Researches On The Mechanisms Of Seed Germination And Seedling Emergence In The Alpine Meadow

This research,which aimed at plant communities of different stages of abandoned field succession from Alpine meadow were uscd to analyze the germination characteristics and seedling emergence,for a purpose of providing insights into the rules of individual establishment in various microsites.The results as shown follows:1.Of all the 15 plant species,single factor or combination of factors had effects on germination of 14 plant species,Scirpus pumilus is the only species that did not respond to any factor or combination of factors.Study is essential to understand the germination behavior and dormancy mechanism of plant species under specific conditions.2.11 species were limited by a combination of seeds and microsites;12 species were seed limited,and 3 species were found not to be seed limited,but the limiting factor was not identified.3.Our field results showed that cold stratification and disturbance treatment affected the seedling emergence of 12 species except Kobresia humilis,Potentilla fragarioides and Scirpus pumilus.Different field affected 10 species significantly.Cold stratification affected 5 species significantly and disturbance affected 5 species significantly.The interaction of cold stratification and disturbance affected 5 species significantly.As a consequence,we indicated that successful establishment of plant species is mainly affected both by available seeds and safe sites.4.Different disturbances created specific microsites and provided the seeds with ecological factors what they require during germination,seedling emergence.Different disturbances increased seedling ratio of most species.However,cold-stratification affected species differently in different fields:cold-stratification broke the dormacy and improved seedling emergence in abandoned field and inhibited the seedling emergence of 7 species in Kobresia humilis meadow.5.The results showed that there was specific difference between Roegneria nutans, Heracleum millefolium,Amblytropis multiflora of seedling emergence in special microsites.And Kobresia humilis,Potentilla fragarioides and Scirpus pumilus responded similarly in different microsites.But various microsites affected Daucus carota significantly,there was higher seedling emergence in the bare ground of Kobresia humilis meadow and higher seedling emergence in the lacerating sward of abandoned field.6.Patterns of species distribution over plant communities vary a lot in both time and space. Process of plant community with diverse species is one process in which individuals subjected to different species are successively iterated.Process of community assembly should follow the process determined by both deterministic process and stochastic process,that is,random and deterministic mechanisms work together in determining the patterns of species distribution in plant communities.