Estimation Of Vegetation Net Primary Productivity In The Hebei Province Based On The MODIS Data

With the rapid development of the global economy and the increasingly seriousproblems of the population, resources and environment problems, the atmosphericconcentration of greenhouse gas concentration rise significantly, leading to globalwarming, which may lead to a series of environmental problems in the global scope,asking the world to give high attention and take effective strategy. CO2as thegreenhouse gas, is a main content in the research of global carbon cycle, terrestrialecological system adjust the amount of CO2,which promote the ecological balance inthe global climate change. So the research of terrestrial ecosystem and carbon cyclehas the important significance in the aspects of dealing with the problems of theglobal climate. NPP, net primary productivity, is the key parameter of terrestrialecosystem and is also an important indicator of the carbon cycle.The Hebei province rings Beijing and Tianjin, what’s advantage of location andresources is obvious, the research of NPP has certain practical significance, tounderstand the NPP situation accurately, and provide guidance for the governmentand related departments to formulate the relevant decision-making in the Hebeiprovince.This paper uses CASA model, taking Hebei province as the research object, withArcGIS and ENVI software as support, uses composed multi-temporal MODISimages, vegetation type data and meteorological data (precipitation data, thetemperature data, the sun total radiation, the sun net radiation, etc), analysis ofvegetation NPP in Hebei province and pattern and NPP impact factor driving forcesize, and tries to explore NPP and the relationship between the human activity. Thispaper analyses the space-time pattern and the impact factor driving force size of NPPin Hebei and try to explore the relationship between NPP and the human activity.The results of the study show that:The NPP value of different vegetation types are changing as time, which showbasically the characteristics of unimodal curve. In July, the NPP value of all kinds of vegetation is maximum which is the peak value and in November that is minimum.The trends of NPP value about different vegetations are roughly similar, but theamplitude is not the same.Also the NPP value of the different vegetation types are changing as season andthis change is relatively obvious. The NPP accumulation of the different vegetationtypes mainly concentrated in the summer, the second is the spring, and the last is theautumn. Comparing the contribution of total NPP, the forest is biggest, accounting for41.48%in the total NPP contribution of the six types of vegetation types; the secondis garden, accounting for18.88%; after the cultivated land, accounting for15.9%; thegrass is minimum, accounting for15.34%.In2009, the highest uniform annual value of NPP is1140gc/·y. In Hebei province,the Hebei north is the highest, the value is568gc/·y, the second is the Central andsouthern, the value is272.8, the last is the coastal areas, and the value is545gc/·y.In the11cities of Hebei province, the area of the highest annual mean NPP is chengde,the second is qinhuangdao, hengshui, baoding, shijiazhuang, xingtai, handan city arebigger, and zhangjiakou is minimum. The distribution trend of the total NPP and themean NPP are slightly different in the11cities of Hebei. The total annual NPP ofchengde, zhangjiakou and baoding are up to5.45×107gc/·y or above, accounting formore than12.5%in the total amount of NPP; The second is shijiazhuang accountingfor7.4%in the total amount of NPP; The total annual NPP of cangzhou, xingtai,tangshan, handan, hengshui and qinhuangdao are smaller, accounting for6.67%in thetotal amount of NPP; And langfang are minimum, accounting for only3.06%in thetotal amount of NPP. In the study, we make a statistical analysis about amount of NPPeach area unit GDP in2009, and find that zhangjiakou and chengde city are largest;hengshui, xingtai, baoding is in middle position, shijiazhuang, tangshan are minimumtotal NPP, which appeal to protecting vegetation to promote sustainable developmentof economy and environment.The analysis of driving force size of NPP impact factors show that the drivingforce size of NPP is decided by mutual influences and various parameters, all of themrelate to each other, but temperature and precipitation play a main role.