Intraspecific Competition in Hot Deserts
Intraspecific Competition in Hot Deserts.
With:
Park S. Nobel, Professor, Department of Biology
University of California, Los Angeles (UCLA)
[Click on a photograph for details]
Funded by United States Department of Energy.
Selected References
Robberecht, R. 1988. Big galleta grass --- a warm-season bunchgrass in the Sonoran and Mojave Deserts. Rangelands 10:58-60.
Summary The Sonoran and Mojave Deserts of the American southwest present
formidable environments for the establishment and survival of
plant species. Plants in these hot, arid environments have evolved
many adaptations to the high temperatures and limited soil water
supply, as exemplified by the numerous species of succulents in
these areas. A dominant warm-season grass species in the hot
deserts of southeastern California, southern Nevada and Utah,
western Arizona, and parts of Baja California is big galleta grass
(Hilaria rigida (Thurb.) Benth. ex Scribn). This perennial
plant has a bunchgrass growth form and exhibits some interesting
physiological adaptations to hot, arid environments. In addition
to the stress imposed on plants by these desert habitats, this
bunchgrass species may be subject to a high degree of utilization
by native bighorn sheep and domestic livestock (Hughes 1982).
Despite its potential importance as a forage species in these
hot deserts, little is known about its life history, ecology,
and response to grazing.
Nobel, P. S., and A. C. Franco. 1986. Annual root growth and intraspecific competition for a desert bunchgrass. Journal of Ecology 74:1119-1126.
Robberecht, R. and P.S. Nobel. 1986. Intraspecific competition in Hilaria rigida, a C4 bunchgrass endemic to southwestern United States desert rangelands. Pages 463-464 in P.J. Joss, P.W. Lynch, and
O.B. Williams, editors. Rangelands: A resource under siege. Australian Academy of Sciences, Canberra, Australia.
Robberecht, R., B.E. Mahall, and P.S. Nobel. 1983. Experimental removal of intraspecific competitors - effects
on water relations and productivity of a desert bunchgrass, Hilaria
rigida. Oecologia 60:21-24.
Abstract Intraspecific competition in the C4 bunchgrass Hilaria
rigida was examined on a Sonoran Desert site in southeastern
California. Potential competition within monospecific stands
was experimentally altered by removal of the aboveground portions
of all plants within a 1.5 m radius of a monitored plant. Compared
with unaltered plots, altered plots had less negative soil water
potentials during periods of soil drying. Leaf blades on monitored
plants of altered plots remained green longer and had greater
stomatal conductances than those on monitored plants on unaltered
plots. Production of new culms was twice as great on altered
plots. Greater root biomass and root length were observed in
altered plots, and root extension into soil areas formerly occupied
by roots of neighboring plants occurred within one year after
treatment. The results indicate that removal of the aboveground
biomass of neighboring plants reduces the competition for limited
available soil water in this desert environment.
Nobel, P. S. 1981. Spacing and transpiration of various sized clumps of a desert grass, Hilaria rigida. Journal of Ecology 69:735-742.
Nobel, P. S. 1980. Water vapor conductance and CO2 uptake for leaves of a C4 desert grass, Hilaria rigida. Ecology 61:252-258.