ility 
tal 
  
Ochi, Shiro 
NPP — e| fAPARdt K KK KRKKKKOIKXKREKETXRRAYXKRK 
NPP [ gDM/m2/time], efficiency[g/MJ], fAPAR : Function of Absorbed PAR [MJ/m2] 
JAPAR=-008 +1075xNDVI K K K K K K )K K K K K K K K 
is 1.5 for global average. 
The annual total NPP can be estimated as follows: 
12 
NPP-0.5 |f, (NDVI)x«PAR, K KK KG KK KK 
izl 
By using this formula, annual total of Net Primary Productivity(NPP) from 1981 to 1989 was generated. The output was 
verified using existing study concerning the global NPP and the regional NPP. Table-1 and Table-2 show the 
comparison of Global NPP versus our study and Regional NPP versus our study respectively(Ochi and Murai,1999). By 
comparing with other studies, the adopted method in our study for estimation of NPP is acceptable for the purpose of 
our study goal, though there have been no reference data. 
  
  
  
  
Table —1 Verification of Global NPP Table-2 Verification of Regional NPP 
NPP(g ton) 
Africa 22.9 
Whittaker(1979 115.6 t 
RE T I EE North/Central Ameri] ^ 19.1 
: South America 30.3 
Eurasia 38.6 
Oceania 8.5 
Total 119.4 
  
  
3.2 Correlation between Global NPP and Cereal Production 
Figure-2 shows the relationship between Global NPP derived by this study and world Cereal Production prepared 
by FAO. The correlation factor(R) of the two items is 0.91 in the period from 1982 to 1990. However, the 
correlation become worse when the data from 1991 to 1993 are involved. It is said that the NDVI data and PAR 
data include some noise due to the aerosol caused by Mt. Pinatubo Eruption of 1991 therefore the data after the 
eruption are not adequate for the use. It was found that the NPP can be used for the estimation of crop(or cereal) 
production. 
3.3 Change of NPP in major river basins in Asia 
By overlaying USGS/IGBP cover map with global NPP map, NPP from each land cover category can be extracted. 
Figure-3 shows that changes of NPP from 1982 to 1990 in major six river basins in Asia ; Amur, Yellow, 
Yangzhu, Mekong, Ganges and Indus, as shown in Figure-4. NPP are mainly produced in the crop and grass land 
with high population density in the Yangzhu, Yellow, Ganges and Indus river basins. On the contrary, NPP are 
produced in the forested area in Amur and Mekong river basins where population density is not so high. NPP of 
crop land are more stable than NPP of other land covers. 
  
International Archives of Photogrammetry and Remote Sensing. Vol. XXXIII, Part B7. Amsterdam 2000. 1053