Neighbor trees and habitat suitability of Cinnamomum balansae Lecomte in North Central Coast and Northern Vietnam

Cinnamomum balansae Lecomte is an endangered species, distributing mainly in Northern Vietnam. Information on distribution characteristics of C. balansae is important for the species conservation, especially under a changing climate. This study, therefore, sought to determine neighbor species composition of C. balansae, and predict current and future distribution of the species in North Central Coast and Northern Vietnam. In 2019, we conducted surveys in 9 provinces in the study site to identify species occurrence localities and record neighbor trees. Nine bioclimatic and topographic variables, and 52 occurrence localities were used to develop Maxent model for C. balansae distribution. Our study indicated that C. balansae distributed with at least 82 woody species, and its most frequent neighbors were fast-growing and light-demanding species. In addition, frequent neighbor species tended to distribute closely to the focal C. balansae species. The Maxent model for C. balansae distribution showed a good performance (test AUC = 0.861), compared with null model (test AUC = 0.535). Precipitation of warmest quarter-Bio 18 (26.19%) and mean diurnal temperature variation-Bio 2 (21.34%) were the two most important variables in predicting C. balansae distribution. The most suitable area for current distribution of C. balansae was 2776.9 km 2 , occupying about 1.7% of the study site. Our data suggest that the most suitable area of C. balansae could increase in both RCP (Representative Concentration Pathway) 4.5 and RCP 8.5 scenarios. In the future, three northwest provinces of Vietnam could be new suitability areas for C. balansae distribution.