Although there are many global issues that are a primary threat to <span>biodiversity in the tropical regions of Central Africa, Southeast Asia, and the Amazon basin the best answer is "deforestation". </span>
To "scour" means to clear an area or region of enemies or outlaws (i.e. "scour the area for our enemies and make sure they are eliminated). To "search" is to examine an area or region with the intention of locating something or someone. "Scouring" involves locating and eliminating an enemy; to search is to simply locate someone or something.
It eroded it because the colonists were forced to fight the French on the American territories. They didn't want to do this because the French were good trading partners and the colonists had good relations with them, so they became unsatisfied that they were drawn into a war that was against their well being by the British.
