Dominant species drive stability in forest regeneration
image: The results of final piecewise structural equation modeling showing the causal relationships among climate and local habitat conditions, species asynchrony, species richness, and dominant species stability to temporal stability of (a) seedling survival and (b) recruitment.
Credit: Zhichao Xu, Meihui Zhu, Jonathan A. Myers, Lin Jiang, Fei Lin, Ji Ye, Shuai Fang, Zikun Mao, Xugao Wang
A team led by the Chinese Academy of Sciences, in collaboration with Washington University in St. Louis and Georgia Institute of Technology, has identified the key mechanisms that determine whether forests can regenerate reliably under changing climate conditions. Published in Forest Ecosystems, the study provides the first empirical evidence from a forest seedling perspective on what maintains or undermines the stability of forest regeneration.
Forest regeneration is the most vulnerable stage in a tree’s life cycle. Even when average survival is high, large year-to-year fluctuations can cause regeneration to fail. Using 15 years of data from more than 60,000 seedlings in northeastern China, the researchers examined how seasonal drought (vapor pressure deficit, VPD), winter snowpack, soil fertility, and competition from neighboring trees affect the stability of seedling survival and recruitment.
The study tested three stabilizing mechanisms: dominant species stability, species asynchrony (the staggered responses of species to environmental change), and species richness. The results showed that dominant species stability plays the strongest role in maintaining regeneration stability, outweighing both asynchrony and diversity.
Climate effects were pronounced. Seasonal drought reduced regeneration stability by weakening both dominant species and species asynchrony, disrupting the natural buffering capacity of forest communities. In contrast, deeper snowpack enhanced stability by protecting seedlings from winter stress and supporting more consistent recruitment.
Local habitat conditions added further complexity. High tree density reduced survival stability by intensifying competition and lowering dominant species stability, but it tended to increase recruitment stability by ensuring a more consistent seed supply. Soil fertility showed no direct effect but indirectly reduced recruitment stability by suppressing species asynchrony.
“The findings provide a detailed perspective,” said researcher Xugao Wang. “Dominant species are key to regeneration stability, but drought disrupts both these species and the asynchronous dynamics that help forests withstand environmental fluctuations.”
As seasonal drought intensifies in many temperate regions, the study suggests that conserving functionally important dominant species and maintaining winter snow cover could be critical for sustaining long-term forest stability. Overall, the study offers a new way to connect short-term climate fluctuations with the long-term stability of forest regeneration. By considering these stabilizing processes, future forest–climate models could better predict regeneration success, carbon storage, and ecosystem resilience under more extreme conditions.
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