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This study mapped potential areas for planting golden camellias in Cao Bang province, North Vietnam. Natural conditions (elevation above sea level, annual precipitation, and annual air temperature), where 6 golden camellia species (Camellia impressinervis, C. kirinoi, C. megasepala, C. tuyenquangensis, C. hamyenensis, and C. tienii) naturally distribute, were used for mapping. Three map layers (topography, precipitation, and air temperature) were used. Each main condition was classified into 3 levels for planting, “not suitable”, “suitable”, and “very suitable”. The results indicated that 1,970 ha, accounting for 0.3 % of the total land area of Cao Bang province, was classified as “very suitable” for planting golden camellias. “Suitable” areas counted for 62.7 %, and “not suitable” areas accounted for 37 % of the total land area, respectively. Mapping suitable planting areas is the 1st step for the successful planting of any species. It is recommended that golden camellias should be first planted in very suitable areas, after which planting may be extended to some suitable areas.

Plus tree selection is the first step to improve production and quality in forestry. An individual-based method is widely used to select plus trees for timber production, timber form, freedom from diseases and insects. In this study, a method to select plus trees for flower production is described and named as a crown-area-based method. Both individual-based and crown-area-based methods were used to select plus trees for Camellia impressinervis, a golden camellia; its yellow flowers have been used to treat sore throat and diarrhea, and to prevent cancers in China and Vietnam. Flower production of 21 concerned individuals was compared to the population mean and it was generated as a percentage. The population mean of the individual-based method is the mean of production of 21 trees as mean production/tree. While population mean of the crown-area-based method is mean production/m2 crown area (first production/m2 crown area for each tree was generated, then mean for population). The results indicated that both methods show seven individual trees with flower production >100% population mean. However, individual trees are different. Only five of 7 trees are the same in both methods. The tree rankings by flower production percentage in both methods are totally different. The highest ranking by individual-based method (310% mean) is 4th ranking by crown-area-based method (181% mean). While the highest ranking by crown-area-based method (270% mean) is third ranking by individual-based method (260% mean). It is concluded that crown-area-based method is better in selecting plus trees for flower purpose, as it considers the crown area which is known as a productive part of a tree to form flowers.