关键词: 海拔梯度, 生活型, 养分限制, 生态化学计量, 青藏高原

Abstract: To understand the responses of plant nutrients and their stoichiometric characteristics to altitude in the alpine glacier ecosystems in Southwest China, we investigated the changes in carbon (C), nitrogen (N), and phosphorus (P) stoichimetry in leaves of plants from different life-forms (i.e., trees, shrubs, and herbs) along an altitude gradient (2900, 3100, 3300, 3600, 3900, 4100, 4300, and 4500 m) in the Yulong Snow Mountain, southeastern margin of the Qinghai-Tibet Plateau. The mean values of leaf C, N, and P contents were 489.03, 16.26, and 1.65 g·kg^-1, and the mean values of leaf C∶N, C∶P, and N∶P ratios were 33.39, 354.72, and 10.78, respectively. Leaf C contents of trees and shrubs were significantly higher than that of herbs, while leaf N and P contents were significantly lower than those of herbs. Leaf C∶N, C∶P, and N∶P ratios of trees and shrubs were significantly higher than those of herbs, and leaf N∶P ratios of trees, shrubs, and herbs were 10.70, 12.07 and 8.80, respectively. Leaf C contents, C∶N and C∶P ratios for all of the plants decreased with altitude, while leaf N and P contents increased with altitude. Leaf N and P contents of trees showed an increasing trend with altitude, but leaf C∶N and C∶P ratios showed a decreasing trend. Leaf N contents and N∶P ratios of shrubs tended to increase with altitude, while leaf C∶N ratios tended to decrease with altitude. Leaf N contents and N∶P ratios of herbs showed a decreasing trend, whereas leaf C∶P and N∶P ratios showed an increasing trend. Our results indicated that altitude significantly affected leaf nutrient contents and stoichiometry in the Yulong Snow Mountain, and that plants were generally limited by N availability.

Key words: altitude gradient, life form, nutrient limitation, ecological stoichiometry, Qinghai-Tibet Plateau