Clonal Growth Of Hippophae Rhamnoides L.ssp. Sinensis In Response To Fertilization Of Nitrogen In Combination With Phosphorus In Mu Us Sandland

Habitat heterogeneity is ubiquitous and closely related with clonal growth in nature. Therefore, patchness difference of resources must finally cause changes of growth pattern and morphological plasticity of modules in order to adapt to heterogeneity of habitat resources, which has meaning of ecological adaptability. As one of the most important habitat resources, soil nutrient concerns with plant growth, so that clonal plasticity and ecological adaptability to soil nutrient can be studied by fertilization experiment. These researches mentioned above mainly focus on herbage and woody herbage (bamboo), while the woody plant of Hippophae rhamnoides L. ssp. sinensis is studied in order to augment the content on ecology of clonal plant population in this paper; and there is nothing about quantitative research between clonal growth and fertilizer and its ratio among these researches at present, which is used to analyze only in ecological meaning and difficult to control clonal growth. The clonal growth in response to nitrogen in combination with phosphorus is studied by experiment adopted 3×3 regression design and drew the advantages from Latin layout. By means of regression some quantitative models are founded, so that the results are benefit to reveal ecological adaptability to soil nutrient and control clonal growth, which had important produce value and theoretical meaning. The results show:(1) Response dynamics and optimum amounts of fertilizer and optimum ratio: growth increment amplitude and biomass amplitude show convex surface models with the increasing of amounts of nitrogen in combination with phosphorus, and convex parabola models with the increasing of amounts of single nitrogen or single phosphorus. That is to say, growth increment amplitude and biomass amplitude increase first and then decrease with the increasing of amounts of fertilizer (N or P). The results also demonstrate the Mitscherlich's law again. By means of regression simulated equations between the different yield and N, P content are set up, and the optimum amounts of fertilizer and optimum ratio of fertilizer at different parameters are calculated. Meanwhile, there is obviously symplastic growth at different yield parameters. In addition, the marginal yield of N or P is also different in different parameters, so that the contribution rate of N or P to different population characteristics is not the same. Thus, according to plantation purposes, function and objectives, the best results may be achieved by changing and controlling the fertilizer and its ratio in actual production.(2) Trade-offs: modular biomass allocation shows surface models with the increasing of amounts of fertilizer, and parabola models with the increasing of amounts of single nitrogen or single phosphorus. That is to say, with the increasing of amounts of N and P (N or P), biomass allocation of trunks, living branch, dead branch (the vertical spacers), clonal organs (horizontal spacers) and the above-ground show convex surface models (or convex parabola models), while biomass allocation of leaves, root (modules of resources obtaining) and the underground portion show concave surface models (or concave parabola models). Therefore, fertilization causes the pacthness of the soil nutrients and affects the distribution of materials and energy investment, which indicates strategies of resources obtaining and ecological adaptation. In the role of fertilization, the contrary law of biomass allocation between the aboveground and the underground, clonal organ and root or modules of resources obtaining and spacer actually suggest trade-offs between obtaining and storing of resources, growth and survival or clone and growth.(3) The ability of clonal growth and foraging growth pattern: clonal growth characteristics (clonal organ characteristics and the number of daughter ramets) show convex surface models with the increasing of amounts of fertilizer and convex parabola models with the increasing of amounts of single nitrogen or single phosphorus. That is to say, with the increasing of amounts of fertilizer (N or P), clonal organ characteristics and the number of daughter ramets increase first and then decrease. The results also demonstrate the Mitscherlich's law again. So it is not difficult to infer that the ability of clonal growth shows convex surface models with the increasing of amounts of fertilizer as well as clonal growth characteristics. The ability of clonal growth and ramets density increase with the increasing of amounts of fertilizer, so that ramets get shorter spacer from each other and distribute intensively in the habitat, which causes the foraging growth pattern tend to be phalanx type and a higher population fitness; on the other hand, when N, P exceed a certain amount of scope, excessive soil nutrients will become the limiting factor to plant growth. Later, while the amount of fertilizer continues to increase, the ability of clonal growth would be restrained. Then ramets density reduces so that ramets get longer spacer from each other and distribute sparsely in the habitat, which causes the foraging growth pattern tend to be guerrilla type and a lower population fitness. It is not difficult to infer that the ability of clonal growth and population fitness increase and then decrease with N, P fertilizers transform from low to high, accompanied by transform in the foraging growth pattern, namely gradually transform from guerrilla type to phalanx type and then from phalanx type to guerrilla type.(5) Reasonable fertilization range and op-curve equations: optimum amounts of fertilizers may be not the most economical fertilizers when the cost of fertilizers and investment gains are considered. Some reasonable fertilization ranges of nitrogen in combination with phosphorus for different yield index are given, namely the area surrounded by two coordinate axis and two ridge lines in yield-equality lines plots. Fertilizers is not the same on the two sides of the ridge lines, however, the output is equivalent. The ridge lines and coordinate axis intersect on the cut-off points. Therefore, on a certain level of production, fertilizer beyond reasonable fertilization range contributes nothing but a waste of fertilizer. In addition, op-curve equations is given too, which shows that fertilizer pay is the lowest cost and the yield is the highest only when amounts of N and P are on op-curve, that is to say, the greatest benefits cound be achieved following op-curve in actual.