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Elevated CO2 and warming effects on grassland plant mortality are determined by the timing of rainfall


Hovenden, MJ and Newton, PCD and Porter, M, Elevated CO2 and warming effects on grassland plant mortality are determined by the timing of rainfall, Annals of Botany, 119, (7) pp. 1225-1233. ISSN 0305-7364 (2017) [Refereed Article]

Copyright Statement

Copyright 2017 The Authors

DOI: doi:10.1093/aob/mcx006


Background and Aims: Global warming is expected to increase the mortality rate of established plants in water limited systems because of its effect on evapotranspiration. The rising CO2 concentration ([CO2]), however, should have the opposite effect because it reduces plant transpiration, delaying the onset of drought. This potential for elevated [CO2] (eCO2) to modify the warming effect on mortality should be related to prevailing moisture conditions. This study aimed to determine the impacts of warming by 2C and eCO2 (550 μmol mol-1) on plant mortality in an Australian temperate grassland over a 6-year period and to test how interannual variation in rainfall influenced treatment effects.

Methods: Analyses were based on results from a field experiment, TasFACE, in which grassland plots were exposed to a combination of eCO2 by free air CO2 enrichment (FACE) and warming by infrared heaters. Using an annual census of established plants and detailed estimates of recruitment, annual mortality of all established plants was calculated. The influence of rainfall amount and timing on the relative impact of treatments on mortality in each year was analysed using multiple regression techniques.

Key Results: Warming and eCO2 effects had an interactive influence on mortality which varied strongly from year to year and this variation was determined by temporal rainfall patterns. Warming tended to increase density adjusted mortality and eCO2 moderated that effect, but to a greater extent in years with fewer dry periods.

Conclusions: These results show that eCO2 reduced the negative effect of warming but this influence varied strongly with rainfall timing. Importantly, indices involving the amount of rainfall were not required to explain interannual variation in mortality or treatment effects on mortality. Therefore, predictions of global warming effects on plant mortality will be reliant not only on other climate change factors, but also on the temporal distribution of rainfall.

Item Details

Item Type:Refereed Article
Keywords:climate change, elevated CO2, FACE, global warming, grassland, mortality, rainfall timing, survivorship
Research Division:Environmental Sciences
Research Group:Climate change impacts and adaptation
Research Field:Ecological impacts of climate change and ecological adaptation
Objective Division:Environmental Policy, Climate Change and Natural Hazards
Objective Group:Understanding climate change
Objective Field:Global effects of climate change (excl. Australia, New Zealand, Antarctica and the South Pacific) (excl. social impacts)
UTAS Author:Hovenden, MJ (Professor Mark Hovenden)
UTAS Author:Porter, M (Ms Meagan Porter)
ID Code:118187
Year Published:2017
Web of Science® Times Cited:6
Deposited By:Plant Science
Deposited On:2017-07-06
Last Modified:2018-05-03

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