[Effects of nitrogen addition on the contents and stoichiometric ratio of nitrogen and potassium in a meadow steppe of Hulunbuir, China]. / æ°®ç´ æ·»åŠ å¯¹å‘¼ä¼¦è´å°”è‰ç”¸è‰åŽŸæ¤ç‰©æ°®é’¾å ƒç´ å«é‡å’Œè®¡é‡æ¯”çš„å½±å“.

ABSTRACT

Potassium (K) is the second most abundant nutrient in plant leaves after nitrogen (N) and the most abundant cation in plant cells. It plays an important role in plant growth regulation, homeostasis maintenance, and stress response. Previous studies on the effects of N input on plant nutrient status mainly focus on N and phosphorus (P), but less on K and its stoichiometry. We examined the effects of N input and mowing on K content and NK at both plant functional group and community levels. We analyzed the relative contribution of changes in functional groups and community composition to changes of community level nutrition status. The results showed that N input increased N content of each plant functional group and increased K content of rhizomatous grasses and legumes. Mowing reduced N content of rhizomatous grasses and bunchgrass, but did not affect K content and NK of all functional groups. Nitrogen input significantly increased plant N and K contents at the community level, while mowing significantly increased plant N content. Both N input and mowing did not affect plant NK at functional group and community levels. The contribution of nutritional changes in plant functional groups to the variation at the community level was greater than that of changes in community composition. For all the three examined nutritional traits, the contribution of nutrients at functional group level and that of community composition showed negative covariation. Our results indicated that plant NK had high homeostasis in meadow steppe and that plants could regulate N and K balance, which was of great significance for maintaining NK stoichiometry under the background of increasing N deposition.