Spatio-temporal Dynamics Of The Net Primary Production (NPP) Using GLOPEM-CEVSA Model In Chongqing Province

Forest ecosystem circulation research is of great importance in the research of global climate change, and the Net Primary Productivity (NPP) is one of the important indexes of terrestrial vegetation dynamics. In the terrestrial ecosystem carbon balance adjustment, NPP plays an irreplaceable role. With the development of the urban expansion and economic, the ecological environment quality is more and more important, People are becoming more and more attention about the environment. Chongqing is located in the southwest of China, and it is located in the eastern Sichuan basin.There are many higher mountains surround it. Because of its unique geographical location and terrain conditions, and the most of Chongqing in the three gorges reservoir area.It is one of the ecological environment sensitive areas,the space-time dynamic changes on the estimation of vegetation productivity has important theoretical and practical significance on climate change and carbon source/sink research. So it is necessary to figure out the vegetation production capacity of Chongqing area. This article is based on remote sensing (RS) and GIS technology, using remote sensing-process coupling model (GLOPEM-CEVSA), The 34 site meteorological data were adopted, such as temperature, precipitation and sunshine time. For spatial interpolation of meteorological data, based on the use of smooth sheet sample interpolation software ANUSPLIN.And the EOS/MODIS remote sensing data were used to absorb the photo synthetic active radiation ratio (FPAR).Then the parameters in the model and the related data to drive the model together.we calculated the net primary productivity (NPP) from 2001a to 2011 in the Chongqing area, a total of 11 years. APAR and NPP for 11 years and the dynamic space-time distribution were analyzed. The purpose is to understand that net primary productivity (NPP) of Chongqing area. For the point of Chongqing region ecological environment protection and CO2 emissions, in order to provide some data support and related suggestions. The main conclusions were as follows:(1) From the aspect of the land cover in Chongqing, the point of spatial distribution, NDV1 showed a downward trend from northeast to southwest; According to the variation distribution of NDVI, it can be seen that the land cover has a good trend, as the whole it is increasing, increases by about 8% for parts of southeast and northeast in Chongqing, in the region of west Chongqing, the NDVI significantly increased. On the scale of time, NDVI showed a rising trend during 2001-2011 as a whole, the interannual scale, the mean NDVI from 0.59 to 0.66, on the scale of month, NDVI increased from 0.45 in January to 0.79 in July, it is more obvious that the NDVI were growing from March to June.(2) In the distribution of Photosynthetic active radiation (APAR), In the northeast of Chongqing, Dabashan mountain and Wuling mountain, in urban area and the west of chongqing and Chongqing urban area, the APAR were gradually decreasing. On the scale of time series, the surface total photosynthetic radiation (APAR) presents that it is reducing in the future. On the total amount of 5.58 x 1013 MJ～6.18×1013 MJ, it has obvious seasonal variation characteristics. Summer was higher, winter was lower. From in terms of the altitude, APAR showed that the increasing trend with altitude first, and then the APAR reduced after reaching a certain height. APAR is higher in southern slope, it is lower in northern slope.(3) Average NPP distributed within 0-1040.3 g C/m2a, was 534.47 g C/m2a.In the study period, the NPP, fluctuated upward trend, on the season change, the summer> spring> autumn> winter. The annual NPP are mainly concentrated in between 300-500-g C/m2a. Occupy 44.33% of the overall area of Chongqing.Roughly in the spatial distribution of the southern chongqing northeast to chongqing in the west region and decreasing, the APAR in space distribution is consistent.(4) According to different land cover types, NPP were analyzed. Results show that different land cover types of NPP value size difference is remarkable. In the order, Average NPP were evergreen broad-leaved forest> deciduous evergreen coniferous forest> deciduous broad leaved forest> coniferous forest> shrub> grassland> cultivated land> water area> city proper.(5) From the correlation between NPP and meteorological factors (precipitation, average temperature and sunshine hours), and the sensitivity of the NPP for meteorological factors, and the impact of human factors for NPP accumulated, analysis these three aspects to elaborate the influence factors of NPP. The correlation between NPP and meteorological factors:correlation (NPP-precipitation)> correlation (NPP-sunshine time)> correlation (NPP-annual average temperature); In terms of sensitivity analysis, the change of average temperature is most sensitive to NPP and the sensitivity of precipitation and sunshine time is lesser, the sensitivity of sunshine time showing a rising trend; from the aspect of the influence in human factors, with the further implementation of the project of returning farmland to forest and grass, woodland effect appeared gradually to the growth of NPP, the contribution rate of NPP is the largest in the chongqing area.