Fern classification expert Mou Shan-chieh says that the greatest threat to the ferns in the Nankang Hills area comes from the many "well-meaning" people, among those who come to exercise here, who clear away the "weeds" -i.e. ferns-from the paths and flat areas, and plant garden plants everywhere, so that the hills are now being colonized by introduced poinsettia (Euphorbia pulcherrima) and crown-of-thorns (Euphorbia milii).
羊齒植物的分類高手牟善傑就表示，南港山蕨類的最大威脅之一，正是許多來此運動的「好心人」，剷除了步道、平台上的「雜草」──蕨類，到處種了「園藝作物」，只見外來的聖誕紅、麒麟花，也在南港山上攻城掠地、落地生根。