Thailand in the 1950s planted millions of leucaena trees for fodder and reforestation, but scientists now say they have spread into natural forests, replacing native vegetation with dense single-species stands

Thailand’s ambitious 1950s tree-planting initiative, aimed at restoring barren lands with the fast-growing Leucaena leucocephala, has backfired. Once hailed as a ‘miracle tree’ for its soil enrichment and fodder benefits, it has now become a serious ecological threat. The invasive species aggressively outcompetes native vegetation, forming dense monocultures that devastate biodiversity and disrupt natural forest regeneration, posing a significant conservation challenge.