Why is tall grass prairie north america's rarest biome? historically it only occurred in a very tiny region of north america. because over 90% of this biome has been converted to agriculture. global warming has resulted in the conversion of most tall grass prairie to short grass prairie. pollution has degraded most of our tall grass prairie region?

The answer is - because over 90% of this biome has been converted to agriculture.

This biome has been much larger before the development of the agriculture in this part of the USA, but because this biome provided large territories with deep fertile soil and predominantly lowland areas, people started using it for agriculture because it was the most suitable for that. So little by little, the biome was declining and more and more of it was becoming agricultural land.

We can plant more trees and plants.