Simulation of the Impact of Environmental Disturbances on Forest Biomass in Taiwan

Abstract

AbstractThis study seeks to understand the impact on the forest biomass of different kinds of environmental disturbance, including high winds from typhoons, land‐use/land‐cover changes (LULCC), and CO2 fertilization. A series of factorial experiments addressing the impact of different types of environmental disturbance on the forest biomass in Taiwan was conducted using the advanced ORCHIDEE‐CAN land surface model with a recently developed wind‐throw module. The climatic forcing driving the ORCHIDEE‐CAN land surface model was first simulated by an atmospheric general circulation model, then dynamically downscaled to a more satisfactory spatial and temporal resolution. The initial and boundary conditions applied in the numerical simulations were based on the long‐term CO2 concentration and LULCC reconstruction, respectively. The model simulation showed an increase in the aboveground wood volume from 209 m3 ha−1 in 1979 to 229 m3 ha−1 in 2017, and the dynamics were consistent with those recorded in the national forest inventory. The annual average carbon sequestration rate over the past 39 years was 0.5 m3 ha−1 yr−1 for a forested area of 2.4 M ha. The most surprising finding was the contribution of the wind disturbance to wood loss, which was at almost the same level as the annual carbon sequestration rate. The LULCC experiment showed a trade‐off between afforestation and deforestation in forest biomass accumulation in Taiwan from 1979 to 2017. The CO2 fertilization effect contributed to an enhancement of forest biomass stock of around 39%, while the CO2 concentration increased from 296 to 406 ppm over 39 years.