动态冠层模型ICM的改进及其对中高纬地区植被季节和年际变化的模拟试验

植被动态冠层模型Interactive Canopy Model(ICM)考虑了生态系统中较完整的碳氮循环过程,能够较为客观真实地描述较短时间尺度上植被的动态变化特征.本文在ICM原有碳氮分配方案基础上,考虑了植物花、果实等新生组织对碳氮分配的影响,假设新生组织碳库是花期以后植物的主要碳汇之一,并利用物候模型Fore-...

Seasonal and Interannual Variations of Boreal Vegetation Simulated by an Improved Interactive Canopy Model (ICM)

The dynamic vegetation model, Interactive Canopy Model (ICM), which includes the ecosystem carbon and nitrogen cycling processes, is able to model the vegetation variations on short time scales. A reproductive organs carbon pool that constitutes flowers and fruits has been added into the original carbon and nitrogen reservoirs. It is assumed that the reproductive organs carbon pool will be a main carbon sink from the dates of vegetation flowering. A phenological model, ForcSar, is used to predict the flowering dates when the main partitioning positions of carbon and nitrogen change. The simulated LAI (Leaf Area Index) from the modified ICM is compared with the observations from satellite data in boreal middle and high latitudes where the vegetation varies the most severely all the year round. It shows that the seasonal variations of boreal vegetation can be better simulated than before. The modified ICM represents its maximal LAI in July, conforming to the reality, so that the problem of modeled vegetation growth lag in the original ICM has been rectified. The correlation coefficients of observed and simulated seasonal LAI are obviously higher than before. And the errors are decreased for all types of boreal vegetations. Besides, the correlation of observed and simulated interannual LAI is increased to some extent, even not very prominent. The changeable LAI from the ICM will alter the land surface conditions such as energy balance and water cycle. Solar radiation absorbed by vegetation, sensible heat fluxes and latent heat fluxes change significantly before the blossom of vegetation in the case of temperate deciduous broadleaf trees in eastern USA. And therefore the modeled physical properties of land surface will be influenced.