福建省森林生态系统NPP的遥感模拟与分析

利用MODIS遥感影像,结合气象资料等数据,采用BEPS过程模型对2004年福建省的森林生态系统植被净初级生产力(NPP)进行了模拟验证。研究结果表明,2004年福建省森林生态系统NPP平均值为578.97gC/m²·a,NPP总量累计达到46.18×106tC;不同林地NPP全年平均值大小依次为:竹林≈阔叶林>杉木>马尾松,其值分别为:788.6gC/m²·a,780.0gC/m²·a,519.8gC/m²·a,437.3gC/m²·a;时空分析结果表明,2004年6-8月NPP形成较为明显的"坑"形分布形态,主要的原因之一很可能是有效降水量偏少;在空间分布上,福建省森林生态系统NPP与海拔高程显著相关,体现了该地区森林生态系统NPP空间分布的地域特征,这在一定程度上表明随着海拔上升,山高坡陡,人类对森林生态系统的干扰活动减少,有助于森林生态系统生产力的提高和维持。最后,分析了应用BEPS过程模型模拟福建省森林生态系统净初级生产力的不确定性问题。

Simulation by Remote Sensing and Temporal-spatial Analysis of Forest Ecosystem Net Primary Productivity in Fujian Province,China

Net primary productivity（NPP）,defined as the net flux of carbon from atmosphere into green plants per unit time,is a fundamental ecological variable to measure the energy input of biosphere and terrestrial carbon dioxide assimilation,to indicate the condition of land surface area and status of a wide range of ecological processes.In recent decades,model simulation becomes a major technique for NPP estimation over large areas,which can be divided into several categories as statistical model,parameter model and process-based model.As one of the essential process-based simulator models,the boreal ecosystem productivity simulator（BEPS） was adopted to simulate the forest ecosystem NPP in this paper.With support of MODIS images,meteorological data and so on,forest ecosystem NPP for Fujian Province of China in 2004 was simulated by BEPS model and validated by forest carbon sink investigation data.The simulated result shows that,in 2004,annual mean NPP of forest ecosystem is about 578.97g C/m^2·a,and the sum NPP reaches 46.18×10^6t C;the order of woodlands NPP is： bamboo ≈ broad-leaved treesfirChinese red pine,and the average NPP is 788.6gC/m^2·a,780.0gC/m^2·a,519.8gC/m^2·a and 437.3gC/m^2·a respectively.The time-serials analysis of monthly NPP demonstrates that the forest NPP declined a lot during the period from June to August,which is the highest NPP under usual conditions.The precipitation decrease from June to August in 2004 is most likely to be one of the major factors for NPP decline,after the statistic analysis of meteorological data with monthly NPP.On the other hand,the positive correlation between annual forest NPP and elevation is outstanding,where the determination coefficient reaches 0.99.This special phenomenon implies,to some extent,that with the increase of elevation,the interference from human activity is lightened and the forest ecosystem NPP is improved and sustained.In other words,diminishing human interference to forest ecosystem is one of the key measures to maintain the robust productivity of forest,further to mitigate global climate warming.Finally,the uncertainty of BEPS simulation was discussed in brief with the data and the simulator itself.