Biodiversity in an ecosystem is important because it helps plants and animals survive. When there are a lot of different species of plants and animals, they can all help each other out. For example, bees help pollinate plants, which helps them grow and make food. If there aren't enough bees, then some plants won't be able to survive. So, having a lot of different kinds of plants and animals is like having a big team that can all work together to keep the ecosystem healthy.
