Stomatal frequency of Quercus glauca from three material sources shows the same inverse response to atmospheric pCO2

Abstract

Background and AimsThe inverse correlation between atmospheric CO2 partial pressure (pCO2) and stomatal frequency in many plants has been widely used to estimate palaeo-CO2 levels. However, apparent discrepancies exist among the obtained estimates. This study attempts to find a potential proxy for palaeo-CO2 concentrations by analysing the stomatal frequency of Quercus glauca (section Cyclobalanopsis, Fagaceae), a dominant species in East Asian sub-tropical forests with abundant fossil relatives.MethodsStomatal frequencies of Q. glauca from three material sources were analysed: seedlings grown in four climatic chambers with elevated CO2 ranging from 400 to 1300 ppm; extant samples collected from 14 field sites at altitudes ranging from 142 to 1555 m; and 18 herbarium specimens collected between 1930 and 2011. Stomatal frequency–pCO2 correlations were determined using samples from these three sources.Key ResultsAn inverse correlation between stomatal frequency and pCO2 was found for Q. glauca through cross-validation of the three material sources. The combined calibration curves integrating data of extant altitudinal samples and historical herbarium specimens improved the reliability and accuracy of the curves. However, materials in the climatic chambers exhibited a weak response and relatively high stomatal frequency possibly due to insufficient treatment time.ConclusionsA new inverse stomatal frequency–pCO2 correlation for Q. glauca was determined using samples from three sources. These three material types show the same response, indicating that Q. glauca is sensitive to atmospheric pCO2 and is an ideal proxy for palaeo-CO2 levels. Quercus glauca is a nearest living relative (NLR) of section Cyclobalanopsis fossils, which are widely distributed in the strata of East Asia ranging from the Eocene to Pliocene, thereby providing excellent materials to reconstruct the atmospheric CO2 concentration history of the Cenozoic. Quercus glauca will add to the variety of proxies that can be widely used in addition to Ginkgo and Metasequoia.

Integrating stomatal physiology and morphology: evolution of stomatal control and development of future crops

“…Passalia 2009 ; Smith et al 2010 ; Jing and Bainian 2018 ; Steinthorsdottir et al 2019 ). Species specific SD and SI responses (in both occurrence and extent) to the availability of CO 2 can be assessed by analysis of the number of stomata and epidermal cells in the leaves of historical herbarium specimens collected during the last ~ 250 years as [CO 2 ] has risen from 280 to above 400 μmol mol −1 , [CO 2 ] enrichment studies, and over altitudinal gradients where the partial pressure of CO 2 ( p CO 2 ) varies (but the concentration of CO 2 remains constant, uncoupling the effect of [CO 2 ] from CO 2 -availability) (Woodward 1987 ; Woodward and Bazzaz 1988 ; Beerling and Chaloner 1993b ; Kürschner et al 1997 , 2008 ; Kouwenberg et al 2003 ; Haworth et al 2010 ; Lammertsma et al 2011 ; Hu et al 2019 ). However, the SD and SI response to [CO 2 ] varies between species in the occurrence of any relationship (some plant groups such as the cycads do not alter SD or SI to [CO 2 ] and are known as ‘SD non-responders’: Haworth et al 2011c ), the extent of the SD or SI response and the [CO 2 ] range over which SD or SI responds (Beerling and Chaloner 1993a ; Kürschner et al 1996 ; Kürschner 1997 ; Haworth et al 2013 ; Hu et al 2015 ; Hill et al 2019 ).…”

“…The stimulation in P N associated with elevated [CO 2 ] allows plants to lower G s to maintain a constant C i : C a ratio and increase WUE (Mott 1988 ; Eamus 1991 ; Franks and Beerling 2009a ). This reduction in G s can be achieved through decreases in stomatal pore aperture (Assmann 1999 ; Ainsworth and Rogers 2007 ), SD (Woodward 1987 ; Hu et al 2019 ) or SS (Lammertsma et al 2011 ; Haworth et al 2016 ). Sub-ambient [CO 2 ] (i.e.…”

Herbaria as Big Data Sources of Plant Traits

“…The trait has even been used to reconstruct several millennia of CO2 levels from ancient Egypt to today using preserved olive leaves from King Tutankhamun's tomb dating to 1327 BCE alongside a chronosequence of traditional herbarium specimens (Beerling and Chaloner 1993). More commonly, paleobotanists now routinely rely upon both fossils and herbarium specimens, alongside living material, to assess the functional significance of stomatal density and index in reconstructions of paleoenvironments (Hu et al 2019).…”

“…Corney et al 2012;David P. A. Corney et al 2012;Guerin et al 2012;Schmerler et al 2012;Dalrymple et al 2015;Flores-Moreno et al 2015;Onstein et al 2016;Tomaszewski and Górzkowska 2016;Beauvais et al 2017;Stropp et al 2017;Václavík et al 2017;Guzmán et al 2018;Petrulaitis and Gudžinskas 2018;Smith et al 2019;Borges et al 2020;Weaver et al 2020;Buitrago Aristizábal et al 2020;Kommineni et al 2021) Leaf compoundness or type (categorical) No* Light capture, structural investment e.g. (Lohbeck et al 2013) 2011; Tripp and Fatimah 2012;Hill, Guerin, et al 2014;Large et al 2017;Hu et al 2019) Herbivory/granivory damage (% tissue loss, presence/absence, sooty mold)…”

Variations in morphological and epidermal features of shade and sun leaves of two species: Quercus bambusifolia and Q. myrsinifolia

“…Leaves directly (sun leaves) and indirectly (shade leaves) exposed to sunlight demonstrate considerable phenotypic plasticity, similar to that in leaves exposed to xerophytic vs. mesophytic habitats respectively (Zalensky, 1904). Sun and shade fagaceous leaves have been studied from different perspectives: leaf morphology (Bruschi et al, 2003a(Bruschi et al, , 2003b, anatomy (Batos et al, 2010;Daly and Gastaldo, 2010;Hu et al, 2019), ultrastructural studies of cuticular membranes (Osborn and Taylor, 1990), leaf physiology (Ashton and Berlyn, 1994;Morecroft and Roberts, 1999;Kitao et al, 2006;Hu et al, 2015) and leaf morphological plasticity (Rubio de Casas et al, 2007;Kusi and Karsai, 2020).…”