New Zealand planted millions of pines for timber more than 175 years ago, but today scientists are spending millions trying to stop them from overrunning native mountains

New Zealand's high country is battling an invasion of non-native pine trees, introduced generations ago for forestry. These 'wilding conifers' now cover millions of hectares, outcompeting native flora and drastically altering ecosystems. Despite costly control efforts, these fast-growing, adaptable trees, aided by invasive fungi, continue to spread, highlighting how well-intentioned introductions can become ecological nightmares. The situation offers a stark warning for land managers globally.