| The Fenhe River Basin is located in the east of the Loess Plateau,with a wide drainage area,complex landforms,and various land use types.As an important part of the terrestrial ecosystem,the Fenhe River Basin has an important impact on regional and global ecological balance and environmental changes.Vegetation Net Primary Production(NPP)not only reflects the productivity of vegetation in the natural environment,it can be used to evaluate the quality and sustainable development of the terrestrial ecosystem,and it is also the main factor for determining the ecosystem 's carbon sink and regulating ecological processes Plays an important role in global carbon balance.Studying the spatiotemporal changes of vegetation NPP in the Fenhe River Basin has profound significance for grasping climate change and ecological protection in the semi-arid region of the Loess Plateau.In this paper,using remote sensing and GIS technology,driven by MOD13Q1 data,meteorological data,and land use type data from 2000 to2015 in the Fenhe River Basin.The CASA model was used to estimate the vegetation NPP in the Fenhe River Basin.The simulation accuracy of vegetation NPP was improved by selecting the best meteorological interpolation method and localizing the maximum utilization of light energy of vegetation.Using trend analysis,correlation analysis and other methods to study the driving factors of NPP in Fenhe River Basin.The conclusions were as follows:(1)The best results were obtained by using ANUSPLIN method to interpolate the temperature and precipitation of Fenhe River Basin.ANUSPLIN method can ensure the smoothness and accuracy of the interpolation results in the process of meteorological data interpolation in Fenhe River Basin.(2)From a spatial perspective,the annual average NPP spatial distribution of vegetation in the Fenhe River Basin from 2000 to 2015 gradually increased from the middle to the two wings.Among them,the vegetation NPP in Taiyuan Basin and Linfen Basin was generally low,and the two wings of the river basin,Luliang Mountain The vegetation NPP of Taihang Mountain and other mountain areas are relatively large.The annual average NPP of different land use types is quite differen.In terms of time,the annual average NPP of the Fenhe River Basin from 2000 to 2015 showed an increasing trend of fluctuation,with an average value of 291.57 g C · m-2 · a-1 and an average annual increase of 6.62 g C · m-2 · a-1.In terms of the total NPP in the Fenhe River Basin,the total NPP in the Fenhe River Basin increased steadily.The average annual vegetation NPP change trend in 16 years showed a peak shape.The vegetation NPP was the largest in July and the vegetation NPP was the smallest in December.There were differences in the annual changes of vegetation NPP between 2000 and 2015 in the Fenhe River Basin.In the past 16 years,the average value of NPP of each land use type in the Fenhe River Basin has shown an increasing trend.(3)The vegetation NPP in the Fenhe River Basin has a positive correlation with temperature.The vegetation NPP in the watershed has a positive correlation with precipitation as a whole.Precipitation is an important driving factor for vegetation NPP in the Fenhe River Basin.The correlation between different land use types and meteorological factors is significantly different.The time lag effect of vegetation NPP on temperature in the Fenhe River Basin is one month,and the time lag effect on precipitation is not obvious.There are some differences in vegetation NPP on different soil types,but the maximum value of vegetation NPP for each land use type appears in brown soil.(4)NPP was influenced by topography and anthropogenic activities,and it was higher in the area with higher elevation,steeper slope,and less human activities,and vice versa.In addition,the farther away from the Fenhe River,the larger NPP in the gradient of the east-west transect;the NPP was relatively less on the gradient of north-south transect with excessively coal mining and high urbanization rate. |
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