A jungle is land covered with dense forest and tangled vegetation, usually in tropical climates. Application of the term has varied greatly during the past recent century.
Jungle in Cambodia.
Jungle on Tioman Island, Malaysia
El Yunque National Forest is the only tropical rainforest in the U.S. National Forest Service
Mound from Los Naranjos archeological site in Honduras.
An old-growth forest is a forest that has developed over a long period of time without disturbance. Due to this, old-growth forests exhibit unique ecological features. The Food and Agriculture Organization of the United Nations defines primary forests as naturally regenerated forests of native tree species where there are no clearly visible indications of human activity and the ecological processes are not significantly disturbed. One-third of the world's forests are primary forests. Old-growth features include diverse tree-related structures that provide diverse wildlife habitats that increases the biodiversity of the forested ecosystem. Virgin or first-growth forests are old-growth forests that have never been logged. The concept of diverse tree structure includes multi-layered canopies and canopy gaps, greatly varying tree heights and diameters, and diverse tree species and classes and sizes of woody debris.
Old-growth European beech forest in Biogradska Gora National Park, Montenegro
Cool temperate rainforest in Tasmania, Australia
First growth or virgin forest near Mount Rainier, 1914
Antarctic beech old-growth in Lamington National Park, Queensland, Australia