The Study Of Flowering Phenology Of Alpine Plants On Eastern Tibetan Plateau

The study of phenology has a long history.Phenology,as a suitable method for climate change research,turned to be focused by ecologist and climatologist with the increasing of public attention to global climate change.Alpine ecosystem may be under a greater pressure from climate change than the other type of ecosystems.However,there was little comprehensive and systematic research of alpine plant phenology.The factors that influence flowering phenology were thought to be the abiotic factors(day length,temperature,precipitation and so on),biotic factors(pollinator,disperser,predator and so on),phylogeny and functional traits.While most of the studies of flowering phenology focused on only one or two factors related to flowering phenology and much less about the interaction of these factors.We used 5-year(from 2008 to 2012)phenological data of alpine meadow community and swamp meadow community and 7-year(from 2008 to 2014)flowering phenology data of alpine meadow community respectively,and molecular phylogenetic trees,functional tree,climate data to analyze the flowering phenology of alpine plants in different aspects and different angles.Generalized linear model,mixed effect model,phylogenetic eigenvector regressions,null model and phylogenetic signal measures were applied in our analysis.Our main conclusions are as follows:1.The flowering phenology of alpine plant(also the first flowering budding and first fruiting)was phylogenetic conservatism which means that the closely related plants tend to reproduce at similar time.And the result was consistent through the two alpine plant communities,the years and the phylogenetic trees.2.Day length was the most important factor to drive the flowering phenology of alpine meadow and swamp meadow,and temperature following behind.There was no significant correlation between precipitation and flowering phenology of alpine plant communities.3.Phylogenetic conservatism and climate factors shape the flowering phenology of alpine plant communities together: the number of species in flower was highly correlated withclimate factors and species' relative timing was more related to phylogeny.4.Closely related plants tend to flower and fruit in respond to similar day length and temperature.The foundation of phylogenetic conservatism in plant phenology seems to be the similarity in related species' responses to external environmental cues.5.We also used 7-year(from 2008 to 2014)flowering phenology data(first flowering, flowering peak date and flowering duration day)of alpine meadow community, phylogenetic tree and functional tree to propose the plant community hypothesis of flowering phenology: when the interspecific competition was strong in plant community, the flowering phenology of these plants may delay and when the interspecific competition was weak or the interspecific facilitation was strong in plant community,the flowering phenology may advance.And this hypothesis has been testified by our data with mixed effect model.6.The plant community hypothesis of flowering phenology was consistent at species level, family level and also the community level which suggests the stable and general natural selection on flowering phenology of alpine plants.7.The variation of plants' flowering responses to plant communities based on different category levels(life form,pollination model,plant height,plant dry matter mass and flowering peak date)implied the different life strategies of these alpine plants.