Response of leaf functional traits and C,N,and P stoichiometry of Fraxinus mandshurica Rupr.to altitude
[Objective]Fraxinus mandshurica Rupr.is the main precious timber species in the Xiaolongs-han.Investigating the adaptability of leaf traits to changes in microhabitat will provide a basis for in-depth research on the main environmental factors affecting this species.[Methods]Taking F.mandshurica in the Heihe Nature Reserve area as the research object,four altitude gradients were set up.The significant difference and correlation of 14 leaf functional traits and leaf nutrient contents were analyzed.[Results](1)As the altitude was increased,the leaf thickness,leaf dry matter content,and chlorophyll content of F.mandshurica were gradually increased,and reached maximum at altitude of 1 741 m,1 926 m,and 1 741 m,respectively.The specific leaf area,maximum net photosynthetic rate,transpiration rate,and leaf C and N content were gradually decreased,reaching their maximum at altitude of 1 268 m except for leaf C content.The leaf area,stomatal conductance,and leaf C∶N showed a trend of first increasing and then decreasing with increase in altitude.The intercellular CO2 concentration,C∶P,and N∶P showed a trend of first decreasing and then increasing.(2)With elevation rise of 200 m,the functional traits and C∶N average were increased 1.13％-30.72％.Specific leaf area,maximum net photosynthetic rate,and C and N content were decreased 2.22％-15.75％respectively.(3)The N∶P values of leaves at various alti-tudes were 4.36-6.89,and showed a significantly positive correlation with the maximum net photosyn-thetic rate.The maximum net photosynthetic rate was significantly positively correlated with specific leaf area,C and N content,C:P and N:P.There was a significantly negative correlation with leaf thickness,leaf dry matter content,and chlorophyll content.There was a significantly negative correlation between specific leaf area and leaf dry matter content,and a significantly positive correlation with C and N content and C:P.[Conclusion]Altitude significantly affected the functional traits and leaf element contents of F.mandshurica leaves.The protected area below 1 700 m was conducive to the leaf development and the nu-trient accumulation of F.mandshurica.
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