期刊
FUNCTIONAL ECOLOGY
卷 36, 期 3, 页码 699-712出版社
WILEY
DOI: 10.1111/1365-2435.13975
关键词
embolism resistance; flow path; hydraulic architecture; hydraulic conductivity; vessel tapering; vulnerability curve; wood anatomy; wood density
类别
资金
- Cluster of Excellence COTE [NAR-10-LABX_45]
- European Research Council [FP7-339728]
- German Science Foundation [DFG GRK 1086]
- Investments for the Future [ANR-10-EQPX-16]
- Bordeaux International Post-Doctoral Program [UB101 CR1024-R s/CR 1024-6M]
Contrary to common belief, coarse roots are not highly vulnerable to xylem embolism, indicating that hydraulic failure during soil drying might be restricted to fine roots.
1. Xylem hydraulic safety and efficiency are key traits determining tree fitness in a warmer and drier world. While numerous plant hydraulic studies have focused on branches, our understanding of root hydraulic functioning remains limited, although roots control water uptake, influence stomatal regulation and have commonly been considered as the most vulnerable organ along the hydraulic pathway. 2. We investigated 11 traits related to xylem safety and efficiency along the hydraulic pathway in four temperate broad-leaved tree species. 3. Continuous vessel tapering from coarse roots to stems and branches caused considerable reduction in hydraulic efficiency. Wood density was always lowest in roots, but did not decline linearly along the flow path. In contrast, xylem embolism resistance (P-50) did not differ significantly between roots and branches, except for one species. The limited variation in xylem safety between organs did not adequately reflect the corresponding reductions in vessel diameter (by similar to 70%) and hydraulic efficiency (by similar to 85%). Although we did not observe any trade-off between xylem safety and specific conductivity, vessel diameter, vessel lumen fraction and wood density were related to embolism resistance, both across and partly within organs. 4. We conclude that coarse roots are not highly vulnerable to xylem embolism as commonly believed, indicating that hydraulic failure during soil drying might be restricted to fine roots. A free Plain Language Summary can be found within the Supporting Information of this article.
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