Research On The Population Structures And Reproductive Strategies Of Agropyron Mongolicum Keng.in The Desert Steppe In Ningxia

Desert steppe is a kind of arid landscape, which can be characterized by its drought, sparse vegetation and it’s one of the most vulnerable ecological environments on the earth. How to improve desert steppe ecological function with ecological management has become one of the most important issues in saving the desert steppe. In this paper we set an object of study in the desert steppe in Ningxia, which could reveal the temporal and spatial variation regularities of Agropyron mongolicum Keng. and the influencing factors, also could provide some theories about examining the consequence in ecological recovery projects and using method optimizations. The experimental results show that:(1) The population has formed uniform distribution and state of aggregation in spatial distribution in the wild. In a certain time the growth rate of the Agropyron mongolicum Keng. population was mostly the same and uniformly distributed, however the lack of resources led to slower growth rate or even the death.(2) Accumulation of aboveground biomass of the Agropyron mongolicum Keng. population conformed to the growth of Logistic, yet accumulation of underground biomass was in serial changing processes.(3) The germination percentages were various in different habitats, which was apparently higher in laboratory than in the wild and was in a high germination percentages with the temperature15℃-25℃.(4) There were both sexual reproduction and asexual reproduction in the Agropyron mongolicum Keng. population. The reproductive tiller plants would raise up the rate of the regrowth growth in order to prove the potential fertility when there was in a bad internal environment of the population, while in good environment they would devote more energy to the growth of stalks to improve competiveness.(5) There are variations of quantitative characters between population vegetative reproductions that the number of the plants, the biomass and the reproduction branches are all in exponential growth along with the plant range, however the weight of the reproduction branches are in power function growth along with the plant range.(6) There is most reproductive biomass in caryopsis and there is no significant relationship between the seed weight and reproductive biomass. There is an obvious negative correlation between the reproductive allocation II and the height of the plants which shows that energy will be reduced in the seeds when the plants grow higher.