Seedling Tree Responses to Nutrient Stress under Atmospheric CO sub 2 Enrichment

摘要

Three species of seedling trees were grown in pots containing low-nutrient soil for periods of up to 40 weeks under a range of atmospheric CO sub 2 concentrations. In all cases, total dry weight increased with CO sub 2 enrichment, with a greater relative increase in root weight than shoot weight. In an experiment with Pinus virginiana in open-top field chambers, phosphorus and potassium uptake did not increase with an increase in CO sub 2 from 365 to 690 mu L/L, even though dry matter gain increased by 37% during the exposure period. In experiments with Quercus alba and Liriodendron tulipifera under controlled environment conditions there were obvious symptoms of nitrogen deficiency and total nitrogen uptake did not increase with CO sub 2 enrichment. However, dry weight gain was more than 90% higher at 690 mu L/L CO sub 2 . The three experiments with CO sub 2 enrichment treatments demonstrate that increases in plant dry weight can occur without increased uptake of some nutrients from the low-nutrient soil. A mechanism for these responses may involve increased mobilization of nutrients in association with increased sucrose transport under elevated CO sub 2 conditions. (ERA citation 11:048903)