Increasing CO[sub 2]: Comparative responses of the C[sub 4] grass Schizachyrium and grassland invader Prosopis

Journal Article · Wed Jun 01 04:00:00 EDT 1994 · Ecology; (United States)

DOI:https://doi.org/10.2307/1939421· OSTI ID:7008365

Polley, H W; Johnson, H B; Mayeux, H S ^[1]

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1. Department of Agriculture, Temple, TX (United States)

Woody C[sub 3] Prosopis glandulosa (honey mesquite) and C[sub 4] perennial grass Schizachyrium scoparium (little bluestem) were grown along a gradient of daytime carbon dioxide concentrations from near 340 to 200 [mu]mol/mol air in a 38 m long controlled environment chamber. The authors studied the effects of historical and prehistorical increases in atmospheric CO[sub 2] concentration on growth, resource use, and competitive interactions of a species representative of C[sub 4]-dominated grasslands in the SW United States and the invasive legume P. glandulosa. Increasing CO[sub 2] concentration stimulated N[sub 2] fixation by individually grown P. glandulosa and elicited in C[sub 3] seedlings a similar relative increase in leaf intercellular CO[sub 2] concentration, net assimilation rate, and intrinsic water use efficiency (leaf net assimilation rate/stomatal conductance). Aboveground biomass of P. glandulosa was not altered by CO[sub 2] concentration, but belowground biomass and whole-plant water and nitrogen use efficiencies increased linearly with CO[sub 2] concentration in seedlings that were grown alone. Biomass produced by P. glandulosa that was grown with S. scoparium was not affected by CO[sub 2] concentration. Stomatal conductance declined and leaf assimilation rates of S. scoparium at near maximum incident light increased at higher CO[sub 2] concentration, but there was no effect of CO[sub 2] concentration on biomass production or whole-plant water use efficiency of the C[sub 4] grass. Rising CO[sub 2] concentration, especially the 27% increase since the beginning of the 19th century, may have contributed to more abundant P. glandulosa on C[sub 4] grasslands by stimulating the shrub's growth or reducing the amount of resources that the C[sub 3] required. Much of the potential response of P. glandulosa to CO[sub 2] concentration, however, appears to be contingent on the shrub's escaping competition with neighboring grasses. 62 refs., 10 figs., 1 tab.

• OSTI ID: 7008365
• Journal Information: Ecology; (United States), Journal Name: Ecology; (United States) Vol. 75:4; ISSN 0012-9658; ISSN ECOLAR
• Country of Publication: United States
• Language: English

Related Subjects

560300* -- Chemicals Metabolism & Toxicology
63 RADIATION, THERMAL, AND OTHER ENVIRON. POLLUTANT EFFECTS ON LIVING ORGS. AND BIOL. MAT.
BIOLOGICAL EFFECTS
C4 SPECIES
CARBON COMPOUNDS
CARBON DIOXIDE
CARBON OXIDES
CHALCOGENIDES
ECOLOGICAL CONCENTRATION
GRAMINEAE
GROWTH
LEGUMINOSAE
LILIOPSIDA
MAGNOLIOPHYTA
MAGNOLIOPSIDA
MESQUITE
OXIDES
OXYGEN COMPOUNDS
PLANT GROWTH
PLANTS
POPULATION DYNAMICS
TREES