Abstract
With an increase in the frequency and intensity of extreme heat events, plants are likely to reach their thermal limits and show slower growth or increased mortality. We investigated differences amongst coastal native and invasive shrubs and grasses to investigate if particular species might be more at risk in the future. Using an ecologically relevant experimental set of heat waves over a month, we assessed changes in biomass and photosynthetic efficiency in a laboratory setting using 25 coastal Australian species divided into native and exotic shrubs, and native and exotic grasses. We also compared three C3 and three C4 grasses within the native and exotic groups. Overall, native shrubs suffered higher mortality, lower growth and increased photosynthetic stress. There was some evidence that C3 grasses, had lower growth with heat waves, compared to C4 species although, in general, grasses showed evidence of photosynthetic acclimation over the month. Increases in leaf abscission suggest that part of the acclimation process was to develop new, thermally tolerant leaves. Our results indicate that in the future we would expect an increase in exotic shrubs and grasses occupying spaces in coastal plant communities that arise from native mortality following extreme heat events. Management of these coastal communities will need to focus strongly on maintaining a diverse native shrub composition that can resist climate-based disturbances (such as wildfire), as well as controlling the extent and biomass of exotic species, if coastal communities are to remain healthy and diverse in a changing climate.
Highlights
Whilst the fifth IPCC report (2013) predicts that we will see a worldwide increase in average temperatures in the future, it suggests an increased frequency and severity of extreme heat events in some regions (Coumou and Robinson, 2013), including Australia (Hughes, 2003)
Our results indicate that in the future we would expect an increase in exotic shrubs and grasses occupying spaces in coastal plant communities that arise from native mortality following extreme heat events
Leaf loss in most species occurred after 3–5 extreme heat event days and new leaves were apparent within 2 weeks
Summary
Whilst the fifth IPCC report (2013) predicts that we will see a worldwide increase in average temperatures in the future, it suggests an increased frequency and severity of extreme heat events in some regions (Coumou and Robinson, 2013), including Australia (Hughes, 2003) The impacts of these periods of extreme heat may be large compared to their duration (Wigley, 1985; Hughes, 2003): past studies have shown significant loss in gross primary productivity (Ciais et al, 2005) and high mortality (Allen et al, 2010). Found that C3 plants showed a greater ability for temperature acclimation of photosynthesis across a broad temperature range With their improved water-use efficiency, C4 species may dominate communities in the future, provided their leaves do not reach lethal temperatures. We predicted that C4 grasses would be less stressed than those with C3 photosynthesis and that shrubs would acclimate better than grasses over the month-long period of extreme heat events
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
