The Queen, and her gardening team, are generally not worried about contamination from other worlds here. After all it is the Kingdom that has the magical plants - the ones that eat the unwary passer by, those that grow upside down, those who spray their pollen at great distances and deliberately target the hayfever sufferers and those that give the bees and wasps that pollinate them so much nectar it is not uncommon to see swarms of drunken insects, a known hazard during the early springtime especially.
There are no plans to bring back examples of wildlife as there are concerns these wouldn’t survive the transportation process yet alone conditions in the Kingdom. It is felt plants are generally hardier and adapt quicker to a new environment.