The status, biology, and conservation of Serianthes nelsonii (Fabaceae), an endangered Micronesian tree Original Research Article

Serianthes nelsonii Merr. is a rare leguminous tree endemic to Rota and Guam in the Mariana Islands of Micronesia. Current population estimates are 121 adult trees on Rota and one adult tree on Guam. Surviving trees occur exclusively on limestone substrates, although the species formerly inhabited volcanic soils in southern Guam. Populations on both islands are senescent, with little or no regeneration occurring. More than 84% of the trees have trunk sizes >40 cm diameter at breast height. The species is threatened primarily by browsing from introduced deer and pigs and infestations of herbivorous insects, especially undetermined seed predators, four species of mealybugs, and a butterfly. Recovery goals call for the reestablishment of at least two large subpopulations on each island. Prevention of ungulate browsing through fencing and control of insect damage are essential for recovery of the species.