植物生态学报 ›› 2014, Vol. 38 ›› Issue (4): 343-354.doi: 10.3724/SP.J.1258.2014.00031

• 研究论文 • 上一篇    下一篇

川西亚高山季节性冻土期针叶林主要树种叶片和细根的生态生理特征

肖群英1,2, 尹春英1*, 濮晓珍1,2, 乔明锋1,2, 刘庆1   

  1. 1中国科学院成都生物研究所, 中国科学院山地生态恢复与生物资源利用重点实验室, 生态恢复与生物多样性保育四川省重点实验室, 成都 610041;
    2中国科学院大学, 北京 100049
  • 收稿日期:2013-11-04 修回日期:2014-02-19 出版日期:2014-04-01 发布日期:2014-04-08
  • 通讯作者: 尹春英 E-mail:yincy@cib.ac.cn
  • 基金资助:

    国家自然科学基金项目;中国科学院成都生物所青年研究员计划;中国科学院知识创新工程重要方向项目

Ecophysiological characteristics of leaves and fine roots in dominant tree species in a subalpine coniferous forest of western Sichuan during seasonal frozen soil period

XIAO Qun-Ying1,2, YIN Chun-Ying1*, PU Xiao-Zhen1,2, QIAO Ming-Feng1,2, and LIU Qing1   

  1. 1Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China;

    2University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2013-11-04 Revised:2014-02-19 Online:2014-04-01 Published:2014-04-08
  • Contact: YIN Chun-Ying E-mail:yincy@cib.ac.cn

摘要:

川西亚高山森林存在明显的季节性冻土现象, 该地区的土壤经历着初冬冻融、深冬冻结、早春冻融等过程, 同时, 该区域冬季受气候变化的影响强烈。为了全面地认识亚高山森林的生态过程, 该研究以川西亚高山针叶林两种主要树种——岷江冷杉(Abies fargesii var. faxoniana)和云杉(Picea asperata)为材料, 研究其叶片及细根内丙二醛含量、渗透调节物质的含量、组织含水量、过氧化物酶活性以及硝酸还原酶活性在季节性冻土期的变化, 同时还比较了冻土期和冻融期细根的比根长, 比表面积, 直径以及组织密度的变化。研究结果显示: 在季节性冻土期, 土壤温度昼夜波动幅度小于空气温度波动幅度, 细根却表现出更强的过氧化物酶活性以及更高的渗透调节物质含量, 说明细根较叶片对季节性冻土更为敏感。与冻结期相比, 冻融期土壤温度、空气温度以及空气相对湿度昼夜波动幅度增加, 促使云杉叶片可溶性糖含量以及两针叶树种叶片内过氧化物酶活性、脯氨酸含量显著增加, 而细根的组织含水量显著降低, 脯氨酸、可溶性蛋白质及可溶性糖含量均显著增加, 表明冻融期对两针叶树种的影响较冻结期更为强烈。岷江冷杉和云杉的过氧化物酶活性及渗透调节物质含量具有相同的变化趋势, 但叶片和细根的膜脂过氧化程度及酶活性变化并不一致, 就岷江冷杉而言, 细根的丙二醛含量显著增加, 而叶片、细根的硝酸还原酶活性均显著降低, 云杉仅叶片的丙二醛含量发生变化, 且显著降低, 说明云杉更能忍耐冻融循环造成的胁迫。研究还发现细根形态在季节性冻土期无显著变化。

Abstract:
Aims There is an obvious seasonal freezing and thawing process (early winter freezing-thawing, late winter freezing, and early spring freezing-thawing) in the subalpine coniferous forests, where there is also a strong effect of climate change in winter. Hence, global warming will likely affect the seasonal freezing and thawing process in this area. Our objective was to determine the ecophysiological characteristics of leaves and fine roots in dominant tree species in a subalpine coniferous forest of western Sichuan during seasonal frozen soil period, in order to improve our understanding of the ecological processes in subalpine coniferous forests.
Methods We analyzed the changes in malondialdehyde (MDA) content, osmoregulation substance content, tissue water content, peroxidase (POD) activity, and nitrate reductase (NR) activity in leaves and fine roots of Picea asperata and Abies fargesii var. faxoniana seedlings, and measured specific root length, specific surface area, diameter and tissue density of fine roots over the course of the seasonal frozen soil period.
Important findings The POD activity and the contents of proline and soluble proteins in leaves were significantly lower than in fine roots, despite that the daily fluctuations of soil temperature was less than that of air temperature during the seasonal frozen soil period, suggesting that fine roots were more susceptible to the seasonal frozen soil than leaves. In comparison with the soil freezing period, a greater daily fluctuations of air and soil temperature resulted in an increase in the soluble sugar content in leaves of P. asperata and the POD activity and proline content in leaves of the two species during the soil freezing-thawing period, whereas the tissue water content was significantly decreased and the contents of proline, soluble proteins and soluble sugars were significantly increased in fine roots, indicating that the effects of soil freezing-thawing on plants were stronger than soil freezing. In soil freezing-thawing period, the POD activity and osmolyte contents were significantly increased in both A. fargesii var. faxoniana and P. asperata, but changes in the MDA content and the NR activity in the fine roots and leaves were not consistent in the two species. In A. fargesii var. faxoniana, the MDA content was significantly increased in fine roots and the NR activity was significantly reduced in both leaves and fine roots. A change in the MDA content was only observed in leaves of P. asperata, which was significantly decreased, indicating that P.asperata had more tolerance to soil freeze-thaw cycles. Moreover, no significant changes in fine root morphology and growth were observed during the seasonal frozen soil period.