Native plants in the Tongariro National Park are being hit hard by the spread of invasive heather with a 40% to 50% drop in native species in some areas, a new study published in Oecologia has found. Native plants in the Tongariro National Park are being hit hard by the spread of invasive heather with a 40% to 50% drop in native species in some areas, a new study published in Oecologia has found. Plants & Animals Ecology Phys.org – latest science and technology news stories