Carbon and nitrogen relationship in soil N Transformation of a forest ecosystem

本研究的目的是描述无机N和C的形态之间的关系，并评估C作为N循环的能源的重要性。本文采用沿着坡面样带的方法，对黄山地区柳杉种植园下的林龄进行了研究。滋贺龙大。土壤氮素转化的地形差异虽然氮素矿化速率没有显著差异，但硝化速率在不同坡位之间存在差异。在坡面下部，硝化作用对矿化作用的贡献率几乎为100%，而在坡面上部则没有硝化作用发生。在坡面中部，高硝化作用和低硝化作用呈斑块状分布.土壤氮素净转化的控制因素：土壤含水量、全碳、全氮、水溶性有机碳、全氮（如：C和N）和pH值进行了调查沿着样带。原理分析表明，硝化作用是前硝化作用的函数。C，前。氮和水分含量，而矿化是全C的函数N.it说明硝化作用受有效基质控制，矿化作用受总基质调节.土壤总氮转化的控制因素采用15 N稀释法研究土壤总氮转化。在坡体下部，土壤总氮矿化和硝化作用均表现为高值，这与土壤C/N的低值相一致;在坡体上部，土壤总氮矿化和硝化作用均表现为低值，土壤C/N较高，说明在坡体下部，土壤C在低C/N条件下是限制性的，以自养硝化作用为主。

The objectives of this study are to describe the relationship between the form of inorganic N and C and to evaluate the importance of C as energy source for N cycling. We studied the transect along a slope under the same aged Cryptomeria plantation in Mt. Ryuoh, Shiga prefecture.1. Topographical variation of soil N transformation ; Although there was no significant difference in N mineralization rate, nitrification rate was different between the positions of the slope. Nitrification ratio to mineralization was almost 100% at the lower slope, while no nitrification occurred at the upper part of the slope. At the middle part of the slope, patchy distribution of high nitrification and low nitrification was shown.2. Controlling factor of net soil N transformation ; Soil moisture content, total C and N, water extractable organic C and N (ex. C and N) and pH were investigated along the transect. The principle analysis showed nitrification was the function of ex. C, ex. N and moisture content, while mineralization was the function of total C and N.it indicated that nitrification was controlled by available substrate, mineralization was regulated by total substrate.3. Controlling factor of gross soil N transformation ; Gross soil N transformation was investigated by using 15N dilution method. The high gross N mineralization and nitrification were shown at the lower part of the slope, It was consistent with the low soil C/N.At the upper part of the slope, low mineralization, low nitrification and high soil C/N was shown, It suggests that C is limiting under low C/N at the lower part of the slope and autotrophic nitrification dominated.