Tropical forests are experiencing an increase in vapor pressure deficits (D), which can have a negative impact on tree growth. However, the mechanisms by which climate change drives tree growth are poorly understood. The role of turgor limitation in driving tropical tree growth also remains largely unexplored.
In a study published in Plant, Cell and Environmentresearchers from the Xishuangbanna Tropical Botanical Garden (XTBG) of the Chinese Academy of Sciences and their collaborators investigated how environmental conditions can cause turgor limitation in stem growth, and in turn, explain the diel and seasonal patterns of stem diameter growth in the widespread tropical tree species Toona ciliata (red cedar).
The researchers conducted continuous monitoring for a year in a tropical rainforest near XTBG, Yunnan Province in southwest China. They applied a turgor-driven mechanistic model to quantify the environmental conditions that cause turgor to limit intra-annual stem diameter growth rates in Toona ciliata.
To simulate turgor-driven growth during the growing season, researchers collected hourly sap flow and dendrometer measurements. They found that the simulated seasonal patterns of radial growth agreed well with the growth observation. Growth primarily occurred at night, and predawn accumulation appeared to be limited under the higher vapor pressure deficit.
The team also found that the nighttime turgor pressure required for growth was negatively correlated with the previous lack of midday vapor pressure in all seasons. “This may be due to the relatively high canopy conductance of the high vapor pressure deficit, relative to stem rehydration,” said FAN Zexin of XTBG.
The study shows that mechanical modeling of cambium turgor dynamics is an effective tool for simulating and understanding diel and seasonal growth dynamics of a tropical tree species. In red cedar, the turgor limit is very sensitive to changes in atmospheric drought, which is probably driven by poor stomatal control.
“Our results provide the first evidence that tropical trees grow at night and turgor pressure limits tree growth,” said Fan Zexin of XTBG.
Richard L. Peters et al, High vapor pressure deficit enhances turgor limitation of stem growth in an Asian tropical rainforest tree, Plant, Cell and Environment (2023). DOI: 10.1111/pce.14661
Awarded by the Chinese Academy of Sciences
Citation: Turgor pressure limits growth of red cedar in tropical forests (2023, July 13) retrieved on July 14, 2023 from https://phys.org/news/2023-07-turgor-pressure-limits -red-cedar.html
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