United States 

Departmentof Clearcuttina Affectsstream 

Agriculture 

Forest Service Chemistry h the White Mountains 

Northeastern Forest 

Experiment Station 

of New Hampshire 

Research Paper 

N E-579 

C. WAYNE MARTIN 

ROBERT S. PIERCE 

GENE E. LIKENS 

F. HERBERT BORMANN 
The Authors 

C. Wayne Martin is a research forester with the Northeastern Forest 

Experiment Station's research unit at the Hubbard Brook Experimental 

Forest, West Thornton, New Hampshire. He received a B.S. degree in forest 

management, and an M.S. degree in forest hydrology from the University of 

New Hampshire. He joined the USDA Forest Service in 1966. 

Robert S. Pierce is Project Leader of the research unit studying the 

impact of forest management and acid precipitation on nutrients in soil and 

water at the Hubbard Brook Experimental Forest. He received a Ph.D. 

degree in forest soils from the University of Wisconsin. He has directed 

research programs at Hubbard Brook Experimental Forest since 1958. 

Gene E. Likens is Director of the Institute of Ecosystem Studies for 

the New York Botanical Garden. He also is adjunct professor of ecology at 

Cornell University and professor of biology at Yale University. He received a 

Ph.D. degree in zoology from the University of Wisconsin. He has been 

codirector of the Hubbard Brook Ecosystem Study since 1963. 

F. Herbert Bormann is the Oastler Professor of forest ecology and 

Director of ecosystem research in the School of Forestry and 

Environmental Studies at Yale University. He has been codirector of the 

Hubbard Brook Ecosystem Study since 1963. 

Abstract 

Clearcutting of northern hardwood forests in New Hampshire resulted 

in accelerated loss of dissolved nutrients to streams similar to that shown 

in experimental studies at Hubbard Brook. Stream water samples were 

collected during 4 years from nine watersheds that had been completely 

clearcut and from five nearby reference watersheds that were uncut. Differences in stream chemistry between clearcut and reference watersheds 

were greatest during the second year after cutting. During the 4 years of 

the study, specific conductance of the reference streams ranged from 20 to 

30 pSlcm; average pH ranged from 5.0 to 5.7; nitrate ranged from less than 

0.1 to about 4.0 mgll; calcium from 1.0 to 3.0 mgll; ammonium from less 

than 0.01 to 0.05 mgll; magnesium from 0.2 to 0.8 mgll; sodium from 0.6 to 

1.6 mgll; potassium from 0.1 to 0.7 mgll; sulfate from 3.0 to 8.0 mgll; and 

chloride from 0.3 to 0.6 mgll. During the second year after clearcutting, 

specific conductance of streams draining the cuts ranged from 22 to 68 

uSlcm; average pH ranged from 5.1 to 6.0; nitrate ranged from 1.4 to 27.3 

mgll; calcium from 1.4 to 6.7 (ngll; ammonium from less than 0.01 to 0.05 

mgll; magnesium from 0.3 to 1.4 mgll; sodium from 0.8 to 3.0 mgll; potassium from 0.1 to 1.5 mgll; sulfate from 2.1 to 6.3 mgll; and chloride from 0.4 

to 0.9 mgll. During the first year after cutting, streams from the cuts were 

more acidic than those from the reference streams; however, they were 

less acidic by the end of the second year. Concentrations of most ions in 

streams from clearcuts approached reference levels by the end of the 

fourth year after clearcutting, though streams from clearcuts remained less 

acidic by nearly a whole pH unit, sulfate remained depressed, and potassium remained elevated. During the 4 years following cutting, stream 

exports from cut sites exceeded those from reference sites by 57 kglha for 

inorganic nitrogen, 61 kglha for calcium, and 15 kglha for potassium. 

Manuscript received for publication 6 May 1985. 
Introduction 

Even-age forest management is practiced widely 

with many forest types in the Northeastern United 

States (USDA 1973). However, site changes created by 

clearcutting at the end of the management cycle may 

cause major changes in soil fertility and in water 

quality of streams flowing through the cut areas. Our 

paper examines these changes as they occur in northern hardwood forests on glaciated soils of the White 

Mountains of New Hampshire. 

Soils underlying these forests are spodosols 

formed on glacial till and outwash. Under forest cover, 

these soils are characterized by organic horizons over 

mineral soil. Most of the available nutrients and, in 

turn, the majority of plant roots are found in the 

surface organic horizons (Hoyle 1973; Wood 1980). 

Because of low clay content, low basic minerals, and 

high acidity, the mineral horizons tend to be relatively 

infertile. Removal of the forest canopy during harvesting increases temperature and moisture in the forest 

floor, increases nitrification, and decreases uptake of 

water and nutrients by plants (Bormann and Likens 

1979). The warmer, wetter microclimate leads to an 

increased rate of organic matter decomposition, 

nitrification, and mineralization, with a net reduction in 

the amount of humus (Hart 1961; Dominski 1971; 

Covington 1981). These processes rapidly convert 

unavailable nutrients in organic matter into available 

plant nutrients. 

Abundant available nutrients, water, and light 

usually lead to rapid revegetation of the site by flora 

adapted to these disturbed conditions (Bormann and 

Likens 1979). However, because of the accelerated 

mineralization coincident with reduced net uptake and 

storage of nutrients by forest vegetation for the first 

few years after cutting, some of these available nutrients are leached to groundwater or streams (Bormann 

and Likens 1979). Different soils and vegetation types 

vary in their ability to retain these mineralized nutrients 

on the sites (Corbett et al, 1978; Vitousek and Melillo 

1979). 

In this paper, we present 4 years of postcutting 

data on stream water chemistry from nine clearcut 

watersheds dispersed throughout the White Mountains 

of New Hamphire. We compare stream water ion 

concentrations and nutrient removal between clearcut 

areas and adjacent uncut reference watersheds. 

Preliminary data from this study were published by 

Pierce et al. (1972), and nitrate and calcium data from 

these watersheds were published by Martin and Pierce 

(1 980). 

The objective of this study was to test the applicability of the findings of experimental clearcutting 

studies at the Hubbard Brook Experimental Forest in 

central New Hampshire (Pierce et al. 1970; Hornbeck et 

al. 1975; Likens et al. 1977) to a broader geographic 

area, and to document nutrient-cycling parameters that 

should be considered in evaluating the impact of 

clearcutting on site productivity. 

The Study 

Beginning in 1970, we examined numerous 

commercial clearcutting operations in the White 

Mountain National Forest to locate potential study 

sites. We located five areas with similar topography, 

vegetation, soils, and geology. Each area included at 

least one clearcut watershed and in two cases several 

clearcuts (Table 1). These sites had well-defined watersheds with perennial headwater streams, and all stems 

more than 5 cm in diameter at breast height (d.b.h.) 

had been cut. Each area had an adjacent or nearby 

uncut watershed that served as a reference (Reinhart 

1967). Descriptions of the sites, volumes of trees 

before cutting, time of cutting, volume and species of 

wood removed, and maps were provided by the staff of 

the White Mountain National Forest. 

Before cutting, all of the watersheds had been 

covered by second-growth forests, 50 to 100 years old. 

They contained the following ranges of species by 

volume: 1 to 40 percent sugar maple (Acer saccharum 

Marsh.); 8 to 17 percent yellow birch (Betula 

alleghaniensis Britton); 15 to 77 percent beech (Fagus 

grandifolia Ehrh.) and other northern hardwoods; and 3 

to 30 percent spruce (Picea rubens Sarg.) and balsam 

fir (Abies balsamea (L.) Mill.). 

Methods 

Stream water samples were collected twice each 

month from April through November-and monthly 

during the winter-except at Hubbard Brook and East 

Branch, where samples were collected weekly. Specific 

conductance was measured in the field. Laboratory 

measurements included pH, concentrations of nitrate, 

calcium, magnesium, sodium, and potassium. 

Concentrations of ammonium, sulfate, and chloride 

were measured but not in all streams. The methods 

used for collecting samples, intensity of sampling, and 

procedures for chemical analyses were reported by 

Likens et al. (1977). Mean pH was calculated by 

converting pH to hydrogen ion concentrations, averaging, and reconverting to pH. 

Watersheds were clearcut between 1968 and 1972 

(Table I), whereas stream water sampling began in the 

autumn of 1970 and continued through 1974. All of the 

clearcut watersheds were harvested between August 

and December before what we term the "first year after 

cut" (Figs. 1-6). Since the principal objective was to 

estimate stream water chemistry at different times 

after clearcutting, it was necessary to average stream 

water chemistry as follows: stream water concentrations in samples taken in 1971 for all stands cut in 

1970 were averaged to represent the first year after cutting; stream water concentrations taken in 1971 for 

stands cut in 1969 were averaged to represent 2-yearold cuts along with concentrations collected in 1972 

for stands cut in 1970, and so forth. Concentrations for 

the reference watersheds for 1971-74 also were 

averaged by years. 
Table 1.-Site characteristics of the watersheds 

Year 

Total Soil Northern Bedrock of 

Watershed area Aspect Slope texturea Hardwoods Geologyb CutC 

1. Gale River 49 

2. Beaver Brook 50 

3. Conner Brook 45 

4. East Branch 8 

5. Hubbard Brook 13 

6. Hubbard Brook 

7. East Branch 

8. Gale River 

9. Gale River 

10. Gale River 

11. Gale River 

12. Beaver Brook 

13. Beaver Brook 

14. Conner Brook 

Percent Percent 

REFERENCE 

10 s I 90 

15 s I 90 

32 Is 80 

15 SI 70 

20 SI 95 

COMPLETELY CLEARCUT 

35 s I 95 

10 SI 70 

10 SI 95 

10 SI 95 

10 s I 95 

10 s I 95 

15 s I 90 

15 SI 90 

32 s I 80 

a sl = sandy loam, Is = loamy sand. Conner Brook soils are in the Berkshire-Lyman-Marlow 

association; all other sites are in the Becket-Lyman-Hermon association. 

b kqm = Kinsman quartz monzonite, bg = Bethlehem gneiss, Ifg = Littleton formation 

sillimanite-zone gneiss with mica shist intrusions. 

C A = autumn, October through mid-December; G = growing season, August and September. 

Construction of the nutrient budgets required 

some assumptions. Previous work (Martin 1979) 

indicated that although the quantity of precipitation is 

quite variable throughout the White Mountains, 

precipitation chemistry is not. Consequently, precipitation chemistry was measured only at the Hubbard 

Brook Experimental Forest. Precipitation quantity was 

drawn from the National Weather Service volunteer 

network (NOAA 1971, 1972, 1973) and from Hubbard 

Brook. Volume-weighted ionic concentrations in 

precipitation from Hubbard Brook were summed by 

month. Monthly concentrations (mgll) were multiplied 

by the estimated monthly precipitation quantity (Ilha) 

for each site. Then the total estimated monthly 

quantity for each ion from each site was summed for 

the year to give the input data as kglhalyr for each 

watershed. Streamflow estimates were derived for each 

area from a hydrologic model developed at the 

Hubbard Brook Experimental Forest (Federer and Lash 

1978). This model estimates streamflow increases due 

to cutting and decreases due to revegetation. Output 

i 

I budgets were calculated by averaging monthly ionic 

concentrations in stream water and multiplying by the 

estimated monthly streamflow for each site and 

summed for the year. 

I 

i 

Results 

Although the results presented here are averages, 

the highest concentrations (as represented by the 

range bars in Figures 1-5) generally are from one 

particular watershed and the lowest are consistently 

from another. The differences in the results between 

cut watersheds probably reflect local differences in 

climate, weather, topography, soils, and glacial till. We 

have attempted to minimize these differences by 

averaging the data. In so doing we can discuss the 

general effects of harvesting on water chemistry in the 

region. But it must be realized that at any one site, the 

effects may be larger or smaller. 

Specific Conductance 

Specific conductance of the streams that drained 

the reference watersheds ranged between 20 to 30 

pSlcm with few exceptions throughout the 4 years of 

the study (Fig. 1). No single stream was consistently 

higher or lower than the rest. A seasonal pattern was 

evident with the lowest values occurring in the summer 

and the highest values in the winter. 
------b Clearcut 

- Forest 

JMMJSNIJMMJSN~JMMJSN~JMMJSN 

1 st year 2nd year 3rd year 4th year 

Figure 1.-Mean monthly specific conductance of streams from both forested and 

clearcut watersheds for 4 years after cutting (vertical bars represent the range of 

mean monthly data among the individual streams studied). 

The first winter after cutting, specific conductance 

of the streams that drained clearcut watersheds was 

similar to that of the reference streams. But early in 

the first spring after cutting, the conductance began to 

rise. It increased steadily through the summer, autumn, 

and winter to peak during the spring of the second 

year after cutting (about 18 months after cutting). 

Although there was variation among watersheds, 

specific conductance of all streams rose steadily 

during this period. The maximum values for each 

stream during the first 18 months after cutting ranged 

from 48 to 66 pSlcm. 

In most cases, conductance declined the second 

summer after cutting, only to increase again the next 

autumn (about 26 months after cutting). Specific 

conductance of the stream draining the clearcut at 

Hubbard Brook dropped to 24 pSlcm in September (21 

months after cutting) and rose to only 35 pS1cm by 

December. At the other extreme, two streams at Gale 

River dropped only to about 59 pSlcm during the 

second summer after cutting, and rose to nearly 69 

pSlcm during the autumn (25 months after cutting). 

During the third year after cutting, specific 

conductance declined in all streams draining cut areas 

but the differences among these streams remained 

large, as indicated by the relative size of the range bars 

(Fig. 1). The streams at Hubbard Brook dropped below 

reference values while the two streams at Gale River 

remained above 47 pSlcm. 

During the fourth year after cutting, the specific 

conductance of all of the streams draining clearcut 

watersheds returned nearly to reference levels. The 

variation among streams also was greatly reduced 

during the fourth year. 
------ Clearcut 

- Forest 

4.0 1 

JMMJSN~JMMJSN~JMMJSN~JMMJSN 

I st year 2nd year 3rd year 4th year 

Figure 2.-Mean monthly pH of streams from both forested and clearcut watersheds 

for 4 years after cutting (vertical bars represent the range of mean monthly data 

among the individual streams studied). 

The range of pH was considerable both within and 

among the reference streams (Fig. 2). The average pH 

of all five reference streams ranged from 5.0 to 5.7. But 

the most acidic reference stream ranged from pH 4.7 

to 5.1, while the least acidic dropped below pH 6.0 only 

six times in 30 months. Generally, conditions in the 

streams were most acidic during the snowmelt period 

in the spring, and least acidic during leaf fall in 

autumn. 

During the first and second years after cutting, the 

mean and range of means of pH for all streams draining the clearcut watersheds were similar to those of 

the reference steams (Fig. 2). Although the average 

acidity for streams ir! reference and clearcut watersheds was similar, individual paired watersheds exhibited marked differences. For example, two streams 

from clearcut watersheds remained more acidic than 

their reference counterparts-with an average pH of 

about 5.5 versus 6.4 throughout the second year after 

cutting. But one stream from another clearcut 

remained less acidic than its reference, with an 

average pH of about 6.3 versus 5.5, throughout nearly 

all of the second year after cutting except in late 

summer and early autumn when their pH levels were 

similar. 

In the third and fourth years after cutting, all 

streams draining clearcuts were less acidic than their 

paired reference watersheds; the average pH was about 

6.0 versus 5.4 (Fig. 2). 

Nitrate 

Nitrate concentrations (Fig. $3) in the streams that 

drained the reference watersheds ranged from less 

than 0.1 mgll to about 4.0 mgll. A seasonal trend was 

apparent; concentrations were higher through the 

winter and spring than during the summer, a pattern 

similar to that reported in long-term studies of forested 

watersheds at Hubbard Brook (Likens et al. 1977). 

During the summer, nitrate concentrations dropped to 

less than 0.5 mgll in some streams but remained 

higher than 2.0 mgll in others. 

All of the clearcut watersheds were harvested 

between August and December. The first year after cutting, nitrate concentrations in most of the streams 

draining these watersheds were higher than in the 

reference streams by February (2 to 6 months after cutting). Although there was wide variation among 

streams, nitrate concentrations in all cases continued 

to increase throughout the first year after cutting. 

Nitrate concentrations in all streams were highest 

between January and April of the second year (16 to 20 

months) after cutting. This maximum value ranged 

between 23 to 28 mgll among streams. Following the 

peak, nitrate in most of the streams began a steady 

decline that approached reference levels by the middle 

of the fourth year (48 to 54 months) after cutting. This 

decline was much more rapid in some cases than in 

others, as the range lines in Figure 3 indicate. 
,...... . Clearcut 

- Reference 

1 st year 2nd year 3rd year 4th year 

Figure 3.-Mean monthly nitrate concentrations in streams from both forested and 

clearcut watersheds for 4 years after cutting (vertical bars represent the range of 

mean monthly data among the individual streams studied). 

Ammonium 

Ammonium concentrations were measured in 

stream water from three pairs of reference and clearcut 

watersheds. Ammonium ranged from less than 0.01 to 

0.05 mgll, inclusive. No seasonal trends, treatment 

effects, or differences between watersheds were 

apparent. 

Calcium 

Calcium concentrations in the reference streams 

ranged from 1.0 to 3.0 mgll (Fig. 4). Variation among 

streams or over time within individual streams was 

slight. 

Calcium concentrations in the streams draining 

harvested watersheds began to rise immediately after 

clearcutting. Values generally were highest (6.5 to 8.1 

mgll) during the winter of the second year (12 to 16 

months) after cutting. Calcium in the stream at 

Hubbard Brook (lower limit of range lines in Figure 4) 

had returned to reference levels 28 months after cutting; but in two streams at Gale River (upper limits of 

the range bars in Figure 4), calcium concentrations 

were twice those of reference levels 50 months after 

cutting. 

Magnesium 

Magnesium concentrations in the reference 

streams were stable, varying by no more than 0.1 mgll 

over the 4 years of the study. There was some variation 

between watersheds: one averaged 0.2 mgll; another 

averaged 0.8 mgll. 

Following clearcutting, magnesium concentrations 

generally rose slowly throughout the first year (Fig. 5) 

and peaked in the second year after cutting. In some 

streams, this peak occurred early in the spring of the 

second year, in some in midsummer, and in others not 

until late autumn (2 full years after cutting). Generally, 

this second-year peak, as high as 1.4 mgll, was 3 to 5 

times as large as the concentrations in the paired 

reference streams. 
8.0 : - 400 

- ------* Clearcut 

a, 

- w =L 

- 200 I 2 

0 

8.0 - - 160 

- 

= 

- 120 2 

- w =t 

- 80 

a a 

u - LL 

A ! J 

3 

v, 2.0 - - 40 2 

- 

0 -0 

JMMJSN JMMJSN JMMJSN JMMJSN 

1 st year 2nd year 3rd year 4th year 

Figure 4.-Mean monthly calcium and sulfate concentrations in streams from both 

forested and clearcut watersheds for 4 years after cutting (vertical bars represent the 

range of mean monthly data among the individual streams studied). 

Magnesium concentrations declined slowly 

throughout the third and fourth years after cutting. 

Examination of individual grouped watersheds revealed 

that magnesium concentrations in about half of the 

streams returned to reference levels by the summer of 

the fourth year, while the remainder at 0.6 mgll were at 

least double reference levels after 50 months. 

Sodium 

Sodium concentrations in the reference streams 

ranged from 0.6 to 1.6 mgll. A seasonal pattern was 

apparent: the higher concentrations usually were 

recorded in late summer and the lower concentrations 

in the sDrina. This att tern likelv resulted from a dilucases (Fig. 5). In the spring of the fourth year after cutting, sodium, in all streams, decreased below reference 

levels for several months and then returned to reference levels. 

Potassium 

Potassium levels in the streams draining reference 

watersheds ranged from 0.1 to 0.7 mgll, with most 

streams near 0.3. Following clearcutting, mean monthly 

concentrations ranged from 0.1 to 1.5 mgll, with the 

average at 0.7 mgll. However, on a paired-watershed 

basis, potassium concentrations were 3 to 4 times 

greater than reference levels following cutting, and 

thev remained elevated throu~houthe study. There I tion effict guring spring snowmelt (Johnson et al. was neither an obvious second-year peak nor a gradual I 1969). Following cutting, sodium concentrations rose return toward reference levels during the 4 years (Fig. 

steadily through the first 2 years to 3.0 mgll in some 5). 
.----- Clearcut 

= 1.5 - - Forest c 

- 

30 \, 

O JMMJSN~JMMJSN~JMMJSN~JMMJSN 

I 1 st year 2nd year 3rd year 4th year I 1 

I Figure 5.-Mean msnthly magnesium, sodium, and potassium concentrations in 

several streams from both forested and clearcut watersheds for 4 years after cutting 

(vertical bars represent the range of mean monthly data among the individual streams 

studied). 

Sulfate 

Sulfate concentrations in the streams that drained 

both reference and clearcut watersheds were variable 

both among streams and from month to month in the 

same stream (Fig. 4). Sulfate in the streams that 

drained clearcut watersheds were below reference 

levels after cutting, and remained so throughout this 

study. 

Chloride 

During the first 2 years after cutting, average 

chloride concentrations from reference watersheds 

ranged from 0.3 to 0.6 mgll. Those from the clearcuts 

ranged from 0.4 to 0.9 mgll. During the third and fourth 

years after cutting, both reference and clearcut values 

ranged from 0.2 to 0.8 mgll. 

Downstream Concentrations 

The stream system at Gale River provided us with 

an opportunity to compare dilution effects downstream 

from the clearcuts. A headwater stream was used as 

the forested reference. Samples were collected from 

several small streams that drained 100 ha that had 

been completely clearcut, and the data were averaged. 

Collections were also made downstream at points 

where the clearcutting represented 63, 17, 13, and 6 

~ercent of the area of the watershed. 

Only nitrate data are presented (Fig. 6) because 

that ion reacted most dramatically to clearcutting. 

These data indicate that the smaller the area of a 

watershed clearcut, the smaller the increase in 

concentration. Nitrate concentrations in streams from 

the watersheds with 13 and 6 percent of the area clearcut were not different from the reference values. 
-I 100% Clearcut 

... .... 63% Clearcut 

1-11 

- 

17% Clearcut 

Reference 

6% and 13% 

clearcut are 

the same. 

197 1 1972 1973 1974 

Figure 6.-Mean monthly nitrate concentrations in streams from an uncut, 

completely clearcut, and four partially clearcut watersheds. Data from the streams 

draining watersheds that were 13 and 6 percent clearcut were the same as from the 

reference. 

Input-Output Nutrients Budgets 

It is useful to know the total quantity of an element that has been removed from a watershed via 

streamflow. Nutrient flux values are presented to indicate the mass inflow and outflow of ions per hectare of 

watershed per year (Table 2). Losses of nutrients in 

particulate matter due to erosion were not considered, 

but are likely to have been small (Bormann et al. 1974). 

Dissolved inorganic nitrogen (NO3-N plus NH4-N) 

in precipitation averaged 7.5 kglhalyr (Table 2) over the 

2-year period. The reference watersheds lost 3.7 

kglhalyr in streamwater for a net gain of 3.8 kglhalyr of 

inorganic nitrogen. This net gain compared favorably 

with the long-term mean of 2.5 kglhalyr observed for 

forested watersheds at Hubbard Brook from 1963 to 

1974 (Likens et al. 1977). 

Watersheds that had been clearcut for 1 year lost 

2.2 times as much inorganic nitrogen as entered in 

precipitation. Losses the second year after cutting 

were 4 times greater than inputs. The net loss of 

inorganic nitrogen over the 4-year period was 42 kglha. 

For the same period, the reference watersheds were 

accumulating 15 kglha N (Table 2). On the basis of 

precipitation inputs and streamflow outputs only, by 

the fourth year after cutting, inorganic nitrogen was 

beginning to accumulate in the harvested watersheds 

again by about 2 kglhalyr. Gaseous exchange of 

nitrogen was not considered. 

Small quantities of the cations (Ca + + and K+) 

entered the watersheds dissolved in precipitation, and 

relatively large quantities were lost from the reference 

watersheds (Table 2). The second year after cutting, 

cation losses from cutover watersheds were nearly 3 

times those from the reference watersheds. Over the 4- 

year span, 61 kglha of additional calcium and 15 kglha 

of additional potassium were removed from the 

harvested watersheds than from the references in 

stream water. 
Table 2.-Input-output budgets. lnput data are ionic additions from precipitation 

only; output data from the references and the clearcuts are dissolved substance 

losses to streamwater 

ltem 

lnput (precipitation) 

Output (references) 

Output (clearcuts) 

1st year after cutting 

2nd year after cutting 

3rd year after cutting 

4th year after cutting 

Item Inorganic nitrogenb Calcium Potassium 

4-YEAR SUMMARY 

Inputs minus outputs (references) + 15.2 - 45.2 - 5.6 

Input minus output (clearcuts) - 41.7 - 106.1 - 20.3 

Net change (references minus clearcuts) - 56.9 - 60.9 - 14.7 

a Standard error. 

b Nitrate plus ammonium. 

Discussion 

Clearcutting northern hardwood ecosystems sets 

in motion complex hydrological, biogeochemical, and 

ecological changes. Removal of the forest canopy: 

(1) increases soil temperature; (2) reduces transpiration; 

(3) increases soil moisture and streamflow; 

(4) increases decomposition of organic matter; 

(5) increases mineralization and nitrification; and 

(6) increases exchange of ions in the soil (Bormann and 

Likens 1979; Likens et al. 1970; Federer and Gee 1974; 

Federer 1973; Hornbeck et al. 1970; Covington 1981; 

Dominski 1971). 

These changes, in turn, trigger a complex array of 

vegetative growth responses so that cutover sites are 

revegetated quickly. Increases in water, nutrients, and 

temperature resulting from cutting are reduced quickly 

as vegetation regrows; within a few years, these-variables approach precutting levels. However, nutrient 

uptake by vegetative growth is, at first, less than nutrient release by accelerated mineralization; consequently, nutrients are lost from some systems in 

drainage water (Bormann et al. 1974; Bormann and 

Likens 1979). 

This study and that of Pierce et al. (1972) confirm 

the findings of experimental studies at Hubbard Brook 

(Likens et al. 1970; Pierce et al. 1970) that commercial 

clearcutting of northern hardwoods throughout the 

White Mountain region results in accelerated nutrient 

loss in drainage water. The general pattern of nutrient 

loss in drainage water shows a maximum in the 

second year after cuttling, with a general decline to 

near reference levels by the fourth vear. This pattern is 

similar to that seen in the experimentally deforested 

watershed, W2, at Hu b bard Brook. 

Not all ions followed the same patterns. Nitrate, 

calcium, magnesium, sodium, and chloride peaked in 

the second year and then declined to reference levels 

by the fourth year. Potassium showed no obvious 

second-year peak nor a gradual return to reference 

levels. Sulfate concentrations dropped well below 

reference levels after cutting but returned to reference 

levels during the fourth year. 

Although the average pH values showed no distinct patterns of change during the first 2 years after 

cutting, comparisons of stream water pH for individual 
paired watersheds (cut versus reference) showed 

discernible differences-generally, acidity was greater 

immediately after cutting. This increase probably was 

due in part to increased nitrification, which caused the 

release of additional nitrate and hydrogen ions to the 

streams immediately after cutting: (Bormann et al. 1968; 

Likens et al. 1969; Bormann and Likens 1979; Vitousek 

et al. 1979). While the implications of increased acidity 

to stream water biota are not fully understood, there is 

evidence that low pH mobilizes soil aluminum that can 

be leached to streams and that may be injurious to 

aquatic life (Johnson 1979; Hall et al. 1980; Driscoll and 

Likens 1982). Also, Eaton et al. (1973) and Hornbeck et 

al. (1977) have shown that the forest canopy plays a 

major role in neutralizing acidic precipitation during 

the summer in New Hampshire. Removal of the canopy 

by harvesting may contribute to the increased acidity 

of the streams during the first year after clearcutting 

(Fig. 2). Many forest streams in New Hampshire 

currently are marginal for trout production because of 

the low pH and high concentrations of aluminum. A 

further decrease in pH, even for short periods, may be 

detrimental. 

There is no clear explanation for the gradual 

decrease in acidity for the clearcut watersheds during 

the third and fourth years. 

Our data indicate that nitrate concentrations in 

streams draining watersheds clearcut during the growing season usually are higher than those in streams 

from watersheds cut during the dormant season (Table 

3). However, both the watershed with the highest 

concentration of nitrate in the stream and the one with 

the least were cut in the dormant season. 

Table 3.-Mean annual nitrate concentrations 

( + standard error) from three watersheds cut 

during the summer growing season and from three 

watersheds cut during the autumn dormant 

season 

Cut 

Year after cut Growing season Dormant season 

Nutrient concefitrations in streams draining clearcuts decrease distinctly as the proportion of the watershed cut becomes smaller. Dilution occurs as water 

with low concentrations of nutrients enters the 

streams from uncut areas, either from tributary streams 

or from subsurface flow. Chemical reactions within the 

stream and nutrient assimilation by the organisms in 

the stream channel itself and in the bottom sediments 

may contribute to the reduction in nutrients with 

distance downstream (Sloane 1979). Whatever the 

reason, our data show that 10 to 15 percent of a watershed in the White Mountains could be clearcut without 

measurably affecting the nitrate and calcium levels in 

streamflow at the base of the watershed. 

If it is desirable to clearcut larger proportons of a 

watershed, it would seem prudent to harvest in a series 

of small cuttings spaced at least 2 years apart. The 2- 

year spacing wolild minimize the synchronization of 

maximum nutrient loss the second year after cutting 

over large areas of a watershed (Hornbeck et al. 1975). 

Our estimated losses of nutrients in streamwater 

from commercially cut northern hardwood forests are 

substantially less than from the experimentally devegetated wa.tershed, W2, at Hubbard Brook (Table 2) 

(Likens et al. 1970; Pierce et al. 1972). Nevertheless, the 

amounts of nutrients lost are not insignificant. Over 

the 4 years after cutting, losses (net change for reference minus net change for cutover) of 57, 61, and 15 

kglha for N, Ca+ +, and K+ constitute about 70, 98, and 

23 percent of the annual estimated uptake for these 

elements (Likens et al. 1977). Compared to the total 

amounts of these elements in the system, these losses 

are small, but it is not known how they compare to the 

actual proportion of the total that is available for use 

by the vegetation. Studies underway at Hubbard Brook 

suggest that losses of this magnitude will not reduce 

production substantially so long as sufficient time is 

allowed between cuts for the ecosystem to reaccumulate nutrients from the atmosphere, weathering, or 

biological fixation. At this time, the 100-year rotation in 

northern hardwood forests used by the USDA Forest 

Service seems ample. However, repeated short rotations might ultimately prove deleterious to future 

productivity. 
Conclusions Literature Cited 

1. Clearcutting of northern hardwood forests on gl&- 

cia1 till throughout northern New Hampshire 

resulted in a response similar to that of 

experimentally clearcut watersheds at Hubbard 

Brook. Substantial quantities of nutrients were 

lost in drainage water during a 4-year period after 

cutting. 

2. Conductivity of the streams draining clearcuts 

more than doubled during the second year after 

cutting but returned to reference levels during the 

fourth year. 

3. Streams became slight!y more acidic during the 

first year after clearcutting; however, during the 

third and fourth years after cutting, the streams 

were substantially less acidic than the references. 

Greater acidity may have adverse consequences 

for fish and invertebrates in streams that are 

marginal habitats with respect to pH levels before 

cutting. 

4. Concentrations of nitrate nitrogen, calcium, magnesium, sodium, and potassium increased substantially in the streams from the clearcuts during the 

first 3 years after cu,tting, representing losses of 

these plant nutrients from the forest soils to 

streams. 

5. Concentrations of sulfate decreased in streams 

draining the clearcuts during the first 3 years 

after cutting. 

6. Clearcutting seemed to nave almost no effect on 

the concentrations of chloride and ammonium 

nitrogen. 

7. All ions except hydrogen and potassium returned 

to reference levels i'n the streams from the clearcuts. By the end of the fourth year after cutting, 

there were considerably fewer hydrogen ions and 

considerably more eotassium ions in the streams 

from harvested area@ than in those from the reference areas with no indicaton of impending 

recovery. 

8. Concentrations of ions in streamwater were diluted 

in proportion to the area of the watershed clearcut. Clearcutting about 15 percent of a watershed 

did not measurably change the chemistry of the 

major streams in the watershed. 

9. Clearcutting during the dormant season affected 

stream chemistry less than harvests during the 

growing season. 

10. During the 4 years of study, the clearcut watersheds lost 57 kglha of inorganic nitrogen, 61 

kglha of calcium, and 15 kglha of potassium in 

streamflow. This loss does not include losses in 

forest products removed, accelerated denitrification, or gains due to fixation, which were not 

measured. 

Bormann, F. H.; Likens, G. E. Pattern and process in a 

forested ecosystem. New York: Springer-Verlag; 

1979. 253 P. 

Bormann, F. H.; Likens, G. E.; Fisher, D. W.; Pierce, 

R. S. Nutrient loss accelerated by clear-cutting in the 

forest ecosystem. Science, 159:882-884; 1968. 

Bormann, F. H.; Likens, G. E.; Siccama, T. G.; Pierce, 

R. S.; Eaton, J. S. The export of nutrients and recov. 

ery of stable conditions following deforestation at 

Hubbard Brook. Ecological Monographs. 

44(3):255-277; 1974. 

Corbett, E. S.; Lynch, J. A.; Sopper, W. E. Timber 

harvesting practices and water quality in the eastern 

United States. Journal of Forestry. 76(8):484-488; 

1978. 

Dominski, A. D. Accelerated nitrate production and loss 

in the northern hardwood forest ecosystem underlain 

by podzol soils following clearcutting and addition of 

herbicides. Ph.D. thesis. New Haven, CT: Yale 

University; 1971. 157 p. 

Driscoll, C. T.; Likens, G. E. Hydrogen ion budget of an 

aggrading forested ecosystem. Tellus. 34:283-292; 

1982. 

Eaton, J. S.; Likens, G. E.; Bormann, F. H. Throughfall 

and stemflow chemistry in a northern hardwood 

forest. Journal of Ecology. 61:495-508; 1973. 

Federer, C. A. Forest transpiration greatly speeds 

streamflow recession. Water Resources Research. 

9: 1599- 1604; 1973. 

Federer, C. A.; Gee, G. W. Tree water stress in relation 

to water yield in a hardwood forest. Res. Rep. 7. 

Durham, NH: University of New Hampshire, Water 

Resources Research Center; 1974. 30 p. 

Federer, C. A.; Lash, D. BROOK: A hydrologic simulation model for eastern forests. Res. Rep. 19. Durham, 

NH: University of New Hampshire, Water Resources 

Research Center; 1978. 84 p. 

Hall, R. J.; Likens, G. E.; Fiance, S. B.; Hendry, G. R. 

Experimental acidification of a stream in the 

Hubbard Brook Experimental Forest, New 

Hampshire. Ecology. 61:976-989; 1980. 

Hart, G. E., Jr. Humus depths under cut and uncut 

northern hardwood forests. For. Res. Note 113. Upper 

Darby, PA: U.S. Department of Agriculture, Forest 

Service, Northeastern Forest Experiment Station; 

1961. 4 p. 
Hornbeck, J. W.; Likens, G. E.; Eaton, J. S. Seasonal 

patterns in acidity of precipitation and their implications for forest stream ecosystems. Water, Air, and 

Soil Pollution. 7:355-365; 1977. 

Hornbeck, J. W.; Pierce, R. S.; Federer, C. A. Streamflow changes after forest clearing in New England. 

Water Resources Research. 6(4):1124-1132; 1970. 

Hornbeck, J. W.; Pierce, R. S.; Likens, G. E.; Martin, 

C. W.. Moderating the impact of contemporary forest 

cutting on hydrologic and nutrient cycles. In: The 

hydrological characteristics of river basins: proceedings of the symposium; 1975 December 1-8; Tokyo, 

Japan. IAHS-AISH Publ. No. 17. Tokyo, 

Japan: International Association of Hydrological 

Sciences; 1975:423-433. 

Hoyle, M. C. Nature and properties of some forest soils 

in the White Mountains of New Hampshire. Res. Pap. 

NE-260. Upper Darby, PA: U.S. Department of 

Agriculture, Forest Service, Northeastern Forest 

Experiment Station; 1973, 18 p. 

Johnson, N. M. Acid rain: neutralization within the 

Hubbard Brook ecosystem and regional implications. 

Science. 204(4392):497-499; 1979. 

Johnson, N. M.; Likens, G. E.; Bormann, F. H.; Fisher, 

D. W.; Pierce, R. S. A working model for the variation 

in streamwater chemistry at the Hubbard Brook 

Experimental Forest, New Hampshire. Water 

Resources Research. 5(6):1353-1363; 1969. 

Likens, G. E.; Bormann, F. H.; Johnson, N. M. Nitrification: importance to nutrient losses from a cutover 

forested ecosystem. Science. 163(3872):1205-1206; 

1969. 

Likens, G. E.; Bormann, F. H.; Johnson, N. M.; Fisher, 

D. W.; Pierce, R. S. Effects of forest cutting and 

herbicide treatment on nutrient budgets in the 

Hubbard Brook watershed-ecosystem. Ecological 

Monographs. 40(1):23-47; 1970. 

Likens, G. E.; Bormann, F. H.; Pierce, R. S.; Eaton, J. S.; 

Johnson, N. M. Biogeochemistry of a forested 

ecosystem. New York: Springer-Verlag; 1977. 146 p. 

Martin, C. W. Precipitation and streamwater chemistry 

in an undisturbed forested watershed in New 

Hampshire. Ecology. 60(1):36-42; 1979. 

Martin, C. W.; Pierce, R. S. Clearcutting patterns affect 

nitrate and calcium in streams of New Hampshire. 

Journal of Forestry. 78(5):268-272; 1980. 

NC: National Oceanic and Atmospheric 

Administration, Environmental Data Service; 1971 

National Oceanic and Atmospheric Administration. 

Climatological data, New England, vol. 84. Asheville, 

NC: National Oceanic and Atmospheric 

Administration, Environmental Data Service; 1972. 

National Oceanic and Atmospheric Administration. 

Climatological data, New England, vol. 85. Asheville, 

NC: National Oceanic and Atmospheric 

Administration, Environmental Data Service; 1973. 

Pierce, R. S.; Hornbeck, J. W.; Likens, G. E.; Bormann, 

F. H.. Effects of elimination of vegetation on streamwater quantity and quality. In: Proceedings, 

symposium on the results of research on representative and experimental basins; 1970 December 1-8; 

Wellington, NZ. AlHS Publ. No. 96. Wellington, 

NZ: lnternational Association of Hydrological 

Sciences: 1970:311-328. 

Pierce, R. S.; Martin, C. W.; Reeves, C. C.; Likens, G. E.; 

Bormann, F. H. Nutrient loss from clearcuttings in 

New Hampshire. In: Csallany Sandor C.; McLaughlin, 

Thad G.; Striffler, William D., eds. Watersheds in 

transition: proceedings of the symposium; 1972 June 

12-22; Fort Collins, CO: Colorado State University; 

l972:285-295. 

Reinhart, K. G. Watershed calibration methods. 

In: Sopper, William E.; Lull, Howard W., eds. 

International symposium on forest hydrology: proceedings of the symposium; 1965 August 29- 

September 10; Un7iucrsity Park, PA. Long Island City, 

NY: Permagon Press; 1967:715-723. 

Sloane, J. Nitrogen flux in small mountain streams in 

New Hampshire. M.S. thesis. Ithaca, NY: Cornell 

University; 1979. 131 p. 

US. Department of Agriculture. Silviculture systems for 

the major forest types of the United States. Agric. 

Handb. 445. Washington, DC: U.S. Department of 

Agriculture; 1973. 124 p. 

Vitousek, P. M.; Gosz, J. R.; Grier, C. C.; Melillo, J. M.; 

Reiners, W. A.; Todd, R. L. Nitrate losses from disturbed ecosystems. Science. 204:469-471; 1979. 

Vitousek, P. M.; Melillo, J. M. Nitrate losses from disturbed forests: patterns and mechanisms. Forest 

Science. 25(4):605-619; 1979. 

Wood, T. E. Biological and chemical control of 

phosphorous cycling in a northern hardwood forest. 

Ph.D. thesis. New Haven, CT: Yale University; 1980. 

National Oceanic and Atmospheric Administration. 

Climatological data, New England, vol. 83. Asheville, 
Martin, C. Wayne; Pierce, Robert S.; Likens, Gene E.; 

Bormann, F. Herbert. Clearcutting affects stream 

chemistry in the White Mountains of New 

Hampshire. Res. Pap. NE 579. Broomall, PA: U.S. 

Department of Agriculture, Forest Service, 

Northeastern Forest Experiment Station; 1986. 12 p. 

Commercial clearcutting of northern hardwood forests 

changed the chemistry of the streams that drained 

from them. By the second year after cutting, specific 

conductance doubled, nitrate increased tenfold, calcium tripled, and sodium, magnesium, and potassium 

doubled. Chloride and ammonium did not change; sulfate decreased. Concentrations of most ions returned 

to reference levels after 4 years, though sulfate 

remained depressed, potassium remained elevated, 

and acidity decreased. 

ODC 11 6.38 

Keywords: nutrient cycling; watershed; forestry; logging; nitrogen 

-U.S. GOVERNMENT PRINTING OFFICE: 1986-605-026:20@46 
Headquarters of the Northeastern Forest Experiment Station are in 

Broomall, Pa. Field laboratories are maintained at: 

Amherst, Massachusetts, in cooperation with the University of 

Massachusetts. 

Berea, Kentucky, in cooperation with Berea College. 

Burlington, Vermont, in cooperation with the University of 

Vermont. 

Delaware, Ohio. 

Durham, New Hampshire, in cooperation with the University of 

New Hampshire. 

Hamden, Connecticut, in cooperation with Yale University. 

Morgantown, West Virginia, in sooperation with West Virginia 

University, Morgantown. 

Orono, Maine, in cooperation with the University of Maine, 

Orono. 

Parsons, West Virginia. 

Princeton, West Virginia. 

Syracuse, New York, in cooperation with the State University of 

New York College of Environmental Sciences and Forestry at 

Syracuse University, Syracuse. 

University Park, Pennsylvania, in cooperation with the 

Pennsylvania State University. 

Warren, Pennsylvania.