Tropical jungles are found, as the name suggests, in the tropics between 10 degrees north and south of the equator. At these latitudes, precipitation rates are consistent, exceeding 2,000 mm or 79 inches annually with two peaks based on the intertropical convergence zone or ITCZ. The ITCZ is a region in the tropics with low average pressures due to the high uplift of warm air. Temperatures don't vary much here, staying relatively stable around 25 degrees Celsius or 80 degrees Fahrenheit year-round. Given this very stable environment, with little change in both precipitation and temperature, species have been able to thrive with little to no stress or disturbance. Approximately 50% of the earth's species are present here, even though it covers only 11% of earths vegetation.
The plant forms that grow here include broad-leaved evergreen and deciduous trees. These trees are able to photosynthesize all year long so instead of losing all their leaves, such as deciduous trees in Massachusetts, they can maintain the leaf year-round and expel it to immediately renew it. The abundance of plant life creates 5 layers of jungle known as the emergent layer, canopy, understorey, shrub layer, and forest floor. The forest floor, in particular, creates a paradox. It appears the soil here is very low in nutrients, so how could it support so much life? Unsurprisingly, the abundance of life is the reason why the soil is so nutrient-poor. Plants take in nutrients from the soil to grow, and if enough plants are growing then the soil gets leeched of all nutrients.