Abstract: This paper studied the physiological responses of Hypnum plumaeforme to two kinds of inorganic nitrogen, i.e., KNO₃ and NH₄NO₃. The addition of KNO₃ or NH₄NO₃ within the range of 20-60 kg N·hm^-2·a^-1 caused the starch and soluble sugar contents in H. plumaeforme decreased, while the total nitrogen, soluble protein, free amino acid, arginine, histidine, and proline contents increased. With the addition of KNO₃ or NH₄NO₃, the total nitrogen content in H. plumaeforme had significant negative correlations with the starch and soluble sugar contents, suggesting the competition for carbon skeleton between the H. plumaeforme’s nitrogen and carbon assimilation. The coefficients of the negative correlations under NH₄NO₃ addition were far higher than those under KNO₃ addition, suggesting that the decrease in the starch and soluble sugar contents under KNO₃ addition was also related to the decrease of net photosynthesis rate and carbohydrate production, besides the carbon skeleton consumption during nitrogen assimilation. As compared with KNO₃ addition, NH₄NO₃ addition resulted in a greater increase of arginine but a less increase of proline in H. plumaeforme, indicating that H. plumaeforme possessed a welldeveloped NH₄⁺ detoxification system.

Key words: landscape pattern, spatial scale, scale effect, characteristic scale.