User blog comment:Master Sima Yi/Assassinews 05-08-'14 – Assassin's Creed: Rogue announced/@comment-24760042-20141119173901/@comment-3046679-20141120225353

Adewale mentions that Mackandal sent one of his men into a temple in Haiti, which housed another Tree. And like the one in Lisbon, it caused an earthquake that leveled Port-au-Prince.

When Shay activates the one in Lisbon, it's a repeat performance. Then says so to Achilles, who shrugs him off, and admits he was wrong only when he sees another one actually perform its function in the arctic.

As to why, the usual reason - "Get it before the Templars do, we don't trust them with it, nor do they trust us with it, since the artifacts are too powerful and could tip the balance of power."