Land uses of key importance are forests (about 29 percent of global lands), grasslands (about 27 percent), and agriculture (11 percent). Exact statistics vary because definitions and methods of tabulating these areas differ.
Forests are declining worldwide, but the greatest forest losses are in Africa, South America, and Asia. In general, tropical developing countries are exploiting their forests most rapidly, however, forests in Siberia, Canada, and other northern countries are also experiencing relatively rapid depletion.
Forests are lost most often to settlement, conversion to agriculture or pasture, exploitation for wood products, or fire. Traditional swidden agriculture can be highly productive and sustainable if forests are allowed to regenerate; increased pressure from migrants and lost land rights often make this type of farming unsustainable, however.
In parts of North America and Europe, forests are expanding due to replanting or a decline in agriculture. Debt-for-nature swaps and other conservation efforts are slowing forest declines in some developing countries.
Open canopy forests have tree crowns covering less than 20 percent of ground surface; closed canopy forests have tree crowns over more than 20 percent of the ground. Old-growth forests are considered those in which trees can live out a natural life-cycle without interruption by humans. Worldwide, old-growth forests are biologically important but severely threatened.
About half of world wood consumption is for fuel, and half is industrial timber or paper pulp. More than half the world's people depend on wood and charcoal for cooking. Wealthy countries produce less than half of industrial wood products, but they consume more than 80 percent.
In the United States, forest management is often controversial. Issues of greatest disagreement include old-growth harvesting, road building, below-cost timber sales, fire management, salvage logging, forest thinning (or fuel reduction), and habitat or wilderness preservation. Public forests have traditionally been an important source of timber and jobs, but the number of logging-related jobs has declined because of industry automation, international trade, and conservation efforts.
Options for sustainable forest use include alternative harvesting methods, reliance on plantation forests for wood products, and non-timber forest products. Thousands of alternative products can be produced from forests, and often these products are highly valuable. Finding markets for alternative products is often a challenge, however.
Grasslands are extremely important to human livelihoods: they support grazing animals, both domestic and wild, and they have widely been converted to agriculture. Grasslands cover about 30 percent of the world's land surface.
Grasslands support animals and humans best when herds are allowed to move frequently and pastures are not overstocked. Grasslands are being lost to degradation and desertification, as well as to agriculture. Although grassland losses are noted less than forest losses, they are occurring at a much faster rate.
In the United States, overgrazing on public rangelands is a significant problem for both environmental health and resource management. Subsidized grazing permits are widely blamed for range degradation. Reducing herds is extremely controversial, however. Rotational grazing is an environmentally sound option that can help restore pasture and range health.
Land ownership for the poor can help reduce overexploitation of land. Although it is a difficult process, land reform has been attempted in many places to restore land rights to peasants and indigenous people.
