J Plant Ecol ›› 2016, Vol. 9 ›› Issue (3): 285-295.DOI: 10.1093/jpe/rtv059

• Research Articles • Previous Articles     Next Articles

Inverse analysis of coupled carbon-nitrogen cycles against multiple datasets at ambient and elevated CO2

Zheng Shi1, Yuanhe Yang1,2,*, Xuhui Zhou1, Ensheng Weng1, Adrien C. Finzi3 and Yiqi Luo1   

  1. 1 Department of Botany and Microbiology, University of Oklahoma, Norman, OK 73019, USA; 2 State Key Laboratory of Vegetation and Environmental Change, Institute of Botany, Chinese Academy of Sciences, Beijing 100093, China; 3 Department of Biology, Boston University, Boston, MA 02215, USA
  • Received:2015-07-08 Accepted:2015-07-14 Published:2016-05-25
  • Contact: Yang, Yuanhe

Abstract: Aims Carbon (C) sequestration in terrestrial ecosystems is strongly regulated by nitrogen (N) processes. However, key parameters that determine the degree of N regulation on terrestrial C sequestration have not been well quantified.
Methods Here, we used a Bayesian probabilistic inversion approach to estimate 14 target parameters related to ecosystem C and N interactions from 19 datasets obtained from Duke Forests under ambient and elevated carbon dioxide (CO2).
Important findings Our results indicated that 8 of the 14 target parameters, such as C:N ratios in most ecosystem compartments, plant N uptake and external N input, were well constrained by available datasets whereas the others, such as N allocation coefficients, N loss and the initial value of mineral N pool were poorly constrained. Our analysis showed that elevated CO2 led to the increases in C:N ratios in foliage, fine roots and litter. Moreover, elevated CO2 stimulated plant N uptake and increased ecosystem N capital in Duke Forests by 25.2 and 8.5%, respectively. In addition, elevated CO2 resulted in the decrease of C exit rates (i.e. increases in C residence times) in foliage, woody biomass, structural litter and passive soil organic matter, but the increase of C exit rate in fine roots. Our results demonstrated that CO2 enrichment substantially altered key parameters in determining terrestrial C and N interactions, which have profound implications for model improvement and predictions of future C sequestration in terrestrial ecosystems in response to global change.

Key words: Bayesian probabilistic inversion, carbon-nitrogen interactions, carbon-nitrogen coupled model, Duke FACE

摘要:
Aims Carbon (C) sequestration in terrestrial ecosystems is strongly regulated by nitrogen (N) processes. However, key parameters that determine the degree of N regulation on terrestrial C sequestration have not been well quantified.
Methods Here, we used a Bayesian probabilistic inversion approach to estimate 14 target parameters related to ecosystem C and N interactions from 19 datasets obtained from Duke Forests under ambient and elevated carbon dioxide (CO2).
Important findings Our results indicated that 8 of the 14 target parameters, such as C:N ratios in most ecosystem compartments, plant N uptake and external N input, were well constrained by available datasets whereas the others, such as N allocation coefficients, N loss and the initial value of mineral N pool were poorly constrained. Our analysis showed that elevated CO2 led to the increases in C:N ratios in foliage, fine roots and litter. Moreover, elevated CO2 stimulated plant N uptake and increased ecosystem N capital in Duke Forests by 25.2 and 8.5%, respectively. In addition, elevated CO2 resulted in the decrease of C exit rates (i.e. increases in C residence times) in foliage, woody biomass, structural litter and passive soil organic matter, but the increase of C exit rate in fine roots. Our results demonstrated that CO2 enrichment substantially altered key parameters in determining terrestrial C and N interactions, which have profound implications for model improvement and predictions of future C sequestration in terrestrial ecosystems in response to global change.