Abstract
This paper reports on measurements of net CO2 and H2O exchange from single- and multiple-species microcosms composed of California annual grassland species grown at either ambient or elevated (ambient + 36 Pa) CO2. Microcosms consisted of grassland species grown in PVC tubes (~ 0.95 m deep x 0.2 m diameter) containing ~45 kg of either serpentine or sandstone derived soil or parent material in open-top enclosures under ambient meteorological conditions. Half of the microcosms were left unfertilized (low nutrient) while the other half received an intermediate level of a slow-release (N,P,K) fertilizer (high nutrient). Gas exchange was performed by sealing individual microcosms within a transparent chamber (on clear sunny days) and coupling this to an open gas-exchange system. In fertilized single-species microcosms, elevated CO2 consistently enhanced net 'ecosystem' CO2 exchange (NCE) on a ground area basis in both early and late spring. Among unfertilized single-species microcosms, no significant trends or differences were observed in NCE between those grown at ambient versus elevated CO2. The NCE in sandstone and serpentine multiple-species microcosms was monitored seasonally over a majority of the 1993-1994 growing season. Rates were largely unaffected by growth CO2 or fertilization until after mid-February, 1994. Water-use efficiency (WUE = NCE/evapotranspiration (ET)) was generally enhanced by elevated CO2, but this was primarily a result of enhancements in NCE as opposed to decreases in ET. Enhancements in NCE by elevated CO2 in fertilized single-species microcosms at the growth-CO2 concentration were partially explained by higher above-ground biomass in elevated CO2 microcosms. However, ecosystem-level 'acclimation' occurred such that microcosms grown at elevated CO2 consistently had lower NCE than ambient CO2 treatments at a single measurement CO2 concentration (ambient or elevated). The reduction in apparent ecosystem-level photosynthetic capacity in elevated CO2 microcosms was accompanied by decreases in foliar Rubisco activity, such that NCE measured at ambient CO2 was highly correlated. (r = 0.98) with foliar Rubisco activity across the three single-species microcosms in which it was measured.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 147-157 |
| Number of pages | 11 |
| Journal | Environmental and Experimental Botany |
| Volume | 40 |
| Issue number | 2 |
| DOIs | |
| State | Published - Oct 1998 |
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Keywords
- California annual grassland
- Ecosystem photosynthesis
- Ecosystem WUE
- Elevated CO
- Grassland microcosms
- Mediterranean climate
ASJC Scopus subject areas
- Ecology, Evolution, Behavior and Systematics
- Plant Science
- Environmental Science(all)
Cite this
Influence of fertilization and atmospheric CO2 enrichment on ecosystem CO2 and H2O exchanges in single- and multiple-species grassland microcosms. / Fredeen, Arthur L.; Koch, George W; Field, Christopher B.
In: Environmental and Experimental Botany, Vol. 40, No. 2, 10.1998, p. 147-157.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - Influence of fertilization and atmospheric CO2 enrichment on ecosystem CO2 and H2O exchanges in single- and multiple-species grassland microcosms
AU - Fredeen, Arthur L.
AU - Koch, George W
AU - Field, Christopher B.
PY - 1998/10
Y1 - 1998/10
N2 - This paper reports on measurements of net CO2 and H2O exchange from single- and multiple-species microcosms composed of California annual grassland species grown at either ambient or elevated (ambient + 36 Pa) CO2. Microcosms consisted of grassland species grown in PVC tubes (~ 0.95 m deep x 0.2 m diameter) containing ~45 kg of either serpentine or sandstone derived soil or parent material in open-top enclosures under ambient meteorological conditions. Half of the microcosms were left unfertilized (low nutrient) while the other half received an intermediate level of a slow-release (N,P,K) fertilizer (high nutrient). Gas exchange was performed by sealing individual microcosms within a transparent chamber (on clear sunny days) and coupling this to an open gas-exchange system. In fertilized single-species microcosms, elevated CO2 consistently enhanced net 'ecosystem' CO2 exchange (NCE) on a ground area basis in both early and late spring. Among unfertilized single-species microcosms, no significant trends or differences were observed in NCE between those grown at ambient versus elevated CO2. The NCE in sandstone and serpentine multiple-species microcosms was monitored seasonally over a majority of the 1993-1994 growing season. Rates were largely unaffected by growth CO2 or fertilization until after mid-February, 1994. Water-use efficiency (WUE = NCE/evapotranspiration (ET)) was generally enhanced by elevated CO2, but this was primarily a result of enhancements in NCE as opposed to decreases in ET. Enhancements in NCE by elevated CO2 in fertilized single-species microcosms at the growth-CO2 concentration were partially explained by higher above-ground biomass in elevated CO2 microcosms. However, ecosystem-level 'acclimation' occurred such that microcosms grown at elevated CO2 consistently had lower NCE than ambient CO2 treatments at a single measurement CO2 concentration (ambient or elevated). The reduction in apparent ecosystem-level photosynthetic capacity in elevated CO2 microcosms was accompanied by decreases in foliar Rubisco activity, such that NCE measured at ambient CO2 was highly correlated. (r = 0.98) with foliar Rubisco activity across the three single-species microcosms in which it was measured.
AB - This paper reports on measurements of net CO2 and H2O exchange from single- and multiple-species microcosms composed of California annual grassland species grown at either ambient or elevated (ambient + 36 Pa) CO2. Microcosms consisted of grassland species grown in PVC tubes (~ 0.95 m deep x 0.2 m diameter) containing ~45 kg of either serpentine or sandstone derived soil or parent material in open-top enclosures under ambient meteorological conditions. Half of the microcosms were left unfertilized (low nutrient) while the other half received an intermediate level of a slow-release (N,P,K) fertilizer (high nutrient). Gas exchange was performed by sealing individual microcosms within a transparent chamber (on clear sunny days) and coupling this to an open gas-exchange system. In fertilized single-species microcosms, elevated CO2 consistently enhanced net 'ecosystem' CO2 exchange (NCE) on a ground area basis in both early and late spring. Among unfertilized single-species microcosms, no significant trends or differences were observed in NCE between those grown at ambient versus elevated CO2. The NCE in sandstone and serpentine multiple-species microcosms was monitored seasonally over a majority of the 1993-1994 growing season. Rates were largely unaffected by growth CO2 or fertilization until after mid-February, 1994. Water-use efficiency (WUE = NCE/evapotranspiration (ET)) was generally enhanced by elevated CO2, but this was primarily a result of enhancements in NCE as opposed to decreases in ET. Enhancements in NCE by elevated CO2 in fertilized single-species microcosms at the growth-CO2 concentration were partially explained by higher above-ground biomass in elevated CO2 microcosms. However, ecosystem-level 'acclimation' occurred such that microcosms grown at elevated CO2 consistently had lower NCE than ambient CO2 treatments at a single measurement CO2 concentration (ambient or elevated). The reduction in apparent ecosystem-level photosynthetic capacity in elevated CO2 microcosms was accompanied by decreases in foliar Rubisco activity, such that NCE measured at ambient CO2 was highly correlated. (r = 0.98) with foliar Rubisco activity across the three single-species microcosms in which it was measured.
KW - California annual grassland
KW - Ecosystem photosynthesis
KW - Ecosystem WUE
KW - Elevated CO
KW - Grassland microcosms
KW - Mediterranean climate
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U2 - 10.1016/S0098-8472(98)00033-1
DO - 10.1016/S0098-8472(98)00033-1
M3 - Article
VL - 40
SP - 147
EP - 157
JO - Environmental and Experimental Botany
JF - Environmental and Experimental Botany
SN - 0098-8472
IS - 2
ER -