Chin J Plant Ecol ›› 2020, Vol. 44 ›› Issue (10): 995-1006.DOI: 10.17521/cjpe.2020.0143

• Research Articles •     Next Articles

Trade-off between shooting and leaf developing of woody species saplings in subtropical evergreen broad-leaved forests

MO Dan, WANG Zhen-Meng, ZUO You-Lu, XIANG Shuang*()   

  1. CAS Key Laboratory of Mountain Ecological Restoration and Bioresource Utilization & Ecological Restoration and Biodiversity Conservation Key Laboratory of Sichuan Province, Chengdu Institute of Biology, Chinese Academy of Sciences, Chengdu 610041, China; and University of Chinese Academy of Sciences, Beijing 100049, China
  • Received:2020-05-11 Accepted:2020-09-17 Online:2020-10-20 Published:2020-10-16
  • Contact: XIANG Shuang
  • Supported by:
    National Natural Science Foundation of China(31370594);National Key R&D Program of China(2017YFC0505000)


Aims Own to their genetic characteristics and long-term adaptation to the understory environment, the saplings of subtropical evergreen broad-leaved forest woody species could shoot twigs and develop new leaves several times a year, in which how they survive in the habitats and ultimately grow to adult trees are vital. The objective of this study was to examine what specific adaptation strategies have woody plants taken in the face of environmental pressure in subtropical evergreen broad-leaved forests, especially the growth priorities of twig elongation, stem thickening and leaf area increasing during the shooting process.
Methods The study site is located in Qingcheng Mountain scenic area, Sichuan Province. We chose five species with high second shooting rate in similar habits. Five plants with no disease and insect pests of each species were randomly selected for tree height measurement and long-term shooting observation. Each plant was randomly labeled with three young current-year twigs from different direction outside of tree canopy, and the twig length, twig diameter, leaf number and area were recorded when the twigs burst. The scaling relationships between traits of twig and leaf were analyzed by standardized major axis estimation (SMA).
Important findings 1) The first and second shootings started from spring (April) and late summer (the late August) respectively. The proportion of the second shooting of trees was lower than that of shrubs, and the proportion of second shooting of evergreen plants was lower than that of deciduous counterparts respectively. 2) The twig length and individual leaf area, the twig diameter and leaf number (expect for the Symplocos grandis) of the first shooting were all higher than those of the second shooting, but the relative growth rate of individual area and leaf mass per area of the first shooting were lower than those of the second shooting. 3) The maximum relative growth rates of the twig length and leaf number, the twig diameter (expect for Eurya loquaiana and Castanopsis carlesii var. spinulosa) and total leaf area (expect for Castanopsis carlesii var. spinulosa) of the first shooting were all higher than those of the second shooting, and appeared in the first and second weeks of shooting. 4) In the two shootings, all the plants put priorities on the growth of leaf area and number, then on the growth of twig length, and finally on the twig diameter. The individual and total leaf area showed a significant allometric scaling relationship with the increasing of twig length and diameter, indicating that the growth rate of leaves was higher than that of twigs. The relationship between the individual leaf area and the leaf number was significantly greater than 1, suggesting that the growth rate of the individual leaf area was higher than that of the leaf number. Besides, the relationship between the twig length and diameter was also significantly greater than 1, suggesting that the growth rate of the twig length was higher than that of twig diameter. The study reveals the shooting strategies formed by plants improved their survival and reproductive ability by obtaining more resources (especially intercept the light resources).

Key words: shooting, second shooting, relative growth rate, allometry, trade-off, subtropical evergreen broad-leaved forest