为了探究海拔对我国西南高寒地区植物稳定碳同位素组成特征及水分利用效率的影响，本研究以梅里雪山东坡不同海拔(2200、2500、2700、3000、3200和4200 m)上不同功能型植物为对象，分析了不同光合途径(C3和Crassulacean acid metabolism，CAM)植物和C3植物中不同生活型(灌木、阔叶乔木和针叶乔木)植物叶片稳定碳同位素组成特征(δ13Cp)及内在水分利用效率(intrinsic water use efficiency，iWUE)随海拔梯度的变化。结果表明:(1)梅里雪山东坡C3植物叶片的δ13Cp值分布范围在-26。72‰～-31。67‰，均值为-29。12‰，而 CAM 植物的 δ13Cp 值分布范围在-13。24‰～-14。59‰，均值为-13。77‰;(2)CAM 植物 δ13Cp 值和iWUE显著高于C3植物，其中，C3植物中不同生活型植物δ13Cp和 iWUE值呈现灌木＞阔叶乔木＞针叶乔木的变化规律;(3)海拔3200 m以下乔木和灌木植物δ13Cp和iWUE值随海拔升高而降低，主要受土壤水分的影响，3200 m以上灌木植物δ13Cp和 iWUE值随海拔升高有增大的趋势，可能受温度的调控。梅里雪山东坡不同功能型植物水分利用效率对海拔梯度的响应反映了不同植物对高寒山地气候不同的适应性。
Changes in stable carbon isotope composition and intrinsic water use efficiency of plants along an altitude gradient in the Meili Snow Mountain
To explore the effects of altitude on stable carbon isotope composition(δ13Cp)and intrinsic water use ef-ficiency(iWUE)of different functional plants at different altitudes(i.e.,2200,2500,2700,3000,3200 and 4200 m)on the eastern slope of the Meili Snow Mountain,Southwest China,we examined the variations in δ13Cp and iWUE of plants with different photosynthetic pathways(C3 and Crassulacean acid metabolism,CAM)and dif-ferent life forms in C3 plants(shrubs,broad-leaved trees,and coniferous trees)along the altitude gradient.Results showed that:(1)The δ13Cp values of C3 plants ranged from-26.72‰ to-31.67‰,with an average value of-29.12‰.δ13Cp values of CAM plants ranged from-13.24‰ to-14.59‰,with an average value of-13.77‰.(2)The δ13Cp and iWUE values of CAM plants were significantly higher than those of C3 plants,and the δ13Cp and iWUE values for different life forms in C3 plants varied in the order of shrubs＞broad-leaved trees＞coniferous trees;(3)Below 3200 m,the δ13Cp and iWUE values of trees and shrubs decreased with increasing altitude,which was influenced by soil moisture.Above 3200 m,however,the δ13Cp and iWUE values of shrubs increased with increa-sing altitude,which was influenced by temperature.Overall,the response of water use efficiency of species from different functional groups in the Meili Snow Mountains to the variations of altitude may reflect the different adapta-bility of different plant species to alpine climate.
C3 plantCAM plantsoil moisturetemperatureplant functional type
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