LPJ-WHyMe模型对1997～2010年中国东北地区潜在植被分布和碳循环的模拟研究

利用一套高分辨率的气候驱动场和全球动态植被模型LPJ-WHyMe(Lund-Potsdam-Jena-Wetland Hydrology and Methane),模拟了中国东北地区潜在植被分布,并对中国东北地区1997～2010年平均净初级生产力（Net Primary Production, NPP）、净生态系统生产力（Net Ecosystem Production, NEP）、燃烧面积、火灾碳排放、土壤温度和土壤湿度进行了估算。LPJ-WHyMe的特点在于能够描述冻融的物理过程以及土壤中多层的湿度和温度。数值结果表明,在LPJ-WHyMe模型提供的植被功能类型（Plant Function Type, PFT）划分的条件下,中国东北地区主要分布了5种植被功能类型,即温带夏绿阔叶林带、北方常绿针叶林带、北方夏绿针叶林带、北方夏绿阔叶林带和温带草本植物。在研究时间段内,中国东北地区NPP的年平均值为376 g(C) m-2,变化范围在324.15～424.86 g(C) m-2之间。火灾机制的引入使得LPJ-WHyMe模型对NEP的模拟能力进一步提高,即NEP年平均值为42.36 g(C) m-2,表明中国东北地区陆地生态系统总体表现为“碳汇”。中国东北地区年平均燃烧面积分数为0.84%,火灾碳排放量为42.41 g(C) m-2,整体上模型高估了燃烧面积值和火灾碳排放量,模型对东北地区火灾的模拟仍然存在一定的局限性。中国东北地区土壤温度与气温呈正相关关系,且各层土壤温度与气温的相关性随着深度的增加而减弱。中国东北地区土壤湿度与降水呈正相关关系,土壤湿度与气温呈反相关关系。上述结果表明LPJ-WHyMe模型模拟中国东北地区潜在植被分布和碳循环是有效的。

Simulation of Potential Vegetation Distribution and Carbon Cycle in Northeast China from 1997 to 2010 by LPJ-WHyMe Model

The potential vegetation distribution, the net primary production (NPP), net ecosystem production (NEP), burned area, carbon emissions from fires, soil temperature, and soil moisture in Northeast China from 1997 to 2010 was simulated by using a high-resolution climate-driven field and global dynamic vegetation model, i.e., Lund-Potsdam-Jena Wetland Hydrology and Methane (LPJ-WHyMe) model. The LPJ-WHyMe model is characterized by the capability to describe the physical processes of freezing and thawing, as well as the humidity and temperature of multiple layers in the soil. The five main plant functional types in Northeast China are temperate broad-leaved summergreen tree, boreal needle-leaved evergreen tree, boreal needle-leaved summergreen tree, boreal broad-leaved summergreen tree, and C3 perennial grass. During the period under study in Northeast China, the average value of NPP is 376 g(C) m^-2, ranging from 324.15 g(C) m^-2 to 424.86 g(C) m^-2. The introduction of the mechanism of fire further improves the simulation capability of the LPJ-WHyMe model for NEP. The average value of NEP is 42.36 g(C) m^-2. The annual average burned area is 0.84% and the carbon emission from fire is 42.41 g(C) m^-2 in Northeast China. Overall, the model overestimated the burned area and carbon emission from fire. Moreover, the model still has some limitations in the simulation of fire in Northeast China. A positive correlation between soil and air temperatures is observed in Northeast China, and the correlation in each layer decreases with the increase in depth. A positive correlation between soil moisture and precipitation and a negative correlation between soil moisture and air temperature are observed in Northeast China. These results show that the LPJ-WHyMe model is effective in simulating the potential vegetation distribution and carbon cycle in Northeast China.