Early Competiton Dymanic Research In Pure And Mixed Communities Of Festuca Arundinacea Shreb., Lolium Perenne L. And Poa Pratensis L.

This paper aimed to have a research and analysis on the early growth dynamic changes of pure turf and mixed tuff in which Festuca arundinacea Shreb. (G for short), Lolium perenne L. (H for short) and Poa pratonsis L. (Z for short) were chosen as the target grasses, and analyzed the dynamic change of appearence and biomass of the three grasses by using bioassay method. And the elementary results were as follows:â… . The dynamic changes of community in which G was regarded as the target grass.(1)The differences of leaf-width dynamic change were related to the type of the other kind of grass in mixed-turf, and it disappeared gradually in community succession. To be different from high-density and low-density level, there were little differences of leaf-width growth between pure and mixed community under medium-density level.The leaf-length growed later than leaf-width,and growed faster in late stage than it did in early stage. The differences between pure tuff and mixed turf increased with density. The root-length growed later and faster than leaf-length.(2)Along with the density increased, the fresh biomass growed more and more slowly. During the whole successin, the fresh biomass of F. arundinacea Shreb. in GZ was higher than that in G, while the fresh biomass in GH was lower than that in G..The dry biomass in GH was always higher than that in G, the dry biomass in GH was higher than that in G at low density and high density in the third assay. The ratio of root biomass to the total biomass increased with density.â…¡. The dynamic changes of community in which the H was regared as the target grass.(1) The leaf-width of L.perenne L. growed later and faster in mixed turf than it did in pure turf. The density effect was So obvious in pure rye turf, while not obvious in mixed turf.The leaf-length also growed later and faster in mixed turf than it did in pure turf. The leaf-length was higher in pure turf than that in mixed turf in the first assay, and it was lower in pure tuff than that in mixed turf in the third assay. Density effect was not obvious in mixed turf.The root growed later than leaf, and the density effet disappeared in the third assay.(2)The fresh biomass in pure turf was obviously larger under low density level than that in mixed turf, but the differences between pure turf and mixed rurf were reduced gradually with density increased. The rye grass had a later response to density effect in HZ than that in H, and it had little response to density effect in GH. Aboveground dry biomass was obviously higher than underground dry biomass. The dry biomass in mixed turf was much higher than that in pure turf. Along with the community developed, the dry biomass in HZ reduced late and fast while that in GH reduced early and slowly.â…¢. The dynamic changes of community in which the Z was redared as the target grass.(1)The medal differences were not obvious at first, but it increased rapidly in the third assay. The statistically significant differences between pure turf and mixed turf also appeared in the third assay, and had an obvious response to density effect.The leaf-length had complicated responses to mixed grass types and density effect. Under the low and medium density level, t-test value between leaf-length in pure turf and that in mixed turf reduced at first and increased later. While the t-test value under high density level increased as community developed, and differences between leaf-length in pure turf and that in mixed turf became significant in the third assay. The differences between root-length growth in pure turf and that in GZ existed under all three density levels, and the differences between root-length growth in pure turf and that in HZ mixed turf appeared just under the high density level. The density effect are obvious in two mixed communities.(2)The density gradient in pure community had little effect on fresh biomass. While the fresh biomass in mixed turf were much lower than that in pure turf under medium and high density level. The ratio of Ma to Mt reduced as community developed. The change trend of dry biomass was similar with that of fresh biomass.Based on the above research results, it concluded as follows:(1) Grass types in mixed turf, density and community development stages all had effect onEarundinacea Shreb. Growth.The length growth in mixed turf was better than that in pure turf, the density was higher, the growth was better. And biomass change was effected by grass types in mixed turf, density and community development s.(2) The grass types in mixed turf had effect on L.perenne L. growth.The medal developement of L.perenne L. in mixed turf was obviously restrained in early community stage. And the changes of restrain effect was not related to the grass types in mixed turf. But the biomass was related to the grass types in the mixed turf, and the correlativity changed with community development stages, and the change trend was not related to the density.(3) Grass types in mixed turf and density both had effect on P.pratensis L. growth.P.pratensis L. grew slowly in early stage, and the differences between two mixed turf appeared in late community development stage. The medal developement of P.pratensis L. in mixed turf was obviously restrained, and the restrain effect was enhanced as community developed. The biomass growth was obviously restrained in mixed turf under high density level, but was little restrained under low density level, even was accelerated to some extent.