The limit of biomass resources human beings use becomes obvious. Therefore, it is expected that competitions between of biomass uses such as food, material, and energy will become severe; consequently land use competitions between forest, arable land, pasture, and other lands will become severe, too.

(a) Competitions between forest, arable land, pasture, and other lands.

Forests have decreased by activity of human beings for long years. The forest area in the world has decreased by 1.2 billion hectares since 1700. Especially, the forest area of North Africa and the Middle East, and China decreased below half. In the same period the arable land in the world increased by 1.2 billion hectares. In the same period, the pasture in the world decreased a little by 70 million hectares. Thus, in the historical view point, the deforestation was caused by the increase of arable land. Conversely, the deforestation area was converted to arable land.

Concerning land use change after 1950, deforestation in developed regions has been stopped and forest areas in Western Europe and North America increase reversely. On the other hand, in developing regions such as tropical regions, China, and Middle East, deforestation continues. The reasons are conversion to arable land and pasture and un-sustainable slash-and-burn farming, etc.

The deforestation in the developing regions causes not only a regional environmental destruction but also global environmental problem of CO2 emission. In addition, in regions in high population density and industries in high speed such as Japan, South Korea, and Taiwan, the arable lands are decreasing. This is because in those regions land demands for housing and factory increase and the agriculture is not competitive in the global agriculture markets. In Japan the arable land decreased by 10% from 5.0 million hectares to 4.6 million hectares between 1976 and 1991. In South Korea, the arable land decreased by 6.6% in the same period.

(b) Competition between food production and energy crop production

On arable land, energy crops are also producible besides food. In countries where surplus arable land is available such as the United States and Brazil, they could use the surplus arable land for energy crop production rather than for fallow field. Especially, in those countries in 2006 to 2007 when the oil price hits the historical record, they produce energy crops and produce biofuel such as bioethanol and bio-diesel (BDF). In the United States they produce bioethanol from corn on a large scale. In Brazil they produce bioethanol from sugarcane on a large scale. In addition, BDF is produced from vegetable oil such as rapeseed oil and palm oil.

However, since arable lands are limited, the production of energy crops reduces the arable land where food crops are producible. It is pointed out that excessive production of energy crop may lead to food shortage. In addition, it is explained in 6.7.5 that the competition between food production and energy crop production is handled in an energy model.

Further information

BIN (Biomass Industry Network) et al., “Bio-nenryo Riyo ni kansuru Kyodo Teigen”, 2007 (in Japanese) The Japan Institute of Energy, “Biomass Yogo Jiten”, Ohmsha, 2004 (in Japanese)

Yamaji, K. et al., “Bioenergy”, Myosin Shuppan, 2000 (in Japanese)