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