Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil - Archive ouverte HAL Access content directly
Journal Articles Nature Climate Change Year : 2017

Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil

Abstract

Rising atmospheric CO2 stimulates photosynthesis and productivity of forests, offsetting CO2 emissions1, 2. Elevated CO2 experiments in temperate planted forests yielded ~23% increases in productivity3 over the initial years. Whether similar CO2 stimulation occurs in mature evergreen broadleaved forests on low-phosphorus (P) soils is unknown, largely due to lack of experimental evidence4. This knowledge gap creates major uncertainties in future climate projections5, 6 as a large part of the tropics is P-limited. Here, we increased atmospheric CO2 concentration in a mature broadleaved evergreen eucalypt forest for three years, in the first large-scale experiment on a P-limited site. We show that tree growth and other aboveground productivity components did not significantly increase in response to elevated CO2 in three years, despite a sustained 19% increase in leaf photosynthesis. Moreover, tree growth in ambient CO2 was strongly P-limited and increased by ~35% with added phosphorus. The findings suggest that P availability may potentially constrain CO2-enhanced productivity in P-limited forests; hence, future atmospheric CO2 trajectories may be higher than predicted by some models. As a result, coupled climate–carbon models should incorporate both nitrogen and phosphorus limitations to vegetation productivity7 in estimating future carbon sinks.

Dates and versions

hal-01608517 , version 1 (03-10-2017)

Identifiers

Cite

David s. Ellsworth, Ian c. Anderson, Kristine y. Crous, Julia Cooke, John e. Drake, et al.. Elevated CO2 does not increase eucalypt forest productivity on a low-phosphorus soil. Nature Climate Change, 2017, 7 (4), pp.279-282. ⟨10.1038/nclimate3235⟩. ⟨hal-01608517⟩

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