This file was created by scanning the printed publication.
Errors identified by the software have been corrected;
however, some errors may remain.
AN INTERNATIONAL APPROACH FOR
SELECTING SEEDING SITES: A CASE
STUDY
JerryR. Cox
Fernando A. lbarra-F
Martha H. Martin-R
ABSTRACT
would persist under a wide variety of climatic and edaphic
conditions. Established populations, however, spread to
nonplanted sites only at a few locations in south Texas and
northwestern Mexico. At other seeded sites, plant populations have either persisted but not spread or disappeared.
Because T-4464 was originally collected in north-central
Kenya, and spreads most frequently in southern Texas and
northwestern Mexico, we believe climatic and edaphic conditions around the original collection site and where the
plant spreads in North America to be more similar than
where the plant fails to spread or dies. If this hypothesis is
true, then climatic and edaphic information from southern
Texas, northwestern Mexico, and north-central Kenya can
be used to select high-potential buffelgrass seeding sites in
the Northern and Southern Hemispheres. Information that
defines the relationship among climate and soils, and plant
germination, emergence, persistence, and reproduction will
reduce the failures associated with rangeland revegetation
attempts.
Climatic and edaphic data were collected at 210 buffelgrass (Cenchrus ciliaris) seeding sites in North America
and at 30 sites in Kenya. Site selection in North America
was based on three survival categories: (1) where the grass
persisted and spread outside the seeding site; (2) where the
grass persisted but did not spread; and (3) where the grass
persisted for 10 years before disappearing. Sites in Kenya
were near the original seed collection site. Of the climatic
and edaphic characteristics evaluated, only organic carbon
and total nitrogen can be used to select sites where buffelgrass can be expected to establish, persist, and spread. This
approach may aid revegetation specialists in the Western
United States who wish to reestablish native plants.
INTRODUCTION
Buffelgrass (Cenchrus ciliaris), a perennial, warm-season
bunchgrass is native to Africa, Asia, and the Middle East
{Bogdan 1961; Holt 1985; Khan and Zarif 1982). The species predominates where surface soils are sandy and annual
precipitation varies from 200 to 1,200 mm (Cox and others
1988).
Buffelgrass seed collected in the Turkana Desert, northcentral Kenya, was sown and evaluated for seedling establishment, forage production, and long-term persistence in
Texas during the 1940's (Holt 1985). Seedlings from seed
sown in summer were easily established and mature plants
survived winter in south Texas. In 1949 the Soil Conservation Service informally released T-4464 buffelgrass.
T-4464 plants initially persisted at most planting sites in
south Texas, and between 1949 and 1985 the grass was established on over 4 million ha (Cox and others 1988). Seed
were transported south to Mexico and successfully established along the eastern and western coasts (Agostini and
others 1981; Cota and Johnson 1975; Hanselka 1985; Molina
and others 1976). Land managers assumed that the plant
STUDY SITES
Two hundred and ten buffelgrass seeding sites were selected subjectively in North America, and 30 sites were selected where T-4464 seed were originally collected in northcentral Kenya. In southern Texas and Mexico soils were
collected at: {1) 60 sites where the grass persisted and spread
outside the seeding site; {2) 100 sites where the grass persisted but failed to spread; and (3) 50 sites where the grass
persisted for 10 years or more before disappearing.
Site elevations vary from 20 to 700 min North America,
and from 15 to 580 m in Kenya. Slopes range from 2 to
10 percent. Precipitation ranges from 200 to 1,200 mm in
North America, and is bimodally distributed in either spring
and summer or winter and summer. In Kenya precipitation
ranges from 200 to 400 mm, and is bimodally distributed
in early and late summer.
From more than 300 weather stations we selected: {1) 25
in southern Texas and eastern Mexico; {2) 10 in southern
Mexico; and (3) 17 in western Mexico {Climatography of the
United States 1985; Climatography of Mexico 1982). Seven
stations were selected in north-central Kenya {Agroclimatological Data for Mrica 1984). Station selection was based
on: {1) records in excess of 20 years; (2) less than 10 km from
a seeding or collection site; and {3) elevational similarities
between weather stations and either seeding or collection
sites.
Paper presented at the Symposium on Ecology, Management, and Restoration oflntermountain Annual Rangelands, Boise, ID, May 18-22, 1992.
Jerry R. Cox is Resident Director of Research, Texas A&M University,
Vernon, TX 76384. When the paper was presented Cox was Range Scientist, USDA Agricultural Research Service, Forage and Range Research
Laboratory, Utah State University, Logan, UT 84322-6300; Fernando A
lbarra-F and Martha H. Martin-R are Graduate Students in the Range
Science Department, Utah State University, Logan, UT 84322-5230.
291
WEATHER PARAMETERS
Weather categories were (1) precipitation, and (2) maximum and (3) minimum temperatures. Site parameters were
summed by month and divided by record length.
eE
200
-150
c
SOIL SAMPLING
0
Soils were collected to 10-cm depths near the crown of
three buffelgrass plants or in open areas where buffelgrass
plants persisted 10 or more years before disappearing. Composited samples (three) were air-dried, passed through a
2-mm sieve, and thoroughly mixed. Duplicate subsamples
from each composite were analyzed for particle-size distribution (Day 1950), pH (saturated paste), electrical conductivity (EC) of the saturated extract, and cation exchange capacity (CEC) (U.S. Salinity Laboratory Staff 1954), ammonium
acetate-soluble cations including calcium (Ca), potassium
(K), sodium (Na), and magnesium (Mg), total nitrogen (TN),
organic carbon (OC) (Jackson 1958), and available phosphorus (P) (Olsen and Sommers1982).
EXPERIMENTAL DESIGN
Because site selection is not random, and sites within
treatments were unequal, the treatment variances are
compared. For each soil component a Hartley test was
used to determine differences (P :::; 0.05) among treatment
variances.
RESULTS AND DISCUSSION
Weather Parameters
Total mean annual precipitation where buffelgrass spreads
= 440 mm) is approximately 35 percent less than where
the species persists but does not spread (.f = 675 mm), and
45 percent less than where the species dies (fig. 1). Adult
buffelgrass plants may be more drought tolerant than anticipated since precipitation in northeastern Kenya (f = 300 mm)
is about 30 percent less than that recorded where the species spreads in North America.
In North America precipitation amounts (fig. 1) and temperature extremes (figs. 2 and 3) are variable in summer,
but where buffelgrass spreads summer precipitation ranges
from 330 to 550 mm. In contrast, the plant persists but does
not spread or dies when growing season precipitation ranges
from 600 to 1,200 mm. When summer precipitation exceeds
600 mm, spittlebug (Aeneolamia albofasciata) populations
rise, and nymphs and adults extract fluids from buffelgrass
leaves and shoots (Flores and Velazco 1974). When spittlebug populations exceed 100 per plant, buffelgrass plants
may die (Cazares and others 1985).
Fall and winter precipitation amounts are similar at
Mrican and North American sites (fig. 1), but temperature
extremes differ within and between continents (figs. 2 and
3). In southern Mexico winter temperatures are mild and
buffelgrass seed germinate when soil moisture is available,
but seedlings almost always die because winter rains occur
infrequently (Molina and others 1976; Oquendo and others
1983). Along the coastal areas of southern Texas and eastem Mexico winter temperatures are similar to southern
-
i
·"()a 1oo
!
D.
50
Spring
Summer
Fall
Winter
Seasons
Figure 1-The variation in mean monthly precipitation
distribution at buffelgrass seeding sites in North
America and where seed were originally collected in
Africa. Lines represent sites where the plant persists
and spreads from a seeding (•), persists but does not
spread from a seeding (•), dies (o), and where seed
were originally collected in north-central Kenya (A.).
Mexico in 1 of 5 years, and buffelgrass seed may germinate
in winter. In most years, however, summer-produced seed
survive until the following summer. At sites where buffelgrass spreads, cool maximum winter temperatures limit germination when soils are moist. ·Under cool-dry and cool-wet
conditions buffelgrass seed remain viable for 3 or more years
(Winkworth 1963).
Mean spring precipitation amounts where buffelgrass persists but does not spread or dies are 1.5 to 2.5 times greater
(f
292
-00
!
45
40
::I
35
B.
30
!
E
~ 25
E
20
E
::I
·;c
ftl
:&
15
10
Spring
Summer
Fall
Winter
Seasons
Figure 2-The variation in mean monthly maximum
temperatures at buffelgrass seeding sites in North
America and where seed were originally collected in
Africa. Lines represent sites where the plant persists
and spreads from a seeding (•), persists but does not
spread from a seeding (•), dies (o), and where seed
were originally collected in north-central Kenya (A.).
--e
00
-&
:::s
30
Soil Physical and Chemical Properties
25
Where buft'elgrass spreads, soils are generally coarse textured and low in total nitrogen and organic carbon (table 1).
At inland sites in southern Texas and northwestern Mexico,
buft'elgrass was found on alluvial fans. At these sites, geologically young acidic granitic soils developing at higher elevations were deposited by water over geologically old alkaline sedimentary soils at lower elevations (Hausenbuiller
1978; Hendricks 1985). Geologically young granitic soils
are usually acid if they have undergone little leaching and
weathering (Birkeland 1974).
When buffelgrass either persists but does not spread or
dies, the combined fine soil particles (clay plus silt) usually
exceed 50 percent, and total nitrogen and organic carbon are
2 to 3 times greater than where the plant spreads (table 1).
Under high-precipitation regimes, water leaches exchangeable cations beneath the rooting zone, and acidity increases
when hydrogen and aluminum ions accumulate (Brady
1974). This process does not occur at buffelgrass seeding
sites in southern Mexico because a hardpan limits downward nutrient movement (Mac Vicar and others 1977).
However, seasonal flooding saturates these soils, and poor
soil aeration is known to limit buffelgrass growth and persistence (Humphreys 1967).
Of the measured edaphic properties, only total nitrogen
and organic carbon variances differed (P S 0.05) among treatments (table 1). Total nitrogen and organic carbon quantities were least where the species spread, intermediate
where the species persisted but did not spread, and greatest where the species died. Under moist tropical conditions
bacterial, fungal, and nematode populations in soils supporting buffelgrass are 10 to 50 times greater than in arid soils
(Khan and Zarif 1982; Nada 1985; Rees 1972; Van den Berg
1985). As buffelgrass stands disappear at tropical seeding
sites they are replaced by deep-rooted bunchgrasses that
require additional water and nutrients (Winkworth 1963).
North-central Kenya soils are more coarse and in our
opinion less fertile than those where the species has been
20
t!
E
~
E
:::s
E
·c:
15
10
5
i
0
Spring
Summer
Fall
Winter
Seasons
Figure 3-The variation in mean monthly minimum temperatures at buffefgrass seeding sites
in North America and where seed were originally
collected in Africa. Lines represent sites where
the plant persists and spreads from a seeding
(•), persists but does not spread from a seeding
(•). dies (o), and where seed were originally collected in north-central Kenya (a).
than where the species persists and spreads (fig. 1). Abundant spring rains along the Texas and eastern and southern
Mexico coast enhance the production of established buffelgrass stands, and forage quality and quantity exceeds that
of existing perennial grasses (Hanselka 1985; Molina and
others 1976). However, seedlings from seed germinating in
spring usually die during the midsummer drought (Oquendo
and others 1983). Spring precipjtation occurs less frequently where buffelgrass spreads at inland sites in southern
Texas (Crystal City to Laredo) and in northwestern Mexico.
Table 1-Means and standard deviations for particle-size distribution and selected chemical properties at sites where buffelgrass either spreads,
does not spread, or dies at planting sites in south Texas and Mexico, and where the seed of the plant was originally collected in northcentral Kenya. An asterisk (*) indicates a significant difference (P s 0.05) among variances in the three survival categories
Property
Sand(%)
Silt(%)
Clay(%)
Silt + Clay (%)
pH
EC (ds m-1)
TN(%)
OC(%)
P (mg kg-1)
CEC (cmol kg-1)
Na (cmol kg-1)
K (cmol kg-1)
Ca (cmol kg-1)
Mg (cmol kg-1)
Persists
and spreads
61.1 ± 20.2
17.5 ± 10.8
21.5 ± 11.6
39.0 ± 18.7
7.8 ±
.5
.3 ±
.2
.1 ±
.1
.9± .7
10.6 ± 11.9
22.5 ± 13.4
.4± .6
1.1 ±
.7
35.9 ± 26.5
1.9 ± 1.5
Survival categories
Persists
but does not
spread
44.9 ± 24.6
24.1 ± 13.2
31.0 ± 15.3
55.1 ± 24.3
7.6 ±
.6
.1
.3 ±
.3 ± .2
2.6 ± 2.9
12.9 ± 12.7
38.1 ± 24.4
.4± .4
1.9 ± 1.3
42.0 ± 23.0
3.2 ± 2.2
293
Dies
35.3 ± 15.4
32.3 ± 7.2
32.4 ± 11.2
64.7 ± 16.2
7.5± .4
.1
.3 ±
.3
.5 ±
4.4 ± 3.6
10.0 ± 22.3
61.8 ± 24.9
.4± .2
1.8 ±
.9
47.8 ± 16.6
3.7 ± 2.5
Hartley
test
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
NS
Kenya
82.0 ±14.8
11.9 ± 9.2
6.1 ± 6.1
18.0 ±14.8
8.1 ± .5
.2 ± .1
.1 ± .1
.3 ± .2
17.2 ± 9.2
15.6 ±13.7
.2 ± .2
1.0 ± .9
12.4 ±13.5
2.1 ± 1.6
seeded in North America (table 1). Nevertheless, soils at
sites where the species spreads are generally equivalent
to those in Kenya, with the exception of phosphorus.
CONCLUSIONS
For more than 100 years revegetation specialists have
tried to artificially improve western rangelands (Cox and
others 1988). The procedures most widely used were to:
(1) chemically or mechanically reduce competition; (2) prepare a seedbed; (3) plant seeds of as many species, accessions, or cultivars as possible; and (4) pray for rain. In
about one of every 10 attempts the planting was a success,
but it was not possible to predict future planting success
because plant establishment and persistence were not correlated with site climatic and edaphic conditions.
To determine the importance of climate and soil on longterm buffelgrass persistence we classified 210 buffelgrass
seeding sites in three survival categories. Our evaluations
indicate that a planting success (persists and spreads) or
planting failure (dies) can be predicted with measurements
of soil organic carbon and total nitrogen. High variability
in our second survival category (persists but does not
spread) occurs because we were unable to assess long-term
management impact. For example, if grazing management
was altered or implemented, sites in the second survival
category might be reclassified under persists and spreads.
Conversely, sites in the second survival category might be
reclassified under dies if management were removed.
To obtain a regional estimate ofbuffelgrass adaptability
the land manager might use local, regional, and global climatic and soils maps. Precise seeding site definition may
be aided by satellite imagery if a correlation exists between
soil color and either soil organic carbon or total nitrogen.
REFERENCES
Agostini, J. J.; Morales, J. A.; Emkerlins, D. 1981. Yield and
quality of two hybrids ofbuffelgrass (Cenchrus ciliaris)
damaged by different populations of the spittlebug
CAneolamia albofascita) and mites (Prosapia simulans).
[In Spanish]. Agronomia. 200:42-47.
Agroclimatological Data for Mrica. 1984. Rome: Food and
Agriculture Organization of the United Nations. 407 p.
Birkeland, P. W. 1974. Pedology, weathering and geomorphological research. New York: Oxford University Press.
285p.
Bogdan, A. V. 1961. Breeding behavior of Cenchrus ciliaris
in Kenya. East Mrican Agriculture and Forestry Journal.
26:241.
Brady, N.C. 1974. The nature and properties of soils. New
York: MacMillan. 639 p.
Cazares, 0. H.; Martin-R, M. H.; lbarra-F, F. A. 1985. What
is the spittlebug? [In Spanish]. Ranchers Bulletin. 3: 1-21.
Hermosillo, Mexico.
Climatography of Mexico. 1982. Mexico City: National Meteorological Service. 797 p.
Climatography of the United States. 1985. Asheville, NC:
National Oceanic and Atmospheric Administration. 8 p.
Cota, A.; Johnson, D. 1975. Adaptation and production of
ten perennial grass species in Sonora. [In Spanish].
Pastizales-CI-MP-001. Hermosillo, Mexico. 55 p.
294
Cox, J. R.; Martin-R, M. H.; lbarra-F, F. A.; Fourie, J. H.;
Rethman, N. F. G.; Wilcox, D. G. 1988. The influence
of climate and soils on the distribution of four African
grasses. Journal of Range Management. 41:127-139.
Day, P.R. 1950. Physical basis of particle size analysis by
the hydrometer method. Soil Science. 74:81-86.
Flores, F.; Velazco, H. 1974. The impact of adult spittlebugs on forage grasses. [In Spanish]. Folia Entomologica.
28:71-75.
Hanselka, C. W. 1985. Grazing management strategies for
buffelgrass. In: Runge, E. C. A.; Schuster, J. L., eds. Buffelgrass: adaptation, management and forage quality symposium: proceedings; 1984 June 7; Weslaco, TX. College Station, TX: Texas Agricultural Experiment Station: 53-64.
Hausenbuiller, R. L. 1978. Soil science. Dubuque, IA:
Brown. 335 p.
Hendricks, D. M. 1985. Arizona soils. Tucson, AZ: University of Arizona Press. 288 p.
Holt, E. C.1985. Buffelgrass-a briefhistory. In: Runge,
E. C. A.; Schuster, J. L., eds. Buffelgrass: adaptation,
management and forage quality symposium: proceedings; 1984 June 7; Weslaco, TX. College Station, TX:
Texas Agricultural Experiment Station: 1-5.
Humphreys, L. R. 1967.. Buffelgrass (Cenchrus ciliaris) in
Australia. Tropical Grasslands. 1: 123-134.
Jackson, M. L. 1958. Soil chemical analysis. Englewood
Cliffs, NJ: Prentice-Hall. 175 p.
Khan, S. M.; Zarif, R. M. 1982. Enhancing range productivity through grass seeding in subtropical semiarid shrublands near Pashawar. Pakistan Journal of Forestry. 32:
89-94.
Mac Vicar, C. M.; Loxton, R. E.; Lambrechts, J. J. N.;
LaRoux, J.; Von M. Harmse, H. J.; DeVilliers, J. M.;
Vester, E.; Merryweather, F. R.; Van Rooyan, T. H. 1977.
Soil classification: a binomial system for South Africa.
Pretoria, South Africa: Department of Agricultural and
Technical Services. 328 p.
Molina, S. 1.; Garza, T. R.; Torres, H. M. 1976. Beef production on guinea and buffelgrass with two fertilizer rates,
during one year in Tizimin, Yucatan. [In Spanish].
Tecnica Pecuaria en Mexico. 31: 17-21.
Nada, Y. 1985. Palatability and adaptability of ten tropical
grasses used as pasture grazing in Kyushu. Journal of
Japanese Society of Grassland Science. 30: 434-440.
Olsen, S. R.; Sommers, L. E. 1982. Phosphorus. In: Page,
A. L., ed. Methods of soil analysis, Part II. Madison, WI:
American Society of Agronomy.
Oquendo, G. J.; Gerardo, J.; Mantecon, E. 1983. Performance of pasture cultivars in brown soils in Guaimaro.
[In Spanish]. Pastos and Forr~es. 6: 319-329.
Rees, M. C. 1972. Winter and summer growth of pasture
species in a high rainfall area of southeastern
Queensland. Tropical Grasslands. 6: 45-54.
U.S. Salinity Laboratory Staff.- 1954. Diagnosis and improvement of saline and alkaline soils. Agric. Handb. 60.
Washington, DC: U.S. Department of Agriculture. 160 p.
Van den Berg, F.1985. Notes on the genusA.frina brzeski
(Anguinidae: Nematoda) with descriptions of new and
known species. Phytophylactica. 17:67-79.
Winkworth, R. E. 1963. The germination ofbuffelgrass
seed after burial in a Central Australian soil. Australian
Journal of Experimental Agriculture and Animal Husbandry. 3:326.