Elevated CO₂ is widely accepted to enhance terrestrial carbon sink, especially in arid and semi‐arid regions. However, great uncertainties exist for the CO₂ fertilisation effects, particularly when its interactions with other global change factors are considered. A four‐factor (CO₂, temperature, precipitation and nitrogen) experiment revealed that elevated CO₂ did not affect either gross ecosystem productivity or ecosystem respiration, and consequently resulted in no changes of net ecosystem productivity in a semi‐arid grassland despite whether temperature, precipitation and nitrogen were elevated or not. The observations could be primarily attributable to the offset of ecosystem carbon uptake by enhanced soil carbon release under CO₂ enrichment. Our findings indicate that arid and semi‐arid ecosystems may not be sensitive to CO₂ enrichment as previously expected and highlight the urgent need to incorporate this mechanism into most IPCC carbon‐cycle models for convincing projection of terrestrial carbon sink and its feedback to climate change.

Item Type:	Refereed Article
Keywords:	elevated CO2, global climate change, experiment, grassland, productivity, carbon cycle, climate warming, CO2 enrichment, forb, grass, increased precipitation, modelling, multi-factor experiment, nitrogen addition, species composition
Research Division:	Biological Sciences
Research Group:	Other biological sciences
Research Field:	Global change biology
Objective Division:	Expanding Knowledge
Objective Group:	Expanding knowledge
Objective Field:	Expanding knowledge in the environmental sciences
UTAS Author:	Hovenden, MJ (Professor Mark Hovenden)
ID Code:	130136
Year Published:	2019
Funding Support:	Australian Research Council (DP150102426)
Web of Science® Times Cited:	28
Deposited By:	Plant Science
Deposited On:	2019-01-11
Last Modified:	2020-08-07
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