Effects of Forest Disturbance 

Forest Service 

Northeastern Forest 

and Soil Depth on 

Experiment Station Digestible Energy for Moose 

Research Paper NE-682 and White-Tailed Deer 

Hewlette S. Crawford 

R. A. Lautenschlager 

Martin R. Stokes 

Timothy L. Stone 
Abstract 

Spruce budworm defoliation, clearcutting for salvage, and prescribed burning of 

clearcut areas on deep and shallow soils influenced deer and moose foraging in 

eastern Maine spruce-fir forests from 1980 to 1984. Plant standing crop biomass, 

seasonal plant selection by tractable moose and white-tailed deer, and digestible 

energy for deer and moose were determined for each treatment. Early successional 

plant species were most abundant on burned areas, and were common on cfearcut 

areas. Increase in biomass after defoliation was substantial. Deer and moose ate 

many of the same plant species, but in different proportions. Deer found more 

desirable foods on deep than on shallow soils and were more selective of plant 

parts than moose. Deer digested their diets slightly better than moose from late 

spring through fall. Deer obtained more digestible energy than moose during fall and 

early winter on all treatments. Moose obtained more digestible energy than deer 

during spring and summer on burned areas where forage was abundant. Available 

energy by treatment was significantly different for moose year round and for deer 

during spring and fall: clearcut and burn xiearcut >defoliated >undefoliated 

(control). 

The Authors 

HEWLElTE S. CRAWFORD retired in 1991 as principal wildlife research biologist 

with the Northeastern Forest Experiment Station at Orono, Maine. 

R. A. LAUTENSCHLAGER is a forest vegetation management scientist with the 

Ontario Forest Research Institute at SauR Ste. Marie, Ontario. 

/ 

MARTIN R. STOKES is an associate professor with the Department of Animal, 

Veterinary and Aquatic Sciences at the University of Maine, Orono. 

TIMOTHY L. STONE is a computer specialist and certified wildlife biologist with the 

Northeastern Station at Orono, Maine. 

Manuscript received for publication 28 May 1993 

Northeastern Forest Experiment Station 

5 Radnor Corporate Center 

100 Matsonford Road, Suite 200 

P.O. Box 6775 

Radnor, Pennsylvania 1 9087-4585 

November 1993 
Spruce budworm (Choristoneura Pumiferana) infestations in 

northern coniferous ecosystems have defoliat 

(Picea-Abies) forests periodically for centuries (Blais 1983). 

These infestations often last 7 to 10 years until much of the 

balsam fir (Abies balsamea) is killed, and may progress 

cross-continent, covering a substantial poftion of the 

continental spruce-fir type ( ardy et al. 1986). The outbreaks 

of 191 0,1940, and 1970 affected 10,25, and 55 million ha 

(25, 62, and 136 million acres), respectively (Blais 1985). 

During severe infestations, nearly half of the spruce (Picea 

glauca and P. rubra) and most of the balsam fir can be killed. 

The entire forest canopy can be killed over extensive areas 

depending on the composition of the stand. Stands s 

severe mortality contain large amounts of highly flammable 

fuel, which has led to severe wildfires in past infestations. 

Spruce budworm defoliation, by itself or in combination with 

wildfires or salvage cuts, sets plant succession back to early 

seres and modifies extensive areas of moose and deer 

habitat. 

ithin the concomitant range of white-tailed deer and moose 

in Canada, the most recent spruce budworm infestation 

occurred on approximately 54, 40, 27, 25, 30, and 31 million 

ha in 1975 through 1989 (Hardy et al. 1986). Defoliation solely 

within the range of moose approximated 18, 23, 25, 20, 14, 

and 14 million ha over the same period. Additionally, spruce 

dworm caused substantial tree moriahty in Maine and 

nnesota, with lesser losses reported in New Hampshire, 

Vermont, New Y'ork, and Michigan. Selser eta!. (1 985) 

reported dead trees on 120,000 ha and trees at severe to 

heavy risk on 2.2 million ha in Maine in 1983. Also, secondary 

insects and diseases invaded and killed weakened trees. 

Many trees in northern New Hampshire and northeastern 

Vermont were defoliated, eliminating critical winter ha 

deer. 

Historically, the effects of spruce budworm defoliation, 

clearcutting of defoliated stands, and fire, singly and in 

combination, substantially modified the composition and 

abundance of vegetation available as food and cover for 

herbivores. In the most recent infestation, increased 

construction of logging roads and additional financial 

investment in forest lands resulted in greater fire-control 

efforts and a decrease in the area burned. As fire becomes 

less important as an ecological factor affecting seral stages 

and deer and moose habitat, will clearcutting or budworm 

defoliation serve the same role and benefit deer and moose 

habitat? Here we quantitatively describe the effect of spruce 

budworm defoliation, clearcutting, and fire, singly and in 

combination, on forage availability, forage use, and digestible 

energy for deer and moose. 

Study Area, Plot Location, and Treatments 

We established six 4- to $-ha study blocks, three on shallow 

and three on deep soil on the oosehorn National Wildlife 

Refuge in eastern Washington County, Maine, in 1977 

through 1979. Budworm defoliation began In this area in 1974. 

Two undefoliated (CONTROL) blocks, one on a shallow and 

60 to 8Q years old, 

rrn infestation. As in 

ost even-aged budwo , the overstory was 

sparse and included several fern species: Carex spp., Cornus 

spp., a few forbs such as Mainanthemum canadense an 

Trienfalis borealis, balsam fir, spruce and hemlock (Tsuga 

canadensis) regeneration, and mosses. 

Soils were mapped on all plots and differentiated on the basis 

of depth of solurn. The shallow soils were mostly a 

an-Tunbridge complex or a Tunbridge-Peru complex. 

Depths generally were less than 1 m, and rock outcrops were 

common. The deep soils were Buxton and occasional pockets 

of Scantic, and a Croghan-Adams complex with Adams soils 

on higher elevations. These soils generally 

ore deep. 

Commercialiy valuable trees were removed from CUT and 

riy summer sf 4 979. All 

b.h were cut and lefa on 

r 1979. This residue 

provided copious fuel for prescribed burning. Plots were 

burned in May and June 1980. Strip he 

1986) were used on all plots except for one ring burn. 

Vegetation Sampling Techniques 

Plant biomass.' Standi biomass of herbaceous vegetation 

and woody shoots s 1 cm in diameter on all plots was 

sampled during July-September of 4 80, 1981, 1983 (burned 

plots only), and 1984. Biomass (kglha) of vegetation was 

determined on 10 randomly located temporary and 10 

randomly established permanent quadrats (5.0 x 0.5 x 2.5 m) 
stratum contained more than 50 g of vegetation, a microwave 

link was set up on each end of th'e 5-m-long quadrat and 

signal loss caused by the vegetation was determined. When 

microwave anenuation was used, we visually estimated the 

percent composition by plant species in the signal path since 

signal loss determines only total vegetation weight. 

After taking these measurements on the 10 temporary 

quadrats in each plot, it was determined randomly (P = 0.2) 

whether to clip the quadrat and record fresh and oven-dry 

ht of vegetation by species. Vegetation samples were 

collected daily and oven dried at 65°C to a constant weight. 

Estimated weights and reduced microwave signal strength 

were regressed on fresh and oven-dry weights to derive 

formulae to convert estimates to actual weights. Permanent 

quadrats were not clipped. 

Plant selection by deer and moose. Tractable animals were 

reared, maintained, and trained by the techniques of 

Lautenschlages and Crahrd (1983, 1984). They were held in 

pens on the Moosehorn National Wildlife Refuge, transported 

to the plots in a horse trailer or enclosed truck, and fed a 

pelleted dairy ration after returning from the plots. We 

observed the plants selected by two female deer (mean live 

weight 50 kg), and three moose (two female and one 

neutered malemean live weight 300 kg). Plant selection 

was observed during feeding periods: summer (1 July31 

August), fall (1 September31 October), and early winter (1 

November31 December) of 1980; late winter (1 January-1 9 

March-moose only), early spring (20 March30 April), late 

ay-30 June), summer, and fall of 1981. During 

each feeding period, each animal visited each treatment on 

each block on both shallow (12 plots) and deep soil (1 2 plots), 

as well as plots on the 14BURN block. No data were recorded 

during the summer of 1980 for moose and the summer and 

the fall of 1980 for deer; that time allows the animals to 

become accustomed to the area and the available foods, and 

for the observers to refine techniques. 

bservers were trained to estimate the wet weight of plants 

selected by the animals and were checked for accuracy 

wing feeding periods. Foraging was simulated by one crew 

member while an observer estimated its wet weight. The 

observer's estimated weights were later regressed against 

actual weights to provide a correction coefficient. Three 

handlers accompanied each animal to each plot for 30 

minutes during each feeding triai. They estimated the wet 

weight by species of plants eaten in alternate bites, and 

collect6d 5- to 50-g samples of each plant eaten by the 

animals during every feeding trial. When possible, 

reproductive and vegetative parts similar to those selected by 

the animals were collected from the browsed plants; 

otherwise, similar samples were taken from nearby plants. 

This procedure was repeated with the remaining deer and 

moose until each animai had visited the plot. Animals were 

moved to the next plot and the procedul-e was repeated after 

allowing time for rumination and rest. When possible, we 

sampled two plots each morning and two each evening. 

Animals were allowed to move freely about plots and were 

redirected only if they attempted to leave a plot. The weight 

consumed by each animal during each 30-minute feeding 

period was summarizec! by plant species. 

Plant digestibility. A representative sample of plant species 

eaten on each plot was oven dried at 60°C to a constant 

weight, ground in a Wiley mill through a I-mm mesh screen, 

and stored in airtight plastic bags. Dried samples of plants that 

made up the top 90 to 100 percent by weight of the diet were 

combined to represent mixed wet-weight diets selected by 

deer and moose. Digestible dry matter (DDM) of mixed diets 

was determined with bovine rumen fluid (Crawford and 

Hankinson 1984) by a two-stage in vitro technique (Tilley and 

Terry 1963) modified by Palmer et al. (1 976). Standard 

reference forages of known digestibility for white-tailed deer 

were provided by R. L. Cowan of Pennsylvania State 

University to convert in vitro DDM values to in vivo (Palmer 

and Cowan 1980) data for both deer and moose. Because no 

source of standard reference forages for moose were 

available, we used bovine rumen fluid and deer standards, 

assuming that digestibility of forages selected by moose 

would be closer to digestibility values of deer than those of 

cattle. Caloric values were determined by bomb calorimetry 

(AOAC 1 975). 

Analysis 

Digestible energy available for moose and deer was 

calculated for each plot by multiplying forage plant biomass 

available by its caloric value and percent digestibility. 

Treatment differences in digestible energy were determined 

by an ANOVA with a split-plot factorial design for plots on the 

Moosehorn Refuge, an ANOVA with factorial to compare the 

CONTROL with DEFOL, and with Tukey's Studentized Range 

Test. Variation for the statistical analysis was determined from 

the values determined for digestible energy available on 

treatment plots. Individual values of the component parts of 

biomass, energy, and digestibility are presented in graphs or 

tables or discussed in the text. The oven-dry weight of all 

forage available during summer was assumed to remain 

available to animals until the following growing season, except 

when covered by snow. Leaching loss of dry matter was 

assumed insignificant for treatment comparisons at our 

iatitude (45" N). Seasonal differences were not analyzed 

statistically because observations between seasons were not 

independent. 

Results 

Plant Biomass 

We failed to detect a significant difference in plant biomass by 

treatment or soil depth, though probability levels were 0.07 for 

soil differences in 1981 and 0.06 for treatment differences in 

1984. In general, biomass means for deep soils were greater 

than those for shallow soils, and biomass means were lowest 

in CONTROL and DEFOL, greater in CUT, and greatest in 

CUTBURN (Figs. 1-2). 

On CUTBURN, Comptonia peregrina was by far the most 

abundant plant. The weight of this nitrogen-fixing species was 

about 1,000 kg/ha, nearly twice'that of the next most 

abundant species on both deep and shallow soils. It also was 

the dominant species in 1983 and was abundant in 1981 as 

well, especially on shallow soils. Other abundant plants on 

CUTBURN in 1 984 were Populus tremuloides, Corylus 

cornuta, Rubus idaeus, R. allegheniensis, Pteridium 

aquilinum, and Solidago spp. on deep soils; and Prunus 
TREATMENT 

Figure 1 .-Total available plant dry-weight biomass in kglha by treatment and year on 

deep soils, excluding woody stems > 1.3 crn in diameter. Only CUTBURN plots were 

sampled in 1983. 

TREATMENT 

Figure 2.-Total available plant dry-weight biomass in kglha by treatment and year on 

shallow soils, excluding woody stems > 6.3 cm in diameter. Only CUTBURN plots were 

sampled in 1983. 
pensyhnica, Popukis grandidenfafa, tmuloides, Acer 

B. papyrifera on shallow soils. 

Common plants in the CUT plots in 1984 were Abies 

and Abies balsamea made up 

of the total on deep soils and more 

mosses and fir were still the most abundant groups on 

. In 1984, other important species were 

eniensis, and A. rubrum. 

more than 75 percent by weight of the total 

NTWOL. These are normal year-to-year 

ense Picea-Abies stands. 

semiwoody genus Rubus; grasses, sedges,.and rushes; fallen 

ifers; fungi; members of the heath 

n shrubs; and mosses. Foods eaten 

atmenl and soils (Table 1). 

Deer ate more species of plants, and usually greater 

The deeper soils of CO L plots provided a richer 

aceous flora as food than shallow soils. Here, deer ate 

farbs such as canadense, Trientalis borealis, 

ore ., and grasses. By contrast, deer 

mere on woody plants for food on shallow soils. In 

DEFOL stands where budworm had defoliated Abies and 

Pkea but the rest of the overstory remained intact, M. 

canadense was eaten more than any other species on both 

deep and shallow soils. Phis species provided deer with 

succulent growth shortly after snowmelt. Its leaves and fruits 

were eaten throughout summer, and the cured plant was 

consumed into fall. T. borealis and C. borealis were eaten in 

spring, summer, fall, and early winter, but in slightly lesser 

amounts than M. canadense. Aster shoots, flowers, and basal 

leaves were consumed during summer and fall. Grasses, . 

largely Poa canadensis,,were eaten during spring, summer, 

and fail. Mixed fallen hardwood leaves and fungi were 

important foods in stands with a hardwood overstory, 

regardless of soil depth. The inclusion of fungi in a mixed diet 

with fallen hardwood leaves enables deer to digest the 

energy-rich leaves (Crawford 1982). 

Moose. Moose also ate more deciduous woody plants year 

round than any other food (Table 2). Abies balsamea, Rubus 

spp., ferns, Picea, mixed fallen hardwood leaves, fungi, forbs, 

heath and low evergreen shrubs, grasses, and sedges also 

were eaten. As with deer, foods selected varied by season, 

treatment, and soils. 

Differences in plant consumption by soill type were not as 

great for moose as for deer. In CONTROL plots, Picea and 

Abies were eaten often in winter and spring but less in 

summer and fall. In DEFOL plots these same species were 

eaten most during winter and early spring. Abies was eaten to 

a greater extent than Picea, but the latter was readily selected 

during those seasons. P. rubens was the most common 

species of Picea. It has not been considered as readily eaten 

by moose. P. glauca also was consumed but to a lesser 

extent than P. rubens. In the sparse understory of the shallow 

soil CONTROL plots, moose ate considerable quantities of 

fungi, including gilled and bracket fungus. Fungi was not often 

eaten in DEFOL plots, but Pteridium aqdinum and Aralia 

nudkaulis were, especially in shallow-soil areas. Deciduous 

woody plants as a group were eaten more than any other food 

on all plots with a woody canopy. 

Differences in food selection between soil types were not 

important on CUTBURN and CUT treatments for moose. 

Deciduous woody plants such as Acer rubrum, Populus 

tremuloides, P. grandidentata, P. pensylvanica, Betula 

papyrifera and 6. populifolia, Cornus cornuta, Rubus spp., 

and ferns, especially P. aqujlinum, were eaten frequently. 

Plant Digestibility by Deer and Moose 

The dry-matter digestibility of mixed diets selected by deer 

(Table 3) and moose (Table 4) varied somewhat by soil depth 

and treatment but varied more with season. Digestibility of . 

mixed diets by deer was low in early spring, increased to a 

peak in late spring and summer, then declined throughout the 

rest of the year. Digestibility of mixed diets by moose was low 

in early spring, increased,in late spring, decreased in summer 

on all treatments except the control, increased during fall on 

cut areas, and declined through winter. Deer appeared to 

digest their diets slightly better than moose, particularly from 

late spring through fall. 
Table 1 .-Green weig 

during summer I981 

Family or Control efoliated C u't @bet-burned Percent 

species DS SS DS SS DS SS BS ss oftotal 

Acer rubrum 

Ainus rugosa 

Amelanchier spp. 

Aster spp. 

Betula papyrifera 

Betula populifolia 

Bryales 

Carex spp. 

Clintonia borealis 

Cornus spp. 

Corylus cornuta 

Diervilla bnicera 

Erechtites hieracidolia 

Fragaria virginiana 

Fungus 

Grarniniae 

Leaves, fallen hardwood 

Lichen 

Lonicera canadensis 

Maianthemurn cilnadense 

Populus grandidentata 

Populus tremuloides 

Potentila simplex 

Prunus pensylvanica 

Prunus serotina 

Pteridium aquilinum 

Quercus rubra 

Rubus allegheniensis 

Rubus idaeus 

Salix sp p. 

Solidago spp. 

Trientalis borealis 

Vaccinium spp. 

Veronica officinalis 

Viburnum s pp. 

31 

- 

- 

4 

87 

15 

- 

2 

- 

37 

- 

82 

8 

- 

3 

5 

5 

- 

- 

1 0 

109 

39 

- 

348 

2 

84 

- 

47 

96 

- 

12 

- 

12 

- 

4 

Total 

a Total is < 100 percent because only plants 2 0.5 percent of total are included. 

Errata 

In the headings above Tables 1 and 2 on Pages 5 and 6, 

mspectively, the designation for shallow soils should be (SS). 
reen we y three moose on each treatment and deep (DS) and shallow (SE) soils 

mer 198 

Family or Control Defoliated Cut Cut-burned Percent 

species DS SS DS SS DS SS DS ss of total 

Abies balsamea 

Acer rubrum 

cer spicaturn 

Alnus rugosa 

Aralia nudicauhs 

Befuk papyrifera 

etula populifolia 

Garex s p p . 

Gosnplonh peregrina 

Cornus spp. 

Corylus comuta 

DierviNa lonicera 

Epbbium angustifojiurn 

Fagus grandifoh 

Fungus 

/!ex vert~cjllata 

Onoclea sensibijis 

Osmunda ciaytoniana 

Bicea rubens 

Polygonurn scandens 

PopuIus grandidentata 

Popuius tremuloides 

Prunus pensykmica 

Buercus rubm 

Rubus aflegheniensis 

Rubus idaeus 

Salix spp. 

Tsuga canadensis 

Total 84.6a 

a Total is c 100 percent because only plants z 0.5 percent of total are included. 
ean percent digestible dry matter (standard error) of deer mixe 

treatment, deep (DS) and shallow (SS) soils, and season 

Early Late Early 

Treatment spring spring Summer Fall winter 

Control 

DS 26(1.2) 55(7.1) 46(3.8) 40(1.4) a 

SS 40(3.7) 51 (2.6) 48(1 .I)' 38 (2.6) a 

Defoliated 

DS 32(1.2) 52(3.7) 53(2.3) 43(2.1) 42(5.6) 

SS 28(1.8) 51 (4.7) 5213.6) 39j2.4) 30(3.0) 

a Unsampled. 

TabEe &-Mean percent digestible dry matter (standard error) of moose mixed diets 

by treatment, deep (DS) and shallow (SS) soils, and season 

Early Late Early Late 

Treatment spring spring Summer Fall winter winter 

Control 

DS 33(1.9) . 43(2.7) 41 (2.3) 35(1.9) a 36(1.4) 

SS 35(2.4) 35(2.5) 38(2.7) 38(2.1) 32(0.9) 33(0.8) 

Defoliated 

DS 36(2.0) 46(1.7) 37(2.4) 42(0.9) 34(1.7) 28(1.6) 

SS 34(0.9) 42(2.5) 37(1 .O) 34(1.4) 36(2.3) 35(1.2) 

a Unsampled. 
r deer and moose increased 

g season following treatment) to 

CUTBURN areas had the most digestible energy availabie for 

eer and moose, foilowed in decreasing order by GUT, 

DEFOL, and CONTROL (Fig. 3). These relationships were 

similar in 1981 and 1984. Treatment differences for moose 

were significant (P c 0.05) in all seasons; for deer, the 

treatment differences were significant (P c 0.05) only during 

fall in 1981 and in early spring, late spring, and fall of 1984. 

Early winter was not tested for deer because the number of 

samples taken during this season was insufficient for 

statistical analyses. 

Treatment differences were more pronounced in 1984 than in 

1981. For deer, the available energy in DEFOL was more 

than twice that of CONTROL, CUT was twice as great as 

DEFOL, and CUTBURN was nearly twice that of GUT (Fig. 3). 

These differences were approximately the same for moose in 

1984 except for DEFOL, which had nearly 10 times more 

available energy than CONTROL (Fig. 3). In DEFOL areas, 

more energy was available for moose on deep soils than on 

shallow soils for both 1981 and 1984. Differences due to soil 

depth were not significantly different (Pa 0.05) on the other 

treatments except for CUTBURN in early spring of 1981. 

We failed to detect significant differences (P < 0.05) in energy 

available for deer vs. moose except for the spring of 1981. 

However, our data means indicate that more digestible energy 

was available for deer than for moose during all seasons in 

estible energy in kcallha (XI 000) available for deer and moose by 
MOOSE - 4981 

MOOSE - 1984 

DEER - 1981 

SEASON 

Figure 4.-Digestible energy in kcallha (XI 000) available for deer and moose on CUT 

plots by season in 1981 and 1984. 

MOOSE - 1981 

MOOSE - 1984 

rn DEER - 1981 

DEER - 1984 

100 

50 

0 

SEASON 

Figure 5.-Digestible energy in kcallha (XI 000) available for deer and moose on 

CUTBURN plots by season in 1981 and 1984. 
MOOSE - 1981 

MOOSE - 1984 

1 DEER - 1981 I 

DEER 

Figure 6.-Digestible energy in kcallha (XI 000) available for deer and moose on DEFOL 

plots by season in 1981 and 3984. 

MOOSE - 1981 

MOOSE - 1984 

DEER - 1984 

SEASON 

Figure ?.--Digestible energy in kcallha (XI 000) available for deer and moose on 

CONTROL plots by season in 1981 and 1984. 
1981 except for early winter in CUTBURN. 

appeared to be available for deer than for moose during the 

fall and early winter of 1984 on all treatments. 

iscussio 

Several conditions that existed during this study determine 

how reliably our results can be extrapolated. The same two 

deer were not used throughout the study. The use of different 

animals likely caused greater variation in food selection than 

would have been the case if the same two animals were used 

for the entire study. This variation increased the residual 

variance of the ANOVA and made the test for deer more 

conservative, because we were less likely to reject a null 

hypothesis when it was false (type II error). In the case where 

we failed to detect a significant increase in digestive energy 

from 198Wo 1984 for deer, we suspect that there may be a 

true difference, especiasiy for CUTBURN. This implies that 

treatment effect may be longer lasting than our statistical 

analysis indicates. However, we also assumed that foods 

eaten in 1981 were the same foods eaten in 4984. This could 

have reduced the residual variance of the ANOVA except that 

the variation in foods eaten within year was as great as the 

variation between years and likely would not cause treatment 

bias. 

Also, we failed to detect significant differences in the amount 

of digestible energy for deer etween treatments in all 

seasons. We did detect this treatment difference for some 

seasons for deer and all seasons for moose. We hypothesize 

that the difference is true for all seasons and that all treatment 

differences are read. 

Likewise, where the greater amount of digestible energy 

available for deer than moose tested insignificant, we 

hypothesize that there is a true difference. Deer and moose 

ate many of the same species (Tables 1-2) but we observed 

that deer were more selective of plant parts eaten than 

moose. Deer nipped twig ends and buds and seldom ate the 

more fibrous thicker cell-wall proximal portions of the twigs, as 

did moose. Fibrous and thick cell-wall tissues require more 

time to chew and decrease food intake (Crawford and Whelan 

1973; Spalinger et al. 1986). Deer frequently would take a 

plant in their mouth and then reject it; moose seldom did this. 

Also, deer were more selective of foods growing on deeper 

soils, which generally offer better conditions for plant 

h-more digestible cell material. Moose selected plants 

or plant parts which appeared less digestible than those 

selected by deer (Tables 3-41, 

Large amounts of available energy consumed by deer during 

fall and early winter prepare the animals for late winter 

(Crawford 1982). Moose moved and searched for food in 

snow that would restrict the movement of deer. However, the 

foods moose found during winter were low in digestible dry 

matter. Thus, even though deer movement is restricted by 

snow during winter, the apparent physical advantage of larger 

size in moose may be offset by the ability of deer to select 

more digestible portions of energy-rich foods prior to deep 

snowfall. Such adaptability is influenced by: (1) the greater 

maneuverability of a smaller animal, which enables it to find 

desirable plant portions, and (2) the ability to pick small, more 

digestible parts because of smaller mouth size. However, 

during periods of rapid plant growth during spring and 

summer, a greater amount of the plant is digestible and 

moose compete more favorably with deer for energy because 

of their greater capacity and need to ingest large quantities of 

forage. Apparently, deer are more efficient energy consumers 

than moose during periods of plant dormancy or where 

acceptable biomass is limited. Our data show that biomass 

accepted as food is substantially more abundant after burning 

than it is following defoliation or clearcutting. Wickstrom et al. 

(11 984) indicated that deer are more efficient harvesters than 

elk when acceptable biomass is limiting. 

While periodic defoliations by spruce budworm increase the 

amount of digestible energy available for moose and deer, this 

increase is far more substantial if the infestation is followed by 

clearcutting for salvage and burning. Cutting is more likely to 

follow defoliation today and in the future than in the past 

because balsam fir has increased in value through the years, 

However, the same increase in value plus today's more 

intensive forest management-including improved fire 

control-make it less likely that fire will have much effect on 

future habitats. 

Our data (Fig. 3) indicate that burning benefits moose and 

deer equally. However, deer appear to gain more digestible 

energy than moose from defoliation and ctearcutting. 

While burning initially provides more digestible energy than 

other treatments, this effect may not last long. The amount of 

digestible energy available 3 years after burning (1 983) (Figs. 

8-9) was nearly as great as in 1984, indicating that treatment 

effect may have been at a maximum in 1984. Digestible 

energy available on plots burned by wildfire 15 to 17 years 

ago was substantially lower than yields 3 to 4 years after 

burning. 
YEARS AFTER BURNING 

Figure 8.-Mean digestible energy during summer available for deer after burning. 

YEARS AFTER BURNING 

Figure 9.-Mean digestible energy during summer available for moose after burning. 
Acknowledgment 

We are indebted to many individuals who helped with this 

study. We benefited from the technical reviews of D. 

decalesta, T. Hanley, D. Spalinger, V. VanBallenberghe, and 

6. Walton. P. O'Neil supervised site selection and initial study 

installation. S. Day, L. Muhlberg, S. Owens, L. Rogacki, M. 

Scott, R. Titterington, and W. Wright helped with study 

installation. S. Ahlfeld, J. Carter, A. Cobb, P. Cioffi, D. 

Degnen, J. Diehl, S. Finkelstein, C. George, J. Lawrence, C. 

Matlack, M. Olis, D. Perinne, L. Pucci, M. Ryan, P. Wayne, J. 

West, 6. Wood, and R. Zetsch assisted with data collection. 

Scientists of the USDA Soil Conservation Service in Maine 

made soil identifications. The staff of the Moosehorn National 

Wildlife Refuge, USDl Fish and Wildlife Service, provided field 

facilities and aided in many aspects of the study. H. Haines, 

C. Stubbs, and R. Keys permitted us to conduct part of this 

study on their land. J. Lockyer created the cover illustration. 

Linda Stokes performed most of the laboratory analyses. We 

dedicate this study to her memory. 

Literature Cited 

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13 

*U. S. GOVERNMENT PRINTING OFFICE: 1993-550- 1 12/80005 
Crawford, Hewlette S.; Lautenschlager, R. A,; Stokes, Martin R.; Stone, 

Timothy L. 1993. Effects of forest disturbance and soil depth on 

digestible energy for moose and white-tailed deer. Res. Pap. NE-682. 

Radnor, PA: U.S. Department of Agriculture, Forest Service, Northeastern 

Forest Experiment Station. 13 p. 

Spruce budworm defoliation, clearcutting for salvage, and prescribed burning 

of clearcut areas on deep and shallow soils influenced deer and moose 

foraging in eastern Maine spruce-fir forests from 1980 to 1984. Plant standing 

crop biomass, seasonal plant selection by tractable moose and white-tailed 

deer, and digestible energy for deer and moose were determined for each 

treatment. Increase in biomass after defoliation was substantial. Deer and 

moose ate many of the same species, but in different proportions. Seasonal 

production of available energy by treatment was significantly different for 

moose year round and for deer during spring and fall: clearcut and burn > 

clearcut > defoliated > undefoliated (control). 
heastern Forest Experiment Station is in Radnor, 

cooperation with the University of Massachusetts 

eration with the niversity of Vermont 

shire, In cooperation'with the University of New Hampshire 

onnecticut, in cooperation with Yale University 

eration with West Virginia University 

Orono, Maine, i coopersltIon with the University of Maine 

operation with the State University of New York, 

iences and Forestry at Syracuse'~niversity 

lea cooperation with The Pennsylvania State Uniarren, PennsyDvanl 

e policy d the United States Department of Agriculture, Forest Service, prohibits 

discrimination on the basis of race, color, national origin, age, religion, sex, or 

iiial status, or political affiliation. Persons believing they have been 

against in any Forest Service related activity should write to: Chief, 

Forest Service, US ox 96090, Washington, DC 20090-6090. 

nd and Serving People Through Research'"