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DESCRIPTION:Max Lloyd\n\nAssistant Professor\, Geosciences\, Penn State Uni
 versity\n\nFriday\, October 4 \n\n12:00 pm \n\nFDA 232 \n\nHow well do pla
 nts breathe in glacial climates?\n\nLand plant photosynthesis today repres
 ents about half of global gross primary productivity. During the last glac
 ial period\, land plant productivity was reduced\, potentially by a factor
  of two. The specific cause of the terrestrial biosphere contraction durin
 g glacial periods is uncertain\, but important for understanding controls 
 on climate in the past and near-future. One hypothesized explanation for t
 his productivity decline is low atmospheric CO2 concentrations at the time
 \, because when [CO2] is low\, modern plants can release nearly as much ca
 rbon through photorespiration as they take in through photosynthesis. This
  could stress and starve plants at an individual level and perhaps at a gl
 obal scale. \n\nHowever\, direct evidence that high photorespiration suppr
 essed glacial terrestrial productivity is limited. I will describe new wor
 k applying a recently developed proxy for the relative rate of photorespir
 ation to photosynthesis based on clumped isotopes in wood methoxyl groups.
  We applied this proxy to samples of wood from across North America that s
 pan the last glacial period to the present. We find that photorespiration 
 rates vary in space and time. Specifically\, trees from the last glacial p
 eriod below ~40°N tended to photorespire more than those from higher latit
 udes and more than trees from similar locations in the more recent past. T
 hese differences can be reconciled with a single relationship between temp
 erature\, [CO2]\, and photorespiration. This suggests that despite environ
 mental adaptations\, trees from the glacial period experienced elevated ph
 otorespiratory stress compared to more recent counterparts. This provides 
 direct evidence that CO2 starvation restricted land plant productivity dur
 ing glacial intervals.\n\n \n
DTSTART:20241004T160000Z
DTEND:20241004T170000Z
SUMMARY:EPS Seminar Series: Max Lloyd
URL:/eps/channels/event/eps-seminar-series-max-lloyd-3
 59974
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