急尖长苞冷杉叶光合特性及营养元素对海拔的响应

Response of Photosynthetic Characteristics and Nutrients of Abies georgei var. smithii Needles to Altitudes

  • 摘要: 以滇西北玉龙雪山急尖长苞冷杉为研究对象,研究其叶光合特性及营养元素累积对不同海拔高度的适应性变化规律。结果表明:在海拔3550 m,急尖长苞冷杉叶的瞬时最大净光合速率(Pn)、光合氮利用效率(PNUE)和长期氮利用效率(NUE)均达到最大值;碳同位素组分(δ13C)值随着海拔的升高呈现先降低后增加的趋势,在3700 m海拔点处于最高水平;单位叶面积C、N、P含量也在该海拔点增至最大;同时气孔导度(Gs)、蒸腾速率(E)以及胞间CO2浓度(Ci)都降至最低水平。海拔3550 m处是最适宜急尖长苞冷杉的生长区域;低于海拔3550 m的环境对其生长无显著抑制作用,但其光合作用强度及叶营养元素水平、氮利用效率等均处于中间水平;而高于海拔3550 m环境对其生长发育有限制作用,但同时可促使急尖长苞冷杉调节自身营养代谢分配及提高其用水效率等来应对高海拔的恶劣环境。

     

    Abstract: Abies georgei var. smithii from the Yulong Snow Mountain in Northwest Yunnan was selected to study the response of needle photosynthesis and nutrient accumulation to different altitudes. The results showed that the instantaneous maximum net photosynthetic rate (Pn), photosynthetic nitrogen utilization efficiency(PNUE)and long-term nitrogen use efficiency (NUE) reached the top value at the altitude of 3500 m. The δ13C value of needles decreased firstly and then increased with the increasing altitude, it reached the highest level at the altitude of 3700 m. On the other hand, the contents of C, N, P per unit needle area also increased to the maximum, while the stomatal conductance (Gs), transpiration rate (E), and intercellular CO2 concentration (Ci) reduced to the lowest level at the altitude of 3700 m. The altitude of 3550 m is the most suitable growth area for A. georgei var. smithii. Although the altitude below 3550 m has no obvious negative effect on this tree species, the photosynthetic intensity, needle nutrient contents and nitrogen use efficiency just reached the middle levels. However, the altitude above 3550 m may restrict the growth and development of A. georgei var. smithii, but at the same time, it can adapt to the harsh environment of high altitude by adjusting the nutrient metabolism and improving the water use efficiency.

     

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