The conversion of tropical rain forests to pasture and cropland is having dramatic effects on the environment. Particularly intense and rapid deforestation is taking place in the state of Rondônia, Brazil, part of which is shown in this series of Landsat images.
About 30% (3,562,800 km2) of the world's tropical forests are in Brazil. The estimated average deforestation rate from 1978 to 1988 was 15,000 km2 per year. In Rondônia, 67,764 km2 of rain forest had been cleared through 2003—an area larger than the U.S. State of West Virginia.
Systematic cutting of forest vegetation starts along roads and then fans out to create the "feather" or "fishbone" pattern, which begins to show in the eastern half of the 1986 image. The deforested land and urban areas appear lavender; healthy vegetation appears green.
The early images show main roads cutting through the forest. Highway 421 snakes through the forest south-southwest from the city of Ariquemes, and Highway 364 runs roughly north to south through Ariquemes. More roads branch out from the main ones to create the fishbone pattern. As time goes on, a patchwork of cleared areas, forest remnants, and settlements is left behind.
The primary cause of this deforestation is conversion to cropland and pasture. But the reasons for this conversion are varied.
Countries that have extensive tracts of rain forest build roads into remote areas to improve transportation of goods. Legal and illegal logging follows the road expansion. Once an area is logged, it becomes a prime location for agricultural development, which further clears the surrounding forest. These cleared areas are also prone to wildfires, which can further degrade the forest.
Governments sometimes encourage the development of the rain forest with subsidies and tax breaks. Pressure from the global market for timber and soybeans drives the agricultural development.
Play this animation to see the change in this area happen from 1975 to 2015. The animation uses a Landsat image from most of the years in this time period to demonstrate the rapid rate of deforestation. Huge areas of Rondônia's dense rain forest transform to cleared areas in only a few decades. Unseen in these images are the effects of the deforestation on wildlife habitats and local and global climate.