Canopy layer my friends :D
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.
thousands of years
Explanation:
A delta the size of the Mississippi River will take several thousand of years to form because the process of formation of a delta is geologically controlled.
A delta is a place where river enters or drains into the sea with many mouth or outlets.
Deltas are depositional terrain full of dis-tributaries.
- For a delta to form, a terrain must be close to the mouth of an ocean or a larger body of water.
- The entering stream must be large enough and have large amount of sediment.
- The river mouth must have been cut to the same level with that of the drainage basin.
- Most rivers such terrain should be at their lower course where they flow with very low velocity.
- Wave action should be minimal along such coasts.
These processes takes several thousands of years if not millions.
learn more:
Downcutting brainly.com/question/9259211
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