Phenology Of Alpine Meadow Plants In The Eastern Qinghai-Tibet Plateau: Community, Functional Traits And Phylogeny

Flowering phenology is a key life history trait that strongly influences reproductive success. The relationship between flowering times of all species within a community is the results of interactions among multiple factors and processes, such as light, temperature, pollinator availability and interspecific competition over evolutionary history. Phenological data were obtained by weekly observation of 50 0.5×0.5 m2 quadrates. Specific leaf area (SLA), height, and seed size of 48 alpine herbs were measured. Relationships between flowering phenology overlaps and phylogenetic distances of 71 species were tested by null models.We gained following results:1). Seasonal changes in species number of alpine meadow community are steady even in the early growth season, while phenologcal dynamics of alpine herbs are regular and continuous. Number of flowering species dramatically raised and fell. Species of alpine meadow community flower through out the entire growth season; however, there was still generally a peak in community level.2). The relationship between flowering phenology and functional traits implies that there are tradeoffs between vegetative and reproductive growth. Early-flowering species tend to have lower adults and larger seeds, while late-flowering species are higher, and yield smaller seeds. Although there is a negative relationship between flowering peak dates and flowering durations, the relationships are mainly due to a few annuals.3). LHS (leaf-height-seed) scheme dimensions worked well in describing temporal reproductive strategy. There are relative independences among height, SLA and seed size. There is no correlation between SLA flowering phenology.4). Both flowering phenology and functional traits are phylogenetical conservative. However, the relationship between them is not constrained by their phylogenetical relations.5). Wind-pollinated species flower earlier than insect-pollinated species. There are no phenological differences between life forms and dispersal modes.6). Null model tests found that flowering phenology are phylogenetically constrained:related species tend to co-flower temporally more than expected by chance. Processes shaping this pattern could be due to that environmental filtering is stronger than interspecies competition in alpine area. Or also, clone propagation made sexual reproductive not under strong selection.7). Algorithms retain zero values in data matrix have lower typeⅠerror rates than those change zero values. Moreover, one should note that widely used Mantel test have highest typeⅠerror rates in our analysis.