Plant responses to low [CO₂] of the past

Abstract

SummaryDuring the Last Glacial Maximum (LGM; 18 000-20 000 yr ago) and previous glacial periods, atmospheric [CO 2 ] dropped to 180-190 ppm, which is among the lowest concentrations that occurred during the evolution of land plants. Modern atmospheric CO 2 concentrations ([CO 2 ]) are more than twice those of the LGM and 45% higher than pre-industrial concentrations. Since CO 2 is the carbon source for photosynthesis, lower carbon availability during glacial periods likely had a major impact on plant productivity and evolution. From the studies highlighted here, it is clear that the influence of low [CO 2 ] transcends several scales, ranging from physiological effects on individual plants to changes in ecosystem functioning, and may have even influenced the development of early human cultures (via the timing of agriculture). Through low-[CO 2 ] studies, we have determined a baseline for plant response to minimal [CO 2 ] that occurred during the evolution of land plants. Moreover, an increased understanding of plant responses to low [CO 2 ] contributes to our knowledge of how natural global change factors in the past may continue to influence plant responses to future anthropogenic changes. Future work, however, should focus more on the evolutionary responses of plants to changing [CO 2 ] in order to account for the potentially large effects of genetic change.

Evolutionary context for understanding and manipulating plant responses to past, present and future atmospheric [CO 2 ]

“…This is despite substantial evidence indicating that subambient [CO 2 ] concentrations are an important selective agent [11,71] [63,65,69] or herbivory [85,86], evolutionary effects may be more likely in more stressful biotic environments. Similarly, evolutionary effects of elevated [CO 2 ] also may be more likely when plants experience abiotic stress, such as drought or nutrient limitation.…”

Winners always win: growth of a wide range of plant species from low to future high CO2

“…Given the limited number of species analyzed for low to high CO 2 response (Gerhart and Ward 2010; Temme et al. 2013), we felt that a higher number of species would further our understanding of plant responses to CO 2 more than an in depth look at a limited number of species with more chamber replicates.…”

“…While there is ample data on plant species response to elevated CO 2 (Poorter and Navas 2003; Ainsworth and Rogers 2007; Norby and Zak 2011), far less is known on plant responses to low CO 2 (reviewed in Gerhart and Ward 2010; Temme et al. 2013).…”

“…2012) lead to a much higher SLA. Combined with an increase in LMF, this results in a higher LAR (Gerhart and Ward 2010; Temme et al. 2013).…”

Palaeo-precipitation is a major determinant of palm species richness patterns across Madagascar: a tropical biodiversity hotspot

“…We interpret this pattern as indicating the relative wetness change during the Quaternary, with high values indicating where rainforest has had the greatest possibilities for persistence through glacials. The low CO 2 concentrations during glacial periods would have increased plant -water requirements, and thus changed vegetation -precipitation relationships [59]. Hence, relatively higher precipitation levels-as reconstructed for the northeast of Madagascarmay have been required for maintaining rainforest through glacial periods.…”