| This paper studied the mode of Triploid populus tomentosa - Lolium multiflorum Lam. Triploid populus tomentosa has been planted in May 2000, and Lolium multiflorum Lam is growing one year in its period. Through "Continuous Soil Coring" and obtained the data of vertical distribution and the monthly dynamic change of biomass accumulating on the fine root of Triploid populus tomentosa and the root of Lolium multiflorum Lam.. In pace with the survey of biomass, combined the lab analysis with the root and soil sample dynamic change data of nutrition element N, P, K, Ca, Mg, were determined. These data were collected, gathered, arranged, and at last tendency picture of the vertical, monthly change was drawn. Combined the monthly dynamic content of nutrient with them, the comparative analysis was done. At the same time, comparing the dynamic trends of root nutrient with the soil's efficacious or quick nutrient in the trend picture, the conclusions were drawn as followed:1 > The vertical change law of fine root biomass of Φ 0~ 1 mm of Triploid populus tomentosa is: Middle layer>down layer>upper layer, and toΦ1~2 mm of them, during the whole life, it was: Upper layer >middle layer>down layer, but to # 0~2 mm of them, the annual average of the total biomass' vertical distribution was: Middle layer>upper layer > down layer. The roots of Lolium multiflorum Lam. in the vertical direction showed the "T" distribution that was higher in the upper layer, but lower in down layer. During one growth period of Triploid populus tomentosa, both of fine root, Φ 0~ 1 nun and Φ 1 ~2 mm, showed a single-apex line peaked correspondingly in July and the first ten days of June. The monthly change of total fine root biomass also showed a single-apex line peaked in July. This resulted from the function of roots growing and superposing. Comparing the fine root of Φ0~1 ?on the roots growth with Φ 1 ~2 n?; The latter was later than the former about one month at the beginning of growing, obliviously showing the displacement of fine root growth. The annual change of the grass root of Lolium multiflorum Lam. was the same as Triploid populus tomentosa, showing a single-apex line. The growth of fine root and grass root in the upper layer increased or reduced in the same time. But the biomass of grass root in the upper layer was higher than that of fine root. On the contrary, the biomass of grassroot in the down layer was lower than that of fine root. According to the total growth and biomass' accumulation of fine root and grass root, there were the trends of alternate growth. That is to say, in this mode, in the same period, if one species grow and accumulate the biomass, another species was in the state of stopping growing; or when one grew very fast, another species was in the opposite.2. The characteristic of soil's physical properties and fine root distribution: The soil's weight in the upper layer is much lower than that in the middle and down layer, and the water content, aerating degree, total space degree, organic matter were the other way round, so the grass root biomass in the upper were much higher than that in the down layer. But the change of biomass accumulation of Triploid populus tomentosa is: Middle layer> down layer >upper layer. And the relation of growth characteristic and soil's physical properties remained to be studied further.3. The change characteristic of the root nutrient: The monthly dynamic N-content change of Triploid populus tomentosa was similar to Lolium multiflorum Lam., and displaying that N was absorbed highly when sunny was abundant, guaranteeing the growth of characteristic of light-fertilizer balance. There were different on absorbing P between Lolium multiflorum Lam. and Triploid populus tomentosa, and these differences may be divided roughly into two stages: hi the first stage, it demanded much more P and there were difference of absorbing; In the second stage, there were the same dynamic absorbing characteristic. So in the whole yearly period, fertilizer should be applied or the...
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