POTENTIAL WATER YIELD RESPONSE 

FOLLOWING CLEARCUT HARVESTING ON 

NORTH AND SOUTH SLOPES IN NORTHERN IDAHO 

Richard G. Cline, Harold F. Haupt, and Gaylon S. Campbell 

USDA Forest Service Research Paper INT-191 

INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION 

FOREST SERVICE, U.S. DEPARTMENT OF AGRICULTURE 

This file was created by scanning the printed publication.

Errors identified by the software have been corrected;

however, some errors may remain.
Headquarters for the Intermountain Forest and 

Range Experiment Station are in Ogden, Utah. 

Fie ld programs and research work units are 

maintained in: 

Billings, Montana 

Boise, Idaho 

Bozeman, Montana (in cooperation with 

Montana State University) 

Logan, Utah (in cooperation with Utah State 

University) 

Missoula, Montana (in cooperation with 

University of Montana) 

Moscow, Idaho (in cooperation with the 

University of Idaho) 

Provo, Utah (in cooperation with Brigham 

Young University) 

Reno, Nevada (in cooperation with the 

University of Nevada) 
USDA Forest Service 

Research Paper INT-191 

June 1977 

POTENTIAL WATER YIELD RESPONSE 

FOLLOWING CLEARCUT HARVESTING ON 

NORTH AND SOUTH SLOPES IN NORTHERN IDAHO 

Richard G. Cline, Harold F. Haupt, and 

Gaylon S. Campbell 

INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION 

Forest Service 

u. S. Department of Agriculture 

Ogden, Utah 84401 
THE AUTHORS 

RICHARD G. CUNE earned his B. S. degree in agriculture at Cornell 

University, M. S. degree in soils at North Dakota State University, 

and Ph. D. in soils at Washington State University in 1974. From 

1974 to 1975 he was a soil scientist with the Clearwater National 

Forest. At present, he is holding a similar ,position with the 

Nezperce National Forest. 

HAROLD F. HAUPT is leader of the Water Quality Management research work unit of the Intermountain Station at Moscow. He 

holds a B. S. degree inforestry and M. S. degree in range ecology, 

both obtained at the University of Idaho. For the past 28 years, 

he has conducted research in the fields of snowmelt hydrology, 

logging-road erosion, and soil stabilization at several locations 

in Idaho and Nevada. 

GA YLON S. CAMPBE LL holds a dual appointment as an associate 

professor in Biophysics and associate soil scientist with the Department of Agronomy and Soils, Washington State University. 

He earned his B. S. and M. S. degrees at Utah State University in 

1966 and a Ph. D. at Washington State University in 1968. For 6 

years he has been teaching and conducting research in plant-water 

relations, soil physics, and agriculture meteorology. 
CONTENTS 

Page 

INTR ODU C TI ON • • • • • • • • • 

BACKGROUND INFORMATION. • 

DESCRIPTION OF STUDY AREA. 

TREATMENT AND CONTROL PLOTS. • 

INSTRUMENTATION AND MEASUREMENTS 

RESULTS. • • • •••••••• 

SUMMARY AND CONCLUSIONS 

PUBLICATIONS CITED •••••• 

Use of trade or firm names is for reader information only, and does 

not constitute endorsement by the U. S. Department of Agriculture of 

any commercial product or service. 

1 

1 

2 

3 

4 

5 

14 

15 
RESEARCH SUMMARY 

The hydrologic response of small clearcLlts on north and south slopes 

in northern Idaho was investigated. On the nOl'th slope, substantial gains 

(27 to 35 cm) in potential water ,yield per year resulted from (a) removal 

of transpiring surfaces associated with plant 80ver, (b) elimination of snow 

interception by a closed-canopied forest, and (C) gradual reoccupation of 

the soil mantle by invading he rbaceous species. On the south slope, small 

to moderate gains (4 to 11 cm) in ,yield resulted from ~learclltting, at least 

in 1973, the year studied. In earlier ,years, the gains probably would have 

been negligible. Site fa8tors that compensated for c learcutting kept gains 

in yield small to moderate on the south slope. Initial forest losses fr01n 

interception were light because of the open-canopied structure of the timber and windiness at trcetop level. In the clearcut, water gains from 

reduced transpiration were more than used up within ':I: years by invading 

shrub species. The south slope clearcut was subjected to other sour8CS 

of water loss also. 
INTRODUCTION 

In the heavily timbered, snow-dominated landscapes of , northern Idaho, the problems 

of watershed management differ from those of less heavily timbered and water-short 

regions. "The question is not so much how to increase water yields from the snowpack, 

but rather, how to safely dispose of the increased water yields that accompany timber 

harvesting .... " (Satterlund and Haupt 1972). The Forest Service in cooperation with 

the University of Idaho and Washington State University has a comprehensive program 

underway in snow hydrology and snow management at Moscow, Idaho. The research program 

consists of three parts: (1) studying the physical-biological processes, (2) evaluating manipulative treatments on individual plot areas, and (3) testing the most promising 

findings on monitored watersheds. 

This paper describes one segment of the research program--a plot study to determine the effect of timber harvesting and early site recovery on potential water yield 

under divergent conditions existing on north and south slopes in a prime timber~ 

producing zone. Results from this hydrologic investigation should add to the knowledge 

base needed to better estimate how much, where, and when to expect water yield increase 

from clearcutting practices. 

BACKGROUND INFORMATION 

Previous research on the integrated effects of timber harvest, snow hydrology, 

and soil water has been limited. Packer's (1962) analyses of snow data collected on 

the Priest River Experimental Forest in northern Idaho showed that a change in canopy 

density from a completely closed to a completely open condition increased the average 

water equivalent (WE) uniformly 10.7 cm. This average relation, according to Packer, 

occurred regardless of differences in year, elevation, or aspect. He inferred that 

increase in WE at the time of maximum snowpack was due primarily to loss by interception, and subsequent evaposublimation within tree canopies. 

Anderson (1956) reported much larger gains in the central Sierra Nevada of 

California; on the average, the April 1 snowpack contained 28 cm more water in large 

open areas than in dense forest. He explained that the difference may represent the 

net effect of three factors: loss by interception, difference in winter melt, and 

blowing of snow by wind. 
Recent findings in the West have challenged the importance of loss by interception, particularly in the high-elevation forests of the central Rocky Mountains 

(Hoover and Leaf 1967; Dietrich and Meiman 1974; Gary 1974) and of the central Sierra 

Nevada (Smith 1974). However, in the midelevation forest of Priest River Experimental 

Forest recent lysimetric data indicate that for some forest-terrain situations winter 

loss by interception remains important (Haupt 1972b). This latter evidence substantiates what Packer inferred in 1962 from snow course data. 

The studies reported by Packer and Haupt dealt only with the snowpack and snowmelt 

and not with changes in soil water storage. Elsewhere in the West the literature contains little data on soil water storage at different slope exposures in the timbered 

snow zone. Bethlahmy (1973) concluded by examining flow patterns of 14 mountain 

streams that north slopes, with their denser vegetative cover and deeper soils, generally will lose more water through transpiration and retain more water against the pull 

of gravity than south slopes. South slopes will lose less water through transpiration 

and will yield more water to deep seepage. On the other hand, Tew (1967) studied the 

effect of slope exposure on water use by aspen in central Utah and found that the 

largest amount of water was removed by vegetation on a western exposure. He also 

reported that amounts of water removed from north and south aspects were similar. 

Cutting effect, or site recovery, in the snow zone may involve considerable time. 

Snowpack increases persist for long periods after forests are cut (Hoover 1969). In 

contrast to the slowly diminishing snowpack after timber removal, soil water gains 

tend to decrease quite rapidly. In a Central Sierra study, savings dropped by onehalf in 4 years after a selection-type cutting (Anderson 1963). After clearcutting, 

Zeimer (1964) found that resultant increases in water stored in the soil would fall 

to zero by the 16th year. Neither study documented the effect that slope exposure or 

plant habitat type might have on the rate of site recovery. 

DESCRIPTION OF STUDY AREA 

The study was conducted in the midelevation zone of Priest River Experimental 

Forest. The specific study area overlapped onto both slopes of an east-west oriented 

ridge between an elevation of 1,300 and 1,400 m. The south (180°) slope includes the 

Pseudotsuga menziesii/Physocarpus malvaceus habitat type on 44 to 52 percent slope 

gradients. Stand heights range from 27 to 39 m with crown closure of 20 to 30 percent. 

The open overstory consists of Douglas-fir (Pseudotsuga menziesii var. glauca [Beissn.] 

Franco), western white pine (Pinus monticola Dougl.), western larch (Larix occidentalis 

Nutt.), and grand fir (Abies grandis [Dougl.] Forbes) and the understory contains a rich 

mixture of shrubs dominated by ninebark (Physocarpus malvaceus [Greene] Kuntze). 

The north (335°) slope is classified as Tsuga heterophylla/Pachistima myrsinites 

habitat type (Daubenmire and Daubenmire 1968) on 38 to 48 percent slope gradients. 

Stand heights vary 37 to 49 m with crown closure of 90 to 100 percent. The dense overstory consists of western hemlock (Tsuga heterophylla [Raf.] Sarg.), western redcedar 

(Thuja plicata Donn), and western white pine, and the understory contains a trace of 

low, herbaceous plants. 

2 
Soil profiles on hoth slopes are similar except for thickness and composition of 

the lower horizon. Thp upper mineral horizon, snme 2 em thick, was derived from recent 

volcanic ash; the next horizon, ahout 46 cm thick. is dominated by ash from the 6,700 

BP Mazama eruption. Roth are silt loam in texture. Glacial till, containing coarse 

fragments of granite and schist, lies helow the wind-laid horizons and extends to a 

depth of more than 100 em on the north slope, but less on the south slope. On the 

south slope, this horizon contains more rock fragments. The fourth horizon on the 

north slope is composed of granite and schist materials which are more weathered than 

those in the glacial till immediately ahove. This implies a fourth depositional event 

since the bedrock is helieved to he quartzite. This layer is not present on the south 

slope. Average depth to bedrock is greater on the north slope (163 em) and shallower 

on the south slope (137 em). 

The climate is influenced by the Pacific Ocean some 500 km to the west. Winters 

are cool and wet. Storms and accompanying winds generall; move in from the south 

southwest, and west. Summers are dry and most of the annual preCipitation, 104 em, 

fall s during winter in the form of snow and rain. Preci pitat ion for the study year, 

1973, was 72 em, the lowest total recorded since 1940. The summer months, June, July, 

and August, were extremely dry. 

TREATMENT AND CONTROL PLOTS 

The treatment plots were located in north-facing and south-facing clearcuts, both 

having been logged earlier in 1968 and 1969, respectively. PJots were located during 

autumn 1972 and, therefore, the information reported in this paper deals primarily with 

the postperiod, November 1, 1972, through November 19, 1973. 

Each clearcut was small, 61 by 198 m, with its long axis oriented north-south. 

The north slope clearcut (station 44) opened onto the lower side of a much larger 

unit; the replication on the opposite slope (station 50) opened onto the larger unit 

at the crest of the main ridge (fig. 1). 

Slash on the south clearcut was removed by skidding during autumn 1969; consequently, much of the deciduous woody shrub understory was severely broken, crushed, or 

grubbed out, but not burned. Understory vegetation was almost absent on the north 

slope; slash there was piled by tractor into a windrow during autumn 1968 and burned. 

The treatments consisted of a "revegetated" plot where the vegetative cover was 

in the process of recovering, since slash disposal, and a "bare" plot on which the 

vegetative cover was physically removed in 1972 (but not burned) for the second time. 

The bare plot was assumed to approximate the ground surface condition the first year 

following disposal of slash when ground cover was at a mInImum. Each treatment plot, 

about 25 m square, was positioned near the center of the clearing. 

The forested or "control" plots represented by stations 47 and 42 were deep in 

the uncut forests west of the treatment plots (fig. 1). 

3 
Figure 1.--Stations 42 and 44 (north slope) and stations 47 and 50 (south slope)~ 

Priest River Experimental Forest. Arrow denotes general wind direction south 

to west. 

INSTRUMENTATION AND MEASUREMENTS 

Rainfall and snowfall were indexed near each plot location from November 1, 1969, 

through October 31, 1973, by means of snow courses, recording rain gages, and snow 

lysimeters. Two parallel snow courses, located on the contour of each slope, traversed the clearcut and adjacent forest. Each course included 16 nonrandom snow sampling areas (10 in the clearcut and 6 in the forest). Water equivalent was measured 

periodically with a federal-type sampler during the accumulation-melt period, but only 

those readings taken at peak snowpack are discussed. 

Precipitation in the clearcut opening and through-fall in the forest were recorded 

by a Belfort rain gage equipped with stereo orifice and modified windshield (Haupt 

1972a). A single gage was positioned midway across the clearcut and another under the 

tree canopy on each forested plot. 

Percolate was collected from snow lysimeters (Haupt 1969), which were operated from 

November 1 through May 31. Lysimeters provided point measurements of net precipitation--

precipitation that percolated through the snowpack during rainy periods or ultimately 

entered the soil mantle as the snowpack melted. They were positioned near the rain 

gages. In the forest, they were located beneath a canopy configuration similar to that 

above each rain gage. 

4 
The climatic record also included temperature, wind travel, incoming solar radiation, and atmospheric relative humidity at each station. The relative humidity and 

temperature were obtained with a hair and bimetallic hygrothermograph, radiation with 

a mechanical pyranograph, and wind travel with a three-cup totalizer. These data were 

used to calculate potential evapotranspiration (PET) using the Penman equation with 

the wind function of Wright and Jensen (1972). 

During autumn 1972, neutron probe access tubes were installed by means of a method 

described by Cline and Jeffers (1975). These tubes were laid out in a random pattern 

about 10 m apart with three tubes in each forested plot, revegetated plot, and bare 

plot. A few tubes were placed to a depth of 183 cm, but bedrock forced termination of 

most tubes at a shallower depth. Despite these limitations, probe readings were taken 

in each tube to a depth of at least 137 cm. 

To measure soil water, a neutron probe manufactured by Troxler Electronic Laboratories, Inc., was used. Calibration was performed with volumetric samples from special 

calibration plots. Because of good consistency between volumetric samples and readings 

from the manufacturer's rating curve, no correction was needed. Soil water data were 

collected at l5-cm depth increments in autumn 1972 and spring, summer, and autumn 1973. 

The study design did not include the statistical sensitivity of taking pretreatment 

measurements to determine if inherent site differences existed. The drastic treatments 

used were assumed to overcome these. This proved to be the case in a Colorado study by 

Dietrich and Meiman (1974). 

RESULTS 

Soil water.--A graphic presentation of soil water content from April 4 to November 

19, 1973, is shown in figure 2. The three plot conditions are presented in each part (A 

and B) of the figure and represent the average of three tubes in each plot. Examination 

with reference to the bare plots suggests that water contents in the profile had begun 

to stabilize by the first part of June after fluctuating in early spring. Drainage 

from these soils was assumed to be substantially reduced and field capacity approached 

due to decreasing hydraulic conductivity (Baver and others 1972, p. 381-384). June 4 

was chosen as the beginning of the drawdown season for both slopes and estimated evapotranspiration (ET) water losses were determined for the six profiles from this date to 

August 27 when they contained the least water. 

A Duncan's Multiple Range Test at the 5 percent level of significance was applied 

to the means (water loss), and results are given in table 1. These mean losses do not 

include 2.5 cm of rain received during the first 3 weeks of June. The June storms 

provided the last important period of rain until August 30 when 1.8 cm of rain fell. 

Table 1 shows that, of the revegetated-forested plots, the north slope revegetated plot 

lost the least water to ET during this period. 

5 
50 A NORTH SLOPE 50 B SOUTH SLOPE 

40 40 

30 30 

20 20 

10 Forested 10 

0 0 

Cil 50 Cil 50 Qi Qi 

a; 40 a; 40 .S E 

C C OJ 30 OJ 30 

~ ~ 

a: 20 a: 20 UJ UJ l- I- <t: <t: 10 Bare $: 10 $: ....J ....J 

0 (5 0 (5 C/) C/) 

50 50 

40 40 

30 30 

20 20 

10 Revegetated 10 

0 0 

Apr. May Jun. Jul. Aug. Sep. Oct. Nov. Apr. May Jun. Jul. Aug. Sep. Oct. 

Figure 2.--Seasonal water content in 137-cm profile for (A) north slope plots and 

(B) south slope plots. 

Nov. 

Table 1.--Duncan's multiple range test of six water loss means at the 5 percent level 

of significance 

Treatment Mean (cm of water)l 

North slope, bare soil 4.2 

A 

South slope, bare soil 7.7 

B 

North slope, revegetated 10.4 

(5 years since logging) 

C 

North slope, forested 13.5 

South slope, forested 15.4 D 

South slope, revegetated 18.4 

(4 years since logging) 

IMeans followed by any letter are significantly different from those means not 

having that letter. 

6 
Figure 3.--Extraterrestrial solar 

energy on (5) south 

slope plots and (N) 

north slope plots. 

Alth0ugh not significant at the 

5 percent leveJ. the ordering of the 

last three means in tahle 1 is rea~onable in light of conditions existing 

on these plots. The greater rate of 

ET loss from the revegetated and fc)rested plots on the south slope is 

understandable due to greater 501ar 

1,000 

800 

z 

o 

i= 

« 

(5 

«;:::-

a:;,., 600 ---It"O «"0 

iI~ I-Q) 

t3"Ol 

a:~ a: ---l 400 wI-

« 

a: 

lx 

w 

200 

a 

s 

N 

Jan. Feb. Mar. Apr. May Jun. Jul. Aug. Sept. Oct. Nov. Dec. 

radiation (fig. 3) and therefore greater potential evapotranspiration: the greater rate 

of loss from evapotranspiration lTIay also be due to vegetative structure. The forested 

north slope plot contained primarily conifer0us tree species with no shrub understory 

(fig. 4), whereas the forested south slope plot contained substantial amounts of deciduous woody shrubs in addition to trees (fig. 5). Cline and Camphell (19761 8~rl ~ates 

(1968) suggest greater leaf diffusive conductances in deciduous species than in coniferous trees. This could contribute to the greater apparent use of soil water in plots 

with significant amounts of deciduous brush. 

In spite of variations in spring maximum water content of as much as 25 em 

several similar soil profiles on north and south exposures in the Priest River Experimental Forest contained about 10 cm of water at their driest (Cline 1974). From 

this and from results in table 2, we concluded that both forested and revegetated plots 

on the south slope had depleted soil water reserves to this minimum by August 27. This 

conclusion is also supported by the water content curves (fig. 2B) that inflect toward 

the horizontal starting in late July. 

However, north slope plots did not lose water to a minimum of 10 em nor did the 

loss rate of the forested plot appear to decrease as did those on the south slope 

during August. The curve for the north slope revegetated plot did inflect in August 

(fig. 2A), but the minimum water content of the profile was considerably higher than 

that of the forested plot. This suggests that, unlike the south slope which appeared 

to be completely reoccupied within 4 years, a 5-year period was not sufficient time 

for vegetation to completely reoccupy the soil volume after clearcutting. 

The bare plots in figure 2 lost more water at the beginning of the growing season 

season than they did as the soil surface dried. Starting in mid-July, the south bare 

plot shows an increased rate of water loss not shown by its north slope counterpart. 

The shrubs on the south aspect were characterized by extensive fibrous, horizontal 

root systems. The tendency of shrubs adjacent to the bare plot to branch their roots 

may account for the accelerated water losses in July and August, particularly in the 

7 
Figure 4.--(A) Undisturbed 

forested plot on north 

slope. (B) Revegetated 

plot on north slope 

clearcut. Note dominance of herbaceous spe- cies~ fireweed (Epilobium 

angustifolium L.). 

Table 2.--Water content in 13?-cm profile at spring field capacity and summer minimum 

Treatment 

Forested 

Bare 

Revegetated 

North slope South slope 

Spring Summer Spring Summer 

:field capacity: mlnlmum :fie1d capacity: mlnlmum 

: Mean S.D. :Mean S.D. :Mean S.D. :Mean S.D. 

em 

36.7 

38.2 

41.5 

3.5 

3.3 

4.0 

em 

23.2 

34.0 

31.1 

1.1 

4.0 

4.5 

em 

25.4 

33.4 

29.4 

3.8 

2.2 

4.5 

em 

10.0 

25.7 

11. 0 

3.2 

3.0 

2.8 

30- to 60-cm depth zone. (The borders of the bare plot were not trenched to sever 

roots.) Shrubs on sites like this may recover the total volume of soil water in less 

than 4 years largely because of their ability to grow back rapidly from root stocks. 

These shrubs will recover quickly even where aboveground foliage is completely destroyed 

by broadcast burning after logging (fig. 5). 

8 
Figure 5.--(A) Undisturbed 

forested plot on south 

slope. (B) Revegetated 

plot on south slope clearcut. Note dominance of 

deciduous woody brush~ 

ninebark. (C) Adjacent 

large clearcut where 

understory brush and 

logging slash were broadcast burned the fall of 

1968. 

9 
Frequent rains between August 30 and November 19 succeeded in recharging the soils 

to water levels observed the previous spring. The profiles with greatest water contents 

at the end of August tended to recharge more quickly (fig. 2, bare plots and north revegetated plot) than those that had been depleted of water by trees and dense brush. In 

the fall, the tree-covered and dense-brush plots recharged slowly at first, then more 

rapidly, suggesting that higher order vegetation was still removing water from these 

profiles. By the time the first snows covered the ground in mid-November, the soils 

were almost fully charged and in condition to add ground water reserves. 

Winter precipitation.--Soil water storage is but one component to consider in determining the potential water yield budget. At Priest River, where a major portion of the 

precipitation falls during the dormant season, snow storage, winter release (rain percolate and melt from winter snowpack), and spring melt are important considerations. For 

the period November 1, 1972, through t-1ay 31, 1973, the mea'n peak snowpack (WE) and seasonal totals of precipitation and lysimeter percolate are presented in table 3. To illustrate the effectiveness of timber harvest, a comparison of gains in the clearcut is 

shown in table 4. 

From November 1 to May 31, the lysimeter in the north forest registered the least 

amount of total percolate, but the north clearcut measured the most. The south forest 

and south clearcut ranked between the two extremes. The north clearcut showed the 

greatest gain (19.6 cm) after timber removal; in contrast, the south clearcut showed 

but a slight increase (2.9 cm). 

Table 3.--Mean peak snowpack (WE)l and seasonal 2 totals of precipitation and 

lysimeter percolate for study plots~ water year 1973 

WE Modified Belfort rain gage Lysimeter percolate 

- - - - - - - Centimeters - - - - - - - - - - -

North forest 14.0 South forest 42.9 North forest 38.9 

South forest 18.3 South clearcut 49.4 South forest 51. 2 

South clearcut 25.9 North forest 49.5 South clearcut 54.1 

North clearcut 32.3 North clearcut 60.9 North clearcut 58.5 

lClearcut means based on 20 samples, forest means based on 12 samples. 

2November 1, 1972, through May 31, 1973. 

Table 4.--Comparison of gains in clearcut based on three indexing techniques for the 

period November 1~ 1972, through May 31~ 1973 

Slope Mean peak Modified Lysimeter 

exposure snowpack Belfort rain gage percolate 

- - - - - - - - - - - Centimeters - - - - - - - - -

North +18.3 +11.4 +19.6 

South + 7.6 + 6.5 + 2.9 

10 
The snow courses, which provided broad spatial sampling of the plots, showed an 

identical order of ranking in terms of WE. Again, the north forest proved the least 

effective in storing snow at any time during winter. With timber removal, the WE increased by 18.3 cm on the north clearcut. The difference between south forest and 

south clearcut was much less, 7.6 cm, but exceeded the same comparative difference 

between lysimeters. 

Precipitation totals collected in rain gages deviated from the above pattern; both 

south slope gages caught less precipitation than gages on either the north forest or 

north clearcut (table 3). The south slope catch became suspect early. In a previous 

report, Haupt (1972a) ascribed the lower catch to aerodynamic (shear) stresses associated with rain gages on windswept, exposed (south) slopes. A more subdued effect of 

wind on gage catch was noted on sheltered (north) slopes. 

The relatively large difference (10.4 cm) between the north forest rain gage and 

north forest lysimeter was not expected, however, because both instruments had been 

placed under very similar tree canopies. This relationship held for previous years of 

record (1969-72) although the differences were not as great (unpublished data on file, 

Forestry Sciences Laboratory, Moscow). Perhaps the canopies above the rain gage became 

more porous during snow loading, allowing greater through-fall, and/or that the surface 

of the snow column forming in the lysimeter was subjected to some minor wind scouring 

and evaposublimation, resulting in some loss in total percolate. In view of the lower 

readings for snow courses in the north forest, the conclusion was that the lysimeter 

total was probably more representative of conditions under the timber stand than 

precipitation. 

The anomalous reading given by the south forest rain gage notwithstanding, it 

is significant that less snow storage and lysimeter percolate occurred in the dense 

north forest than in the less dense south forest. There is no evidence to show that 

precipitation incident to the south slope was substantially greater than that which 

fell on the north slope. Rather, the disparity is attributed to greater tree interception in the north forest and to subsequent evaposublimation exchange between the 

canopies and atmosphere. 

The physical processes involved are complex and detailed examination is beyond 

the scope of this paper. Several conditions probably contributed to greater interception losses in the north forest. First, and perhaps most important, the north 

forest, which had greater crown closure and thicker canopies, was capable of catching 

and holding considerably more snow (or rain) during a storm. Second, the north 

forest was afforded topographic shelter from prevailing winds and, as a consequence, 

less snow (or rain) was scoured or shaken from the canopies by this force. Third, 

less solar energy was received after storms in the north forest; so less canopy-held 

snow was transformed into drip and more remained intact in the canopies (Haupt 1972b). 

Fourth, the three conditions above provided more surface area and exposure hours for 

canopy-held snow to be acted upon between storms by evaposublimation processes. Finally, 

the north slope timber, in particular the south-facing portion of the upper tree crown, 

received adequate amounts of radiant energy at periods that were optimum for evaposublimation (not measured). During the dry winter-spring of 1973, optimum periods were 

numerous because of the low storm frequency. Over the 7-month period, total loss back 

to the atmosphere was estimated to be high. 

The lower snow storage efficiency of the south clearcut, compared to that of 

the north clearcut, appeared to be closely associated with its position near the ridgetop and exposure to wind and energy sources. For instance, mean wind travel (1969-73) 

at ground level was twice that in the north clearcut (table 5). Prevailing winds 

scoured snow in the opening, carried some of it over the ridge, and deposited it in 

a cornice to the lee of the ridgetop. In years prior to 1973, the cornice had accumulated significantly more WE by mid-March than would have occurred if the opening had not 

11 
Table 5.--Four-year mean l seasonal hlind travel at ground level in clearcut and forest~ 

by aspect 

Wind travel 

North 

South 

C1earcut 

51 

103 

. -1 - - - - - Meters m~nute 

lNovember 1 through May 31, water years 1970-73. 

Forest 

25 

47 

existed on the south slope (Haupt 1973). This accumulation'implies that some "lossesil 

from the south clearcut may have reappeared as "gains" in the cornice. Because the 

north clearcut measuring sites were located well downslope and slightly upwind (fig. 1), 

it is unlikely that any of the eroded snow from the south clearcut was moved beyond the 

cornice and redeposited there. 

The increased wind movement in the south clearcut also suggests the possibility 

of accelerated evaporation losses from the snowpack. By assuming exposure conditions 

similar to those reported by West (1959) for windy locations near ridges, the expected 

evaporation losses (not measured) could have been a few centimeters greater in the 

south clearcut than in the north clearcut and south forest. 

Potential hlater yield.--Increases in potential water yield could not be estimated without first determining ET loss from the soil profile during the complete 

growth period, spring through fall. The approach followed was an adaptation of the 

water-budget technique, in which losses to the atmosphere and to drainage were considered simultaneously. This is at best a tenuous approach associated with assumptions that may not be correct. 

The ET withdrawal from April 1 (arbitrarily set as the earliest date for any 

substantial ET) to June 4 was obtained by comparing actual soil water loss during 

a week of high evaporative demand in mid-May with potential evapotranspiration (PET) 

calculated from on-site radiation and other meteorological data. This soil water/PET 

relationship was then used to estimate ET for the early, snow-free spring period. 

These values may have overestimated ET loss during the period when deciduous, understory plants were leafing out. The estimated losses appear reasonable, ranging from 

3.6 to 6.8 cm (table 6). Greater loss would be expected on south slopes, which receive 

more solar radiation and wind. 

The assumption that drainage from the l37-cm zone was essentially zero by June 4 

and that ET became the major component in water loss after this date was applied for 

the summer period. Little or no rain fell until August 27; so the values in tables 2 

and 6 are good estimates of ET for this period. 

From August 27 to October 31, precipitation and the rate of recharge became significant parameters in evaluating ET loss. The date that soil water content reached 

the June 4 value was used as the cutoff point for shifting water loss from ET to potential water yield. An estimate of water loss was then based on rates of water loss shown 

in figure 2, since these values account for net precipitation. By October 31, any additional water needed to recharge the profile constituted a deficit. By these calculations, the four vegetated plots and the south-slope bare plot had soil water deficits 

on October 31, whereas the north-slope bare plot produced drainage prior to that date 

(table 6). Deficits or gains were added algebraically to the seasonal (1972-73) lysimeter outflow in order to close the bookkeeping procedure. 

12 
Table 6.--Determination of potential water yield for the period of November 1972 through October 1973 

Land 

type 

Forested 

Bare 

Revegetated 

Forested 

Bare 

Revegetated 

: Estimated 

Lysimeter evapopercolate : transpiration 

Nov. 1 - Apr. 1 

June 4 June 4 

38.9 

58.5 

58.5 

51.2 

54.1 

54.1 

4.6 

3.6 

4.7 

6.8 

4.2 

6.5 

Accumulated soil water 

deficit on last day of 

period 

June 4 - Aug. 27 -

Aug. 27 Oct. 31 

13.5 

4.2 

10.4 

15.4 

7.7 

18.4 

Centimeters -

NORTH SLOPE 

8.4 

.0 

.7 

SOUTH SLOPE 

6.0 

.2 

4.8 

Potential 

water 

yield 

Aug. 27 - . 

Oct. 31 

0.0 

6.1 

.0 

.0 

.0 

.0 

Potential 

water 

yield 

(annual) 

25.9 

61.0 

53.1 

38.4 

49.7 

42.8 

Potential 

gains due 

to 

treatment 

0.0 

+35.1 

+27.2 

0.0 

+11.3 

+ 4.4 

The dense north forest had a potential water yield of 25.9 em, or 12.5 em less than 

the more open south forest (table 6). On the other hand, the last column in table 6 indicates that the greatest gain (35.1 em) and the most sustained gain (27.2 em) occurred 

on the north slope as a result of c1earcutting. More modest gains, 11.3 em and 4.4 em, 

respectively, were registered on bare and revegetated plots on the south slope .. 

Would potential water yields have been comparable in earlier years prior to the 

soil water study? Evapotranspiration losses vary from year to year, being largely 

dependent upon energy input in spring and fall and upon rain in summer. The soil profile probably would not hold more than a fixed amount of water. Consequently, t~e 

supply available for plant use would be limited until water was added. Since the year 

(1973) was extremely dry during late June, July, and August and precipitation was above 

average during September and October, ET estimates are no doubt conservative. In wetter 

summers, rain input would most likely be lost to the atmosphere; little or no water 

would be added to deep drainage, thus increasing seasonal ET. 

If the above reasoning is accepted, the measurement that best correlates with potential water yield would be 1ysimeter percolate measured during winter release and 

spring snowmelt. Differences in lysimeter percolate between forest and clearcut on the 

north slope were consistently large in previous years of record (1969-72); consequently, 

gross gains in potential water yield would be expected to be consistently large (unpublished data on file, Forestry Sciences Laboratory, Moscow). 

On the south slope, conditions were highly variable. In 2 previous years (1971, 

1972) there were no gains in lysimeter outflow in the south clearcut; in fact, compared 

with the south forest, less outflow was produced. This decline was probably due to 

greater snow scouring and evaposublimation loss. In 1970, lysimeter outflow in the 

south clearcut was comparable to the 1973 outflow (unpublished data on file, Forestry 

Sciences Laboratory, Moscow). 

13 
SUMMARY AND CONCLUSIONS 

The practice of clearcutting forested lands to improve water yield is widely 

accepted. The data presented in this study suggest that under certain circumstances 

potential water yield increase may be high; under other conditions, the increase can 

range from negligible to moderate. Slope orientation and wind exposure, as well as 

forest stand density and structure, are important considerations in defining potential 

water yield increase. 

The north slope in this study responded to removal of a mature old stand (western 

hemlock-western redcedar/pachistima habitat type) by supporting greater depths of snow, 

higher percolation from the snowpack, and greater amounts of water draining through the 

soil mantle to ground water reserves. After tractor piling and slash burning, gradual 

reoccupation of the soil mantle by invading herbaceous species (primarily fireweed) 

sustained a large part of the soil water gains for at least 5 years. 

Greater storage of snow was due primarily to removal of tall, mature, closedcanopied timber that before cutting suspended a large amount of winter snowfall (and 

rain) in the foliage. This intercepted precipi~ation, held high overhead, was vulnerable between storms to radiation sources and wind movement at treetop level. It seems 

reasonable to suggest that the net result was considerable evaposublimation loss back 

to the atlnosphere. The residual snow left in the canopies eventually fell to the 

forest floor to add to the reduced snowpack. 

Removal of the mature old stand (Douglas-fir/ninebark habitat type) on the south 

slope had a considerably smaller effect on potential water yield. In the first year 

after clearcutting, the yield increase was only 32 percent of that measured on the 

north slope. The invading shrub species (primarily ninebark) rapidly reoccupied the 

soil mantle. After 4 years of recovery, the shrub monoculture extracted probably more 

water from the soil during the extremely dry summer than did the original tree 

overstory-shrub understory. Had there not been greater snow storage during the dormant 

season to compensate for water removal, a small increase in potential water yield would 

not have resulted. 

Clearcutting on the south slope created less favorable conditions for storing 

additional snow and producing an excess of percolate into the soil mantle. Because of 

more open spacing of mature trees, snowfall easily penetrated to the ground surface. 

Furthermore, the prevailing winds and high incident solar radiation caused more of the 

intercepted snow to either blow off and descend to the forest floor or melt in place 

and fall as drip. By inference, less evaposublimation occurred and therefore the potential for interception savings to accrue after timber removal was also greatly reduced. 

In addition, the exposed clearcut received the brunt of the wind and lost snow by scouring and perhaps by accelerated surface evaposublimation. At the end of melt season, the 

net effect was a slight excess of percolate over that which occurred in the south slope 

forest. In earlier years, under different weather patterns, an excess of percolate might 

have been nonexistent. 

14 
These results apply only to one unreplicated set of three study plots in each of 

two climax habitat types and under the sequence of climatic events recorded. If the 

specific data on potential water yield increase are extrapolated to other old-growth 

timber sites with similar terrain and habitat type, it should be done with the above 

limitations in mind. However, the principles underlying the occurrence of these data 

can be readily applied elsewhere. 

PUBLICATIONS CITED 

Anderson, H. W. 

1956. Forest-cover effects on snowpack accumulation and melt, Central Sierra Snow 

Laboratory. Am. Geophys. Union Trans. 37:307-312. 

Anderson, H. W. 

1963. Managing California's snow zone lands for water. USDA For. Servo Res. Pap. 

PSW-6, 28 p. Pac. Southwest For. and Range Exp. Stn., Berkeley, Calif. 

Baver, L. D., W. H. Gardner, and W. R. Gardner. 

1972. Soil physics. 489 p. John Wiley and Sons, New York. 

Bethlahmy, N. 

1973. Water yield, annual peaks and exposure in mountainous terrain. J. Hydrol. 

20:155-169. 

Cline, R. G. 

1974. Seasonal, diurnal, and spatial water use and water relations of selected 

forest species. Ph.D. Thesis, Wash. State Univ., Pullman, 59 p. 

Cline, R. G., and G. S. Campbell. 

1976. Seasonal and diurnal water relations of selected forest species. Ecology 

57:367-373. 

Cline, R. G., and B. L .. Jeffer!". 

1975. Installation of neutron probe access tubes in stony and houldery forest soils. 

Soil Sci. 120:71-72. 

Daubenmi re, R., and .J. R. Daubenmi re. 

1968. Forest vegetation of eastern Washington and northern 1daho. Wash. Agric. Exp. 

Stn. Tech. Bull. 60, 1()4 p. Pullman, Wash. 

Dietrich, T. L., and J. R. Meiman. 

1974. Hydrologic effects of patch cutting of lodgepole pine. Colo. State Univ. 

Hydro1. Pap. 66, 31 p. 

Gary, H. L. 

1974. Snow accumulation and snowmelt as influenced by a small clearing in a lodgepole pine forest. Water Resour. Res. 10:348-353. 

Gates, D. M. 

1968. Transpiration and leaf temperature. Am. Rev. Plant Physi01. 24:515-570. 

Haupt, H. F. 

1969. A simple snowmelt 1ysimeter. Water Resour. Res. 5:714-718. 

Haupt, H. F. 

1972a. Improved instrumentation for measuring melted precipitation on windswept 

topography. Proc. Int. Symp. on Distribution of Precipitation in Mountainous Areas, 

p. 73-85. WMO, Geil0, Norway 

Haupt, H. F. 

1972b. The release of water from forest snowpacks during winter. USDA For. Servo 

Res. Pap. INT-114, 17 p. Intermt. For. and Range Exp. Stn., Ogden, Utah. 

15 
Haupt, H. F. 

1973. Relation of wind exposure and forest cutting to changes in snow accumulation. 

Proc. Banff Symp. on the Role of Snow and Ice in Hydrology. UNESCO, Paris, 10 p. 

Hoover, M. D., and C. F. Leaf. 

1967. Process and significance of interception in Colorado subalpine forest. 

In Forest hydrology, p. 213-223. W. E. Sopper, and H. W. Lull, ed. Pergamon 

Press, New York. 

Hoover, M. D. 

1969. Water yield improvement for the timber snow zone of the central Rocky 

Mountain area. In Proc. Workshop on Snow and Ice Hydrology, p. 111-116. Colo. 

State Univ., Fort Collins. 

Packer, P. E. 

1962. Elevation, aspect, and cover effects on maximum snowpack water content in 

a western white pine forest. For. Sci. 8:225-235. 

Satterlund, D. R., and H. F. Haupt. 

1972. Vegetation management to control snow accumulation and melt in the northern 

Rocky Mountains. In Proc. Natl. Syrnp. on Watersheds in Transition, p. 200-205. Colo. 

State Univ., Fort Collins. 

Smith, J. L. 

1974. Hydrology of warm snowpacks and their effects upon water delivery ... some new 

concepts. In Advanced concepts and techniques in the study of snow and ice 

resource, p. 76-89. Natl. Acad. Sci., Washington, D.C. 

Tew, R. K. 

1967. Soil moisture depletion by aspen in central Utah. USDA For. Servo Res. Note 

INT-73, 8 p. Interrnt. For. and Range Exp. Stn., Ogden, Utah. 

West, A. J. 

1959. Snow evaporation and condensation. Twenty-seventh Annu. West. Snow Conf. 

Proc., p. 66-74. 

Wright, J. L., and M. E. Jensen. 

1972. Peak water requirements of crops in southern Idaho. J. Irrig. Drainage Div., 

Proc. Am. Soc. Civ. Eng. 98:195-201. 

Zeimer, R. R. 

1964. Summer evapotranspiration trends as related to time after logging of forests 

in Sierra Nevada. J. Geophys. Res. 69:615-620. 

16 

f:f u.s. GOVERNMENT PRINTING OFFICE: 1977-0-777-023-6 
Cline, Richard G., Harold F. Haupt, and Gaylon S. Campbell 

1977. Potential water yield response following clearcut harvesting 

on north and south slopes in northern Idaho. USDA For. Servo 

Res. Pap. INT-191, 16 p. Intermt. For. & Range Exp. Stn., 

Ogden, Utah 84401. 

The hydrologic response of small clearcuts on north and south 

slopes in northern Idaho was investigated. On the north slope, substantial gains (27 to 35 cm) in potential water yield per year resulted from 

(a) removal of transpi ring surfaces associated with plant cover, (b) e limination of snow interception by a closed-canopied forest, and (C) delayed 

reoccupation of the soil mantle by invading herbaceous species. On the 

south slope, small to moderate gains (4 to 11 em) in yield resulted from 

elearcutting, at least in 1973, the year studied. 

KEYWORDS: soil moisture content; clearcutting; snowmelt infiltration; 

canopy interception; logging hydrology 

Cline, Richard G., Harold F. Haupt, and Gaylon S. Campbell 

1977. Potential water yield response following clearcut harvesting 

on north and south slopes in northern Idaho. USDA For. Serv. 

Res. Pap. INT-191, 16 p. Intermt. For. & Range Exp. Stn., 

Ogden, Utah 84401. 

The hydrologic response of small clearcuts on north and south 

slopes in northern Idaho was investigated. On the north slope, substantial gains (27 to :35 cm) in potential water yield per year resulted from 

(a) removal of transpiring surfaces associated with plant cover, (b) elimination of snow interception by a closed-canopied forest, and (c) delayed 

reoccupation of the soil mantle by invading herbaceous species. On the 

south slope, small to moderate gains (4 to 11 cm) in yield resulted from 

clearcutting, at least in 1973, the year studied. 

KE'{WORDS: soil moisture content; clearcutting; snowmelt infiltration; 

canopy interception; logging hydrology