Journal cover Journal topic
Biogeosciences An interactive open-access journal of the European Geosciences Union
Journal topic
Discussion papers
https://doi.org/10.5194/bg-2019-55
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.
https://doi.org/10.5194/bg-2019-55
© Author(s) 2019. This work is distributed under
the Creative Commons Attribution 4.0 License.

Submitted as: research article 18 Feb 2019

Submitted as: research article | 18 Feb 2019

Review status
This discussion paper is a preprint. It is a manuscript under review for the journal Biogeosciences (BG).

Competition alters predicted forest carbon cycle responses to nitrogen availability and elevated CO2: simulations using an explicitly competitive, game-theoretic vegetation demographic model

Ensheng Weng1,2, Ray Dybzinski3, Caroline E. Farrior4, and Stephen W. Pacala5 Ensheng Weng et al.
  • 1Center for Climate Systems Research, Columbia University, New York, NY 10025, USA
  • 2NASA Goddard Institute for Space Studies, 2880 Broadway, New York, NY 10025, USA
  • 3Institute of Environmental Sustainability, Loyola University Chicago, Chicago, IL 60660, USA
  • 4Department ofIntegrative Biology, University of Texas at Austin, Austin, TX78712, USA
  • 5Department of Ecology & Evolutionary Biology, Princeton University, Princeton, NJ 08544, USA

Abstract. Competition is a major driver of carbon allocation to different plant tissues (e.g. wood, leaves, fine roots), and allocation, in turn, shapes vegetation structure. To improve their modeling of the terrestrial carbon cycle, many Earth system models now incorporate vegetation demographic models (VDMs) that explicitly simulate the processes of individual-based competition for light and soil resources. Here, in order to understand how these competition processes affect predictions of the terrestrial carbon cycle, we simulate forest responses to elevated CO2 along a nitrogen availability gradient using a VDM that allows us to compare fixed allocation strategies versus competitively-optimal allocation strategies. Our results show that competitive- and fixed-allocation strategies predict opposite fractional allocation to fine roots and wood, though they predict similar changes in total NPP along the nitrogen gradient. The competitively-optimal allocation strategy predicts decreasing fine root and increasing wood allocation with increasing nitrogen, whereas the fixed allocation strategy predicts the opposite. Although simulated plant biomass at equilibrium increases with nitrogen due to increases in photosynthesis for both allocation strategies, the increase in biomass with nitrogen is much steeper for competitively-optimal allocation due to its increased allocation to wood. The qualitatively opposite fractional allocation to fine roots and wood of the two strategies also impacts the effects of elevated [CO2] on plant biomass. Whereas the fixed allocation strategy predicts an increase in plant biomass under elevated [CO2] that is approximately independent of nitrogen availability, competition’s effect on wood allocation amplifies plant biomass under elevated [CO2] with increasing nitrogen availability. Our results indicate that the VDMs that explicitly include the effects of competition for light and soil resources on plant strategies may generate significantly different ecosystem-level predictions than those that use fixed allocation strategies.

Ensheng Weng et al.
Interactive discussion
Status: final response (author comments only)
Status: final response (author comments only)
AC: Author comment | RC: Referee comment | SC: Short comment | EC: Editor comment
Ensheng Weng et al.
Ensheng Weng et al.
Viewed  
Total article views: 381 (including HTML, PDF, and XML)
HTML PDF XML Total Supplement BibTeX EndNote
297 83 1 381 28 0 0
  • HTML: 297
  • PDF: 83
  • XML: 1
  • Total: 381
  • Supplement: 28
  • BibTeX: 0
  • EndNote: 0
Views and downloads (calculated since 18 Feb 2019)
Cumulative views and downloads (calculated since 18 Feb 2019)
Viewed (geographical distribution)  
Total article views: 341 (including HTML, PDF, and XML) Thereof 339 with geography defined and 2 with unknown origin.
Country # Views %
  • 1
1
 
 
 
 
Cited  
Saved  
No saved metrics found.
Discussed  
No discussed metrics found.
Latest update: 16 Sep 2019
Publications Copernicus
Download
Short summary
Our study illustrates that the competition processes for light and soil resources in a game-theoretic vegetation demographic model can substantially change the prediction of the contribution of ecosystems to the global carbon cycle. The model that tracks the competitive allocation strategies can generate significantly different ecosystem-level predictions than those with fixed allocation strategies.
Our study illustrates that the competition processes for light and soil resources in a...
Citation