Plant Phenology And Its Relationships With Other Traits At Alpine Swamp Meadow In Qinghai-Tibet Plateau

Plant phenology is an important theme in studies of ecology.Different phenological time among plants have an important role in community assembly. At the same time, plant phenology is an important functional trait of plants. Therefore, studying plant phenology and its relationships with other traits is of important ecological significance. The study was conducted at The Research Station of Alpine Meadow and Wetland Ecosystems of Lanzhou University, Maqu (102°03'E,33°39'N) on the eastern edge of Qinghai-Tibetan plateau. During the growing season of 2008 and 2009, we recorded the phenological events (vegetative, bud break, flowering and fruiting), and measured the traits (plant height, biomass, leaf size, SLA, seed size, reproductive allocation) of a variety of plants. We built the phenological time series of the alpine swamp meadow community, analyzed flowering pattern and distribution peak of flowering, species coexistence, and the relationships between phenological traits and other traits. We analyzed phenological data by SPSS 15.0 and Execl 2003.The results showed:1) All phenological period(green,budding,flowering,fruiting)concentratr-ated about more than 5 months from late April to October.Different species start turning green from mid-Apri, then begin to budding and flowering,and to fruiting from early June.2)Flowering started from late April, peaked in early August and finished early October at alpine swamp meadow. It ranged almost along the whole growing season.3) Th initial date,duration,and peak date of flowering are different among species.The time of peak flowering date was negatively correlated with the duration for different species,e.g.,earlier flowering species have longer flowering duration.4) Among the 45 studying species (early flowering of two species were not observed in 2008) in 2008 and 2009, intial flowering date of 4 species are the same.9 species delayed and even over a week for 5 of them. Other 30 species exhibiting earlier flowering and 12 species of them over one week.5) The results showed that the distribution of peak flowering among families are radom.At the same time, the distribution of peak flowering of species (frequency above 50%) are also ramdom.Within family, execpt for Gramineae and Gentianaceae, the distribution of peak flowering of species are ramdom The results indicated there the the role about mechanisms of flowering differention is not leading.6) Height is one of the important reasons for differentiation of plant phenology.Individuals of species with lower height tend to flowering earlier while Individuals of species with higher height flowering later,which is the consequences of overtopping strategy for effective pollination for plants of lower height and competing available resources. In addition, seed size is one of the important reasons for phenological differentiation of flowering. Due to the short growing season in this alpine swamp meadow, species with larger seed size should flower earlier in order to have enough time for seed development.7) Regeneration niche due to phenological differentiation among species is important for species coexistence in the alpine swamp meadow community. The temporal niche of species differed by different time of turning green, budding, early flowering and peak flowering.