Chinese Journal of Agrometeorology ›› 2016, Vol. 37 ›› Issue (04): 445-453.doi: 10.3969/j.issn.1000-6362.2016.04.009

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Spatial and Temporal Variation of Net Primary Productivity and Its Relationship with Climate Factors in the Chinese Loess Plateau

SHI Xiao-liang, YANG Zhi-yong, WANG Xin-shuang?, GAO Jun, HU Yan   

  1. 1.College of Geomatics, Xi’an University of Science and Technology, Xi’an 710054, China;2.Department of Water Resources, China Institute of Water Resources and Hydropower Research, Beijing 100038; 3.Shannxi Geomatics Center of National Administration of Surveying, Mapping and Geoinformation, Xi’an 710054;4.Institute of Forest Resources Information Techniques, Chinese Academy of Forestry, Beijing 100091
  • Received:2016-03-20 Online:2016-08-20 Published:2016-08-10

Abstract:

Based on AVHRR GIMMS NDVI and MODIS NDVI data, spatial-temporal variations of the net primary productivity (NPP) in the Chinese Loess Plateau from 1982 to 2014 was simulated using CASA model. Besides, the relationship between NPP and climate factors was analyzed at grid scale. The results showed that average annual NPP from 1982 to 2014 was 254.0gC?m-2 in the Chinese Loess Plateau and the NPP has increased over the past three decades. The average annual NPP of deciduous broadleaf forest was 513.0gC?m-2, which was the highest for different vegetation types, followed by evergreen coniferous forest, meadow, cropland, shrub and steppe. The NPP differs greatly between different vegetation types. There was significant spatial difference of vegetation NPP, and the NPP of the south parts of the study area was higher than that of the north part. Since 1999, the government of China began to carry out the police that is “replace agriculture with forestation and conserve forest” in the study area. Before the project of returning farmland to forestland or grassland (1982-1998), there was no significant change of vegetation NPP in most regions of the study area. However, since the implementation of large-scale vegetation construction from 1999, the annual mean NPP of the study area has increased significantly at a rate of 5.38gC?m-2. About 66.6% of the study area showed an increasing NPP trend, especially in northern Shaanxi Plateau, Taihang-Lvliang mountains, where significant increase in vegetation NPP has been seen. The green for grain project has greatly improved the vegetation state. The NPP had a significant positive correlation with the precipitation, but it had no obvious relationship with temperature. Therefore, precipitation is the main factor driving vegetation NPP change.

Key words: Net primary productivity(NPP) , AVHRR GIMMS NDVI, MODIS NDVI, CASA model, The Chinese Loess Plateau, Spatial and temporal variation, Climate factors