
pine (Pinus -....--. ponderosa Laws.), 20 menziesii [Mirb.] Franco), Dougl.),
the
mixed of
percent
conifer
about
40
Douglas-fir
forest percent
zone.
The
ponderosa
(Pseudotsuga
8 percent sugar pine (Pinus _I__-- lambertiana
6 percent incense-cedar (Libocedrus --____c__ decurrens Torr.), 3 per-
cent white fir (Abies concolor [Gord. & Glend.] Lindl.), and 23 per---I_ P_II_ cent hardwoods composed mainly of tanoak &
Arn.]
Rehd.), madrone
black oak (Quercus
(Lithocarpus densiflorus [Hook
(Arbutus - menziesii Pursh.), and California
kellogii
Newb.).
The ground cover is predominantly
bracken fern (Pteridium --L--c--- aquilinum --- [L.] Kuhn var. pubescens - - - - Underw.), poison-oak (Toxicodendron diversilobum T. & G.), Sierra gooseberry (Ribes -roezlii- Kegel.), several
species
of
California-lilac
(Ceanothus
spp. L.), and manzanita (Arctostaphylos spp. Adans.), together with sprouts of tanoak
and madrone.
14
The area was logged extensively from 1870-1880. stand
found
of tanoak
on
the
Experimental
Forest
ranges
from
The nearly
second-growth pure
stands
with little current commercial value to dense stands of pine
and fir with stems of 40 inches dbh not uncommon.
In the general study
area, total stand density, expressed as basal area, averaged about 250 square
feet
per
acre.
CHAPTER III
LOCATION AND INSTRUMENTATION OF SOIL MOISTURE SAMPLING SITES
Plot
Selection The
manent
Challenge
Fores t staff established about 60 per-
Experimental
growth plots prior to logging in
following
1962.
The
plots
had
the
properties: Each
plot
center
was
located such that the plot had a basal
area of about 160 square feet
per
acre
of
conifers
greater
than 11.5 inches in diameter 2) Within a one-half acre circu lar
plot
all trees larger than 11.5 inches
3)
An
around
each
plot
center,
in diameter were measured
and
tagged.
In
addition, within a concentric one-fourth acre circular
plot,
all
eter
were
after-logging
trees
between
measured
mortality
3.5 inches and 11.5 inches in diam-
and tagge survey
In 1963, 21 of these growth
was made of all growth plots in 1962. plots were selected for a studv of
soil moisture storage and depletion.
A 50- by 50-foot grid of 100
blocks was located at the center of each plot and 3 of the blocks were selected
at
random.
Within each block a neutron access tube was in-
stalled to a depth of 20 feet if soil summer
1964,
a
water
table
observation
conditions allowed. well
was
drilled
to a depth of 50 feet using a truck-mounted auger,
in
A 2-inch
In
late
each
plot
diameter
plastic casing with 1 mm perforations in the bottom 2 1/2 feet was installed in each auger hole.
On the basis of 2 years' observations of
16
soil
moisture
depletion
and
one
winter
of
observing
the
water
table
well, 3 of the 21 plots were selected for this study--one logged plot (Ll) and two adjacent unlogged control plots (Cl and C2). Growth and mortality for
measurements
the
duration
were
of
made
the
study.
annually The
in
each
criteria
of
for
these
plot
three
selection
plots were:
1) No water table present to a depth of 50 feet at any time during 2)
the
Uniform of
year.
pattern
lateral
of
or
soil.
moisture
subsurface
recharge
with
no
indication
flow.
3) Well-drained site with no surface ponding
or water runoff
concentration. 4) No unexplained anomalies in soil moist ure data dur ing depletion
or
recharge.
5) Uniform soil with all access tubes at least 15 fee t in depth.
the
These criteria were established to reduce the
variabil ity
control
of
between
Plot
and
plots
study
and
Description
plots
between
and
and
access
to
make
tubes
comparison
within
a
plot
between
depletion
data
possible.
Instrumentation --_II
All hardwoods in the logged plot (Ll) were poisoned with 2,4,5-T During summer 1962, 2 years prior to the be-
in the fall of 1961. ginning
of
this
study, 88 percent of the original basal area of the There
were
only
one-half
acre
permanent
logged plot (Ll) was cut. dbh
left
in 1962--l
uncut
on
the
ponderosa pine (28.5-inch
inch and 27.7~inch),
12
growth
larger plot
than
4
inches
established
diameter), 2 sugar pines (28.7-
1 incense-cedar (9.4-inch),
inches), and 4 madrones
trees
4 tanoaks
(
