Leaf trait plasticity alters competitive ability and functioning of simulated tropical trees in response to elevated carbon dioxide

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Authors

Marlies Kovenock , Charles D. Koven , Ryan G. Knox, Rosie A. Fisher , Abigail L. S. Swann

Abstract

The response of tropical ecosystems to elevated carbon dioxide (CO$_2$) remains a critical uncertainty in projections of future climate. Here we investigate how leaf trait plasticity in response to elevated CO$_2$ alters projections of tropical forest competitive dynamics and functioning. We use vegetation demographic model simulations to quantify how plasticity in leaf mass per area and leaf carbon to nitrogen ratio alter the responses of carbon uptake, evapotranspiration, and competitive ability to a doubling of CO$_2$ in a tropical forest. Observationally constrained leaf trait plasticity in response to CO$_2$ fertilization reduces the degree to which tropical tree carbon uptake is affected by a doubling of CO$_2$ (up to -14.7\% as compared to a case with no plasticity; 95\% confidence interval $CI_{95\%}$ -14.4 to -15.0). It also diminishes evapotranspiration (up to -7.0\%, $CI_{95\%}$ -6.4 to -7.7), and lowers competitive ability in comparison to a tree with no plasticity. Consideration of leaf trait plasticity to elevated CO$_2$ lowers tropical ecosystem carbon uptake and evapotranspirative cooling in the absence of changes in plant type abundance. However, ‘plastic’ responses to high CO$_2$ which maintain higher levels of plant productivity are potentially more competitively advantageous, thus, including changes in plant type abundance may mitigate these decreases in ecosystem functioning. Models that explicitly represent competition between plants with alternative leaf trait plasticity in response to elevated CO$_2$ are needed to capture these influences on tropical forest functioning and large-scale climate.

DOI

https://doi.org/10.31223/X50W24

Subjects

Biogeochemistry, Climate, Terrestrial and Aquatic Ecology

Keywords

tropical forests, evapotranspiration, carbon-nitrogen dynamics, demographic vegetation model, evapotranspiration, leaf trait plasticity, tropical forests, carbon-nitrogen dynamics, demographic vegetation model, leaf trait plasticity

Dates

Published: 2020-10-21 09:25

Last Updated: 2020-10-21 16:25

License

CC BY Attribution 4.0 International

Additional Metadata

Data Availability (Reason not available):
Model output used in this study is available through the University of Washington Libraries ResearchWorks digital repository at http:// hdl.handle.net/1773/46218

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