Tropical forests constitute some of the most productive, most diverse, and oldest terrestrial ecosystems on the planet Earth. The majority of the world's tropical forests are located between the latitudes of 30°N and 30°S in Asia, Africa (including Madagascar), South America, and Central America (including various islands in the Caribbean). In addition, there are tropical forests found in eastern Australia and New Zealand, which fall outside of the aforementioned latitudinal range. Although the tropical forests cover approximately 7% of the Earth's land surface, they are estimated to contain at least two-thirds of the biomass of all vascular plants and more than half of all plant and animal species. Because of the importance of these forests in preserving the integrity of the Earth's ecological health, the conservation of tropical forests is one of the major areas of focus for naturalists and environmentalists. See also: Biodiversity; Biomass; Conservation (species); Conservation of resources; Ecological communities; Ecosystem; Forest and forestry; Forest ecosystem; Plant geography; Speciation; Terrestrial ecosystem; Tropics: latitudinal biodiversity gradient

Hawaiian tropical forest. (Photo courtesy of the Pacific Island Ecosystems Research Center, U.S. Geological Survey, Hawaii)

Most tropical forests experience little seasonal variation in day length or temperature as a result of their proximity to the Equator. However, these forests are often subject to distinct wet and dry seasons. If they do, then they are termed tropical seasonal forests. In contrast, if they do not experience these two seasons and instead are characterized by abundant rainfall year-round, then they are termed tropical moist forests. Cloud forests and tropical rainforests are the two predominant types of tropical moist forests. Cloud forests occur at higher elevations, with cooler temperatures and frequent mist and fog. Tropical rainforests occur at low elevations, with warm temperatures and 125–660 centimeters (50–260 inches) of rainfall spread over the course of a year. Other types of tropical forests include dry forests, tropical pine savanna forests, and semi-evergreen rainforests, which must survive long dry seasons. See also: Equator; Fog; Precipitation (meteorology); Rainforest; Savanna; Tree; Tropical meteorology

Deforestation and habitat fragmentation pose serious threats to tropical forest ecosystems, and the consequences of these disruptions affect the globe as a whole. Tropical forests are being decimated by deforestation, which entails the permanent removal of trees and related undergrowth from a forest in order to expand farming, grazing, ranching, logging, and other land development operations. If the current rate of deforestation continues, more than half of all remaining tropical forests will be eliminated, along with their associated animal species, by the year 2100. In addition, the pattern in which deforestation occurs is important as it can lead to habitat fragmentation, which creates many small patches of undisturbed forest surrounded by vast regions of destroyed habitat, ultimately isolating the patches of native habitat. This fragmentation makes it difficult for animals and plants to successfully disperse as the distances between patches grow, leading to an increasingly unsustainable situation in which all of the populations within a patch disappear. The use of corridors of native habitat between patches is one method used by landscape ecologists to preserve the connectivity of these regions, but it is inadequate when preservationist environmental efforts are lacking. See also: Connected wildlands: corridors for survival; Deforestation: a global concern; Endangered species; Environmental management; Extinction (biology); Forest engineering; Forest management; Forest timber resources; Land-use planning; Landscape ecology; Population dispersal; Population dispersion; Reforestation; Restoration ecology