Effects Of Altitude And Flowering Phenology On Reproductive Allocation Of32Alpine Plants

Reproductive allocation is one of the key points in researches on life history.How resources are allocated to growth and reproduction,and the trade-off in resource allocation between growth and reproduction could mirror the adaptation to different habitats.There could be great differences in habitats for plant species,which then could induce changes of resource allocation to reproduction.Generally,how changes of altitude and flowering phenology affect the reproductive allocation on community level still need to be clarified.In thesis,two alpine meadows with different altitudes on Jade Dragon Snow Mountain,respectively as Yushui village with altitude of 2200 m and Wenhai village with altitude of 3200 m,were selected around Lijiang city,and then plant species with initial flowering phenology were collected in early July,August and September.In total,35 populations of 32 species belonging to 17 families were collected.After plant height was measured for each individual,vegetative organs and flowers were bagged separately and dried in laboratory.The vegetative biomass and reproductive biomass were weighed.In light of these data,effects of altitude and flowering phenology on reproductive allocation were compared,and the relationships between plant size,measured as vegetative biomass,and reproductive allocation were analyzed.The main results were in the following.(1)Generally,plant height,aboveground biomass,vegetative biomass and reproductive biomass of plant species in the community at the low altitude around Yushui village were higher than those at the high altitude around Wenhai village,but both absolute reproductive allocation and relative reproductive allocation of plant species in the community at the low altitude were less than those at the high altitude.In addition,plant height aboveground biomass,vegetative biomass and reproductive biomass of plant species with early flowering phenology(July)were higher than those with late flowering phenology(August and September),but both absolute reproductive allocation and relative reproductive allocation of plant species with late flowering phenology(September)were higher than those with early flowering phenology(July and August).These results suggested that more resources would be allocated to reproductive organs in plant species in the high altitude and with late flowering phenology,indicating that resources allocated to reproduction would be a priority over growth and that reproduction could be more important than groth in plant species inhabiting stressful environment.(2)Except Prunella vulgaris,there were significant relationships between plant size and reproductive biomass in other 34 populations,but there was no consistent trends between plant size and reproductive allocation across all the 35 populations.In detail,there were negative relationships between plant size and reproductive allocation in 26 populations,but the relationships were significant in 8 population out of 26.In contrast,there were positive relationships between plant size and reproductive allocation in 9 populations,but the relationships were significant in 2 population out of9.These results suggested that reproductive biomass was size dependent,and also suggest that the relationships between plant size and reproductive allocation could be affected by multiple factors,leading the inconsistent trends in the results.Conclusively,plant species inhabiting high altitude and with late flowering phenology would allocate more resources to reproduction,indicating the importance of reproduction to these species.Furthermore,resources allocated to reproductive organs are size dependent,but there was no consistent trend between reproductive allocation and plant size,indicating resource allocation pattern could result from different factors.