Why is the vegetation in the prairies similar to that of the arctic?

Question

What are some climatic conditions that they have in common? (The Arctic has small shrubs and the prairies only have grass, why can't either of them grow big forests etc)

tia

Answer 1

1. Rain -  Both are semi-arid.  There is not enough rainfall to grow trees.

2. Temperature -  The Arctic can't grow trees anyway because it is too cold.  There is a point called the Tree Line where trees can't grow due to temperature.  

3.  Wind -  Prairies can't grow trees because it is just too windy.  Prairies are flat lowlands.  Winds can spread fire rapidly through prairies burning down every tree in sight.

4.  Deforestation -  The Indians and European settlers cut down the few trees that the brush fires missed. They probably weren't very impressive trees anyway.