TY - JOUR

T1 - Ecophysiological responses of two closely related Magnoliaceae genera to seasonal changes in subtropical China

AU - Liu, Hui

AU - Zhu, Liwei

AU - Xu, Qiuyuan

AU - Lundgren, Marjorie R.

AU - Yang, Keming

AU - Zhao, Ping

AU - Ye, Qing

N1 - This is a pre-copy-editing, author-produced PDF of an article accepted for publication in Journal of Plant Ecology following peer review. The definitive publisher-authenticated version CHui Liu, Liwei Zhu, Qiuyuan Xu, Marjorie R Lundgren, Keming Yang, Ping Zhao, Qing Ye; Ecophysiological responses of two closely related Magnoliaceae genera to seasonal changes in subtropical China, Journal of Plant Ecology, Volume 11, Issue 3, 6 March 2018, Pages 434–444, https://doi.org/10.1093/jpe/rtx011 is available online at: https://academic.oup.com/jpe/article/11/3/434/3003168

PY - 2018/3/6

Y1 - 2018/3/6

N2 - Plants use a variety of hydraulic strategies to adapt to seasonal drought that differ by species and environmental conditions. The early-diverging Magnoliaceae family includes two closely related genera with contrasting leaf habits, Yulania (deciduous) andMichelia (evergreen), which naturally inhabit temperate and tropical regions, respectively. Here, we evaluate the hydraulic strategy of species from both genera that have beenex situ conserved in a subtropical region to determine how they respond to the novel cool-dry season climatic pattern.We measured ecophysiological traits in fiveMichelia and fiveYulania species conserved in the South China Botanical Garden in both wet and dry season conditions and monitored the whole-year sap flow for four of these species.We found that Magnoliaceae species that have beenex situ conserved in a subtropical climate did not suffer from excessive water stress due to the mild drought conditions of the dry season and the ecophysiological adjustments the species made to avoid this stress, which differed by leaf habit. Specifically, deciduous species completely shed their leaves during the dry season, while evergreen species decreased their turgor loss points, dry mass based photosynthetic rates, stomatal conductance and specific leaf areas (SLAs) compared to wet season measurements. In comparing the two distinct leaf habits during the wet season, the leathery-leaved evergreen species had higher leaf hydraulic conductance and leaf to sapwood area ratios than the papery-leaved deciduous species, while the deciduous species had greater hydraulic conductivity calculated on both a stem and leaf area basis, dry mass based photosynthetic rates, leaf nutrients, SLAs and stomatal sizes than the evergreen species. Interestingly, species from both genera maintained similar sap flow in the wet season. Both photosynthetically active radiation and vapour pressure deficit affected the diurnal patterns of sap flow in the wet season, while only vapour pressure deficit played a dominant role in the dry season. This study reveals contrasting hydraulic strategies inYulania andMichelia species under subtropical seasonal conditions, and suggests that these ecophysiological adjustments might be affected more by leaf habit than seasonality, thus reflecting the divergent evolution of the two closely related genera. Furthermore, we show that Magnoliaceae species that areex situ conserved in a subtropical climate are hydraulically sound, a finding that will inform future conservation efforts of this ancient family under the threat of climatic change.

AB - Plants use a variety of hydraulic strategies to adapt to seasonal drought that differ by species and environmental conditions. The early-diverging Magnoliaceae family includes two closely related genera with contrasting leaf habits, Yulania (deciduous) andMichelia (evergreen), which naturally inhabit temperate and tropical regions, respectively. Here, we evaluate the hydraulic strategy of species from both genera that have beenex situ conserved in a subtropical region to determine how they respond to the novel cool-dry season climatic pattern.We measured ecophysiological traits in fiveMichelia and fiveYulania species conserved in the South China Botanical Garden in both wet and dry season conditions and monitored the whole-year sap flow for four of these species.We found that Magnoliaceae species that have beenex situ conserved in a subtropical climate did not suffer from excessive water stress due to the mild drought conditions of the dry season and the ecophysiological adjustments the species made to avoid this stress, which differed by leaf habit. Specifically, deciduous species completely shed their leaves during the dry season, while evergreen species decreased their turgor loss points, dry mass based photosynthetic rates, stomatal conductance and specific leaf areas (SLAs) compared to wet season measurements. In comparing the two distinct leaf habits during the wet season, the leathery-leaved evergreen species had higher leaf hydraulic conductance and leaf to sapwood area ratios than the papery-leaved deciduous species, while the deciduous species had greater hydraulic conductivity calculated on both a stem and leaf area basis, dry mass based photosynthetic rates, leaf nutrients, SLAs and stomatal sizes than the evergreen species. Interestingly, species from both genera maintained similar sap flow in the wet season. Both photosynthetically active radiation and vapour pressure deficit affected the diurnal patterns of sap flow in the wet season, while only vapour pressure deficit played a dominant role in the dry season. This study reveals contrasting hydraulic strategies inYulania andMichelia species under subtropical seasonal conditions, and suggests that these ecophysiological adjustments might be affected more by leaf habit than seasonality, thus reflecting the divergent evolution of the two closely related genera. Furthermore, we show that Magnoliaceae species that areex situ conserved in a subtropical climate are hydraulically sound, a finding that will inform future conservation efforts of this ancient family under the threat of climatic change.

KW - hydraulic conductivity

KW - leaf habit

KW - leaf turgor loss point

KW - phylogeny

KW - photosynthesis

KW - sap flow

KW - stomata

KW - XYLEM SAP FLOW

KW - TROPICAL FOREST

KW - WATER RELATIONS

KW - HYDRAULIC CONDUCTANCE

KW - STOMATAL CONDUCTANCE

KW - PLANT HYDRAULICS

KW - LEAF CONDUCTANCE

KW - CLIMATE-CHANGE

KW - RAIN-FOREST

KW - STEM XYLEM

U2 - 10.1093/jpe/rtx011

DO - 10.1093/jpe/rtx011

M3 - Journal article

VL - 11

SP - 434

EP - 444

JO - Journal of Plant Ecology

JF - Journal of Plant Ecology

SN - 1752-9921

IS - 3

ER -