[pp.15-20]

A Study on Estimation and Changing of Net Primary Productivity in the Yellow River Basin using Satellite Data and Climat

Xiufeng WANG , Yang LIU , Nobuhiro MATSUOKA , Hiroshi TANI , Lianjie ZHANG and Shinji MATSUMURA （Hokkaido University / Chiba University / Northeast Forestry University, China / Kagawa University）

Abstract:
Net primary production (NPP) in the Yellow River Basin, China, during 1982–1999 was estimated with the CASA model using satellite data. The yearly NPP (NPPT) tended to increase during 1982–1999 throughout the Yellow River Basin. A large mean annual NPP for each grid cell was indicated in both the upper and the lower reaches, and a low value was indicated in the middle reaches. As for climate data, the mean annual temperature in the Yellow River Basin tended to increase and annual precipitation tended to decrease during 1982–1999. When the relationships between NPP and climate data were analyzed, a strong positive correlation was exhibited between NPP and precipitation. Also, a positive correlation between NPP and temperature was shown in the region, i.e., 2°C below the normal temperature. Conversely, the region 2°C warmer than normal had a weak negative correlation in the areas with less than 500 mm of precipitation. It is estimated that about 50% of the drainage area (mainly the middle reaches) in the Yellow River Basin has such conditions.

Key Word:
NDVI, NPP, Remote sensing, Yellow River Basin

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