Episode 95: Plants and Atmosphere

The interaction between plants and atmosphere forms the basis of the carbon cycle and is amongst the most important processes for maintaining life on the planet today. Photosynthesis removes carbon dioxide from the atmosphere and in return forms the base of the food chain and produces the oxygen we, as animals, need to breathe. Equally, the composition of the atmosphere influences the climate and thus the availability of resources, governing where plants are able to survive.

The relationship between the two can be committed to the fossil record by such physical proxies as the number of stomata in leaves and by the palaeolatitude of different species. Other chemical proxies, such as isotopic ratios, can also help elucidate what the atmosphere was like at the time a plant was preserved. Similarly, atmospheric proxies can also be used to make inferences about past plant life in the absence of fossil remains.

Joining us to discuss the link between plants and atmosphere is Prof. Jennifer McElwain of Trinity College Dublin*, Ireland.

Plant growth chamber facilities are used to conduct plant experiments in simulated paleoatmospheric and paleoclimatic conditions.

A reconstruction of East Greenland, Astartekloft in the early Jurassic showing fern dominated vegetation following the Triassic-Jurassic extinction event. Image: Marlene Hill Donnelly.

A leaf fossil of Lepidopteris ottonis, a seed fern from the Late Triassic that goes extinct at the Triassic-Jurassic boundary

Confocal image of epidermal peel from Osnunda regalis (royal fern) showing red chloroplasts in the kidney shaped guard cells and jigsaw shaped epidermal cells. Changes in the density of stomata are used to reconstruct paleo-CO2 concentrations through earth history.