Last spring we called a firm in to remove three Norway spruces that had been in our northern Strasbourg garden from the time we acquired the keys to the house in October 1994, when both the trees and our two children were small. But our children had become adults and left home, and the trees—which I suspect had been lifted as seedlings from the Rhine forest at the end of our road by the previous owner (and should never have been in a suburban garden in the first place)—had become giants, were undermining my wife’s potagers with their roots, and…