植物生态学报 ›› 2011, Vol. 35 ›› Issue (12): 1271-1280.DOI: 10.3724/SP.J.1258.2011.01271

• 研究论文 • 上一篇    下一篇

科尔沁沙地樟子松人工林不同年龄针叶生理生态性状

魏雅芬1,2, 方杰1,2, 赵学勇3, 李胜功1,*()   

  1. 1中国科学院地理科学与资源研究所生态系统网络观测与模拟重点实验室, 北京 100101
    2中国科学院研究生院, 北京 100049
    3中国科学院寒区旱区环境与工程研究所, 兰州 730000
  • 收稿日期:2011-04-06 接受日期:2011-09-07 出版日期:2011-04-06 发布日期:2011-12-15
  • 通讯作者: 李胜功
  • 作者简介:*(E-mail:lisg@igsnrr.ac.cn)

Eco-physiological traits of different-age needles of Pinus sylvestrisvar.mongolica plantation in Horqin sandy land of China

WEI Ya-Fen1,2, FANG Jie1,2, ZHAO Xue-Yong3, LI Sheng-Gong1,*()   

  1. 1Key Laboratory of Ecosystem Network Observation and Modeling, Institute of Geographic Sciences and Natural Resources Research, Chinese Academy of Sciences, Beijing 100101, China
    2Graduate University of Chinese Academy of Sciences, Beijing 100049, China
    3Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences, Lanzhou 730000, China
  • Received:2011-04-06 Accepted:2011-09-07 Online:2011-04-06 Published:2011-12-15
  • Contact: LI Sheng-Gong

摘要:

樟子松(Pinus sylvestris var. mongolica)又称蒙古松, 是我国“三北”防护林建设的主要造林树种。人工林建立初期, 在水分、养分匮乏的干旱、半干旱沙地, 樟子松仍表现出较强的适应性; 近年来, 各地樟子松人工林均出现衰退迹象。在沙地这种特殊生境下, 樟子松针叶的光合作用、水分利用效率、氮利用效率等主要性状的研究对于理解樟子松的沙地适应性具有非常重要的意义。该文以位于科尔沁沙地南缘的中国科学院寒区旱区环境与工程研究所奈曼沙漠化研究站(42°55′ N, 120°43′ E) 30龄樟子松人工林为研究对象, 对不同年龄针叶的光合作用、蒸腾作用、针叶碳氮含量、针叶形态(叶长、宽、厚)等主要生理生态属性进行测定, 计算出针叶的蒸腾系数(Kc)、光合氮利用效率(PNUE), 阐明了这些性状与樟子松叶龄的关系, 进而探讨了叶片性状在樟子松适应沙地生境中的意义。结果表明, 1)不同年龄针叶的光合速率(Pn)、KcPNUE存在显著差异, 四龄针叶的PnKcPNUE显著低于其他龄针叶。氮含量减少是导致Pn差异的根本原因, Pn随着氮含量的减小而降低。2)各龄针叶的长、宽等形态参数及碳含量受其形成前一年的降水量影响显著。3)从水分及养分利用(KcPNUE)角度来看, 一至三年生针叶的利用效率更高, 四龄针叶较低。合理的叶龄结构既能增强针叶对氮素的利用又能增大植株的光合叶面积, 有利于提高个体乃至冠层的光合能力。此外, 遇到严重干旱时, 老叶脱落可以增强樟子松个体的适应性。

关键词: 叶龄, 光合氮利用效率, 光合速率, 樟子松, 蒸腾系数

Abstract:

Aims Pinus sylvestris var. mongolica (Mongolian pine) is one of the main tree species used for forestation in the northern China and grows well in the early growth stage on sandy lands in the semi-arid area. In recent years, some of trees of Mongolian pine plantations in the sandy lands have been found to be degraded. Study of foliar traits is key to understanding the adaptability and survival strategy of this tree species on sandy land. Our major objective is to examine the impact of needle age on the main eco-physiological foliar traits of Mongolian pine in Horqin sandy land and thus to highlight the importance of needle age for coping with water and nutrients in the semi-arid area.
Methods We chose trees of Mongolian pine planted in early 1980s on a sand dune in the southern margin of Horqin sandy land, located in the permanent experimental plot of the Naiman Desertification Research Station, Cold and Arid Regions Environment and Engineering Research Institute, Chinese Academy of Sciences (42°55′ N,120°43′ E). We measured foliar photosynthetic rate, transpiration rate, carbon content, nitrogen content and morphological parameters (leaf length, width and thickness) for different-age needles. Based on these measurements we calculated transpiration coefficient (Kc) and photosynthetic nitrogen use efficiency (PNUE).
Important findings Net photosynthetic rate (Pn), Kc and PNUE varied among different needle ages and were significantly lower for 4-year old needles than 1-, 2- and 3-year old needles. This can be accounted for by foliar nitrogen content, with decrease in nitrogen leading to the decline in photosynthesis. Strong correlations were found between foliar form (e.g., leaf length, width, thickness and specific leaf area) and precipitation of the year prior to leaf formation and between foliar carbon content and precipitation of the year prior to leaf formation. In terms of transpiration coefficient and PNUE, juvenile needles (mainly 1- and 2-year old needles) were more efficient in using water and nutrients than old needles (4-year old needles), and hence a tradeoff between juvenile and old needles in water and nutrient use is a mechanism for growth and survival of Mongolian pine on sandy land. In addition, shedding old leaves under environmental stresses, as we observed in the field, has significant implication for this species to adapt to harsh habitat in the semi-arid area.

Key words: needle age, photosynthetic nitrogen use efficiency, photosynthetic rate, Pinus sylvestrisvar. mongolica, transpiration coefficient