Independence of stem and leaf hydraulic traits in six Euphorbiaceae tree species with contrasting leaf phenology |
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Authors: | Jun-Wen Chen Qiang Zhang Xiao-Shuang Li Kun-Fang Cao |
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Institution: | (1) Kunming Division, Xishuangbanna Tropical Botanical Garden, The Chinese Academy of Sciences, 88 Xuefu Road, 650223 Kunming, Yunnan, People’s Republic of China;(2) College of Agronomy and Biotechnology, Yunnan Agricultural University, 650201 Kunming, Yunnan, People’s Republic of China;(3) College of Life Science, South China Normal University, 510631 Guangzhou, Guangdong, People’s Republic of China |
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Abstract: | Hydraulic traits and hydraulic-related structural properties were examined in three deciduous (Hevea brasiliensis, Macaranga denticulate, and Bischofia javanica) and three evergreen (Drypetes indica, Aleurites moluccana, and Codiaeum variegatum) Euphorbiaceae tree species from a seasonally tropical forest in south-western China. Xylem water potential at 50% loss of
stem hydraulic conductivity (P50stem) was more negative in the evergreen tree, but leaf water potential at 50% loss of leaf hydraulic conductivity (P50leaf) did not function as P50stem did. Furthermore, P50stem was more negative than P50leaf in the evergreen tree; contrarily, this pattern was not observed in the deciduous tree. Leaf hydraulic conductivity overlapped
considerably, but stem hydraulic conductivity diverged between the evergreen and deciduous tree. Correspondingly, structural
properties of leaves overlapped substantially; however, structural properties of stem diverged markedly. Consequently, leaf
and stem hydraulic traits were closely correlated with leaf and stem structural properties, respectively. Additionally, stem
hydraulic efficiency was significantly correlated with stem hydraulic resistance to embolism; nevertheless, such a hydraulic
pattern was not found in leaf hydraulics. Thus, these results suggest: (1) that the evergreen and deciduous tree mainly diverge
in stem hydraulics, but not in leaf hydraulics, (2) that regardless of leaf or stem, their hydraulic traits result primarily
from structural properties, and not from leaf phenology, (3) that leaves are more vulnerable to drought-induced embolism than
stem in the evergreen tree, but not always in the deciduous tree and (4) that there exists a trade-off between hydraulic efficiency
and safety for stem hydraulics, but not for leaf hydraulics. |
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Keywords: | Evergreen Deciduous Hydraulics Functional structure |
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