Biodiversity means the amount of species in a given ecosystem or biome. A tropical rainforest has warmer temperatures, greater amount of insulation throughout the year and a constant supply of rain. Therefore, a tropical rainforest has greater biodiversity. In one tree, for example, there can be hundreds of species of insects, birds, reptiles, mammals, and even other plants growing on top of the tree. In contrast, because of the harsh cold winter, the short growing season, the frozen ground(permafrost) for much of the year, the tundra is the least biodiverse. Moss and lichens are the predominant plants, as tree roots could not penetrate the frozen ground and are not adapted for this biome. There are a small amount of animals adapted to the climate that can survive here. There are many insects in summer, some birds, some mammals like the arctic hare and reindeer but the numbers of different species cannot compare to those in a tropical rainforest.