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Among other things, he said that when you do restoration work, there’s no obvious answer to the obvious question: What state do you restore a given landscape to? What’s “natural”? The way it was in your childhood? Before European settlement? Before Indian settlement?
“Sometimes it is even unclear whether a species is alien or native. . . . There is also the question of how far back one takes ‘human’ activity in determining whether a species is native or alien.” Humans introduced at least 157 plant species to Britain between 4,000 and 500 years ago, and in 2004 one group of researchers proposed that these should be classified in a category in between native and exotic—dissolving the once razor-sharp distinction between “natural” and “unnatural.” Everything over 4,000 years old is natural, everything under 500 years old is unnatural, and everything in between is half-natural? Why not 400 years? Six hundred?
