Seasonal tropical forest

Seasonal tropical forest, also known as moist deciduous, semi-evergreen seasonal, tropical mixed or monsoon forest, typically contains a range of tree species: only some of which drop some or all of their leaves during the dry season. This tropical forest is classified under the Walter system as (i) tropical climate with high overall rainfall (typically in the 1000–2500 mm range; 39–98 inches) and (ii) having a very distinct wet season with (an often cooler "winter") dry season. These forests represent a range of habitats influenced by monsoon (Am) or tropical wet savanna (Aw/As) climates (as in the Köppen climate classification). Drier forests in the Aw/As climate zone are typically deciduous and placed in the Tropical dry forest biome: with further transitional zones (ecotones) of savannah woodland then tropical and subtropical grasslands, savannas, and shrublands.

Distribution

Seasonal (mixed) tropical forests can be found in many parts of the tropical zone, with examples found in:

In the Asia-Pacific region: seasonal forests predominate across large areas of the Eastern Java, Wallacea, Indian subcontinent and Indochina

Eastern Java monsoon forests

Wallacea Forest

Brahmaputra Valley semi-evergreen forests

Upper Gangetic Plains moist deciduous forests

Mondulkiri Province, Cambodia

Cat Tien National Park, Vietnam

Khao Yai National Park and Huai Kha Khaeng Wildlife Sanctuary, Thailand

Northern Australia: Cape York Peninsula (Queensland), Arnhem Land (Northern Territory), The Kimberly (Western Australia)

In the Americas

Atlantic forests of Brazil

Central and eastern Panama: with Barro Colorado Island especially well studied

In Africa

Coastal West Africa: Guinean seasonal forest: from south-western Gambia to eastern Ghana

Climate

The climate of seasonal forests is typically controlled by a system called the Intertropical Convergence Zone (ITCZ), located near the equator and created by the convergence of the trade winds from the Northern and Southern Hemispheres. The position of these bands vary seasonally, moving north in the northern summer and south in the northern winter, and ultimately controlling the wet and dry seasons in the tropics.

These regions appear to have experienced strong warming, at a mean rate of 0.26 degrees Celsius per decade, which coincides with a global rise in temperature resulting from the anthropocentric inputs of greenhouse gases into the atmosphere. Studies have also found that precipitation has declined and tropical Asia has experienced an increase in dry season intensity whereas Amazonian has no significant pattern change in precipitation or dry season. Additionally, El Niño-Southern Oscillation (ENSO) events drive the inter-annual climatic variability in temperature and precipitation and result in drought and increased intensity of the dry season. As anthropogenic warming increases the intensity and frequency of ENSO will increase, rendering tropical rainforest regions susceptible to stress and increased mortality of trees and other plants.