Why is there a change in natural zones on the surface of the Earth?

The change in natural zones occurs due to the proximity to the equator. You have probably noticed that the closer to it, the richer the ecosystems, the closer to the poles, the poorer they are. It also depends on the height at which the zone is located. For example, there is eternal snow not only at the poles, but also in the mountains, which means that the change takes place in an upright position.