Drought tolerance traits predict survival ratio of native tree species planted in a subtropical degraded hilly area in South China

Low soil water availability in the dry season substantially influences the survival of native tree species planted in subtropical degraded hilly lands in South China. In this study, we investigated the survival and hydraulic-related traits of 16 native tree species from a six-year-old mixed plantation, to investigate whether the survival ratios of species are associated with their drought tolerance and hydraulic efficiency. Our results showed that the six-year survival ratios ranged from 1% to 96% among the 16 species, with less 25% survival for four species. Across species, the survival ratio was significantly correlated with xylem vulnerability to cavitation, hydraulic safety margin, and leaf turgor loss point. It was not correlated with sapwood density and hydraulic conductivity. These results indicated that drought tolerance was the determinant of species survival in the mixed plantation. Additionally, we found that a large proportion of high survival species were non-pioneers, indicating that mixed plantations consisted of pioneers and non-pioneers are effective and would decrease the time required for the succession from plantation to mature forest. Considering that drought is one of the most important stress factors that affect the success of forest restoration, and increases in frequency and severity in the subtropical region, we suggest drought-tolerance traits are valuable for identification of native tree species suitable for restoration projects.