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Planting Giant Sacaton: Initial Results at
Cienega Creek Natural Preserve
Julia E. Fonseca 1 and Ronald L. Tiller2 · 3
INTRODUCTION
Giant Sacaton (Sporobo/us wrightil) is a bushy, perennial grass that once was common along
the floodplains of major river systems in southeastern Arizona (Humphrey 1958). The type locality
for the species, as described in 1882 by C. G. Pringle (Hitchcock, 1971), today is found within the
Cienega Creek National Preserve, within an abandoned farm field that is now the site of a
revegetation project.
The field was selected for revegetation to improve wildlife habitat along an otherwise extensive
riparian corridor. The site is being rehabilitated with funding from the U.S. Fish and Wildlife Service
s Partners for Wildlife Program and the Arizona Game and Fish Department's Stewardship Program.
Sacaton was selected as one of the species to plant because it was present at the site in 1972
(Lacey et al., 1975), and because the project team hoped that it could be established without
irrigation. Only a few isolated sacaton plants have established in the 40-acre (16.2 ha) field since
it was cleared in 1974.
SITE DESCRIPTION
The field is located in Township 16 South, Range 17 East, Section 35, at an elevation of
approximately 3550 feet above mean sea level. Soils at the site are predominantly silt loams, with
gravelly loams present at the southern margin of the field. Slopes are generally from 0 to 3%.
Annual rainfall is approximately 14 inches.
The site's mesquite woodland was removed in 1974 using chainsaws and bulldozers; a root
plow was used to remove stumps (Neal Hanna, personal communication). For the first several
years, alfalfa was grown under irrigation. Bermuda grass (Cynodon dactylon) was then planted for
livestock forage. Bermuda grass is still the dominant perennial plant at the site. The site was
grazed by cattle until its acquisition by Pima County Flood Control District in 1988. The field was
grazed by five horses from 1989 to May 1996.
METHODS
Archeological trenching at the site revealed the presence of buried pithouses and other features
below a 1-foot (0.3 m) deep plow zone. Because the State Historic Preservation Office prohibits
planting deep-rooted trees or shrubs above archeological sites, sacaton was one of the few plants
suitable for these sensitive areas.
Sacaton seeds were collected in the Preserve by Arizona Native Plant Society in October 1995.
1
2
3
Pima County Flood Control District, Tucson AZ.
Center for Environmental Studies, Arizona State University, Tempe AZ.
Presented as a poster.
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,',
:.;.
The collecting site was located approximately one mile south of the field, along an ephemeral reach
of Cienega Creek, where sacaton grows on infrequently flooded terraces with velvet mesquite
(Prosopis velutina), desert willow (Chilopsis linearis), and bush muhly (Muhlenbergia porten}.
The sacaton seeds were germinated by a local (Coronado Heights) nursery in April and June
1996 in flats in a shaded outdoor structure. One to three seedlings were transplanted into 4-inch
and 14-inch deep containers. Half of plants were grown in the 14-inch by 4-inch container size.
USFWS funded the seedlings at a cost of $0.80 and $1.85 per container, respectively.
A mid-August planting date was chosen to take advantage of higher humidity and soil moisture
generally present during the summer monsoonal season. One week prior to planting, inspection of
the soil profile demonstrated that rain had moistened the entire soil profile to a depth of 14 inches
(Figure 1). On the day of planting, the top six inches of soil appeared dry in many of the planting
sites. An automated rain gauge located approximately one mile from the site was used to monitor
rainfall.
On August 10, 1996, 45 volunteers planted approximately 670 seedlings of sacaton over an
area of approximately three acres. Groups represented at the event include the Audubon Explorers
Post, Pima County Adult Probation, Southwest Center for Biodiversity and Arizona Native Plant
Society. Two one-person gas-powered soil augers with 6-inch bits were used to drill holes for the
deeper containers, otherwise seedlings were transplanted into holes dug by hand. All plants were
planted and hand-watered in four hours.
On August 11, a crew of 10 volunteers watered the seedlings again by hand and planted
several additional remaining containers. Because of slow infiltration rates, few plants received more
than three liters of water during each watering. Pinflags marking clusters of plants and small,
hand-dug basins helped to identify seedling locations.
Volunteers were encouraged to plant seedlings in clusters, with each plant no closer than four
feet. The objective of clustering was to speed the creation of patches of the dense, upright sacaton
for wildlife purposes. The clustering also helped locate individuals for subsequent watering.
Volunteers were encouraged to plant the seedlings in natural swales in the belief that survival might
be higher in the swales, but other, more xeric microsites were also chosen.
As part of a larger research effort funded by the Arizona Water Protection Fund, data on a
number of vegetative characteristics of the transplants is being collected by the junior author. The
goal of the monitoring effort is to facilitate an ongoing study of the ecology and recovery potential of
Sporobolus wrightii to abandoned agricultural fields in southern Arizona. Other sites being monitored
are along the San Pedro River.
Eighty-six transplants were marked for monthly monitoring, 39 of which are the smaller
container size. Characteristics being measured include basal area, height of tallest leaf,
phenological stage and development, topographic position (swale, alluvial fan, or level ground), and
percentage of vegetative cover within a 1 112 foot (0.5 m) radius.
PRELIMINARY RESULTS
Approximately 0.3 inches of rain fell on August 11. By September 11, a total of 3.5 inches of
rain had been received (Figure 1).
By the end of December, only two of the 86 individuals had died. Both of these were from small
pots (n=39). Both of these mortalities were evident by late October. With this low mortality rate,
the influence of topography on survival is not evident. Thirty percent of the individuals grown from
14-inch containers flowered since planting. Flowering is typically preceded by development of
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several new shoots. Nearly all of the plants had senesced by late December. Plants in the swales
appear to senesce more slowly than plants in other topographic positions. Larger plants
maintained higher basal diameters than small plants. Although no statistical tests have been
performed yet, plants growing in gravelly soils of the alluvial slopes appear to have grown more than
individuals located in swales or on level ground.
REFERENCES
Hitchcock, A. S. 1991. Page 966 in Manual of the Grasses of the United States (Vol. 2). Dover
Publications, New York.
Humphrey, R. R 1958. The desert grassland. Botanical Review 24: 193-253.
Lacey, J. R., P. 0. Ogden, and K. E. Foster 1975. Southern Arizona riparian habitat: spatial
distribution and analysis. Office of Arid Lands Studies Bull. 8 .
.•.
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PRECIPITATION AT PANTANO JUNGLE SACATON PLANTING SITE
Data Collected: 07130196through 10/04196
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3.911
3.811
3.70
3.811
3.50
3.40
3.311
3.20
3.111
3.1111
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11.
2.10
2.70
2.10
2.50
2.40
2.311
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2.111
2.00
Ull
1.811
1.70
uo
1.50
1.40
1.311
1.20
1.10
1.00
·.-.·1
uo
11.811
0.70
0.811
0.50
11.40
0.311
0.20
0.10
0.00
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Cumulative Prac:ipitatlon
-
Daily Prac:ipitation
Figure 1.
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