The Strategy Of Spatial Expansion Of Clonal Populations Leymus Chinensis And Carex Duriuscula In Heterogeneous Habitats

In order to explore the spatial expansion strategy of clonal populations, we designed the field experiment, chose the dominant species Leymus chinensis and common species Carex duriuscula in Songnen Plain for research objects. Aim to study the cloning growth of populations in the heterogeneous habitats with four different fertility gradients, answer the scientific questions below: (1) Is expansion direction of clonal plants growing in heterogeneous habitats directed or random? (2) Does ability of spatial expansion reduce in nutrient rich patch and enhance in nutrient poor patch? (3) What's the temporal dynamic law with habitat selection of clonal populations in heterogeneous habitats? (4) Does physiological integration really exist? Does the existence promote the clonal population to expand to the poor nutrition patchs?Main experimental results: (1) The ramets number, buds number, total biomass and roots length of Leymus chinensis and Carex duriuscula populations in rich nutrition patchs were higher than poor nutrition patchs, and some treatments achieved significant (P < 0.05) or extremely significant (P < 0.01) differences. (2) With the gradient differency of nutrition increasing, in the eutrophic patches of suitable habitats, the spatial expansion capacity of rhizomes was reduced, and in the dystrophic patches, the spatial expansion capacity of rhizomes was enhanced. (3) The ramets number under most treatments existed significant (P < 0.05) or extremely significant (P < 0.01) differences between before and after winter; the growth rate of ramets in rich nutrition patchs interactively above or under the poor nutrition patches over time. (4) The biomass of Leymus chinensis and Carex duriuscula populations in poor nutrition patchs both obtained revenues from eutrophication plaques in heterogeneous habitats. Main conclusions: (1) In heterogeneous habitats, the spatial expansion of both Leymus chinensis and Carex duriuscula had a certain directionality. They firstly chose the richer nutrition patchs. (2) Habitat heterogeneity played a certain driving role in the spatial expansion capacity of Leymus chinensis and Carex duriuscula. In the eutrophic patches of suitable habitats, the spatial expansion capacity of rhizomes was diminished, and in the dystrophic patches, the spatial expansion capacity of rhizomes was enhanced. (3) Overwintering buds of clonal population was an important component to realize spatial expansion and occupying, time scale was an important factor to measure the effect of spatial expansion. The time dynamic of clonal habitat occupying, could be the effect combined with soil nutrition, competition and physiological integration under the population level. (4) Physiological integration did exist in clonal plants in heterogeneous habitats, which means that the ramets of clonal populations in poor nutrition patchs obtained revenues from eutrophication plaques in heterogeneous habitats. Maybe the physiological integration of clonal plants was the internal driver of clonal growth in heterogeneous habitats. (5) Different kinds of clonal plants responded differently in heterogeneous habitats. In heterogeneous habitats, habitat selection achieved by the clonal growth of Leymus chinensis and Carex duriuscula may be a competitive strategy to avoid the adaptation components.