雨林(rain forest)
一种茂盛的森林类型，多由高大的阔叶树组成，通常分布於赤道附近的潮湿热带地区，主要分布在中、南美洲，中、西非洲，印尼，部分东南亚地区，以及澳大利亚热带地区。这些地区终年湿度很高，无明显季节变化。依据年降雨量，其树木有常绿树或主要为落叶林，前者需要更多的水量。温度很高，白昼间一般温度在30℃左右，夜间约20℃。土壤的营养情况随地区和气候的不同而变化，大多数雨林的土壤往往终年潮湿且并不肥沃，因为高温高湿条件下，有机物分解很快，并很快地就被树根和真菌所吸收。雨林中植物和动物的发育呈许多垂直层次状态。最高的植物层（冠层）高30～50公尺，该层的动物多数在叶枝之间寻找食物和逃避肉食性动物。次冠层植物由小乔木、藤本植物和附生植物组成。雨林地表面被树枝、细枝和落叶所覆盖。许多种类的动物居於下层。雨林的地面并不如一般所认为的那样不可通行，多数地面除了薄薄一层腐殖质和落叶外多是光裸的。生活於这个层次的动物（例如犀、大猩猩、象、豹和熊）善於行走和短距离的攀爬。在地表下生活着穴居动物，如犰狳、蚓螈。此外土层中许多微生物能将各层动、植物遗留的有机物质分解。地层的气候异常稳定，因为冠层和低层树枝过滤了阳光和热辐射，减弱了风速，使得雨林中昼夜温度相当均匀。
English version：
rain forest
Lush forest, generally composed of tall, broad-leaved trees and usually found in wet tropical regions around the equator, mainly in South and Central America, West and Central Africa, Indonesia, parts of Southeast Asia, and tropical Australia, where the climate is relatively humid, with no marked seasonal variation. Depending on the amount of annual rainfall, the trees may be evergreens or mainly deciduous. The former require more water. Temperatures remain high, usually about 86°F (30°C) during the day and 68°F (20°C) at night. Soil conditions vary with location and climate, though most rain-forest soils tend to be permanently moist and not very fertile, because the hot, humid weather causes organic matter to decompose rapidly and to be absorbed quickly by tree roots and fungi. Rain forests have many vertical layers of plant and animal development. The highest plant layer, the tree canopy, extends to heights of 100-165 ft (30-50 m). Animals there mostly feed and escape from predators among leaves and branches. The next-highest layer is filled with small trees, lianas, and epiphytes. Above the ground surface the space is occupied by tree branches, twigs, and foliage. Many species of animals live in the undergrowth. Contrary to popular belief, the rain forest floor is not impassable, being bare except for a thin layer of humus and fallen leaves. Animals inhabiting this layer (e.g., rhinoceroses, gorillas, elephants, leopards, and bears) are adapted to walking and climbing short distances. Burrowing animals, such as armadillos and caecilians, are found below the soil surface, as are microorganisms that help decompose and free much of the organic litter accumulated by other plants and animals from all layers. The climate of the ground layer is unusually stable because the upper stories of tree canopies and the lower branches filter sunlight and heat radiation and reduce wind speeds, keeping the temperatures fairly even.