Under the global context of climate change, forest ecosystems are facing increasingly frequent and severe drought threats, leading to a significant rise in tree mortality worldwide. Although numerous studies have explored drought impacts on tree mortality in forest ecosystems, the relative importance of leaf habits, plant size, species richness, and diversity in drought-induced mortality remains unclear.
In a study published in Journal of Forestry Research, researchers from Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences have identified leaf habit and plant height as critical predictors of tree and shrub survival during extreme drought. These two factors are more decisive than species diversity.
The 2019 extreme drought event in 2019 in the river valleys in Southwest China provided a natural laboratory for analyzing 2,346 woody plants across 32 species.
The researchers analyzed the mortality patterns of tree and shrub species in a 1-ha (100 × 100 m) plot during an extreme drought in a savanna ecosystem of Southwest China. They calculated species richness and diversity indices using 10 × 10 m quadrats within the plot and measured leaf and wood traits, seasonal minimum water potential, hydraulic safety margins and plotted xylem vulnerability curves.
They found that deciduous species exhibited lower hydraulic safety margins compared to evergreen species, resulting in higher mortality risks during extreme drought. Taller plants with deeper root systems demonstrated significantly lower mortality rates, leveraging soil moisture reserves inaccessible to shallow-rooted neighbors. Species richness and diversity showed no significant correlation with survival rates, challenging conventional biodiversity resilience assumptions.
"This isn't just about plant physiology - it's a roadmap for ecological restoration," said ZHANG Shubin. "Our data suggests prioritizing deep-rooted evergreen trees could boost survival rates by up to 40% in reforestation projects."
The study provided novel insights into plant community dynamics under drought conditions and offered critical guidance for vegetation restoration.
Chinese savanna in Yuangjiang, Yunnan. (Image by XTBG)
Published: 09 May 2025
