SEEDLING RECRUITMENT OF FORB SPECIES UNDER EXPERIMENTAL MICROHABITATS IN ALPINE GRASSLAND

摘要

Which factors limit plant seedling recruitment in alpine meadow of the Qinghai-Tibetan Plateau (QTP), China? Thisstudy examined the relative influence of seed mass and microsites (resulted from grazing disturbance) on field seedlingemergence and survival of nineteen alpine herbaceous species with a range of traits in QTP. Seed mass had significanteffects on seedling emergence and survival eliminating influence of light and nutrient variances among these species. Thelarger-seed species had more advantageous than the smaller-seed species in seedling survival, but it was disadvatage forseedling emergence, especially under high nutrient availability and low light intensity conditions. Light had obvious effectson seedling survival, but less effects on seedling emergence for these species. Moreover, nutrient and light treatments alteredthe regression relationships of seed mass and seedling emergence and survival and the order of significances wasL25L50L100L10L4. These results suggested that seed mass may restrict seedling recruitment processes, however,light and nutrient availability all have significant effects on seedling emergence and survival for these alpine species.Moderate light intensity was propitious to seedling emergence and survival in alpine grassland. This suggests that ecologicalfactors in alpine grassland provide a stochastic influence on different seed-mass species. These trends may help to explainwhy many small-seeded species of Asteraceae and Gramineae tend to be more abundant in disturbed habitats.