| Autor: |
Hilbert DW; Systems Ecology Research Group, San Diego State University, 92182, San Diego, CA, USA., Prudhomme TI; Systems Ecology Research Group, San Diego State University, 92182, San Diego, CA, USA., Oechel WC; Systems Ecology Research Group, San Diego State University, 92182, San Diego, CA, USA. |
| Jazyk: |
angličtina |
| Zdroj: |
Oecologia [Oecologia] 1987 Jun; Vol. 72 (3), pp. 466-472. |
| DOI: |
10.1007/BF00377581 |
| Abstrakt: |
The response of tussock tundra to elevated atmospheric concentrations of CO 2 was measured at Toolik Lake, Alaska in the summer of 1983. Computer-controlled greenhouses were used to determine diurnal ecosystem flux of CO 2 under four treatments: 340 ppm, 510 ppm, and 680 ppm CO 2 , as well as 680 ppm CO 2 with a four degree centrigrade increase in temperature. For the seven days of data analyzed, net daily CO 2 flux was significantly different between treatments. Net uptake was positively correlated with CO 2 concentration in the chamber and negatively correlated with temperature. A nonlinear model was used to analyze this data set and to determine some of the reasons for different net CO 2 flux. This model allowed an estimation of light utilization efficiency, total conductance of CO 2 , and a comparable measure of total respiration. From this analysis we conclude that nutrient limitations in the arctic decrease the capacity of tundra plants to make use of elevated CO 2 concentrations. The plants respond by decreasing conductance in the presence of elevated CO 2 , which results in approximately equal gross uptake rates for the three CO 2 treatments. Apparent changes in system respiration result in higher net uptake under elevated CO 2 but this may be due to biases in the data. The treatment with increased temperature exhibited higher conductances and, consequently, higher gross uptake of CO 2 than the other treatments. Higher temperatures, however, also increase respiration with the result being lower net uptake than would be expected in the absence of temperature inscreases. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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