干旱区研究

›› 2012, Vol. 29 ›› Issue (5): 784-790.

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Photosynthetic Capacity of Malus sieversii Trees in Natural Forest

 MAO  Pei-Li1，2, ZANG  Run-Guo2, BAI  Zhi-Qiang3, XU  Zheng4, GUO  Zhong-Jun3, LIU  Duan3   

  1. 1. Laboratory of Coastal Wetland Ecology & Shandong Provincial Key Laboratory of Coastal Zone Environment Processes, 
    Yantai Institute of Coastal Zone Research, Chinese Academy of Sciences, Yantai 264003, Shandong, China; 
    2. Key Laboratory of Forest Ecology and Environment, The State Forestry Administration; Institute of Forest Ecology 
    and Environment Conservation, Chinese Academy of Forestry, Beijing 100091, China;
    3. Institute of Forest Ecology, Xinjiang Academy of Forestry Science, Urumqi 830000, China;
    4. Center for Research and Development of WildFruit Forest Resources, Institute of Horticulture Research,
     Ili Kazak Autonomous Prefecture, Y[JP8]i’[JP]ning, 835000, Xinjiang, China
  • Received:2011-10-24 Revised:2012-02-27 Online:2012-09-15 Published:2012-10-09

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Abstract: Photosynthesis is a basic eco-physiological process for the functioning of ecosystems. Malus sieversii(Ledeb.) Roem. is the most important dominant species in the wild fruit forest on the northern slope of the Tianshan Mountains in northwest China. M. sieversi population has been declining rapidly due to more and more intensive anthropogenic disturbances. Research on the photosynthetic characteristics of M. sieversii of different size classes is critical to understand the functions of its dominated ecosystems and to take proper measures to conserve this endangered species. Net assimilation rate (A), stomotal conductance (gs)and specific leaf area (SLA) of sun-facing M. sieversii leaves at upper and lower parts of 64 adult trees were measured in a natural wild fruit forest in Xinyuan County on the northern slope of the Tianshan Mountains in Xinjiang, northwest China. The results showed that there was a significant effect of stem diameter class on photosynthetic characteristics of M. sieversii. Both Aarea and Amass were increased with the increase of diameter class, whereas gs was increased at first and then decreased, and the maximum values appeared at the main stem diameter of 25-35 cm at 0.5 m height. There was a significant effect of leaf position on photosynthetic characteristics. Aarea, Amass and gs of the leaves on the upper part of branches were significantly higher than those on the lower part. The results of regression analysis revealed that Aarea and gs were increased in a quadratic polynomial way with the increase of stem diameter, whereas Amass was increased in a linear relation. With the increase of diameter class, the change of SLA was not significant. There was a significant effect of leaf position on SLA. SLA of the leaves on the upper part of crown was significantly lower than that on lower part, and the differences of Amass between the leaves on the upper and lower parts was low. Aarea of the leaves on both upper and lower parts was increased with the increase of gs, but the regression equations were different. Aarea of upper leaves was increased in a power function with the increase of gs, where as Aarea of lower leaves was increased in a quadratic polynomial way with the increase of gs. 

Key words: Malus sieversii, net photosynthetic rate, specific leaf area, stomotal conductance, wild fruit forest, Xinyuan County, Xinjiang