Evaluation On Vegetation Net Primary Productivity Using Modis Data In The Mongolian Plateau

This paper presents an investigation of the MODIS Satellite data is used to map onMongolian plateau terrestrial vegetation NPP by analyzing11years’（2000to2010）Plants are the most important part of the terrestrial ecosystem and biosphere. Netprimary productivity （NPP） is defined as accumulative organic matters by green plantsper unit of space and time. NPP not only reflect the plant community productivitydirectly for a certain natural environment but also fixing ability for CO2byphotosynthesis. It is a key component of the terrestrial carbon cycle and the basis ofmatter and energy cycle of terrestrial ecosystem. NPP is process an integral role in thecycle and balance of carbon on dry land.We have studied and examined regions of Mongolian plateau. The area of ourresearch is the central continental part which consists of high mountains regions in thenorthwestern, northern and northeastern parts and deserts and steppes in the south andsoutheastern parts in total of2.74million square kilometers. Thus, of the human negativeactivity and land degradations, Mongolia have been enduring many area problems suchas pasture degradation, desertification, soil erosion reduces of productivity of globalwarming in the last50years.Based on the CASA model and support of Geographic Information System, this paperstudied the spatial and temporal dynamics of Mongolian plateau NPP for recent elevenyears from2000to2010using NDVI data of MODIS/TERRA satellite, meteorologicaldata （average monthly temperature, average monthly precipitation, total solar radiation）and classified vegetation data.Conclusions:1. NPP is results from years2000-2010show that northern regions such as Khangai,Khuvsgul high mountain, Khentii mountain and east, northeastern regions encompassingthe Da Xing an ling mountain area. NPP value decreased from north to south and fromnortheast to southwest direction. This trend can be explained by the lack of precipitationand the decreased density of vegetation canopy cover in regions. High mountains and forest steppe zones have the highest NPP average more than400gC/m²/yr, steppe zonesand cropland200-300gC/m²/yr, the Great Lakes Basin, Umnugobi, Dornogobi, Alashanand desert Gobi area and water body have very low NPP values, it only ranges from0―100gC/m²/yr, and many parts of it are seem to be0.2. From this study, from2000to2010it was maximum NPP value is in2002and2010,is0,287Pg C/yrand0,294Pg C/yr (1Pg=10¹⁵). And minimum is in2005,2008the valueis0,243Pg C/yr,0,244Pg C/yr. The total NPP ranges from0,243-0,294Pg C/yr. in11years. Getting growth plants for vegetation cover in Mongolia plateau from April andstopped growth plants September. From July and August increases seasonal developmentand total biomass. For the monthly variation, the NPP increases rapidly from April toJuly, and it reached the maximum value in July. The quantity of NPP in July and Augustis49,6%of the total in seven months.3. For the NPP in different vegetation types, deciduous broadleaf and larch forest hasthe highest NPP value as777,69gC/m²/yr, the secondly is larch forest with470,61gC/m²/yr and the thirdly are dark and evergreen forest region, the mean value is all above300-364,15gC/m²/yr, croplands is466.812gC/m²/yr, grassland are shrub regionsaverage232,11gC/m²/yr and219.81gC/m²/yr, the minimum is the desert area with only44,24gC/m²/yr. However, grassland has the highest total NPP value because of its largearea, it has3.54x10¹⁴gC/yr and occupy57.07%of total NPP. Total NPP of the wholeforest ecosystem is7.4x10¹³gC/yr, and occupy12.8%of total NPP. For the NPP valueis of larch and evergreen, deciduous broadleaf forest and cropland are increased,grassland, shrub and plain flood and desert are normal. Thus, total NPP value isdecreased in the dark and evergreen forest duration11years.