为了有效的利用高光谱卫星数据获取植被信息,Furumi等在模式分解方法(PDM)的基础上,建立了一种新的植被指数(VIPD).根据地面实验建立的相应光合成曲线植被净初级生产力(NPP)遥感估算模型,利用2001年前后多个月份的MODIS影像数据,对日本纪伊半岛地区的植被净初级生产力进行了估算.研究表明,根据地面实验建立估算模型估算得到的温带常绿植被净初级生产力年均值,与2001年IPCC调查报告上的估算值,在误差范围内一致.地面实验结果证明该光合成曲线NPP估算模型能够较好的应用于温带植被研究.在北纬32°30'-36°24',东经134°30'-137°06',面积3.94×104 km2研究区域内,2001年NPP约为6.11kg CO2/a.从NPP的空间分布上而言,纪伊半岛范围内单位面积NPP以三重和奈良县山地林地带最高,达2.56kg CO2/m2/a.在纪伊半岛植被分类中,温带落叶植被的年均NPP最大,约为2.23 kg CO2/m2/a,水田的年均NPP最小,仅约为1.42 kg CO2/m2/a.
Industrial development and human activities have greatly altered land cover over the past several decades.Besides, the increased cutting of forests and burning of fossil fuels have raised carbon dioxide concentrations in the atmosphere and has led to global temperature increases. Photosynthesis by vegetation removes carbon dioxide from the atmosphere and so plays an mi portant role in the carbon cycle. Tomeasure net prmi ary production (NPP) is a way to understand the photosynthesis capabilities of the vegetation.NPP has been assessed using satellite data by severalmethods,which includes the light-use efficiency (LUE) model and normalized difference vegetation index (NDVI)both ofwhich are commonly employed using the red and near-infrared channels. In order to study zonal net prmi ary production (NPP) effectively using multi-spectral satellite data,a new vegetation index based on pattern decomposition method and a NPP estmi ation model taking into account photosynthetic saturation are developed by field expermi ents.In this paper, we focus on estmi atingNPP for a temperate forest zone (Kii Peninsula, Japan, mainly covered by temperate forest)usingMODIS data of2001with a spatial resolution of 500m.To understand the photosynthetic capability ofdifferentvegetation types, we calculatedNPP values foreach land cover type usingboth the proposedmethod and aLUE mode.l Based on the land cover classification, global solar exposure, air temperature, andmonthly average effective day length for vegetation photosynthesis,with the proposedmethodwe estmi ated the following annualNPP values(in units of\nkgCO2/m2/a): evergreen, 2.04; deciduous, 2.23; farm,1.74;paddy,1.42;and urban area, 1.06. In comparison,the LUEmodelestmi ated the following values: evergreen, 1.99; deciduous, 2.09; farm, 1.76; paddy, 1.53; and urban area,1.23. An IPCC reporthas listedNPP estmi ates for temperate forests as 2.29 and 2.86 kgCO2/m2/a.The annual values of zonalNPP for the evergreen category calculated using the proposedmethod agreewith those listed by the IPCC reportwithin the algorithm error of26%.To validate the proposedmethod, resultswere compared NPP based on land surveys of temperate forestwith paddy areas. The forest survey took place at an 80×80 m plotonYoshinoMountain inNara Prefecture. The forest resultswere 1.52±0.36 kgCO2/m2/a for the proposedmethod, 1.15 kgCO2/m2/a for theLUEmode,l and 1.50±0.75 kgCO2/m2/a for the survey data. The NPP estmi ations by the survey and proposed method were more agreed within the permissible error. However, the paddyNPP estmi ated using satellite data (1.42 kg CO2/m2/a) was nearly 60% that of the field\nsurvey (2.48kgCO2/m2/a).Because that paddies receive various nutrient and water supplements, unlike a natural forest,and thismayhave affected the parametercalculation. Additional field surveysofpaddy areas are planned in theKii Peninsula to developmore precise paddy parameters.Although theNPP estmi ate forpaddywas only 60% of the surveyNPP, paddy only affected 3% of theKiiPeninsula zonalNPP and thus could be ignored here. Accounting for the 26% estmi ated errorof the algorithm,for thewhole region from 32°30′to 36°24′N,134°30′to 137°06′E (area=3.94×104km2), the annual zonalNPPwas calculated as6.11±1.62 kgCO2/a.This study shows that the proposed NPP estmi ationmethod can be applied to temperate forestregions, such as theKii Peninsula. Verifying themethod in other vegetation areaswill lead to greaterprecision and allow forNPP estmi ation on a global scale.