Abstract
Plant root nutrient acquisition, and to a lesser extent foliar nutrient uptake, maintain plant metabolism and strongly regulate terrestrial biogeochemistry and carbon-climate feedbacks. However, terrestrial biogeochemical models differ in their representations of plant root nutrient acquisition, leading to significantly different, and uncertain, carbon cycle and future climate projections. Here we first review biogeochemical principles and observations relevant to three essential plant root nutrient acquisition mechanisms: activity of nutrient acquiring proteins, maintenance of nutrient stoichiometry, and energy expenditure for these processes. We next examine how these mechanisms are considered in three existing modeling paradigms, and conclude by recommending the capacity-based approach, the need for observations, and necessary modeling developments of plant root nutrient acquisition to improve carbon-climate feedback projections.
Highlights
Since plants often live in environments with a limited supply of macronutrients, they must actively acquire these nutrients to fulfill their metabolic needs, such as surviving environmental stress, increasing biomass, and producing offspring (e.g., Cronan 2018)
Despite decades of research, there has been no consensus on which paradigm to use in terrestrial biogeochemical models (Wang et al 2010; Yang et al 2014; Zhu et al 2017), resulting in large uncertainty, and degrading the fidelity of biogeochemistry-climate feedback projections (e.g., Fleischer et al 2019)
Riley et al (2018) implemented both the relative demand approach and the capacity-based approach in the terrestrial biogeochemical module of the Energy Exascale Earth System Model (E3SM), and found that these two approaches resulted in large differences in predicted global N2O emission warming potential (2.4 Pg CO2 yr− 1) and nitrogen leaching (96% difference), highlighting the need to develop an accurate and mechanistically realistic plant root nutrient acquisition paradigm to improve modeling of biogeochemistry-climate feedbacks
Summary
Since plants often live in environments with a limited supply of macronutrients (i.e., nitrogen and phosphorus), they must actively acquire these nutrients to fulfill their metabolic needs, such as surviving environmental stress, increasing biomass, and producing offspring (e.g., Cronan 2018). Riley et al (2018) implemented both the relative demand approach and the capacity-based approach in the terrestrial biogeochemical module of the Energy Exascale Earth System Model (E3SM), and found that these two approaches resulted in large differences in predicted global N2O emission warming potential (2.4 Pg CO2 yr− 1) and nitrogen leaching (96% difference), highlighting the need to develop an accurate and mechanistically realistic plant root nutrient acquisition paradigm to improve modeling of biogeochemistry-climate feedbacks.
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