Seedling survival mechanism of a deciduous broad-leaved forest in the sub-tropical to temperate transition zone in the Qinling Mountains

Abstract

[Objective] Survival of species seedlings is closely related to various biotic and abiotic factors. Exploring the key factors affecting seedling survival is helpful for the understanding of species coexistence mechanisms. [Methods] This study was focused on the survival dynamics of the woody species seedlings in a 25 hm2 permanent forest of a deciduous broad-leaved forest in the Qinling Mountains, and the survivals of 11 408 seedlings were examined for five consecutive years (2015-2019). The generalized linear mixed models (GLMMs) were used to examine the effect of maior biotic and abiotic factors on the survival of seedlings of different ages at the community level. [Results] (1) At the community level, biotic factors played a major role in seedling survival. Seedling survival was negatively correlated with conspecific seedling density and basal area of conspecific adults. It also positively correlated with interspecific seedling density. The results showed that negative density-dependence (NDD) had significant effects on seedling dynamics. (2) From the seedling age level, in addition to biological factors, abiotic factors such as altitude also affected seedling survival. The effect of abiotic factors decreased with the increase of seedling age. [Conclusion] There are many factors affecting seedling survival, among which biological factors are more significant, and the main mechanism promoting seedling coexistence is the negative density restriction effect in the Qinling Mountains.

Keywords

• seedling survival
• negative density dependence
• biotic factors
• environmental factors