-. '·. t 

GRINDSTONE FLAT AND BIG FLAT EXCLOSURES 

-A 41-YEAR RECORD OF CHANGES IN 

CLEARCUT ASPEN COMMUNITIES 

W.F. MUEGGLER and D.L. BARTOS 

USDA Forest Service Research Paper INT-195 

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.

GRINDSTONE FLAT 

USDA Forest Service 

Research Paper INT-195 

October 1977 

AND BIG FLAT EXCLOSURES 

-A 41-YEAR RECORD 

OF CHANGES IN 

CLEARCUT ASPEN COMMUNITIES 

W.F. MUEGGLER and D.L. BARTOS 

INTERMOUNTAIN FOREST AND RANGE EXPERIMENT STATION 

Forest Service 

U. S. Department of Agriculture 

Ogden, Utah 84401 
THE AUTHORS 

WALTER F. MUEGGLER, Principal Plant Ecologist, has been with the 

Intermountain Station since 1949. He is currently Leader of the 

Aspen-Mountain Grassland Ecology research work unit at Logan, 

Utah. He obtained his B.S. degree from the University of Idaho, 

M.S. degree from the University of Wisconsin, and a Ph. D. degree 

in Plant Ecology from Duke University. 

DALE L. BARTOS is a Range Scientist at the Forestry Sciences Laboratory, Logan, Utah. He joined the Intermountain Station in 1972. 

Bartos holds B.S. and M.S. degrees from Fort Hays State University, and a Ph. D. degree in Range Science from Colorado State 

University. His principal research interest is systems modeling. 
CONTENTS 

PREFACE. 

SETTING ... 

APPROACH. 

EVALUATION 

Response of Trees . . . . . . . . . . 

Response of Browse . . . . . . . . . . 

Response of Understory Vegetation . 

MANAGEMENT IMPLICATIONS. 

PUBLICATIONS CITED. • . . . . • 

RESEARCH SUMMARY 

Page 

iv 

1 

2 

3 

3 

8 

10 

14 

16 

Deer browsing prevented aspen regeneration in both uncut stands 

and small 1/20-hectare clearcuts, even though nearby large burns 

regenerated successfully. Size of the clearcut or burned area may be 

critical in determining success of aspen regeneration; areas less than 

about 2 hectares in size may adversely concentrate deer use. Shrub 

production was less under deer use and forb production was less 

under cattle use than on protected areas. More aspen suckers were 

produced in uncut stands where cattle grazed than in stands protected 

from grazing, suggesting a possible relationship between sucker initiation and reduced competition from the herbaceous understory. .. 

Removal of aspen cover changed herbaceous composition from forb to 

grass dominants and discouraged conifer invasion. 

1 •. •· 
PREFACE 

Opportunities sometimes exist to gain considerable insight into longterm effects of management on vegetation by remeasuring old administrative studies and exhuming from the files data collected during the early 

stages of the study. Such was the case with the Grindstone Flat and the 

Big Flat deer and cattle exclosures discussed in this report. A few days 

spent collecting current data and in perusing old files have permitted us 

to trace the influence of clearcutting and of deer and cattle on plant succession in two stands of aspen over a period of 41 years. 

We wish to acknowledge the contribution of the Fishlake National 

Forest personnel involved in establishing the plots and in gathering data 

over the decades. H. M. Christensen apparently was instrumental in 

starting the study in 1934. Data were collected by R. J. Costley, and 

W. E. Augsbach in 1937, by W. L. Robinette in 1942, and by E. R. Doman, 

and 0. Julander in 1949. A rough-draft report prepared by E. R. Doman, 

D. I. Rasmussen, and H. M. Christensen in 1959 provided helpful background information on the area and assisted interpretation of the early 

data. 

iv 
SElliNG 

Beaver Mountain is a high plateau on the Fishlake National Forest in southern Utah 

that rises to more than 3,650 m (12,000 ft) elevation at its highest points. Large 

expanses of aspen (Populus tremuZoides) dominate the elevations between 2,400 and 

3,000 m (8,000 to 10,000 ft). Mixed stands of spruce (Pieea engeZmannii) and fir 

(Abies Zasioearpa) are common on northerly exposures and at higher elevations. Many 

large grassy openings intermixed with the aspen and conifer communities contribute to 

the diversity of vegetation types. Historically this area has been important summer 

range for both deer (OdoeoiZeus hemionus) and livestock. 

Deer apparently were abundant in about 1865 when Beaver County was first settled, 

for the pioneers had little difficulty keeping themselves supplied with venison. Soon 

after settlement, the summer ranges on Beaver Mountain were heavily stocked with sheep 

and cattle. Livestock overgrazing and unrestricted hunting apparently caused deer 

numbers to decline to a low from 1900 to 1910. The combined effect of placing Beaver 

Mountain under National Forest administration in 1906 with better regulation of forage 

use and the enactment of a "buck law" by the Utah legislature in 1913 with enforcement 

of hunting regulations permitted the deer populations to increase markedly. Excessive 

use of aspen suckers and palatable shrubs by 1926 was attributed to high populations of 

deer. By 1934, aspen regeneration was poor over large areas of Beaver Mountain. Overuse of the summer range coincided with overuse of browse on adjacent winter ranges on 

both the east and west sides of Beaver Mountain. As a result, antlerless deer hunts 

were begun in 1934 to control population numbers. 

Overuse of the livestock summer range on Beaver Mountain was recognized as a 

serious problem in the early 1930's. Cattle and sheep, as well as the deer, were considered too numerous. Overgrazing in the extensive aspen type was of particular concern. Proposed reductions in livestock grazing were protested by ranchers who blamed 

the deer for depleted forage conditions. This dispute resulted in the establishment 

of study plots on aspen range within cattle allotments to demonstrate the relative 

effects of deer and cattle grazing on the forage and on aspen regeneration. 

1 
APPROACH 

Two set$ of plots were .located in aspen types on the Beaver District of the Fishlake National Forest. One set was established near the lower edge of the aspen zone at 

about 2,590 m (8,500 ft) elevation on Grindstone Flat (sec. 29, T. 29 S., R. 4 W.); the 

other set was placed near the upper edge of the aspen zone on Big Flat (sec. 18, T. 

29 S., R. 4 W.) at about 3,200 m (10,500 ft) elevation. Each set uf plots consisted of 

about a 30- by 60-m (100- by 200-ft) deer exclosure where the vegetation was protected 

from use by all ungulates, an adjacent area of like size that excluded livestock but 

was open to deer use, and an adjacent area open to use by both deer and livestock. 

Three-fourths of each exclosure was clearcut of aspen; the aspen was left intact in the 

remaining fourth. The areas were cut and pole fences constructed in the fall of 1934. 

Aspen sprouts and other vegetation were first measured in 1937, 3 years after the 

plots were established. A single, permanent 23.8-m2 (4.88- by 4.88-m; 16- by 16-ft) 

quadrat was established on the cleared and uncleared portion of each exclosure and on 

the range adjacent to the exclosures. Vegetation canopy cover below 1.68 m (5-1/2 ft) 

in height was determined for each species on these quadrats. In addition, individual 

stems of trees and shrubs on the quadrats were counted. Vegetation measurements on 

these quadrats were repeated in 1942, in 1949, and in 1975. Such measurements enable 

tracing the ~equence of successional change after cutting and of change attributable to 

protection from grazing. 

Measurements confined to a single 4.88- by 4.88-m quadrat provided a restricted and 

questionable overall sample of treatment effects. Consequently, we expanded our sampling 

in 1975 to include estimates of productivity and composition of understory vegetation 

and counts of aspen numbers by size-class distribution over the entire treatment plots. 

Understory production was determined from three sets of five 1/2-m2 quadrats randomly 

distributed over each treatment plot. The current year's biomass for plants on each of 

four quadrats was estimated as a percent of the fifth; the fifth was then clipped to 

ground level, dried, and weighed. The percentage estimates were then converted to 

weights and the average of the 15 quadrats converted to kilograms dry weight per hectare. 

Biomass composition by vegetation class and by individual species was estimated for each 

five-quadrat set and averaged for each treatment. Aspen and conifer trees were counted 

by size classes on a 0.0202-hectare (1/20-acre) strip within each treatment. Trees 

representing different size classes in each treatment were then cored and aged. 

Reliable data on changes in deer and cattle grazing pressure on the study sites 

over the 41-year period are not available. We know, however, that judicious management 

dictated reduction in numbers of both species from their high levels early in the 

century. We also know that the general area continued to support substantial numbers 

of deer and cattle over the study period. Interpretation of vegetation differences between treatments is therefore based upon the presence or absence of cattle versus deer 

use rather than on absolute changes in animal numbers. 

2 
EVALUATION 

Understory vegetation at the Grindstone Flat site near the lower edge of the aspen 

zone is appreciably different from that at Big Flat near the upper edge of the aspen 

zone. For example, shrubs are fairly abundant in the aspen understory at Grindstone 

Flat, but are lacking at Big Flat. The two areas, therefore, cannot be considered true 

replications for evaluating treatment effects on understory vegetation. However, those 

species common to both areas might be expected to respond similarly to like treatments. 

Although each study site at Grindstone and Big Flat appeared to be environmentally 

uniform, the vegetation was not sampled before clearcutting or exclosure construction 

to verify uniformity between treatment plots. Consequently, we must assume that subsequent differences in vegetation between plots on a site result from treatment effects 

and not from initial dissimilarities in vegetation between plots. 

RESPONSE OF TREES 

In 1975, the oldest aspen measured at Grindstone Flat was 172 years old (40.6 em 

d.b.h., 17.4 min height); the oldest at Big Flat was 126 years (35.3 em d.b.h., 15.2 m 

in height). Thus, the stands were at least 131 and 85 years old, respectively, when 

the study began in 1934. We also found trees on both areas that were between 30 and 60 

years old in 1934. Judging from the concern about lack of aspen regeneration in the 

early 1930's, we can assume that few trees were less than 30 years old on the study sites 

in 1934. Apparently very few of the aspen suckers that arose between 1905 and 1934 were 

able to escape browsing and become trees. 

The persistent occurrence of suckers over the years despite animal use is evidenced 

by the number of suckers in 1975 less than 0.5 m tall on the uncut plots continually 

used by deer and cattle (table 1). Under continuect-use-, approximately 7, 000 suckers 

per hectare occurred at Grindstone Flat and 26,000 per hectare at Big Flat. Most of 

these suckers were heavily utilized. In 1942 and in 1949, approximately 3,000 suckers 

(less than 1.68 min height) per hectare occurred on the Grindstone Flat plots and 

14,000 to 30,000 per hectare occurred on the Big Flat plots in these years, respectively 

(table 2). Judging from the lack of aspen reproduction in the 0.5 m tall to 5.1-cm d.b.h. 

size class on these grazed plots in 1975 (table 1), few of these suckers were able to 

escape and become saplings. 

3 
Table 1.--Numbers of aspen and conifers by size classes on the Grindstone and Big Flat plots in 19?5, 

41 years after establishment. 

Grindstone Flat Big Flat 

Size class Uncut Cut Uncut Cut 

Closed: Deer:Deer and !Closed: Deer Closed: Deer:Deer and: closed: Deer 

<0.5 m tall 

Populus tremuloides 

Conifers 2 

0.5-2 m tall 

P. tremuloides 

Conifers 

2m tall-<5.1 em d.b.h. 

P. tremu loi des 

Conifers 

5.1-10.2 em d.b.h. 

P. tremuloides 

Conifers 

10.2-15.2 em d.b.h. 

P. tremuloides 

Conifers 

15.2-20.3 em d.b.h. 

P. tremu loi des 

Conifers 

20.3-25.4 em d.b.h. 

P. tremuloides 

Conifers 

25.4-30.5 em d.b.h. 

P. tremuloides 

Conifers 

>30.5 em d.b.h. 

P. tremu loi des 

Conifers 

1Almost all were heavily utilized. 

to 

use 

19 

9 

37 

4 

60 

5 

63 

4 

2.2 

3 

6 

0 

1 

0 

1 

0 

0 

0 

:use : cattle to 

: only: use : use 

:use 

:only 

to 

use 

use : 

only: 

-- Number/0.0202 hectare transect--

10 1 145 

6 28 

8 0 

9 13 

0 

5 

20 

6 

12 

0 

5 

4 

0 

0 

0 

1 

2 

0 

0 

6 

22 

4 

45 

3 

19 

3 

2 

3 

1 

0 

6 

0 

16 

9 

89 

6 

45 

2 

173 

6 

8 

1 

0 

1 

0 

0 

0 

0 

0 

0 

6 

1 

0 

5 

0 

1 

0 

0 

0 

1 

0 

1 

0 

0 

0 

0 

0 

0 

142 

15 

92 

32 

118 

16 

20 

4 

4 

0 

3 

0 

4 

0 

1 

0 

0 

0 

47 

21 

0 

31 

5 

6 

19 

0 

9 

0 

7 

0 

7 

0 

0 

0 

0 

0 

cattle : to 

use : use 

525 

27 

1 

14 

8 

6 

18 

6 

18 

2 

3 

0 

6 

0 

0 

0 

0 

0 

ll6 

9 

87 

16 

251 

4 

28 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

0 

use 

only 

0 

3 

0 

6 

0 

4 

0 

1 

0 

1 

0 

0 

0 

1 

0 

1 

0 

0 

2Approximately 90 percent of conifers at Grindstone Flat were Abies lasiocarpa; at Big Flat, approximately 

70 percent were A. lasiocarpa, and 30 percent were Ficea engelmannii; Pinus albicaulis and Pseudotsuga 

menziesii also occurred. 

As expected, clearcutting greatly stimulated production of aspen suckers. The 

third growing season (1937) after cutting, the ungrazed clearcut plot had approximately 

26 times as many suckers as the ungrazed uncut plot at Grindstone Flat, and approximately 19 times as many at Big Flat (table 2). By 1942, 8 years after cutting, such large 

differences were no longer apparent. Many of the suckers on the ungrazed clearcut 

either grew into saplings or were reduced by natural thinning (fig. lA). By 1975, over 

three-fourth of the aspen sterns on the ungrazed clearcut plots at both areas were over 

0.5 m tall, and approximately 60 percent were over 2 rn tall (table 1, fig. lB). 

4 
Table 2.--Changes in number of stems and canopy cover of browse (aspen and shrubs under 1. 68 m in 

height) on permanent 23.8 m2 quadrats at Grindstone Flat and Big Flat between 1937 (3 years 

after establishment) and 1975. 

-----·---- Location 1937 1942 1949 1975 

and Number Canopy Number Canopy Number Canopy Number Canopy 

SJ2ecies : of stems : cover of stems : cover of stems : cover of stems : cover 

Percent Percent Percent Percent 

UNCU1 

CLOSED TO USE 

Grindstone Flat 

Populus tremuloides 14 12.2 84 17.1 22 6.4 4 2.5 

Rosa woodsii 75 1 136 6.3 108 12· 1.0 

Symp hori carpos vaccinioides 3.3 6.8 25 10.8 77 3.9 

Big Flat 

P. tremuloides 9 4.1 54 7.9 63 17.4 7 5. 5. 

DEER USE ONLY 

Grindstone Flat 

P. tremuloides 28 2.2 11 .1 32 .3 4 .4 

R. woodsii 84 .1 71 .9 75 23 1.2 

s. vaccinioides 14 12.9 9.2 93 17.0 88 5.9 

Big Flat 

P. tremuloides 1.1 .1 39 .1 54 2.9 

DEER AND CATTLE USE 

Grindstone Flat 

P. tremuloides 0 0 7 .3 7 .1 2 . 2 

R. woodsii 91 .1 161 1.8 109 8 . 2 

s. vacci ni oi des 1 1.2 4 1.5 5 1.1 7 .4 

Big Flat 

P. tremuloidRs 41 34 . 2 71 .1 25 1.4 

CU"I: 

CLOSED TO USE 

Grindstone Flat 

P. tremuloides 369 63.8 113 40.5 8 2.3 

R. woodsii 54 .4 81 2.5 12 .6 

s. vacci ni oi des 11.8 15.7 74 3.7 

Big Flat 

P. tremuloides 170 51.9 151 50.2 27 14.1 

DEER USE ONLY 

Grindstone Flat 

P. tremuloides 12 6.6 0 0 0 0 

R. woodsii 9 . 2 35 . 5 1 .1 

s. vaccinioides 3 2.0 16 1.6 25 1.0 

Big Flat 

P. tremuloides 17 . 2 0 0 0 0 

A dash indicates missing data. 

5 
A 

B 

Figure 1.--The clearcut area at Grindstone Flat protected from all ungulate use showing 

(A) amount of reproduction in 1942~ 8 years after cutting~ and (B) subsequent 

development of the aspen stand by 19?5~ 41 years af ter cutti ng . 

6 
Figure 2.--The Grindstone FZat excZosure in (A) 1942 and (B) 1975 showing the cZearcut 

area open to deer use onZy~ and cZearcut cZosed to aZZ unguLate use. Note the 

originaZ uncut aspen stand in the background of figure 2A . 

7 

A 

B 
Although we have no record of sucker production the first two growing seasons after 

clearcutting, we have no reason to believe that initial stimulation of sucker production 

would differ between the plots open and closed to deer use. By 1937, the effect of deer 

use on sucker mortality in the clearcuts was strikingly evident (table 2); the plot open 

to deer use at Grindstone Flat had only 3 percent as many suckers as the protected plot 

and the one at Big Flat had only 10 percent as many suckers as the protected plot. By 

1942, neither the Grindstone nor the Big Flat clearcut plots used by deer contained 

either aspen suckers or aspen saplings (fig. 2A). The extensive data collected in 1975 

(table 1) show that, although a few small suckers were found on the cut plot open to 

deer at Grindstone Flat, none were found at Big Flat. 

Some aspen suckers still arose at the edges of the clearcuts adjacent to the uncut 

plots and adjacent to the cut but protected plots that contained 40-year-old trees. Invariably, these suckers were heavily browsed by deer and remained less than about 30 em 

tall. Suckers were seldom found more than about 4 m from the edge of the cut. A striking exception was an aspen tree, approximately 10 em d.b.h. that grew well into the 

grazed clearcut at Grindstone Flat. This tree was enclosed by 1 m tall wire net fencing. 

Apparently, the tree was enclosed as a sucker and so escaped browsing. 

Generally, aspen suckers were able to develop into saplings and perpetuate the 

aspen stands on these small plots only when protected from deer browsing (fig. 2). This 

was true for both the cut and uncut plots at both Grindstone and Big Flats. Despite 

deer use, small suckers continued to occur in uncut stands, but were invariably suppressed 

by heavy browsing. In contrast, suckers were usually present in grazed clearcuts for 

only a few years after cutting, probably because the small, heavily browsed suckers 

were unable to keep alive the extensive root system (the sucker source) of the cut trees. 

Approximately 10 times as many small suckers continued to occur on the uncut plots 

used by both deer and cattle as on those used by deer alone (table 1). This might be 

related to reduced herbaceous understory where cattle grazed (table 3). Competitive 

relationships might have been altered sufficiently to stimulate aspen suckering. 

Deer and cattle use apparently did not directly affect the success or persistence 

of conifer regeneration. However, conifer reproduction appeared considerably more 

successful in those stands with an aspen overstory than those without (fig. 3). In 

1975, the clearcut, but regenerated -aspen plots, contained over 2 times as many conifers 

less than 10.2 em d.b.h. as those clearcut plots without an aspen overstory (table 1). 

Thus, deer use can indirectly impede conifer establishment by preventing a clearcut 

from going back to aspen cover. This lends credence to the belief that aspen commonly 

serves as a nurse crop for conifers. The plots at Big Flat contained almost 1-1/2 

times as many conifers as those at Grindstone Flat, but this is attributed primarily to 

elevational and seed source differences. 

RESPONSEOFBROVVSE 

Aspen reproduction less than 1.68 m in height constitutes the primary browse at 

both Grindstone Flat arid Big Flat; aspen foliage above this level is not considered 

available to deer. Snowberry (Symphoriearpos vaeeinioides) and rose (Rosa woodsii) are 

important browse species on Grindstone Flat, but such shrubs are lacking on Big Flat. 

Thus, ample aspen reproduction is critical both for maintaining viable aspen stands and 

as a source of browse for deer. 

8 
Table 3. --Production and composition of understory vegetation on the Grindstone Flat and Big Flat aspen-plots 

in 1975, 41 years after establishment 

Grindstone Flat Big Flat 

Understory Uncut Cut Uncut Cut 

vegetation :Closed: Deer: Deer and: Closed: Deer Closed: Deer: Deer and: Closed: Deer 

to :use : cattle to :use to : use : cattle to :use 

use only: use : use : only use : only: use : use : only 

- - - - - Dry kilograms/hectare - -

TOTAL 714 920 392 978 1,474 843 1,024 356 395 780 

Shrubs 228 74 24 78 118 0 0 0 0 0 

Graminoids 21 340 94 68 766 101 72 114 47 ,546 

Forbs 464 506 274 831 590 742 952 242 348 234 

- - - Percent composition by weight !... -

SHRUBS 

Berberis repens 4 1 

Rosa woodsii 2 T 1 T T 

Symphoricarpos vaccinioides 30 4 4 8 8 

GRAMINOIDS 

Agropyron caninum T 2 1 1 2 T 5 

Bromus anomalus 2 30 17 2 2 2 5 10 T 8 

Carex spp. T T 1 1 7 1 2 3 5 

Festuca idahoensis 3 1 20 8 38 

Poa fendleriana 3 7 T T T 1 4 

Sitanion hystrix T T 3 1 

Stipa comata 1 18 

Stipa lettermani 1 2 4 20 5 

Stipa occidentalis 1 3 

FORBS 

Achillea lanulosa T 2 2 1 1 T 3 8 3 8 

Agoseris glauca T T 2 1 

Astragalus bourgovii 3 T 35 2 4 20 

Casti Ueja linariaefolia 10 T T 12 13 T T 

Ci rsi um undu latum 18 20 12 15 4 T T T 2 

Erigeron speciosus 1 5 2 22 T 

Fragaria americana T 3 4 5 T 8 6 10 12 1 

Frasera speciosa 12 T 3 10 2 10 18 1 

Helenium hoopesii T T 7 4 10 T 10 

He li an the lla uni flora 8 T 6 1 

Lupinus leucophyllus 5 20 15 30 7 37 71 8 46 1 

Potentilla pulcherrima T T T T 2 3 T T 3 1 

Smi lacina steUata 7 T 

Solidago decumbens 7 1 2 1 T 

Taraxacum officinale T 2 2 2 1 1 T 2 2 

Thalictrum fendleri T T 7 

Other herbs T T T T T T T T T 4 

In the mid-1930's, aspen reproduction under 1.68 m tall was scarce on Grindstone 

Flat. The 1937 data from the uncut plot open to cattle and deer use, however, indicated 

that suckers still occurred with some abundance at Big Flat (table 2). The amount of 

aspen browse on these uncut areas open to use by both cattle and deer did not change 

appreciably over the years. Even the relatively numerous aspen suckers on the 23.8 m2 

quadrat at Big Flat in 1975 (over 10,000 per hectare) did not provide much more than 

1 percent crown cover. This suggests that even though sprouting ability persisted over 

the years, the small and spindly sprouts provided relatively little browse. 

Barring cattle, but not deer, somewhat benefited aspen browse production. After 

41 years of deer use only, crown coverage of aspen browse was about 3 percent on Big 

Flat, but still less than one-half percent on Grindstone Flat. 

9 
Figur e 3. --Conifer invasion under an uncut aspen stand at Grindstone Flat in 1975. 

Eliminati ng both cattle and deer u se on the uncut areas apparently enabled bot h 

s ucker numbers and aspen foliage to i ncrease for 10 to 15 years follo~Vi g protection 

(table 2) . Browse production then declined a s the aspen suckers grew above the 1. 68 -m 

avai l abl e bro~Vse height. After 41 year s of protection from gr azing, aspen browse covered over 5 per cent of t he Big Flat plot and over 2 percent of the Grindstone Flat p l ot . 

Although foliage mass was greater on the protected than on the graz ed plots , sucker 

numbers were not. This s uggest s that t he protected s uck ers were large and vigorous, 

whereas t he sucker s on the grazed pl ots, though perhaps more nwner ous, ~Vere small and 

v1eak. 

The amount of rose and snowberry on the permanent quadrats fluctuated greatly over 

the years under a l l grazing and cutting treatments (tabl e 2) . However, the extensi ve 

data obtain ed in 1975 (table 3) indicate that deer use of the uncut stands markedl y 

reduced both of these shrubs, particularly the no~Vberr . 

RESPONSE OF UNDERSTORY VEGETATION 

The singl e 4 .88- by 4.88-m permanent quadrat placed in each treatment and sampl ed 

over the years prov ided a very restricted and probab l y inval i d sampl e of respon s e on 

each area because of initial dissimilarity of vegetation on t h ese sma l l quadrats (tabl es 

4 and 5) . We be l ieve the extensive 1975 production i nventory (tabl e 3) gi ves a more 

precise account of species r e sponse to grazing treatment as identifi ed by differences 

accumu l ated over the 41-year period. The 1975 produc tion inventory i s therefore u sed 

as a main indicator of species respon se t o grazing, ~Vith the permanent quadrats used to 

provide supplementary information on s uccessiona l changes. Additiona lly , only the 

10 
Table 4.--Changes in cover composition (%) of veget~tion under 1.68 min height on permanent 23.8 m2 

quadrats at Grindstone Flat between 1937 , 3 years after establishment) and 1975. 

Understory Closed to use Deer use only Deer and cattle use 

vegetation :1937 : 1942 : 1949 : 1975 1937 1942 : 1949 : 1975 1937 : 1942 : 1949 : 1975 

UNCUT 

Total shrubs and trees 25 45 37 38 35 30 37 20 3 20 6 15 

Total graminoids 37 23 26 4 35 35 54 25 5 15 6 15 

Total forbs 38 32 37 58 30 35 9 55 92 65 88 70 

Abies lasi ocarpa T 2 6 25 1 2 4 T 1 2 13 

Achillea lanulosa 1 1 T T 1 3 8 3 1 

Agropyron caninum T 6 6 7 1 T T 

Astragalus bourgovii T T 6 22 1 2 55 44 78 35 

Bromus anomalus 5 6 4 1 1 12 T 10 

Carex spp. 6 7 4 25 9 10 T 7 T 

Castilleja Zinariaefolia 1 4 2 T 

Ci rsi um undu Z.atum 1 2 2 15 2 T 8 T 14 

Erigeron speciosus 2 1 4 1 2 

Fragaria americana T 30 3 2 5 

Frasera speciosa T 6 T T T 

HeliantheUa uniflora T 1 15 

Lupi nus leucophy Uus 20 14 21 9 3 6 3 32 1 3 2 11 

Poa fendleriana 20 4 1 2 13 4 T T 3 T 

Populus tremuloides 9 27 12 5 8 T 3 1 1 T T 

Potentilla pulcherrima 3 6 4 3 1 T T 1 

Rosa woodsii 12 4 2 1 5 T 4 1 3 15 1 T 

Stipa spp. 5 5 17 3 6 5 30 5 3 5 4 4 

Symphoricarpos vaccinioides 4 12 17 7 12 18 18 10 T 2 2 1 

Taraxacum officinale 10 6 1 1 15 3 T 3 1 2 T 1 

ThaZ.ictrum fendleri 2 3 1 2 

Others 3 4 3 3 13 15 17 10 T 2 4 2 

CUT 

Total shrubs and trees 75 65 43 10 10 6 

Total graminoids 15 15 4 50 60 46 

Total forbs 10 20 53 40 30 48 

Abies Z.asi ocarpa 2 31 5 4 

Achillea lanulosa 1 T 

Agropyron caninum 1 

Astragalus bourgovii T 1 3 1 1 T 

Bromus anomalus 4 3 1 1 9 

Carex spp. 8 8 T 31 T 

Casti Ueja ZinariaefoUa T 5 T T 

Cirsium undulatum 16 T 8 

Erigeron speciosus T 8 

Fragaria americana T 1 T 

Frasera speciosa T 11 T 

HeliantheUa un:ifl.ora 1 

Lupinus leucophyUus 4 6 11 15 10 30 

Poa fendleriana T 3 10 40 25 

Populus tremuloides 68 40 5 5 

Potentilla pulcherrima 2 5 4 2 5 1 

Rosa woodsii 2 3 1 2 1 T 

Stipa spp. 1 1 4 3 6 6 

Symphori carpos vacci ni oi des 5 20 6 3 4 2 

Taraxacum officinale 2 5 20 8 2 

ThaZictrum fendleri 

Others 4 7 16 4 . ' 

.. ' 

1 A dash indicates missing data. 

11 
Table 5.--Changes in cover composition {%) of vegetation under 1. 68 m in height on permanent 23.8 m2 

quadrats at Big f"l-at between 1937 (3 years following establishment) and 1975. 

Understory Closed to use Deer use only Deer and cattle use 

vegetation : 1937 : 1942 : 1949 : 1975 1937 : 1942 : 1949 : 1975 1937 : 1942 : 1949 : 1975 

~ 

Total shrubs and trees 10 40 50 51 5 20 5 20 2 25 45 45 

Total graminoids 50 25 15 5 35 35 55 22 52 35 35 15 

Total forbs 40 35 35 44 60 45 40 58 46 40 20 40 

Abies lasiocarpa T 10 15 30 T 18 5 12 T 22 40 25 

Achi llea lanulosa 5 10 7 T 7 22 18 15 5 12 5 5 

Agropyron caninum 

Astragalus bourgovii 24 15 15 10 10 10 5 6 

Bromus anomalus 

Carex spp. 4 4 4 1 17 7 14 1 2 5 T 

Festuca idahoensis 45 18 10 4 17 15 24 5 so 28 34 15 

Fragaria americana 22 5 1 3 24 5 6 7 25 10 5 6 

Frasera speciosa T T 5 15 T T T 12 ... 

Helenium hoopesii 4 8 T T 5 3 1 

Lupinus leucophyllus 6 15 25 8 

Ficea engelmannii T 10 10 1 T 5 

Poa fendleriana T 8 5 T 2 T T 

Populus tremuloides 10 20 25 20 5 2 T 8 2 3 5 15 

Potenti Ua pulcherrima T 3 4 2 T 2 T T 1 T 

Solidago decumbens 7 7 12 1 4 T 2 1 1 

Stipa lettermani 1 3 1 T 2 1 T 

Taraxacum officinale T 2 T T 

Others 2 T T 8 2 4 12 17 3 2 2 

CUT 

Total shrubs and trees 50 55 67 1 1 

Total graminoids 25 20 9 55 80 69 

Total forbs 25 25 24 44 19 31 

Abies lasi ocarpa 5 T 

Achi Uea lanulosa 2 15 T T 2 8 

Agropyron caninum T T 3 7 

Astragalus bourgovii 

Bromus anomalus T 

Carex spp. 1 3 2 1 2 2 

Festuca idahoensis 23 15 7 54 70 45 

Fragaria americana 16 3 6 37 3 T 

Frasera speciosa T T 8 T 

Helenium hoopesii T 3 15 

Lupi nus leucophy l lus 3 6 

Ficea engelmannii T 

Poa fendleriana 

Populus tremuloides 50 55 50 1 

Potentilla pulcherrima 1 1 T 2 2 T 

Solidago decumbens 1 1 2 T 

Stipa lettermani 1 2 5 15 

Taraxacum offici an le 4 4 T 4 9 T 

Others 1 1 17 T 1 2 

A dash indicates missing data. 

12 
uncut areas were compared to evaluate response of understory vegetation to grazing. Response of the cut areas is confounded by the initial elimination of aspen overstory by 

cutting and subsequent maintenance of the grazed openings through destruction of aspen 

suckers by deer. With the exception of aspen, species differences on the cut areas are 

more likely a result of continued lack of aspen competition than of direct utilization 

by deer. 

The most striking difference in understory attributable to animal use was the great 

reduction in total shrubs (table 3). After 41 years, the ungrazed area at Grindstone 

Flat produced almost 10 times more shrubs than the area grazed by both cattle and deer 

and over 3 times more than that grazed just by deer. The graminoids increased under 

grazing at Grindstone Flat, but not at Big Flat. On both sites, cattle use apparently 

hampered total forb production, but deer use-did not. Overall production crf understory 

herbage was greatest on the areas closed to cattle, but grazed by deer. Deer browsing 

may tend to reduce the aspen overstory sufficiently to promote production of understory 

herbs, yet forb use by cattle appears to hinder overall understory production. 

Most of the decrease in shrub production on the grazed areas can be attributed to 

the large reduction in snowberry. Of the graminoids, the sedges (Carex spp.) apparently 

decreased, but the presumably palatable fringed brome (Bromus anomalus) increased unexpectedly and appreciably on the grazed plots. Of the forbs, western yarrow (Achillea 

lanulosa) and milkvetch (Astragalus bourgovii) increased greatly under grazing, particularly where grazed by cattle. Velvet lupine (Lupinus leucophyllus) increased during 

the 41-year period on all of the permanent quadrats except on the uncut, ungrazed area 

on Grindstone Flat (tables 4 and 5). Production of both Wyoming painted-cup (Castilleja 

linariaefolia) and oneflower helianthella (Helianthella uniflora) was conspicuously reduced by deer use. Showy frasera (Frasera speaiosa) appeared to be harmed by grazing 

at Grindstone Flat, but not at Big Flat. 

Clearcutting aspen directly affected the abundance of certain understory species 

by altering light and moisture availability. An insight into environmental requirements 

of certain species can be gained by comparing the clearcut areas maintained as openings 

by deer browsing aspen reproduction and those that reverted to a dense stand of polesize aspen (tables 3, 4, and 5). The effect of deer use on different plant species in 

the maintained openings can be discounted by examining the effect of deer use on the 

uncut areas. 

Eliminating aspen cover greatly benefited the grasses, somewhat improved shrub 

production, and caused a decrease in production of forbs. As aspen reproduction developed into a dense pole-size stand on the protected clearcuts, cover of grasses declined 

and forbs increased. 

The grasses responding most positively to removal of aspen cover were Idaho fescue 

(Festuaa idahoensis) and the needlegrasses (Stipa spp.). Slender wheatgrass (Agropyron 

aaninum), mutton bluegrass (Poa fendleriana), and bottlebrush squirreltail (Sitanion 

hystrix) also increased with clearcutting. 

The only forbs that appeared to directly benefit by removal of aspen cover were 

Oregon fleabane (Erigeron speciosus) and orange sneezeweed (Helenium hoopesiil. 

Although velvet lupine increased on most areas, it increased less in the openings than 

in the closed stands, suggesting that lupine is favored by shade. Virginia strawberry 

(Fragaria americana)~ on the other hand, declined on all areas over the 41-year period, 

but mostly in the openings, suggesting that it too is favored by shade. Fendler 

meadowrue (Thalictrum fendleri) also was favored by an aspen overstory. Interestingly, 

wavyleaf thistle (Cirsium undulatum) apparently was favored by aspen removal at Big 

Flat, but by a closed overstory at Grindstone Flat. This is not unreasonable for the 

600-m elevational difference between the two areas could appreciably alter the 

insolation and available moisture relationships for this species. 

13 
MANAGEMENT IMPLICATIONS 

Extrapolating results from these two smal l exclosure studies to broad management 

units is hazardous, particularly where animal behavior is involved . The exclosure 

results suggest that aspen reproduction on Beaver Mountain is doomed because of current 

levels of deer browsing. This is not true. The error of such a conclusion is readily 

demonstrated by ample reproduction of aspen on extensive burns within a f ew mi l es of 

the exclosures (fig . 4). Apparentl y, aspen suckers were so abundant over hundreds of 

hectares of mixed aspen and conifer stands that burned in 1958 that combined deer and 

livestock use did not hamper successful reestablishment of the aspen stands. Presumably, as these rejuvenated aspen stands mature and become less dense , un gulate use may 

again be sufficient to prevent survival and growth of the new suckers that periodically 

occur. 

Figure 4.--A large 600- hectare area near Grindstone Flat burned in 1958 had ample 

aspen regeneration in 19?5. 

14 
Sampson (1919) found that moderate use by cattle does not appreciably harm aspen 

reproduction in either standing timber or on clearcuts, but that sheep grazing can be 

very destructive unless it is light. Smith and others (1972) concluded from a study 

of four scattered sites in Utah that proper livestock management, especially management 

of sheep, is essential for regeneration of aspen following clearcutting or burning. 

They also concluded that the normal deer populations during the period of their study 

(1961 to 1969) had little effect on development of aspen reproduction in large clearcuts. Jones (1975) found that widespread and "appreciable" elk browsing of aspen 

reproduction on a 2-hectare clearcut in Arizona did not prevent establishment of a 

new aspen stand. On our study areas, however, deer use in both standing timber and in 

small clearcuts apparently was enough to keep suckers from developing into saplings 

and so prevented successful regeneration. 

We believe that successful reestablishment of aspen on clearcuts or burns may be 

dependent upon the size of area treated, unless deer and livestock use can be rigidly 

controlled. Without control of ungulate use, clearcutting or burning less than about 

5 hectares of mature aspen might be futile. Even if livestock are excluded from such 

areas for from 5 to 10 years, deer may concentrate on the small treated areas and 

prevent escape of the sprouts. Smith and others (1972) indirectly recognized this 

possibility by recommending that sufficiently large acreages be cut to provide an 

excess of aspen forage. 

Our data suggest that use of the herbaceous understory in standing timber by 

cattle may alter the vegetation-competition relationships sufficiently to reduce 

mortality of young aspen suckers. This proposal is supported by data from Sampson 

(1919) showing that about twice as many suckers occurred on moderately and heavily 

grazed plots as on lightly grazed plots. Abundance of sucker production, however, is 

no guarantee of successful regeneration. Continued survival and subsequent growth of 

the suckers is affected by the intensity of ungulate browsing and rodent activity, 

disease incidence in wounded stems, as well as dieback from undetermined causes. 

Schier (1975) observed that such sucker dieback is common even in vigorous aspen clones. 

A prounounced shift in species composition of the understory vegetation from forbs 

to grasses can be brought about by clearcutting aspen stands. This difference presists 

until the aspen overstory reforms and creates conditions more favorable for the forbs. 

Shrub production benefits somewhat by aspen removal, bPt not as much as the grasses do. 

If aspen suckers are not suppressed by browsing, succession back to forb dominance of 

the understory may occur within 10 years. Otherwise, the grasses will remain abundant 

as long as an aspen overstory fails to develop--unless, of course, the grasses are 

overgrazed by cattle. 

In extensive areas of aspen, greater habitat diversity and improved forage conditions for both livestock and wildlife might be created by clearcutting small, scattered 

2- to 5-hectare openings. These openings would favor the production of grasses for 

cattle and, at least for the first few years, aspen suckers as browse for deer. Deer 

utilization of the suckers in these small openings would prevent reestablishment of 

aspen and thus prolong grass production for cattle. Ideally, such openings would be 

created as part of an aspen timber sale program where a market for aspen products 

exists. 

15 
PUBLICATIONS CITED 

Jones, R. J. 

1975. Regeneration on an aspen clearcut in Arizona. USDA For. Serv. Res. Note 

RM-285, 8 p. Rocky Mt. For. and Range Exp. Stn., Ft. Collins, Colo. 

Sampson, A. W. 

1919. Effect of grazing upon aspen reproduction. U.S. Dep. Agric. Bull. 741, 29 p. 

Washington, D.C. 

Schier, G. A. 

1975. Deterioration of aspen clones in the middle Rocky Mountains. USDA For. Serv. 

Res. Pap. INT-170, 14 p. Intermt. For. and Range Exp. Stn., Ogden, Utah. 

Smith, A. D., P. A. Lucas, C. 0. Baker, and G. W. Scotter. 

1972. The effects of deer and domestic livestock on aspen regeneration in Utah. 

Utah Div. Wildl. Resour., Publ. 72-1, 32 p. 

16 
Mueggler, Walter F., and Dale L. Bartos 

1977. Grindstone Flat and Big Flat enclosures--41-year 

record of changes in clearcut aspen communities. USDA 

For. Serv. Res. Pap. INT-195, 16 p. Intermountain 

Forest and Range Exp. Station, Ogden, Utah 84401. 

The role of deer and cattle in the failure of aspen stands to 

regenerate on Beaver Mountain in southern Utah was investigated 

by a series of exclosures constructed in 1934. Three-fourths of 

each exclosure was clearcut of aspen in 1934. Aspen reproduction, shrubs, and herbaceous understory were measured in 1937, 

1942, 1949, and 1975. Implications of wildlife and livestock use 

on aspen reproduction are discussed. 

KEYWORDS: Populus tremuloides, clearcuts, aspen regeneration, 

understory vegetation, exc losures 

Mueggler, Walter F., and Dale L. Bartos 

1977. Grindstone Flat and Big Flat enclosures--41-year 

record of changes in clearcut aspen communities. USDA 

For. Serv. Res. Pap. INT-195, 16 p. Intermountain 

Forest and Range Exp. Station, Ogden, Utah 84401. 

The role of deer and cattle in the failure of aspen stands to 

regenerate on Beaver Mountain in southern Utah was investigated 

by a series of exclosures constructed in 1934. Three-fourths of 

each exclosure was clearcut of aspen in 1934. Aspen reproduction, shrubs, and herbaceous understory were measured in 1937, 

1942, 1949, and 1975. Implications of wildlife and livestock use 

on aspen reproduction are discussed. 

KEYWORDS: Populus tremuloides, clearcuts, aspen regeneration, 

understory vegetation, exclosures 
.. a; 

Headquarters for the Intermountain Forest and 

Range Experiment Station are in Ogden, Utah. 

Field 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) 

'fi U.S. GOVERNMENT PRINTING OFFICE: 1977-0-777-023/33