Parameter Optimization For Improving Poplar Plantation Simulation Based On The Measurement And Modeling Of Stomatal Behavior

It is of great significance to study how the interactive factors of climate and management effect on the production of poplar plantation. We conducted a meta-analysis of poplar production data and tried to find the most crucial factor of climate and management to influence poplar production. through statistical analysis of ANOVA and structural equation model., At the beginning of the study, we extracted the mean annual increment of aboveground net primary production (MAI) of poplar plantation, management and climate factor data from published literature to set up the poplar growth database, then analyze the statistical relationship between these factors. We then measured photosynthetic performance of poplar tress of different ages and modelled photosynthetic and stomatal parameters from A-Ci curve. Meta-analysis results showed that the average poplar plantation MAI in global is about 6.3 Mg ha-1 yr-1, and 5.1,8.1,4.4 Mg ha-1 yr-1 in Europe, United States and China, respectively. MAI of poplar plantation was significantly correlated with GDD, precipitation and planting density, and formed a quadratic relationship with stand age. Globally, the reason of low productivity in poplar plantation may be related to lack of moisture, rotation period length and planting density. SEM analysis showed that the effects of climatic factors on poplar growth were more important than management factors, and a longer rotation will significantly increase soil carbon sequestration. Stomatal slope-a model parameter that can reflect the water use efficiency (WUE) will change due to poplar age and environment factors, indicating the sensitivitivity between photosynthetic and stomata with external environment factors will differ with growth stage and environmental factors. Through this study, we find that management factors of rotation period length have the amazing growth increment of aboveground biomass in poplar plantation, it will also improve the soil carbon sequestration, as well as beneficial for quantifying long-term soil carbon storage in short rotation forestry. The stomatal model and photosyntheticmodel we used was accurate.The model parameters will not change along with growth stage, but it will change with species and different habitat environment. The parameter optimization process in ecosystem model--BioCro indicated that modification of photosynthetic and stomatal behavior parameters can significantly improve the accuracy of model simulation. Findings of this research will make a contribution to assuring the sustainable development of poplar plantation, guiding future researches, establishment of policy and management plan.