生物多样性 ›› 2020, Vol. 28 ›› Issue (10): 1161-1173.DOI: 10.17520/biods.2020095

• 研究报告 •    下一篇

珍稀植物连香树在其中国分布区北缘的种子性状及幼苗更新限制

李晶1,2,3,4, 周天阳1,2,3, 鲁雪丽5, 李新涛5, 孙斌6, 孟红杰1,2,*()   

  1. 1 中国科学院水生植物与流域生态重点实验室, 中国科学院武汉植物园, 武汉 430074
    2 中国科学院核心植物园保护生物学中心, 武汉 430074
    3 中国科学院大学, 北京 100049
    4 长江大学, 湖北荆州 434025
    5 河南栾川县龙峪湾林场, 河南栾川 471500
    6 甘肃小陇山林业实验局东岔林场, 甘肃天水 741036
  • 收稿日期:2020-03-12 接受日期:2020-06-03 出版日期:2020-10-20 发布日期:2020-10-20
  • 通讯作者: 孟红杰
  • 作者简介:E-mail: menghongjie@wbgcas.cn
  • 基金资助:
    国家自然科学基金(31800347);中国博士后科学基金(2019M652742)

Seed traits and recruitment limitation of northern marginal Cercidiphyllum japonicum populations in China

Jing Li1,2,3,4, Tianyang Zhou1,2,3, Xueli Lu5, Xintao Li5, Bin Sun6, Hongjie Meng1,2,*()   

  1. 1 Key Laboratory of Aquatic Botany and Watershed Ecology, Wuhan Botanical Garden, Chinese Academy of Sciences, Wuhan 430074
    2 Center of Conservation Biology, Core Botanical Gardens, Chinese Academy of Sciences, Wuhan 430074
    3 University of Chinese Academy of Sciences, Beijing 100049
    4 Yangtze University, Jingzhou, Hubei 434025
    5 Long Yu Wan Forest Farm of Luanchuan County, Luanchuan, Henan 471500
    6 Dongcha Forest Farm of Xiaolongshan Forestry Experimental Bureau of Gansu, Tianshui, Gansu 741036
  • Received:2020-03-12 Accepted:2020-06-03 Online:2020-10-20 Published:2020-10-20
  • Contact: Hongjie Meng

摘要:

连香树(Cercidiphyllum japonicum)是第三纪孑遗植物, 存在严重的幼苗更新限制。为验证生活史早期(种子萌发)限制中国分布区北缘连香树种群幼苗更新, 并探讨其主要成因, 本研究在秦岭和太行山脉采集不同种源地的种子, 测定其形态性状、营养元素含量和质量、不同贮存时间的活力及不同温度条件下的萌发性状, 通过方差分析、相关分析等方法对不同种源地的种子性状进行分析。结果表明: 在中国分布区北缘, 其种子长度(P < 0.001)、萌发率(P < 0.001)、平均萌发时间(P < 0.001)、氮(P < 0.05)和磷含量(P < 0.001)在不同种源间存在显著差异; 而在区域尺度上(秦岭与太行山), 仅种子碳含量存在显著差异(P < 0.01)。天水种群的种子萌发率最高(21.77%), 平均萌发时间最长(11.12 d); 栾川的萌发率最低(1.38%), 平均萌发时间最短(3.47 d)。在25℃条件下, 济源种群的种子萌发率显著高于10℃、15℃和20℃条件下(P < 0.05), 而其他种源地的萌发率在不同温度条件下无显著差异。在4个温度条件下, 栾川种群种子的初始萌发时间无显著差异, 而其他4个种源地的初始萌发时间都随温度升高而缩短。相关分析结果表明, 种子萌发率与种子活力密切相关, 而种子活力与种子质量、种子的氮和磷含量显著相关。在中国分布区北缘, 连香树种子的自身属性(质量、氮和磷含量)通过影响种子活力间接影响萌发率; 且种子萌发对温度的响应主要表现在萌发时间上。本研究证实种子萌发是限制连香树种群幼苗更新的关键阶段, 主要原因如下: (1)连香树种子在9月成熟后, 10月的温度仍适宜种子萌发, 但较短生长期的幼苗在冬季低温下不能存活; (2)连香树种子萌发率低(14.4%); (3)第二年春天种子活力骤降。

关键词: 连香树, 更新限制, 种子质量, 种子活力, 萌发率, 分布区北缘, 秦岭-太行山脉

Abstract

Cercidiphyllum japonicum is a Tertiary relict tree, and recruitment limitation leads to the population declining dramatically. However, the causes of recruitment limitation are currently unclear. This study tests whether early life history traits (seed germination) may limit seedling recruitment of northern C. japonicum populations in China. In this study, we collected C. japonicum seeds in the Qinling-Taihang Mountains and measured their seed morphological traits, seed nutrient content, seed mass, seed vitality, and seed germination. ANOVA and correlation analysis results showed that: (1) There were significant differences in seed length, germination percentage, mean germination time (MGT), and seed nitrogen and phosphorus contents among C. japonicum populations. (2) In the Tianshui population, the percentage of germinating seeds was the highest (21.77%), and MGT was the longest (11.12 d), while the opposite results were found in Luanchuan population (germination percentage = 1.38%, and MGT = 3.47 d). (3) The percentage of germination of the Jiyuan population was higher at 25℃ than at other temperatures (10℃, 15℃ and 20℃), whereas the germination percentages of Tianshui, Ningshan, Luanchuan and Qinshui populations had no significant differences at these different temperatures. Additionally, there were no significant differences in days of the first germination record (T0) in Luanchuan population at four temperature levels, while T0 decreased with increasing germination temperature in the other provenances. (4) Germination percentage was significantly correlated with seed vitality, which was positively related with seed mass, and seed nitrogen and phosphorus contents. Seed intrinsic attributes (seed mass, seed nitrogen and phosphorus contents) influenced seed vitality which directly influenced germination percentage. Different provences had difference germination responses to temperature, notably in T0 and MGT. In this study, we found evidence of seed germination limiting seedling recruitment of northern Chinese C. japonicum populations. The main causes were as follow: (1) Seed may germinate in October after maturation in September, but the seedlings have short growing period and could not survive under low temperature during winter. (2) Seeds have low germination percentage. (3) Seed vitality decrease abruptly in coming spring.

Key words: Cercidiphyllum japonicum, recruitment limitation, seed mass, seed vitality, germination percentage, northern marginal distribution, Qinling-Taihang Mountains