Tropical & Subtropical Moist Broadleaf Forests (TSM)

Tropical and Subtropical Moist Broadleaf Forests are remarkable ecosystems, distinguished by their low variability in annual temperature and exceptionally high levels of precipitation, often exceeding 2000 mm per year. These unique climatic conditions foster an environment that supports the highest levels of species diversity found in any terrestrial biome. In fact, it is estimated that these forests are home to approximately half of the world's terrestrial species, making them crucial for global biodiversity. The biodiversity within these forests is particularly concentrated in the forest canopy, which serves as a vibrant habitat for countless organisms. The intricate structure of these forests can be categorised into five distinct layers: the over-story canopy, featuring emergent crowns that rise above the rest; a medium layer of canopy; a lower canopy; the shrub level; and finally, the understory, which plays a vital role in the forest ecosystem.

By Terpsichores - Own work, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=22441310

Within these lush forests, a square kilometre can host more than 1,000 different tree species, each of which can provide a habitat for thousands of various species from different taxonomic groups. This staggering level of biodiversity is not uniform across the globe; rather, the eco-regions that encompass this biome exhibit distinct species communities shaped by local environmental conditions and geographical factors. Tropical and subtropical moist broadleaf forests are primarily found in regions such as the Indomalayan Archipelago, the Amazon Basin, and the African Congo Basin, where the climatic conditions are ideal for sustaining such rich biodiversity.

The perpetually warm and humid climate of these forests creates an environment that is more productive than any other terrestrial habitat on Earth, enabling explosive plant growth. In fact, a tree in these forests may reach an impressive height of over 23 meters (75 feet) within just five years, showcasing the rapid growth rates supported by the abundant rainfall and sunlight. When viewed from above, these forests present an unending sea of green foliage, punctuated only by the occasional towering "emergent" trees that rise above the canopy. These majestic emergents provide essential habitats for various avian species, including hornbills, toucans, and the magnificent harpy eagle, all of which thrive in this biodiverse environment.

Generally, the highest levels of biodiversity are found in the forest canopy, where a complex web of life flourishes. The canopy can be divided into five distinct layers: the overstory canopy, which features emergent crowns that soar above the rest of the forest; a medium layer of canopy that supports a variety of wildlife; a lower canopy that provides shelter and resources for numerous species; the shrub level, which adds further diversity; and finally, the understory, where a different set of plants and animals coexist. Each of these layers plays a critical role in the overall health and functionality of the forest ecosystem.

The canopy itself is a bustling habitat for many of the forest's animals, including various species of apes and monkeys, which thrive in the high branches where food is abundant. Below the canopy, the lower understory serves as a habitat for a variety of creatures, including stealthy snakes and elusive big cats, which navigate through the dense vegetation in search of prey. On the forest floor, which is relatively clear of undergrowth due to the thick canopy above, one may encounter other animals such as gorillas and deer, both of which play important roles in their respective ecosystems by aiding in seed dispersal and maintaining the balance of plant life.

All levels of these forests contain an unparalleled diversity of invertebrate species, which are often overlooked yet are crucial for ecosystem functioning. Among these invertebrates are the fascinating stick insects of New Guinea, known for their extraordinary ability to blend into their surroundings, and various species of butterflies that can reach impressive sizes, growing over 30 cm (1 ft) in length. These invertebrates contribute significantly to the ecological dynamics of the forest, serving as pollinators, decomposers, and a vital food source for many larger animals.