Between 18,000 and 25,000 land mines remain scattered about in the Falklands from the 1982 war. Further clearance work to remove some of those was to be done in 2011, but not sure if it was.
Virtually all of the surface area of the islands is used for sheep pasture. There is a penguin population, and many beautiful rare birds.
The article I was reading states that no long-term studies have been done as to the adverse affect humans living there have had on the rather pristine land.
Native grasses and other vegetation is heavily impacted adversely by the overgrazing of sheep.
Reindeer have been introduced.
Cats and rats and grey foxes have been introduced, having a detrimental affect on the breeding of the birds, which now mostly just live on the outer islands as a result.
Grey foxes. Rats. Feral cats. Overgrazing. I guess that about covers my opinion as to whether humans have had an adverse affect on the Falklands, despite the lack of long-term research. (I vote "yes".)
2008 population estimate is 3,140. That works out to about 7.96 land mines per human.