Terrestrial plant production and climate change

Area of Science:

• Ecology
• Plant Physiology
• Climate Change Science

Background:

• Global plant production is projected to change due to rising atmospheric CO2 and climate shifts.
• Mechanistic models are crucial for estimating future plant production and assessing uncertainties.

Purpose of the Study:

• To review the sensitivities of the Hybrid6.5 model, a detailed mechanistic model of terrestrial primary production.
• To assess the impact of model assumptions, future CO2 levels, and climate change on global production predictions.

Main Methods:

• Sensitivity analyses were performed on the Hybrid6.5 model.
• The study evaluated the effects of leaf phenology, Generalized Plant Type (GPT) specific parameterizations, and elevated CO2 concentrations on net primary production (NPP).

Main Results:

• Leaf phenology significantly impacts C3 crop and cold deciduous tree production, reducing NPP by up to 41.6%.
• GPT-specific parameters, like photosynthetic capacity, alter predicted NPP for C3 plants by -22.3% to 27.9%.
• Elevated CO2 (720 ppm) is predicted to increase global NPP by 37.3%, with greater increases for C3 plants (43.9-52.9%) than C4 plants (5.9%).

Conclusions:

• Model assumptions, particularly leaf phenology and plant type parameters, significantly influence NPP predictions.
• Future CO2 increases are likely to enhance global NPP, but acclimation processes and biomass allocation create uncertainties.
• Close collaboration between experimentalists and modelers is essential to reduce uncertainties in predicting future plant production.