Sulphur dioxide fumigation effects on stomatal density and index of non-resistant plants: Implications for the stomatal palaeo-[CO2] proxy method

On the reconstruction of plant photosynthetic and stress physiology across the Triassic–Jurassic boundary

“…These morphological and physiological characteristics also correlate, as F v /F m decreases with increasing adaxial epidermal cell density (Figure 3e), while NPQ increases (Figure 3f ) relative to the rest of the section, suggesting that epidermal cell density values of Ginkgoales continue to increase across TJB, suggestive of further physiological stress. As these Bed 6 samples are from a distinctly different taphonomic setting (swamp, as opposed to crevasse splays), this likely affected leaf development (Haworth et al, 2012) and therefore these data are not presented in Figure 2. Reconstruction of Late Triassic and Early Jurassic Ginkgoales leaf shapes using structural engineering principles suggests that Late Triassic Ginkgoales possessed more structurally rigid leaves than their Early Jurassic counterparts (Figure 4), resulting in a higher absorption of light per unit leaf area.…”

“…Ginkgo biloba cuticles were macerated using standard maceration and mounted in glycerol on glass slides (Haworth et al, 2012 (Sokal and Rohlf, 1995). Instead, the adaxial epidermal cell densities of fossil Ginkgoales provide a qualitative indicator of plant photosynthesis and stress physiology with higher epidermal cell densities indicating higher photosynthetic stress and vice versa.…”

Cuticle surfaces of fossil plants as a potential proxy for volcanic SO2 emissions: observations from the Triassic–Jurassic transition of East Greenland

“…Previous studies on plant SD/SI responses when subjected to naturally elevated levels of SO 2 in the vicinity of volcanic vents have been inconclusive, reporting decreased SI (Tanner et al 2007) and SD (Ali et al 2008), as well as no SD/SI response (Bettarini et al 1997;Haworth et al 2010) when compared to non-fumigated plants. The lack of SD/SI response was interpreted to potentially be the result of developmental resistance to SO 2 fumigation by Haworth et al (2010), who subsequently conducted a series of growth chamber experiments on several fossil-equivalent plant species with no prior exposure to SO 2 (Haworth et al 2012). Exposure to high pCO 2 in combination with SO 2 fumigation produced a variety of SD and SI responses between the plants, with SD increasing significantly in about half the plant species, as well as very variable SI responses, including a large SI increase in Ginkgo biloba (Haworth et al 2012).…”

“…The lack of SD/SI response was interpreted to potentially be the result of developmental resistance to SO 2 fumigation by Haworth et al (2010), who subsequently conducted a series of growth chamber experiments on several fossil-equivalent plant species with no prior exposure to SO 2 (Haworth et al 2012). Exposure to high pCO 2 in combination with SO 2 fumigation produced a variety of SD and SI responses between the plants, with SD increasing significantly in about half the plant species, as well as very variable SI responses, including a large SI increase in Ginkgo biloba (Haworth et al 2012). However, all species showed an increase in the ratio between SD and SI (SD:SI), implying this ratio could be used to help detect SO 2 responses recorded by plants in the geological record and that this effect could cause the underestimation of pCO 2 using the stomatal method on material exposed to SO 2 in the past.…”

“…However, all species showed an increase in the ratio between SD and SI (SD:SI), implying this ratio could be used to help detect SO 2 responses recorded by plants in the geological record and that this effect could cause the underestimation of pCO 2 using the stomatal method on material exposed to SO 2 in the past. Haworth et al (2012) then tested this assumption using the data of Steinthorsdottir et al (2011b) by plotting the SD:SI ratio of Ginkgoales fossil leaves across the Tr-J of Astartekløft, East Greenland, thus using the same cuticle database that we here investigate for potential SO 2 damage, and found a very significant increase (>100%) in the SD:SI ratio in bed 6. Although the increase in SD:SI as an SO 2 indicator in bed 6 is consistent with our observations of high levels of cuticle distortion, as well as with the highest reconstructed pCO 2 (Steinthorsdottir et al 2011b), there are important differences.…”