Rainforest StructureThe arrangement of plants within a tropical rainforest is such that there are different layers and different microclimates. The diagram shows the layering of plants from the tallest emergent trees, down to the lowest ground flora. A sharp contrast exists between the two extremes. For example, the top of the forest has full light conditions and the temperature and humidity vary from 10-40oC and 60-90% relative humidity, respectively. The Emergent layer The Emergent layer consists of the tallest and usually oldest trees which are about 40m (120 ft) high and spread out over the tops of other trees.