The Strategy Of Spacial Expansion Of Clonal Plant Hierochloe Glabra Trin. Under Homogeneous And Heterogeneous Habitats

The strategy of spacial expansion is an important part of life history strategy of clonal plant population. In this study, we decide rhizome clonal plant Hierochloe glabra Trin.as research material. We choose strategy of special expansion as breakthrough point of our study,in order to provide a solid scientific basis for clonal plant population ecology. This study has two purposes. One is to examine the capacity of expansion of clonal plant Hierochloe glabra to confirm the conclusions of previous studies, that's the capacity of expansion will decline in order to take full advantage of available resources in rich-nutrient habitats, and the capacity of expansion will raise in order to escape unfavorable habitats. The other one is to examine the appearance of expansion in order to investigate the driving force of expansion of clonal plant in heterogeneous habitat.In this study, we design a field control experiment. Two kinds of habitat are designed, what are homogeneous habitat and heterogeneous habitat. The results show that in homogeneous habitat, with the increase of fertilizer, the number of ramet of clonal plant population, the spacer length, the internode length and total rhizome length didn't show significant difference, but the number of buds show significant difference(p <0.05). The green parts of the populations on the ground show remarkable plasticity, leaf length and plant height significantly increasing with the increase of fertilizer (p <0.05). In the observation of biomass, aboveground biomass and total biomass in high-nutrient treatment significantly increased (p <0.05), while the increase in belowground biomass is not significant, which reflects the population investment tends to give priority to raising the input of the aboveground part. In the heterogeneous habitat experiments ,through the observation about parameters for expansion capacity, we found the number of ramets in the rich-nutrient patch increased more significantly than that in the poor-nutrition patch(p<0.05),total rhizome length increased significantly in rich-nutrient patch(p<0.05), the spacer length and the internode length decreased significantly(p<0.05). Differences in phenotypic characteristics respond to the changes of the growing season and nutrient concentrations. The colonization phenotypes in population differences are significant in early growing season, but such differences will disappear with time changing. In two years experiment, the distribution of biomass in 2008 compared with 2009 ,there is a significant trend in 2008, aboveground biomass, underground biomass and total biomass have shown rich-nutrient patch show significantly higher than poor-nutrition patch at high nutrient concentrations treatment(p<0.05).According to the experiment result ,we can conclude that nutrient condition of soil have not significant influence on the expansion capacity of population in homogeneous habitat, but have significant influence on phenotype, that's propitious to population to obtain more light, then obtain benefit. In the heterogeneous habitat, the observational results of the expand capacity parameters, phenotypic parameters and biomass, can be shown with the clonal plant habitat patches difference between the nutrient concentration increased, the tendency of the clonal plant populations select high-nutrient patches more obviously, that's means the nutrient concentration between different habitat patches is the driving force of space expand.