期刊
PLANT CELL AND ENVIRONMENT
卷 39, 期 2, 页码 320-328出版社
WILEY
DOI: 10.1111/pce.12612
关键词
embolism; fog; foliar uptake; phellem; sequoia sempervirens
资金
- US Environmental Protection Agency STAR fellowship program
- ARS [ARS-0426234, 813574] Funding Source: Federal RePORTER
Coastal redwood (Sequoia sempervirens), the world's tallest tree species, rehydrates leaves via foliar water uptake during fog/rain events. Here we examine if bark also permits water uptake in redwood branches, exploring potential flow mechanisms and biological significance. Using isotopic labelling and microCT imaging, we observed that water entered the xylem via bark and reduced tracheid embolization. Moreover, prolonged bark wetting (16 h) partially restored xylem hydraulic conductivity in isolated branch segments and whole branches. Partial hydraulic recovery coincided with an increase in branch water potential from about -5.5 +/- 0.4 to -4.2 +/- 0.3MPa, suggesting localized recovery and possibly hydraulic isolation. As bark water uptake rate correlated with xylem osmotic potential (R-2 = 0.88), we suspect a symplastic role in transferring water from bark to xylem. Using historical weather data from typical redwood habitat, we estimated that bark and leaves are wet more than 1000 h per year on average, with over 30 events being sufficiently long (>24 h) to allow for bark-assisted hydraulic recovery. The capacity to uptake biologically meaningful volumes of water via bark and leaves for localized hydraulic recovery throughout the crown during rain/fog events might be physiologically advantageous, allowing for relatively constant transpiration.
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