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Soil and Watershed Implications of Ground
Cover at Burned and Unburned Pinyon-Juniper
Sites at Rifle Canyon and Jarvies Canyon
Sherel Goodrich
Chad Reid
Abstract - Quantity, dispersion, and quality of ground cover is
compared for adjacent burned and seeded and unburned pinyonjuniper sites. Comparison of these features indicates greater soil
protection for the burned and seeded site with 15 percent less bare
soil and pavement and 24 percent greater vascular plant and litter
cover 7 years post treatment. Ground cover is also compared
between 5 and 10 years post burning and seeding at one site. This
comparison indicates ground cover continued to increase for up to 10
years post treatment.
Total ground cover, dispersion of ground cover, and quality of ground cover appear to be highly important for soil and
watershed protection (Blackburn and others 1986; Khan
and others 1988; Osborn 1955; Payne 1980; Simanton and
others 1991; Watters and others 1996). Over4 years, Farmer
(1995) found an average offive times more runoff and eight
times more sediment associated with a mature stand of
pinyon-juniper than in all)lajacent area that had been
chained and seeded with litte~1eft in place. The sites in the
Ashley National Forest at Rifle Canyon and Jarvies Canyon
were burned, which greatly reduced ground cover for lor 2
years. However, within 7 years, plant and litter cover exceeded that found in a mature stand of pinyon-juniper, and
ground cover continued to increase for up to 10 years.
Study Sites _ _ _ _ _ _ _ __
The study sites are located within the Green River corridorin Daggett County, Utah, where there areabout8,100 ha
(20,000 acres) within a belt of Colorado pinyon (Pinus edulis
Engelm.) and Utah juniper (Juniperus osteosperma [Torr.]
Little) on the Ashley National Forest. The belt extends well
beyond the National Forest boundary down river toward the
Colorado and Utah line. Prior to the 1980's when a burning
program was started within this area, pinyon-juniper formed
nearly continuous stands and was advancing into the few
remaining sagebrush/grass and mountain brush communities. Much of the belt on National Forest lands was closed to
In: Monsen, Stephen B.; Stevens, Richard, comps. 1999. Proceedings:
ecology and management of pinyon-juniper communities within the Interior
West; 1997 September 15-18; Provo, UT. Proc. RMRS-P-9. Ogden, UT: U.S.
Department of Agriculture, Forest Service, Rocky Mountain Research
Station.
Shere! Goodrich is Forest Ecologist, Ashley National Forest, Forest Service, U.S. Department of Agriculture, Vernal, UT 84078. Chad Reid is
Extension Agent, Utah State University Extension Service, Cedar City, UT
84078.
USDA Forest Service Proceedings RMRS-P-9. 1999
permitted livestock grazing in the 1960's as mitigation for
recreation and other values associated with Flaming Gorge
Reservoir.
Low forage values for wild ungulates were recognized in
this area with extensive stands of mature pinyon andjuniper covering much of the corridor and with young stands
expanding into sagebrush/grass and mountain brush/grass
communities. Bighorn sheep were of special concern as they
were known to use the Green River corridor. Bighorn sheep
avoided mature and old stands of pinyon and juniper (Smith
1992). Burning and seeding of some sites were proposed and
accomplished by the Ashley National Forest and Utah Division of Wildlife Resources. The Bureau of Land Management
also burned some sites lower in the corridor.
Prescribed fire was applied to pinyon-juniper woodlands
at Jarvies Canyon in the fall of 1985 and in Rifle Canyon in
September 1989. Study sites within these burns are about
4.8 km (3 miles) west and about 2.4 km (1.5 miles) northwest
of Dutch John, UT. Mean annual precipitation at the Flaming Gorge Climate Station near Dutch John is 31.75 cm
(12.50 in) (Ashcroft and others 1992). The study sites are
within the Uinta Mountain Section as defined by McNab and
Avers (1994). They are within a landtype composed of ridge
and ravine topography underlain by Precambrian quartzitic
materials and shales of the Uinta Mountain Group.
Within the landtype there are two general phases. One
phase is on dip slopes of northerly exposures where alderleaf mountain-mahogany/bl uebunch w hea tgrass
(Cercocarpus montanus Raf. / Elymus spicatus [Pursh] Gould)
communities with high plant diversity are seral to pinyonjuniper. The other phase is on scarp slopes of southerly
exposures where plant communities of big sagebrush (Artemisia tridentata N utt.) ,rubber rabbitbrush (Chrysothamnus
nauseosus [Pallas] Birtt.), and grasses are seral to pinyonjuniper. On southerly exposures cheatgrass has proven to be
highly competitive. It is generally oflower frequency on the
northerly exposures. Both study sites reported here are on
the phase with southerly exposures at about 2,042 m (6,700
ft) elevation on gradients of about 20 to 40 percent.
Both burns were aerial seeded in November or December
of the same year in which they were burned. Seed for both
sites was provided by Utah Division of Wildlife Resources.
By weight, the seed mix at Jarvies Canyon included smooth
brome (Bromus inermis Leysser) (20 percent), Piute
orchardgrass (Dactylis glomerata L.), hard fescue (Festuca
ovina var. duriuscula [1.] Koch.), Ladak alfalfa (Medicago
sativa L.), and small burnet (Sanguisorba minor Scop.) (13
to 14 percent each), and Fairway crested wheatgrass (Agropyron cristatum [1.] Gaertner), intermediate wheatgrass
(Elymus hispidus [Opiz] Meld.), yellow sweetclover (Melilotus
317
Table 1-Comparison of ground cover at the Rifle Canyon burn site five growing seasons
after treatment
Treatment
Burn and seeded (points)
Unburned, not seeded (points)
Burn and seeded (percent)
Unburned, not seeded (percent)
Veg.
Litter
Moss
Rock
Pave.
31 a
18
202 a
134a
6
0
68 a
110a
23 a
54a
Soil Total
70 a
101 a
400
400
8
0
50
34
1
0
17
28
6
14
18
25
100
101
"The spread in scores for these parameters between the two areas is indicated to be significant at 80
percent probability (Chi Square = 1.642 with one degree of freedom).
officinalis [L.] Pallas), and mountain big sagebrush (Artemisia tridentata var. paucif/ora Winward & Goodrich) (6 percent each). By weight, the seed mix at Rifle Canyon included:
crested wheatgrass, orchardgrass, and ladak alfalfa (20
percent each), and intermediate wheatgrass, smooth brome,
hard fescue, and yellow sweetclover (10 percent each). The
study site at Rifle Canyon provided a sharp contrast between burned and unburned areas.
Methods and Results
At the Rifle Canyon site, quantity of ground cover was
compared in 1996 (7 years post treatment) by recording
ground cover at 400 points along five belt lines 30.5 m (100
ft) long in each ofthe burned and seeded and unburned sites.
Results are shown in table 1. Frequency of plant species
were recorded in 100 quadrats of 50 by 50 cm placed along
the belt lines. Nested frequency was also determined in four
plot sizes of 5 by 5 cm, 25 by 25 cm, 25 by 50 cm, within the
50 by 50 cm quadrat which made up the fourth nested plot
size (U.s. Department of Agriculture, Forest Service 1993).
At the J arvies Canyon site, which is less than 3 miles away
from the Rifle Canyon site, the same study methods described above were applied at five and 10 growing seasons
postfire. Results are shown in table 2.
At the Rifle Canyon Site, dispersion of ground cover was
compared by line intercept measurements along the five
belts for a total intercept of 152 m (500 ft) in each of the
treated and untreated sites. Distance of intercept without
live plant or litter cover was recorded. Range of variability
for distance without live plant or litter cover was 0.3 to 2.7
m (1 to 9 ft) for the burned and seeded area and 0.9 to 21 m
(3 to 69 ft) for the mature pinyon-juniper stand. Mean
distance of intercept without live plant or litter cover was
0.82 m (2.7 ft) for the treated area and 5.4 m (17.6 ft) for the
untreated area.
Quadrat freq uency also indicates dispersion of plant cover.
Seven years after treatment at Rifle Canyon, 86 of the 100
quadrats (50 by 50 cm) contained perennial plants in the
treated area compared to 37 of 100 in the mature pinyonjuniper stand. At the Jarvies Canyon site, perennial plants
were found in 90 and 99 of the 100 quadrats 5 and 10 years
post treatment, respectively. Comparison of perennial plants
in nested plots of 25 by 25 cm also indicated dispersion of
cover. In the mature pinyon-juniper stand at Rifle Canyon
only 15 of100 plots had at least one perennial plant in them.
In the burned and seeded area 59 of 100 plots had at least one
perennial plant in them. At J arvies Canyon, 67 and 92 ofthe
318
100 nested plots of 25 by 25 cm had at least one perennial
plant in them at 5 and 10 years post treatment, respectively.
At the Rifle Canyon site, crown cover of pinyon andjuniper
was also determined by line intercept along the five belts. On
the untreated site, crown cover of pinyon was 20 percent, and
for juniper it was 19 percent for a combined value of 39
percent. On the treated area, crown cover was estimated by
measuring the intercept of dead crowns. This indicated
crown cover of 17 and 18 percent for pinyon and juniper,
respectively, for a combined value of 35 percent. Similar
crown cover for the two sites prior to the burn is indicated.
Crown cover of trees was not determined at the J arvies
Canyon site. However, density of skeletons indicated similar
or greater cover of pinyon-juniper prior to burning.
Essentially all the ground cover provided by live vegetation and litter in the untreated area was composed of basal
area of trees and needles of these trees that were confined
beneath the crowns of trees. Combined crown cover of pinyon
and juniper on the untreated site was 39 percent. Combined
ground cover of vegetation and litter was 34 percent. The
litter of pinyon and juniper was composed of needlelike or
scalelike leaves, cones, and broken twigs. The needlelike
leaves of Colorado pinyon are 1.5 to 5 cm long, and the
pistillate cones are ovoid and 2 to 5 cm long. The scalelike
mature leaves of Utah juniper are 1 to 3 mm long with
juvenile ones 2 to 8 mm long. The pistillate cones are
subglobose and 6 to 12 mm thick (Welsh and others 1993).
Ground cover in the burned and seeded area was composed of numerous fine stems comparatively closely spaced,
which served to anchor litter. Stem length of grasses and
forbs on the site varied from a few cm to over 1 m in length.
Herbaceous litter consisted of comparatively fine, long,
stems with branches or leaves that provided for a higher
Table 2-Comparison of ground cover at 5 and 10 years following
burning and seeding at the Jarvies Canyon site.
Litter Moss
Rock
Pave. Soil
Total
Year
Veg.
1991 (points)
1996 (points)
24 a
96 a
117a
184a
0
93 a
35 a
47
39
119*
45 a
400
400
1991 (percent)
1996 (percent)
6
24
29
46
0
0
23
9
12
10
30
11
100
100
"The spread in scores for these parameters between the 2 years is indicated
to be significant at 80 percent probability (Chi Square =1.642 with one degree of
freedom). The lower value for rock in 1996 is considered a function of plant and
litter cover spreading across exposed rock and not from rock being removed from
the site.
USDA Forest Service Proceedings RMRS-P-9. 1999
interlocking and lodging oflitter than on the untreated site.
This herbaceous litter was associated with course woody
debris of pinyon and juniper trees that had fallen since the
fire in addition to the basal area of the trees that remained
standing. As expected cheatgrass increased rapidly in the
burned area, and higher ground cover here was a function of
this species as well as the seeded species.
Discussion --------------------------------Exposed soil and small gravel fragments are easily displaced by the forces of water especially as gradients increase. Live and dead plant material and rock provide cover
that can protect soils from the forces of water. Ground cover
is the principle protection against both raindrop splash and
sheet erosion (Farmer 1995; Osborn 1955; Blackburn and
others 1986). Plant cover at or near the ground surface is
more effective than canopy cover for preventing erosion
(Siman ton and others 1991; Khan and others 1988) . Watters
and others (1996) found basal cover, average distance to
nearest perennial plant, and frequency of quadrats with no
rooted perennial plant showed strong relationships to a
subjective site stability rating for determining the point at
which accelerated erosion occurs.
Quality of ground cover is indicated by how well it is
anchored or how well it is able to stay in place under rain
drop splash and surface flow of water. Rooted vegetation has
greater ability to stay in place than detached litter. Dispersion of ground cover is important to quality of cover. Vegetation with many fine stems well dispersed provides the best
protection (Osborn 1955). This well dispersed, rooted vegetation also helps keep detached litter in place. Length and
roughness oflitter also contribute to stability oflitter cover.
Long pieces of flexible litter become interlocked more than
do short, ridged pieces. Litter of stems with branches or
leaves is more likely to interlock and lodge against live
vegetation or larger woody debris than is litter composed of
short, unbranched pieces.
The shape of the pistillate· cones of pinyon and juniper
(ovate to subglobose) greatly facilitate their movement down
slope by water and gravity. The staminate cones disintegrate in to small fragments that are easily moved by water
or wind. The pistillate cones were found in great numbers in
the drainage bottom below the Rifle Canyon study site. The
short needles of pinyon and juniper form a comparatively
incohesive duff beneath the trees that is held in place by the
base of the tree and where it is somew ha t protected by the
crowns of the trees. Where this litter is exposed to raindrop
slash, it seems unstable compared to the litter of the burned
site.
Comparisons of runoff and movement of sediment were
not made in this study. However, the conditions described
above are similar to those described by Farmer (1995) where
he found an average offi ve times more runoff and eight times
more sediment produced in a mature or old pinyon-juniper
stand than on a treated area. However, the treated area in
his study had been chained and seeded with debris left in
place. Much higher levels of woody debris can be expected in
that treatment than with burning. Less watershed protection can be expected following burning. Davis and Harper
(1990) found bare soil decreased from 47 percent before
USDA Forest Service Proceedings RMRS-P-9. 1999
treatment to 11 percent 3 years postchaining with debris left
in place. Slower increase for soil cover is indicated for
burning at Rifle Canyon where bare soil and pavement
totaled 39 percent in the untreated area and 24 percent 7
years post treatment in the burned and seeded area.
However, the increase in quantity, quality, and dispersion
of ground cover with burning and seeding at the Rifle
Canyon site indicates a strong trend toward soil stability.
Monitoring at the Jarvies Canyon site indicates recovery
will continue for up to 10 years, after which high values for
soil and watershed protection have been achieved.
At the Rifle Canyon site, ground cover provided by vegetation and litter was 34 percent in the untreated area. In the
treated area this cover was 58 percent 7 years post treatment. At the Jarvies Canyon site no comparison was made
with comparable treated and untreated sites. However,
between the fifth and 10th years postfire and seeding,
ground cover increased from 35 to 79 percent. This increase
of 44 percentage points is indicated by point data to be
significant (see table 2). The higher quadrat frequency and
nested frequency of perennial plants in the treated area also
indicates higher dispersion of cover of many fine stems that
are more closely spaced than found in the untreated area.
In the untreated site at Rifle Canyon, a relationship of
litter cover to crown cover oftrees is indicated by the similar
values of 34 percent litter cover and 39 percent for crown
cover of pinyon and juniper. This relationship is visibly
conspicuous at this site. In the mature pinyon-juniper stand,
little litter is deposited in the inters paces between trees
where it is poorly anchored and of low structural quality.
Comparatively rapid removal of what little litter is deposited in the interspaces is indicated by the barren nature of
the interspaces. Thus, the interspaces which make up over
60 percent of the surface are essentially devoid of plant and
Ii tter cover. A man tle of exposed gravel-sized rock fragments
(28 percent of cover) did provide a well dispersed cover in
these interspaces, which is indicated to be quite effective in
slowing erosion. However, this exposed rock cover is indicated to be a function of past erosion. In the high precipitation summer of 1997, rills were greatly expanded in spite of
the pavement and gravel cover on the untreated area. In the
treated area, rock as well as bare soil are being covered by
vegetation and litter where rills were not greatly expanded
in 1997.
Management Implications
Pinyon and juniper appear to have the capacity to dominate nearly all ecological sites within the thermal belt to
which they are confined. With long-term absence of disturbance, crown closure of these trees increases with a decrease
in understory plants. On some sites this is associated with
lower total ground cover, spotty dispersion of ground cover,
and lower quality of ground cover. On some sites these
conditions are conducive to greater erosion and sediment
delivery to drainages.
However, pinyon and juniper communities appear to be
self-sustaining in this condition. Strongly implied is a long
history of erosion and sediment delivery as a function of
pinyon-juniper dominance of some sites. In view of this
history, Gifford (1987) made a point that the pinyon-juniper
319
type has sustained itself on many diverse landscapes over
the past 5,000 years or more and where it has obviously been
designed to withstand at least 5,000 years of extreme hydrologic events. The concept of pinyon and juniper being selfsustaining on eroding surfaces is supported by their presence on many of the exposed, eroding geologic strata of Utah
that weather to badlands. This contributes to the concept of
a broad ecological amplitude for these species including
strata that are low in nutrients, repel water, and contain
gypsum and other chemicals that might inhibit growth.
Pinyon and juniper are also capable of dominating more
productive alluvial soils.
That pinyon and juniper are self-sustaining on nearly all
soils and geologic strata within their thermal belt including
eroding surfaces is a point ofthis paper. However, conditions
conducive to erosion and sediment yield are associated with
mature and old stands of pinyon and juniper on some areas.
These areas present an opportunity to reduce erosion by
reducing the presence of pinyon and juniper and increasing
the presence of plants with numerous fine stems that are
closely spaced that serves to increase the dispersion and
quality of litter.
The barren interspaces of the mature pinyon-juniper
stand at the Rifle Canyon site collaborate the views of West
and Van Pelt (1987), Everett (1987), and Bunting (1987)that
these trees contribute to the death of herbs and shrubs that
grow on these sites at earlier stages of succession, which
creates barren interspaces that are then exposed to the
forces of erosion as a function of pinyon-juniper dominance.
The general lack of understory species on the untreated site
is consistent with the view of Hironaka (1987) that the
simple mix of overstory and lack of understory in mature
stands makes classification based on climax unsatisfactory.
Langbein and Schumm (1958) reported maximum sediment yields occur on areas where annual precipitation is
between 25.4 cm (10 inches) and 35.5 cm (14 inches). Payne
(1980) considered the pinyon-juniper belt of the Intermountain Region to generally fall within this range. Ronco (1987)
noted precipitation in pinyon-juniper woodlands of the Great
Basin does not appear sufficient to adequately support both
trees and herbaceous vegetation. This is consistent with the
view of Arnold (1959) that pinyon-juniper woodlands produce more sediment than other woodlands. Low percent
ground cover and high rates of erosion might be expected to
be inherent in some mature and old pinyon-juniper stands.
This concept is strongly supported by the work of Farmer
(1995) where over 4 years he found an average of five times
more runoff and eight times more sediment associated with
a mature stand of pinyon-juniper than in an adjacent area
that had been chained and seeded with litter left in place.
Data from the Rifle Canyon and Jarvies Canyon sites
indicate development of potential ground cover will take up
to 10 years or longer following fire. For 1 or 2 years, burning
can be expected to greatly expose the soil surface to the forces
of erosion compared to chaining where debris is left in place.
However, pinyon-juniper communities are indicated to be
self-sustaining under high rates of erosion. Thus short-term
exposure to erosion is indicated to be well within the range
of natural variability for these sites.
The a bili ty of pinyon and j uni per to occu py, dominate, and
to be self-sustaining on eroding surfaces indicates the preservation of many mature and old stands of these trees will be
320
associated with low watershed values. Perhaps the super
dominance of plants with broad ecological amplitudes are
not always appropriate indicators ofa broad range of values
that might be achieved from a landscape. Pinyon andjuniper
are capable of sustaining themselves on an eroding soil
regime to which they are apparent contributors. Treatments
like those at Rifle Canyon and Jarvies Canyon offer an
opportunity for communities that indicate a soil building
regime.
Visual and structural values for mature and old pinyonjuniper stands for some wildlife species are important considerations. The point ofthis paper is not to justify wholesale
elimination of pinyon-juniper from large areas. It is to
recognize a range of values and opportunities within the
pinyon-juniper thermal belt. The challenge is to obtain site
specific data that will facilitate choosing appropriate sites to
manage for a diversity of values (Goodrich, these proceedings).
Where watershed protection and long-term soil productivity are values to be emphasized, early seral communities are
indicated to be of higher value than are mature orold stands
where canopy cover of these trees has reached 40 percent.
Observations in other stands ofthe Dutch John area indicate
high watershed values can be maintained with crown cover
of pinyon and juniper of up to 10 to 15 percent (Huber and
others, these proceedings).
These features strongly indicate that choice of sites to be
managed for mature and old stands should include areas of
more gentle gradient and areas of high percent large rock
where erosion hazards are comparatively low. Depth and
duration of snow cover are comparatively low on the steep
gradients of southerly exposure at the Rifle Canyon and
Jarvies Canyon sites. This indicates high value ofthese sites
for wintering wild ungulates for which early and mid seral
communities are of higher forage value than late seral or old
stands. This concept is supported by a study in central Utah
where Davis and Harper (1990) found lower mortality of
deer where their habitat included early seral communities
compared to that of large stands of mature juniper-pinyon
without openings of early seral communities.
In the case of this study, in an area where nearly 8,100 ha
(20,000 acres) within the pinyon-juniper thermal belt was at
or trending toward mature and old pinyon-juniper stands,
the treatment seems appropriate for diversity of habitats.
Reduced rates of erosion could be an additional benefit
where the slopes at Rifle Canyon and J arvies Canyon are
only about 3.2 km (2 miles) above Flaming Gorge Reservoir.
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