Diversity, distribution and threats of the Juglandaceae in Vietnam

Vietnam is one of the main centers of generic diversity for Juglandaceae worldwide. In this study, we present for the first time a province-wide distribution of all 3 subfamilies, 7 genera, and 11 Vietnamese species, and give an update on the habitats of all Vietnamese Juglandaceae species, their uses, and current threats. Juglandaceae are found throughout Vietnam. However, most species occur predominantly in the north- ern part of the country between 600 and 1200 m. Some taxa range is found extensively from sea level up to 2,500 meters above sea level. According to the IUCN Red List, Rhoiptelea chiliantha, Carya sinensis, and Pterocarya tonkinensis are threatened while Engelhardia spicata, E. serrata, Alfaropsis roxburghiana, Pterocarya stenoptera are classified as least concerned (Carya tonkinensis is threatened locally, and Engelhardia spicata var. colebrookiana and Platycarya strobilacea merit “threatened” designation in Vietnam’s Red Data Book. The most frequent threats are logging, land-use change, and habitat destruction due to artificial wood planta- tions or road construction. Until now, no conservation measures have been applied for any of the species in Vietnam, although some species occur in national parks. Our study gives an important update on the current diversity and distribution of Juglandaceae in Vietnam. We point out the need for a correct assessment of the threat status of various species on a national and international scale to protect the rarest and most endangered of them. Further research, the use of various forms of protection of individual taxa and/or their habitats, and drawing the attention of an international group of researchers to the urgent need to work together to protect biodiversity in Vietnam hot spots are necessary.