Leaf functional traits predict cloud forest tree seedling survival along an elevation gradient

Abstract

Cloud forest tree seedlings of higher leaf mass to area ratio and leaf dry matter content displayed higher survival along an elevation gradient in the forest understorey. Phenotypic plasticity in leaf functional traits was not related to seedling survival. Understanding the relationship between seedling survival and phenotypic plasticity of leaf functional traits is of great importance for predicting tree species responses to climate change. We analysed whether phenotypic plasticity and mean values of leaf functional traits could serve as predictors of cloud forest tree seedling survival along an elevation gradient. We measured survival, leaf mass area (LMA) and leaf dry matter content (LDMC) in planted tree seedlings of 13 shade-tolerant tropical cloud forest species in nine forest understorey sites along an elevation gradient in southern Mexico. Phenotypic plasticity in LMA and LDMC was calculated based on inter-individual phenotypic variation to different elevations. Intraspecific differences in LMA and LDMC occurred with elevation. Across the elevation range, seedlings with higher mean LMA and LDMC had higher survival. Plasticity in leaf traits was small and was not related to survival. Our results support that mean LMA, and to a lesser extent mean LDMC, could be good predictors of cloud forest tree seedling survival along elevation gradients. The small leaf trait plasticity found does not affect the survival of seedlings in the forest understorey along the elevation gradient.