Elevated CO2 does not increase eucalypt forest productivity on low-phosphorus soil ($)

The “Law of the Minimum” put forth by Justus von Liebig states that the most limiting nutrient governs plant growth. Although there is evidence in some conditions that increasing atmospheric CO2 levels can enhance plant growth, this only holds true under conditions in which CO2 is limiting growth. Ellsworth et al. found no productivity gains in mature eucalypt forest growing on phosphate-poor soils when CO2 levels were raised. When phosphate fertilizer was added and so growth was no longer P- limited, they observed a growth enhancement with elevated CO2. These results demonstrate the need to consider the availability of soil nutrients when forecasting plant responses to elevated CO2.  Nature Climate Change 10.1038/nclimate3235