Process‐Based Modeling of Ecosystem‐Level Monoterpene From a Japanese Larch (Larix kaempferi) Forest.

Globally, the emission of biogenic volatile organic compounds (BVOC) by plants represents the dominant source of volatile organic compounds emitted to the atmosphere. Monoterpenes, as the major BVOC group, can contribute to forming secondary organic aerosols and influence cloud properties. In this study, we developed a process‐based monoterpene module in the Vegetation Integrative SImulator for Trace gases (VISIT) model by considering the production, storage, and emission of monoterpene as three main processes. We further evaluated the modeled monoterpene emissions against the ecosystem‐level observation data at a half‐hour scale at a Japanese larch (Larix kaempferi) forest site on Mt. Fuji, Japan. The VISIT model performed with relatively higher accuracy with a Willmott's index of agreement at 0.61, a mean bias error (MBE) at 0.29, and a root mean squared error (RMSE) at 0.43, comparable to that of Model of Emissions of Gases and Aerosols from Nature model with a Willmott's index of agreement at 0.63, a MBE at 0.40, and a RMSE at 0.54. In a long‐term simulation under high CO2 emission scenarios, the ratio between monoterpene emission and gross primary production exhibited a stronger correlation with CO2 concentration than temperature. Our study provides a process‐based modeling approach for more accurately simulating monoterpene emissions from Japanese larch. Plain Language Summary: This study focuses on constructing the process and improving the accuracy of simulating emissions of biogenic volatile organic compounds (BVOC), specifically monoterpenes, from a Japanese larch forest using the Vegetation Integrative SImulator for Trace gases model. By incorporating a process‐based monoterpene module, the model demonstrated better performance compared to the widely‐used Model of Emissions of Gases and Aerosols from Nature model. The simulated results showed temperature acting as the dominant factor in determining the proportion between gross primary production and monoterpene emission in the short term. In future projections, the analysis emphasized the significant role of long‐term increases in CO2 concentration in determining this proportion. This study provides a valuable tool for simulating site‐based BVOC emissions, contributing to our understanding of the complex interactions between vegetation and the atmosphere. Key Points: The process‐based ecosystem model shows better performance than empirical model in modeling monoterpene emission from a Japanese larchHigh emission of CO2 in future will significantly influence the proportion between gross primary production and monoterpene emission [ABSTRACT FROM AUTHOR]