Effects of Land Use and Human Population on Plant Productivity of the Indonesian Archipelago

Dramatic changes have occurred in tropical forest areas and the net primary production (NPP) in South and Southeast Asia because of the influence of human activity during the past two hundred years. Recent research reveals that human population density has a significant impact on forest areas. Using this relation and the Chikugo model, we estimated the deforested area, and calculated the biomass degradation of the Indonesian archipelago. The potential total net production (TNP₀), defined as the area summation of NPP ignoring the impacts of human population, is evaluated to be about 74.9 x 10⁸tonnes dry matter per year. The actual total net production (TNP_a) calculated by considering human land use is estimated to be approximately 65.4 x 10⁸tonnes dry matter per year, and to be 87% of TNP₀of natural vegetation over the whole terrestrial area of Indonesia. However, there is a considerable difference between the islands with a high population density and with a low population density. The percentage of forest area of Java Island is less than 10%, and therefore the TNP_aof Java to Timor Islands is only 38% of the potential. On the other hand, the forest areas of Irian Jaya and Papua New Guinea are more than 80% of the total land area of this island. TNP_ain these islands with higher forest cover reaches at 90% of these TNP₀.