Current state of knowledge on the extinction risk of Malaysian tree species: Proximate needs to mitigate loss

Societal Impact Statement As one of the world's top megadiverse countries for tree species, Malaysia remains committed towards reducing tree population loss and species extinction. In order to ensure efficacy in the planning and implementation of conservation programmes, prioritisation of resources, and mainstreaming across the key drivers of biodiversity loss, it is essential to identify, document, and assess the extinction risk of families with high levels of endemism. In addition to being an integral component of ecosystems and their functions, from a socio-ecological perspective, the rich biodiversity of Malaysia constitutes extraordinary natural capital that many people depend on for their livelihoods and well-being. Malaysia is a megadiverse country for plant species. Knowledge of the diversity of Malaysian plant species is incomplete but has been significantly expanded by the Tree Flora of Sabah and Sarawak and Flora of Peninsular Malaysia projects. More than 400 new plant species, including at least 14 new genera, have been added since 1995. Between 1973 and 2015, Malaysia lost an estimated 29.4% natural forest cover; conserving plant species at immediate risk of extinction will help alleviate future loss of natural forests and biodiversity. With 9.2% of the world's tree species dwelling in Malaysia, of which 29.8% are endemic, species risk assessment is an important conservation planning tool for the Malaysian flora. Through the Global Tree Assessment project, Malaysia verified that approximately 24% of the tree diversity is exposed to a multitude of threats ranging from deforestation and forest degradation to poaching and incursion of invasive alien species. Here, we summarise the extent and types of extinction risk faced by several of our keystone tree families, namely, Dipterocarpaceae, and tree genera of Myristicaceae and Sapotaceae, whose timbers remain highly valued. We summarise the nature and aims of programmes that spur the country's conservation agenda for threatened plant species and describe some specific targets for Peninsular Malaysia, Sabah, and Sarawak. We focus on efforts that enhance in situ conservation and the understanding of population dynamics. Programmes that enable and support the main agenda, such as institutional capacity building and awareness of the importance of biodiversity, are also briefly explained.