Seedlings Recruitment of a Timberline Tree (Larix chinensis Beissn) in Taibai Mountain, China

Аннотация

Larix chinensis Beissn forms a subalpine timberline on Taibai mountain, Shaanxi, China. Seed emergence and survival of seedlings were studied by seed sowing experiments across an altitudinal gradient (3150–3400 m a.s.l). Three main factors were considered: seed addition, shrub shadowing and disturbance. In three different habitats (from low altitude to high: the Abies fargesii forest, the Larix chinensis forest and the shrub meadow), seeds emergence was examined and the seedling number and growth in every plot were recorded continuously over 4 years. Kruskal-Wallis ANOVA was used to analyze the relationship between seedling emergence/recruitment and the explanatory variables in every stand. The results showed that seed addition in disturbed plots always caused significantly increased seedling emergence and recruitment in the A. fargesii forest and the L. chinensis forest, but not in undisturbed plots under the canopy of forests. It demonstrated that recruitment of L. chinensis was limited by seed and microsite availability under closed forest, and litter is one of the factors leading to microsite limitation. However, in the shrub meadow, no treatments improved recruitment, indicating that the shrub meadow was not suitable for seedling establishment because of more intense light and lower temperature. In the L. chinensis forest and the A. fargesii forest, more recruited seedlings indicated that these two forests are safer for L. chinensis seedling establishment, though seeds limitation and the litter obstacle had seriously constrained the regeneration of L. chinensis.