Factors Affecting the Early Survival and Growth of Native Tree Seedlings Planted on a Degraded Hillside Grassland in Hong Kong, China

Abstract

AbstractThe effects of seasonal drought, belowground competition, and low soil fertility on the survival and growth over 2 years of four native tree species planted on a degraded hillside grassland in Hong Kong were studied in a field transplant experiment using three‐way analysis of variance. The tree species wereSchima superba(Theaceae),Castanopsis fissa(Fagaceae),Schefflera heptaphylla(Araliaceae), andSapium discolor(Euphorbiaceae), and the treatments were dry season irrigation, herbicide, and fertilizer. Each species responded differently to the treatments.Sapiumhad a very low survival rate as a result of wind damage at the exposed study site. All three treatments significantly reduced the survival rate ofCastanopsisseedlings, whereas herbicide reduced it forSapiumbut increased it forSchefflera. The significant effects on seedling growth were all positive, except for a strong negative effect of herbicide onCastanopsisgrowth. Overall, the results suggest that all three factors—seasonal drought, belowground competition, and low soil nutrients—can significantly impair seedling growth on a degraded hillside site in Hong Kong but that their relative importance differs among species. The growth benefits of the three treatments were largest and most consistent forSchima, which as a mature forest dominant would be expected to be particularly sensitive to the environmental conditions on degraded open sites. This study highlights the fact that more systematic planting trials are needed to identify suitable native tree species for cost‐effective reforestation on degraded hillsides in Hong Kong and South China.