Restoration of the Moss (Musci) Component
of the Microbiotic Crust to the Western
Snake River Plain, Idaho: Inoculation of
Fragmented Arid-Land Moss Tissue to Three
Rangeland Soil Surface Treatments
Paul R. Jones
Marcia Wicklow-Howard
Mike Pellant
Abstract—Microbiotic soil crusts occupy an invaluable position in
arid and semiarid ecosystems. They are displaced by the conversion
of native vegetation to annual grasslands. Moss inoculated to
various treatments or disturbances could be an essential step in
restoration of microbiotic crusts. Field experiments were conducted
to determine if the fragmented tissue of three moss species would
exhibit vegetative growth after inoculation to three soil surface
treatments. Significant treatment differences were noted in litter
and annual forb frequency. Moss growth frequency, although low,
exhibited interesting patterns.
Microbiotic soil crusts are assemblages of cyanobacteria,
bacteria, eukaryotic algae, fungi, lichens, and mosses (St.
Clair and Johansen 1993). They are found throughout the
Western United States and are best represented in the arid
steppes of the Colorado Plateau, Great Basin, and Columbia
Plateau (Johansen 1993). Additionally, they are found in
other arid regions of the world such as Australia (Eldridge
and Greene 1994; Eldridge and Tozer 1996; Eldridge 1996)
and the Mediterranean (Martínez-Sánchez and others 1994).
The organisms that comprise microbiotic crusts of the
Western United States vary regionally. For example, on
sandy soils of Utah canyonlands the cyanobacterium Microcoleus vaginatus (Vauch.) Gom. is the predominate organism (Belnap and Gardner 1993). Lichens are predominant in
the Great Basin (St. Clair and others 1993) and are well
represented in microbiotic crusts of southern Idaho
(Kaltenecker and Wicklow-Howard 1994; Rosentreter 1986).
Bryophytes, such as mosses, are also found in microbiotic
crusts (Kaltenecker and Wicklow-Howard 1994; Rosentreter
1986) and tend to dominate in areas that receive a majority
of the annual precipitation during a cool-season (Rincon and
Grime 1989).
In: McArthur, E. Durant; Ostler, W. Kent; Wambolt, Carl L., comps. 1999.
Proceedings: shrubland ecotones; 1998 August 12–14; Ephraim, UT. Proc.
RMRS-P-11. Ogden, UT: U.S. Department of Agriculture, Forest Service,
Rocky Mountain Research Station.
Paul R. Jones, Graduate Research Assistant, and Marcia Wicklow-Howard,
Professor, are from Boise State University, Biology Department, Boise, ID
83706. Mike Pellent is Rangeland Ecologist, U. S. Department of the Interior,
Bureau of Land Management, Idaho State Office, Boise, ID 83709.
USDA Forest Service Proceedings RMRS-P-11. 1999
Research indicates that microbiotic crusts serve several
roles important to vascular plant establishment in arid and
semiarid rangeland ecosystems, including stabilization of
the soil surface (Williams, and others 1995a,b; Brotherson
and Rushforth 1983) and influence of soil moisture
(Brotherson and Rushforth 1983) and nutrient relationships
(Belnap and Harper 1994; Beymer and Klopatek 1991;
Evans and Ehleringer 1993). St. Clair and others (1984)
observed a trend of higher seedling establishment among
seeded graminoids (Agropyron elongatum = Elymus elongatus
[Host] Runem., E. cinereus Scribn. and Merr., and E. junceus
Fisch.) on soils with intact microbiotic crust. Common constituents of the microbiotic crust, short mosses, form tight
mats (Kaltnecker 1997) that may provide a physical barrier
to cheatgrass (Bromus tectorum L.) establishment (Jaques
1984; Larsen 1995).
Cheatgrass is a cool-weather, exotic annual grass that has
successfully invaded the shrub steppe of Idaho. It produces
a large amount of litter and when it is widespread provides
a contiguous source of fuel prone to violent wildfires that
destroy existing native vegetation and associated microbiotic crust (Peters and Bunting 1994; Whisenant 1995).
Considering the scope of the invasion of cheatgrass and
exotic annual plant species large expanses of the shrub
steppe habitat is threatened with extirpation. Destruction of
the native vegetation to any degree results in an opening for
invasive annual flora. Small patches and vast expanses of
the complex native ecosystem of the western Snake River
Plain (SRP) are converted to simplistic annual grasslands.
Annual grasslands lack native vertebrates and invertebrates typical of the native ecosystem. Additionally, the
microbiota (microbiotic crust and soil organisms) involved in
the operation of the system (energy flow, water cycling, and
nutrient balance) are lost (Billings 1994).
The main goal of this research is to determine if it is
possible to restore the moss component of microbiotic crust
to a site devoid of perennial mosses and composed of exotic
annual grasses. In order to do this the fragmented gametophytic thalli of three arid-land moss species (Bryum
argenteum Hedw., Ceratodon purpureus [Hedw.] Brid., and
Tortula ruralis [Hedw.] Gaertn., Meyer and Scherb.) were
inoculated to three soil surface treatment plots.
283
Methods _______________________
Treatment Plot Location
Three treatment plot sites are positioned on an approximate north-south line across the western SRP. This area is
located in what is characterized as the sagebrush steppe
vegetation zone of the northern intermountain region of the
Western United States (West 1988). Site number one is
located at Mountain Home Air Force Base (MHAFB). Treatment site number two is located adjacent to Interstate 84
about 15 air km northwest of Mountain Home, Idaho. This
site was once used to demonstrate rangeland rehabilitation
machinery and technique (M. Pellant, personal conversation). The third site is located on a portion of the western SRP
south of the Snake River. This site is east of the Bruneau
River, within the Exclusive Use Area (EUA) of Saylor Creek
Air Force Range (SCR), about 22 air km southeast of Bruneau,
Idaho (fig. 1).
Statistical Design and Treatments
The experiment utilized a split-plot design with site location as a blocking factor (fig. 1). The main plot factor was soil
surface treatment and the subplot factor was moss fragment
inoculation. Soil surface treatments included burning, her®
bicide (Oust ) application, and tilling. These treatments
were chosen because of their similarity to conditions likely
associated with large-scale rangeland rehabilitation efforts
or rangeland disturbance. Treatments were performed on a
schedule consistent with natural conditions. Herbicide application took place before the final spring of 1997 (table 1),
allowing the pre-emergent herbicide to contact seeds and
florets at the surface. Tilling took place before the soil had
completely dried and buried some of the existing litter and
living plants. Back burning took place when cheatgrass had
reached maturity in an effort to eliminate litter and destroy
current seed crop. These treatments were replicated three
times and randomly applied to nine 5 x 8 m plots at each site.
®
Oust was applied using a backpack, hand-pressurized sprayer
with a 1 m wide hand-held boom. Herbicide was applied at a
rate equivalent to 1 oz acre–1 (70 g hectare–1). Plots were tilled
with a large rear-tine rototiller, and 2 m wide buffer strips
were also tilled around the nine plots to act as fire break.
Each treatment plot was halved and randomly chosen for
inoculation with equal amounts of fragmented tissue of
three moss species. The moss species used for the experiment were chosen because they could be readily collected in
the Boise area. Additionally, they represent morphological
types, short and tall mosses, found comprising microbiotic
crusts associated with native and seeded vegetation in the
area (Kaltenecker 1997). Based on the success of growth
cabinet experiments, an equal mass of moss per unit area
was maintained for the field experiment, that is, 3.0 x 10–4g
–2
–2
moss tissue cm or 19.6 g moss tissue 20 m . Subplots were
divided into eight 1 x 2.5 m inoculation strips to get consistent subplot coverage with moss fragments. Each subplot
was inoculated a strip at a time by pushing the contents of
prepackaged moss tissue through a No. 100 (149 μm) standard soil sieve. The soil surface was moistened with demineralized water before and after inoculation to help fragments adhere to the soil surface. Cardboard wind walls (0.5 m
tall) with the dimensions of the inoculation strips were
employed when wind became more than light air (>5 km
–1
hr ). Inoculation was halted when wind became more than
a gentle breeze (>13 km hr–1).
Sampling Protocol and Statistical
Analysis
Plots were sampled 6 months after subplot inoculation
(table 1). Sampling was accomplished by setting three 4 m
long transects at 1.25 m, 2.5 m, and 3.75 m perpendicular to
and along the 5 m base of each treatment plot. At 1 m, 2 m,
and 3 m of each transect a point frame was randomly placed
on one side or the other of the measuring tape. The point
frame (75 x 30 cm) was read at nine placements per treatment combination. The vegetation present at the soil surface
was recorded (table 2) at each of seventy points per frame
(total n = 34,020).
Data were analyzed using the general linear model procedure for analysis of variance (ANOVA) and Fisher’s exact
test (SAS, 1996).
Results and Discussion __________
Litter, cheatgrass, and bare soil were the variables (fig. 2)
distributed appropriately for ANOVA. Of these, litter reflected a reasonably significant (p = 0.04) treatment difference, based on p <0.05. Litter was most frequent on the
herbicided plots. It was reduced by burning and showed the
greatest reduction on the tilled plots. The removal of litter
and exposure of the soil surface is desirable to allow moss
fragments to reach mineral soil. Leaving some litter to trap
fragments and shelter gametophytes may also be important
to the establishment of mosses.
Burning reduced cheatgrass nearly as effectively as the
herbicide. Effect coded data for annual forbs indicated
a reduction in the relative frequency of this variable in
the herbicided plots using Fisher’s exact test, p = 0.0001.
Figure 1—Schematic diagram of treatment plot
position.
284
USDA Forest Service Proceedings RMRS-P-11. 1999
Table 1—Time table (month-day) for treatment application, 1997.
Treatment
Base
Burning
Herbicide application
Rototilling
Inoculation
Lockman
July 8
May 21
June 2
November 13 and 18
Table 2—Variables encountered in field experiment and count.
Variable
Relative frequency
Percent
Litter (annual vascular plant detritus)
60
Bromus tectorum L.
23
Bare soil
12
Annual forbs
2
Rocks
1
Vascular perennial graminoids and forbs
1
0.2
Pre-existing moss (Pterygoneurum ovatum [Hedw.] Dix.)
Woody litter
0.2
Moss protonema
0.2
Charcoal fragments
0.2
Inoculated moss
0.05
Lichen
0.02
Moss recovery or initiation was low over the entire experiment (table 2, fig. 3). Since gametophytes and protonema
were occasionally noted outside the point frame placements
under sampling of the moss variables is suspected. However,
some interesting patterns are notable in these relative
frequencies. The preexisting moss Pterygoneurum ovatum
(Hedw.) Dix. responded to back burn as did moss protonema.
This growth may be due to nutrient release and litter
reduction.
Range
July 9
May 21
June 2
November 15, 21, and 22
July 8
May 20
June 3
November 12
Conclusions ____________________
Weed control is of primary concern and usually the initial
step in restoration efforts (Youtie 1997). Fire, herbicide
application, and tilling temporarily reduced the massive
potential of the annual grassland seedbank in these plots.
Weed control utilizing the treatments may yield positive
results in the restoration of similar sites.
Using fire to open up the soil surface and reduce water
interception by litter and standing biomass could be useful
restoration strategy in annual grasslands with patches of P.
ovatum. This moss species is desirable because of its ability
to quickly spread into open soil and trap fine soil particles.
Low frequency of moss establishment from inoculated
fragments may have been due to a variety of factors. Six
months may have been too little time to detect any appreciable growth from the fragments of these species. Regardless of precautions to prevent loss of fragments from the
plots, it is possible some deflation of fragments may have
occurred. Variable precipitation patterns may have also
influenced the growth of these species from fragmented
tissue.
Future experimentation with inoculation methodology
should be conducted. Investigation into methods that would
increase the residence time of the fragments at the soil
surface and expedite their delivery would be useful. Information about the growth response of larger fragments and
various application times would also be of value.
80
0.5
70
0.4
Percent
Percent
60
50
40
0.3
0.2
30
20
0.1
10
0
Annual forbs
Bare soil
Burned
Cheatgrass
Herbicided
Figure 2—Relative frequency (%) of ANOVA appropriate variables and vascular annual forbs per
treatment (n = 11,340).
USDA Forest Service Proceedings RMRS-P-11. 1999
Litter
Tilled
0.0
INOC
PTOV
Burned
Herbicided
PROT
Tilled
Figure 3—The relative frequency of the moss categories: Inoculated mosses (INOC), moss protonema
(PROT), and pre-existing moss (PTOV).
285
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USDA Forest Service Proceedings RMRS-P-11. 1999