Terrestrial biosphere models may overestimate Arctic CO2 assimilation if they do not account for decreased quantum yield and convexity at low temperature.
New Phytol
; 223(1): 167-179, 2019 07.
Article
en En
| MEDLINE
| ID: mdl-30767227
ABSTRACT
How terrestrial biosphere models (TBMs) represent leaf photosynthesis and its sensitivity to temperature are two critical components of understanding and predicting the response of the Arctic carbon cycle to global change. We measured the effect of temperature on the response of photosynthesis to irradiance in six Arctic plant species and determined the quantum yield of CO2 fixation ( ÏCO2 ) and the convexity factor (θ). We also determined leaf absorptance (α) from measured reflectance to calculate ÏCO2 on an absorbed light basis ( ÏCO2.a ) and enabled comparison with nine TBMs. The mean ÏCO2.a was 0.045 mol CO2 mol-1 absorbed quanta at 25°C and closely agreed with the mean TBM parameterisation (0.044), but as temperature decreased measured ÏCO2.a diverged from TBMs. At 5°C measured ÏCO2.a was markedly reduced (0.025) and 60% lower than TBM estimates. The θ also showed a significant reduction between 25°C and 5°C. At 5°C θ was 38% lower than the common model parameterisation of 0.7. These data show that TBMs are not accounting for observed reductions in ÏCO2.a and θ that can occur at low temperature. Ignoring these reductions in ÏCO2.a and θ could lead to a marked (45%) overestimation of CO2 assimilation at subsaturating irradiance and low temperature.
Palabras clave
Texto completo:
1
Colección:
01-internacional
Banco de datos:
MEDLINE
Asunto principal:
Teoría Cuántica
/
Temperatura
/
Dióxido de Carbono
/
Ecosistema
/
Modelos Teóricos
Tipo de estudio:
Prognostic_studies
Idioma:
En
Revista:
New Phytol
Asunto de la revista:
BOTANICA
Año:
2019
Tipo del documento:
Article
País de afiliación:
Estados Unidos