title: Warming and free-air CO2 enrichment alter demographics in four co-occurring grassland species.
abstract: Species differ in their responses to global changes such as rising CO(2) and temperature, meaning that global changes are likely to change the structure of plant communities. Such alterations in community composition must be underlain by changes in the population dynamics of component species. Here, the impact of elevated CO(2) (550 micromol mol(-1)) and warming (+2 degrees C) on the population growth of four plant species important in Australian temperate grasslands is reported. Data collected from the Tasmanian free-air CO(2) enrichment (TasFACE) experiment between 2003 and 2006 were analysed using population matrix models. Population growth of Themeda triandra, a perennial C(4) grass, was largely unaffected by either factor but population growth of Austrodanthonia caespitosa, a perennial C(3) grass, was reduced substantially in elevated CO(2) plots. Warming and elevated CO(2) had antagonistic effects on population growth of two invasive weeds, Hypochaeris radicata and Leontodon taraxacoides, with warming causing population decline. Analysis of life cycle stages showed that seed production, seedling emergence and establishment were important factors in the responses of the species to global changes. These results show that the demographic approach is very useful in understanding the variable responses of plants to global changes and in elucidating the life cycle stages that are most responsive.
authors: School of Plant Science, University of Tasmania, Locked Bag 55, Hobart 7001, Tasmania, Australia.
authors: Amity L
authors: AL
authors: Williams
authors: School of Plant Science, University of Tasmania, Locked Bag 55, Hobart 7001, Tasmania, Australia.
authors: Karen E
authors: KE
authors: Wills
authors: School of Plant Science, University of Tasmania, Locked Bag 55, Hobart 7001, Tasmania, Australia.
authors: Jasmine K
authors: JK
authors: Janes
authors: School of Plant Science, University of Tasmania, Locked Bag 55, Hobart 7001, Tasmania, Australia.
authors: Jacqueline K
authors: JK
authors: Vander Schoor
authors: AgResearch Grasslands Research Institute, Private Bag 11008, Palmerston North, New Zealand.
authors: Paul C D
authors: PCD
authors: Newton
authors: School of Plant Science, University of Tasmania, Locked Bag 55, Hobart 7001, Tasmania, Australia.
authors: Mark J
authors: MJ
authors: Hovenden
mesh_terms: D000064:Acclimatization; D002245:Carbon Dioxide / Q000378:metabolism*; D017752:Greenhouse Effect; D006109:Poaceae / Q000254:growth & development / Q000378:metabolism*; D011156:Population Density; D011157:Population Dynamics; D013648:Tasmania
chemical_list: D002245:Carbon Dioxide