Study On Reproductive Allocation And Reproductive Strategy Of Stellera Chamaejasme Population In Alpine Degraded Grassland

To a great degree, the adaptation, migration and extinction of plant populations depends on its dynamic characteristics in changing environment under the background of global change, and which closely related to their reproductive process and resource allocation. So it is very important to understand and forecast the changing of plant structure and vegetation zones shift in global change. There are limitative resources during the plant whole life, so the plant has to allocate resources among growth, survival and reproduction. The model of resources allocation can reflect the character of the plant life history, which is the core to study of plant life history, reproductive allocation is about the proportion of reproductive resources in total, the factors which influence the proportion, and the relationship between reproductive allocation and the influence factors. There are a lot of unique plant groups in alpine region of the northern slope of Qilian Mountains. To study the resource allocation, reproductive allocation, reproductive strategy and the relationship of various factors of Stellera chamaejasme population that widely distributed in the region not only help to analyze the Stellera chamaejasme of adaptation in different habitats, but also help to further discuss reproductive strategy theoretical of Stellera chamaejasme. In order to reveal adaptive strategies and reproductive strategy of Stellera chamaejasme, we used the vegetation investigation method and drying weighting method to study the character of reproductive allocation, the relationship between reproductive allocation and plant tissues, and the reproductive strategy in alpine degraded grassland of the northern slopes of Qilian Mountains at different altitudes and at different classes, the results showed that:(1)Aboveground biomass, height and flower number of Stellera chamaejasme decreased with the increase of altitude, this result showed that the higher altitude Stellera chamaejasme grow, the smaller Stellera chamaejasme are, this can explain as the Stellera chamaejasme adapt the shivery environment of high altitude by decreasing biomass, and this is a exemplification of Stellera chamaejasme population adapting the alpine region.(2)Reproductive investment decreased with the increase of altitude, but reproductive allocation increased with the increase of altitude, this mean that the small size plants have higher reproductive allocation values. This result showed that Stellera chamaejasme grow its organism in the lower altitude, but the ones enhance their reproductive activities using the largest resource in the higher altitude.(3)Reproductive investment increased with the increase of aboveground biomass in all of the altitude gradients, but reproductive allocation showed no stationary model. This result showed that reproductive investment entirely followed the size-dependent pattern, but reproductive allocation showed lower level of following the size-dependent pattern. (4)There is a trade-off model between flower number and average flower biomass in the resources allocation of Stellera chamaejasme. This showed that the larger the aboveground biomass is, the more the flower number are, but the average flower biomass wasn't forming a exact trend. This phenomenon showed that reproductive investment entirely followed the size-dependent pattern.(5)The Stellera chamaejasme classes(Ⅰ,Ⅱ,ⅢandⅣ)were more dispersed in distribution in the lower altitude region, but these were centralized in distribution in the higher altitude region. The flower number and average flower biomass were increased with the increase of aboveground biomass in the different classes, and the classⅠof Stellera chamaejasme followed the size-dependent pattern exactly, but classⅡ, classⅢand classⅣhave a poor trend following the size-dependent pattern.(6)Reproductive investment, flower number and average flower biomass showed significant positive correlation as to the aboveground biomass. This phenomenon showed that reproductive investment, flower number and average flower biomass were affected by the altitude, and the variable classes have a direct effect to the reproductive investment and reproductive allocation.(7)The reproductive characteristics of Stellera chamaejasme from altitude gradients were varies from classes. It showed that classⅠand classⅡhave a higher reproductive allocation, but flower number, average flower biomass of classⅢand classⅣwere directly affected by both altitude gradients and variable classes. This phenomenon showed that Stellera chamaejasme can adopt varies of reproductive strategies to adapt to the different altitude gradients and variable classes on a special altitude.