Warming and free‐air CO₂ enrichment alter demographics in four co‐occurring grassland species

Abstract

Summary• 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 µmol mol -1 ) and warming ( + 2 ° 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.

CO2, nitrogen, and diversity differentially affect seed production of prairie plants

“…With the exception of studies on the seed production responses to elevated CO 2 , there are few studies performed in field settings with which to compare our results. Many studies manipulate one global change factor (primarily CO 2 ) and examine reproductive responses, without considering the effects of the multiple environmental changes plant communities will be exposed to (but see Cleland et al 2006, Ramo et al 2007, Williams et al 2007). Moreover, although ecophysiological traits, like photosynthetic pathway or nitrogen-fixing ability, can be predictive of vegetative responses to global change factors, they are not always predictive of seed production responses ( Fig.…”

“…Elevated CO 2 has been found to 6 E-mail: jhrl@u.washington.edu strongly affect seed production of some species, but results are difficult to extrapolate to natural communities, because most studies focus on crop species (Jablonski et al 2002) or examine the response of single species to elevated CO 2 (e.g., Huxman et al 1999, LaDeau andClark 2001). To our knowledge, fewer than 10 studies have examined the reproductive responses of co-occurring plant species to elevated CO 2 in the field (Navas et al 1997, Grunzweig and Korner 2000, Thurig et al 2003, Morgan et al 2004, Stiling et al 2004, Miyagi et al 2007, Ramo et al 2007, Williams et al 2007; and only two studies have examined reproductive responses of co-occurring species to multiple global change factors in the field (Cleland et al 2006, Ramo et al 2007). Determining how global change alters seed production of co-occurring members of a plant community would lend insight into the factors that constrain seed production, and may simplify efforts to forecast population or community dynamics under global change scenarios.…”

Lakes and reservoirs as regulators of carbon cycling and climate

“…Vegetation and soil-Watershed changes in and redistribution of plant communities are clear consequences of global climate change (Williams et al 2007). Modifications in temperature, nitrogen deposition, rainfall, and increased atmospheric CO 2 concentrations will affect the quantity Table 1.…”

The Effects of Climate Warming on Plant-Herbivore Interactions

“…Overall, warming stimulated flower and production , even in the presence of herbivores, although fruits of warmed plants tended to weigh less. Warming also reduced seed mass and increased seed number, similar responses to those reported by studies of arctic and alpine plants (Tøtland 1999, Prasad et al 2002, Kudernatsch et al 2008, although effects vary considerably among species (Williams et al 2007). Our results reinforce the pattern of direct effects of warming on plant fitness, but importantly, demonstrate that these effects are invariant to the presence or absence of insect herbivores.…”