Research About The Net Primary Productivity Of The Farmland In The Northeast Of China Based On The CASA Model

Vegetation net primary productivity of the green plants characterized the light energy utilization degree, or represents the vegetation will light conversion into organic ability, its accurate definition is green plants in unit area, time unit can accumulate organisms quantity, it is the need of plant satisfy oneself growth after the organic consumed by the rest number. Northeast area is the largest granary. Study the net primary productivity, for our country's food supply to implement relevant food policy and provide scientific basis and decision-making basis. This paper use of international fashion, a model for the CASA, combined with improved NDVI remote sensing data and meteorological data, estimate the 1982-2009 farmland of growing season in northeast China net primary productivity, and analyzed the influence of the main vegetation net primary productivity of natural factors and human factors. The work of this paper and main conclusions include:(1)The improvement and construction CASA modelUsing the improved CASA model estimation 1982-2009 northeast area farmland net primary raw growing season Production force in the existing data, on the basis of the characteristic, according to the study of the main parameters are CASA model is improved and processing: first is the sun total radiation calculation, abandoned using FuSheDian calculation, take common climate experience model method to estimate the total radiation; sun Secondly, by means of the existing air temperature, precipitation, etc, and combined with the meteorological data regional evapotranspiration model to estimate water stress factor, and give up using soil parameter calculation, and thereby reducing the amount of data, calculation method is simpler and more convenient. Through the estimation results and statistical data of comparison, discover finally simulation results of comparative believable.(2) AML modelingThis paper all model building and data input and output are using the AML construct, relative to ArcGisEnvironment, Workstation in Arc thing, using AML language environment operation, its speed faster, more efficient, and middle data can be conducive to the preservation, all data query.(3) Northeast NPP spatial distribution of farmland growing season and changing trendsThe spatial distribution of farmland NPP and no big changes in its general distribution pattern is, in the northeast region west NPP yield farmland from west to east, lowest is increasing gradually, but in the east of heilongjiang province the NPP are low yield farmland, general situation is greater than northwest NPP southeastern farmland; Based on the statistical analysis as yuan, the increasing trend of change trend as yuan is mainly distributed in the southwest, reduce the trend mainly distributed in the pixels, combined with central and northeastern above-regions NPP high percentage found that division of farmland output declines, and low but have grown farmland increasing.(4) Northeast China farmland analyzing the influential factors of NPP growing season The growing season average in northeast China NPP yield farmland influence factors of traditional statistical analysis method, through the space, based on statistical methods like yuan, came to the growing season in the northeast NPP yield and farmland precipitation growing season positively correlation with verage temperature of growing season into line negative correlation; Human analysis traffic factors, found that distance closer, farmland path NPP growing season the higher yield.