Here's why:
* Climate: Biomes are large-scale ecosystems characterized by distinct climate patterns, including temperature, rainfall, and humidity. These factors directly influence the types of plants that can grow in a biome, which in turn determines the types of animals that can survive there.
* Vegetation: The dominant plant life in a biome is a key factor in defining it. For example, a rainforest is defined by its dense, towering trees, while a desert is defined by its sparse, drought-resistant vegetation.
* Animals: While animals are an important part of a biome, their presence is largely determined by the availability of food and shelter, which are both directly related to the climate and vegetation.
Therefore, animal populations are more of a consequence of the climate and vegetation than a defining factor themselves.