Estimation Of Hulun Buir NPP Based On The CASA Model And Remote Sensing Data

Hulun Buir is located in northeast part of Inner-Mongolia, which is transitional zone from arid areas in northwest change to the humid area in northeast and dryland farming areas in north China. It is significance meaningful to protect ecological security and sustainable development of China. Grassland vegetation is the primary producers in grassland ecosystem, and has great influence for regional as well as global climate and environmental changes. The thesis is about estimating NPP in Hulun Buir according to the CASA (Carnegie Ames Stanford Approach), on the main body status of grassland vegetation in the grassland ecosystem research to monitor, analyze and evaluate the grassland status using remote sensing data.Vegetation net primary producers (NPP) refer to the accumulated number of organic matter per unit area and unit time for green plants. NPP as the key component of surface carbon cycle, not only direct reflect the production capacity of vegetation type under natural environment and identify the quality status of terrestrial ecosystems, but it is important factors to determine the ecosystem carbon source/sink and adjust the ecological processes, also NPP plays an important role in global changes and carbon balance. With the impact of human being's activities, the greenhouse effect as well as other climate and environmental problems have become increasingly prominent in past 30 years, making the temporal and spatial variation of carbon balance in terrestrial ecosystems to become a research trends.The thesis is about estimating NPP in Hulun Buir in Inner-Mongolia using geographical information system and CASA, and utilizing the MODIS remote sensing data, meteorological data and relative information, and then making a comparison of the estimation result and measured data to verify the accuracy of CASA and improve the model.CASA is verified based on the large-scale and even the world space-proven since beginning of generation, many of the model parameters are obtained from the scale of regional or even global. This thesis plans to use CASA to simulate NPP of Hulun Buir's grassland ecosystem, and conduct the simulation verification use the actual biomass data measured by the system. All is used to validate the CASA dynamic simulation capability. According to the results, we are able to analyze the accuracy of the NPP.The conclusions are as follows:1 CASA model improvement and implementationBased on solar energy utilization efficiency, taking into account the greatest values in different vegetation types existing differences, combined with the same time ,takingε* different values ,this paper build an improved CASA model. By comparing the results of verification NPP found improved CASA model for regional scale vegetation of the simulation results better than before.2 this paper estimates the NPP of Hulun Buir regions, and the studies have shown that the NPP values gradually decrease from east to west in the region.3 NPP of the whole region is affected by vegetation cover, vegetation type, temperature and precipitation.4 although we always estimate the different values of NPP by different models, the increase or decrease trend is consistent.