| Net primary production(NPP)of vegetation is an important component of carbon flux in terrestrial ecosystems,and it is also the result of the combination of the physiological characteristics of plants and the external environment.The study of the spatial and temporal variation of NPP of vegetation in the wind-erosion-water-erosion interlocking zone of Loess Plateau is one of the most serious areas of soil erosion in China,and the ecological environment is fragile.It is also useful for environmental protection.Based on the meteorological data,remote sensing data and land use data of the Loess Plateau wind-erosion-water-erosion interlocking area,this study analyzes the spatial and temporal characteristics of precipitation,temperature,soil water content and land use changes in the winderosion-water-erosion interlocking area of the Loess Plateau with the help of Arcgis platform,and then uses the light energy utilization model as the basis to estimate the spatial and temporal characteristics of the net primary productivity of vegetation in the wind-erosion-water-erosion interlocking area of the Loess Plateau by CASA model.Finally,the spatial and temporal characteristics of vegetation net primary productivity in the wind-erosion-water-erosion interlocking zone on the Loess Plateau were analyzed,and the responses of vegetation net primary productivity to temperature,precipitation,soil water content,elevation,slope,slope direction,land use type and vegetation type were investigated.The spatial and temporal variation of the net primary productivity of vegetation in the interlaced area was investigated by geographical probes.The main conclusions obtained are as follows:(1)From 2000 to 2020,the annual precipitation,annual temperature and annual soil water content of the wind-erosion-water-erosion interlocking area of the Loess Plateau showed an overall trend of increase,and the annual and seasonal precipitation of the wind-erosion-watererosion interlocking area of the Loess Plateau showed a gradual increase from west to east and a low north-south and high middle.The temperature tendency rate ranges from -0.21℃/10a to 0.75℃/10a.On the seasonal scale,the average temperature in spring,summer and autumn shows an increasing trend,while the average temperature in winter shows a decreasing trend.The soil water content of the Loess Plateau wind and water erosion interlacing area is increasing in time throughout the year as well as in all seasons,and gradually increasing in space from west to east.Grassland and cropland of the Loess Plateau wind erosion water erosion interlocking area is the main land use type,accounting for more than 70%of the total area of the study area,the land use pattern changes significantly,the transfer to and from the party love over you mainly concentrated in the occurrence of cropland,forest land and grassland between.(2)From the time scale,the vegetation NPP in the wind and water erosion interlaced area of Loess Plateau showed an overall increasing trend,with 87.54%of the areas passing the significance test.The changes of vegetation NPP are mainly influenced by seasons,and the total vegetation NPP of the year is mainly concentrated in April～October,accounting for more than 85%of the year.From the spatial scale,the vegetation NPP of the Loess Plateau wind and water erosion interlocking area showed a trend of gradually increasing in the west and east,and most areas were not stable and sustainable over time.(3)The climatic drivers of vegetation NPP on the Loess Plateau were analyzed.The correlation analysis reveals that topographic factors and hydrothermal factors all affect vegetation NPP,and vegetation NPP varies greatly under different land use types and different vegetation types.It can be concluded from the geographic probe that the correlation between vegetation NPP and hydrothermal factors is significantly higher than that of topographic factors,and the explanation degree of the interaction between factors will be significantly higher than that of single factors. |
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