Assessment of Net Primary Productivity of the Earth's Natural Vegetation

抄録

The productivity of terrestrial vegetation is a determinate element of the carrying capacity of the Earth for all living things including human beings. In this study, the Chikugo model for evaluating the net primary productivity (NPP) from weather data was used to elucidate the global distribution and latitudinal variation of NPP. Predicted NPP varied from below 1t dry-matter ha^-1yr^-1 in high latitude zones and dry regions to 29t dry-matter ha^-1 yr^-1 in tropical wet regions, depending on climatic conditions. The land area with an NPP above 10t dry-matter ha^-1 yr^-1 was only 36.6% of the entire land area. The latitudinal changes in NPP were characterized by a curve with a clear peak in the equatorial zone and two weak troughs in the subtropical high-pressure belts on both hemispheres. The potential global net production by terrestrial plants was estimated to be 136x10⁹t dry-matter yr^-1, agreeing well with reports by other researchers. Climate change due to CO₂ doubling would increase NPP by 15-20%.