Biodiv Sci ›› 2020, Vol. 28 ›› Issue (10): 1161-1173.DOI: 10.17520/biods.2020095

• Original Papers •     Next Articles

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

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