Effects Of Trampling On The Growth And Architecture Of Trifolium Repens

From May to September, 2006, in the Experimental Grounds of the College of Plant Science Jilin University, the experimental plot was built. White clover was used as test material. In the method of artificial trampling, five trampling intensities are set up. They are the original (T0), the mild (T16), sub- moderate (T8), moderate (T4) and heavy (T1). Each time of trampling lasts 1 minute. This system conducts research on the influence imposed by different trampling intensities on white clover.1. Influence of different trampling intensities on white cloverHow to evaluate the growth of a plant? It depends on every growth components of a plant. Let's take herbaceous plants for example. Growth pros cover density of root, stem, and leaf, growth of new stem, stem elongation, leaf area and height of plant.After the trampling, stem elongation under T16 obviously is longer than that under other trampling intensities, and stem elongation under T1 is shorter. The research on new sticks shows that T16 and T8 are helpful to the growth of new sticks, with a rapid speed and fast increase in number. They make faster growth and larger number than T1 and T4. After trampling, stolon density shows that the higher the intensity, the lower the density is. Vice versa. This result keeps consistence with research home and abroad.The influence on components by different trampling intensities directly affects the speed of growth of plant. This focuses on stolon density, leaf area and petiole. Stolon is made up of root, stem and leaf. Leaf density refers to the number of leaves. Specimen under T1 has a lower leaf density than that under other trampling intensities. Root density refers to the total number of principal root and fibrous root. Specimen under T16 has a higher root density and that under T1 have the lowest. It can be concluded that appropriate trampling facilitate the growth of root. It is found that stem density under T4 is higher than other intensities, but lower than original specimen.In the five test plots, the leaf area of white clover changes when the intensity changes. As for T1 and T4, the higher the intensity, the smaller the leaf area is. As for T8 and T16, the leaf area increases under light trampling. It demonstrates that light trampling can facilitate the increase of leaf area.After trampling, the height of the leaves of white clover increases slightly under T8 and T16, but decreases under T1 and T4. With the increase of intensity, the height decreases obviously.2. Influence of different trampling intensities on white clover's biomass, output and calorific valueBiomass is an important index to research the structure and function of ecosystem. It covers the total amount of organic substances produced by all living things, biomass package (the total amount of root, stem, leaf, fruit and emarcid components), and underground biomass.During the entire experimental cycle, leaf biomass under T0 outnumbers that under others. T8 facilitates the growth of white clover. Under the influence of different intensities on the plots, stem biomass under T8 ranks first. It demonstrates that appropriate trampling can help the growth of stem. While, overtrampling (heavy trampling) can not help. Under different intensities, root biomass of white clover follows that: T0>T16>T8>T4>T1. With the increase of intensity, root biomass of white clover is inhibited and shows the decreasing tendency.Measuring the number of leaves on stem can analyze the disturbance to stem and leaf , and the influence on the output of white clover. The result shows that specimen under T1 has more leaves than any other specimens. The numbers between T4, T8 and T16 are close, but their leaf distribution has obvious difference. T4 and T1 have short stems and dense leaves. T16 and T8 have long stems and sparse leaves. Different trampling intensities can impose influence on the number of fibrous root. Specimen under T1 has more fibrous roots than others, because the soil compactness makes the principal root fail to provide nutrition for stems and leaves and then develops the growth of fibrous roots.Calorific value of root, stem and leaf of white clover decrease when the trampling intensity increases. But calorific value under T16 is higher than that under T0. It demonstrates that appropriate trampling can help the growth of white clover.The intensities lead to soil compactness. Soil volumeweight, soil strength and soil's water holding capacity have direct affect on the growth of white clover.3. Influence of different trampling intensities on space distribution of white cloverPlants can not move, thus, the space distribution between individuals is an important factor for competition result and population dynamics. Stolon's space occupation, stem's diameter and branch angle influence its adaptability and lifespan. Different intensities can increase the use of space of white clover. As a result, white clover can adapt better and make better use of nutrition in small environment.For white clover, the most proper branching angle is 62°, the largest density is 30°, the space between different orders of branching is a sector area. The branching mode is a network structure in per unit of hexagon. Plants occupy a surface in the mode of hexagon, which is a better mode. Under this circumstance, the energy and substances are spent little and space can be fully used. The branching angle of homologous plant exists some regulating mechanism and trampling has slight adjusting function on branch angle.The branching of white clover show different characteristics under different intensities. T1 and T4 are mainly first and second-order branching. T8 and T16 are mainly second and third-order branching. For the original, first, second, third-order branching keep a balance.