Crown pruning and understory removal did not change the tree growth rate in a Chinese fir (Cunninghamia lanceolata) plantation

Renshan Li, Jianming Han, Xin Guan, Yonggang Chi, Weidong Zhang, Longchi Chen, Qingkui Wang, Ming Xu, Qingpeng Yang, Silong Wang

Research output: Contribution to journalArticlepeer-review

7 Scopus citations


How tree growth and the underlying photosynthesis of leaves, especially those multi-aged leaves, change after the application of both pruning and understory removal remains unclear. In this study, the tree growth and photosynthetic responses of various-aged needles to pruning, understory removal and their interactions were investigated in a Chinese fir (Cunninghamia lanceolata) plantation. The biochemical and stomatal limitations to photosynthesis was separated by the combined measurements of stable carbon (δ 13C) and oxygen (δ 18O) isotopes in needles. Our results showed that the tree growth rates did not respond to pruning, understory removal, and their interactions. Pruning significantly stimulated the net photosynthetic rates (PA) and stomatal conductance (gs) of remaining foliage (especially the current- and one-year-needles). Although pruning had no effect on needle total nitrogen (N) concentration, the concentrations of water-soluble N (NS), the ratio of water-soluble N to sodium dodecyl sulfate (SDS)-insoluble N (NS/ND), and the photosynthetic N use efficiency (PNUE) were higher in needles of pruned trees compared with the unpruned trees. A significant and positive correlation between PNUE and NS/ND was also detected. The constant δ 13C and declined δ 18O in the current-year-needles from pruned trees suggested that both the photosynthetic capacity and the gs were responsible for the enhancement in PA of the youngest needles. Conversely, in the previous year needles, δ 13C and δ 18O were not significantly different between the control and pruned trees. Consistent with the response of tree growth rate, the foliar photosynthesis also did not exhibit changes following understory removal in both pruned and unpruned stands. We highlighted that pruning caused an up-regulation in PA of remaining foliage, thereby mitigating the negative effects of canopy loss on carbon assimilation.

Original languageEnglish (US)
Article number118056
JournalForest Ecology and Management
StatePublished - May 15 2020

All Science Journal Classification (ASJC) codes

  • Forestry
  • Nature and Landscape Conservation
  • Management, Monitoring, Policy and Law


  • Carbon sequestration
  • Foliar nitrogen
  • Needle age
  • Nitrogen trade-off
  • Stable isotopic signature
  • Timber yield


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