Articles
The daily use of stem-water storage in two clonal cultivars of Japanese cedar estimated from sap flow and dendrometer measurements
Article number
1419_17
Pages
135 – 142
Language
English
Abstract
There is concern that Japanese cedar (Cryptomeria japonica), which accounts for about 40% of plantation forest in Japan, will become unsuitable for future timber production to drought-induced growth reduction caused by climate change.
Drier growing conditions may force trees to rely more on water stored in living tissue.
The contribution of stored water relative to daily sap flow in whole-tree water use, is likely to be a key to hydraulic acclimation of trees to climate change.
Here, we measured crown and basal sap flow using Granier sensors and point dendrometers in two clonal cultivars of Japanese cedar.
The study was conducted from July, 2021 to March, 2023 at the Tano Forest Science Station in Miyazaki Prefecture, southern Japan.
In both cultivars, the diurnal peak of sap flow in the crown occurred earlier than at breast height, indicating the use of water stored in stem that complemented water supply from roots to meet transpiration demand.
The length of time lags shorter in the early-growth cultivar than in the intermediate-growth cultivar, suggesting stem-stored water contributed less to sustaining sap-flow in the early-growth cultivar under current environmental conditions.
A diurnal pattern of stem radial expansion and contraction was observed in both cultivars, suggesting the contribution of water stored in the inner bark.
The amplitude of diurnal variation was greater in the crown than at breast height for the early-growth cultivar, while there was no such difference for the intermediate-growth cultivar.
When the stem was warmed at breast height, the amplitude of diurnal variation increased only for the early-growth cultivar.
This suggests that higher stem temperature may increase the daily use of stem-water storage in Japanese cedar, but that sensitivity and acclimation potential may vary among cultivars.
Drier growing conditions may force trees to rely more on water stored in living tissue.
The contribution of stored water relative to daily sap flow in whole-tree water use, is likely to be a key to hydraulic acclimation of trees to climate change.
Here, we measured crown and basal sap flow using Granier sensors and point dendrometers in two clonal cultivars of Japanese cedar.
The study was conducted from July, 2021 to March, 2023 at the Tano Forest Science Station in Miyazaki Prefecture, southern Japan.
In both cultivars, the diurnal peak of sap flow in the crown occurred earlier than at breast height, indicating the use of water stored in stem that complemented water supply from roots to meet transpiration demand.
The length of time lags shorter in the early-growth cultivar than in the intermediate-growth cultivar, suggesting stem-stored water contributed less to sustaining sap-flow in the early-growth cultivar under current environmental conditions.
A diurnal pattern of stem radial expansion and contraction was observed in both cultivars, suggesting the contribution of water stored in the inner bark.
The amplitude of diurnal variation was greater in the crown than at breast height for the early-growth cultivar, while there was no such difference for the intermediate-growth cultivar.
When the stem was warmed at breast height, the amplitude of diurnal variation increased only for the early-growth cultivar.
This suggests that higher stem temperature may increase the daily use of stem-water storage in Japanese cedar, but that sensitivity and acclimation potential may vary among cultivars.
Publication
Authors
W.A. Azuma, M. Takagi, C. Uchiyama, H. Ishii
Keywords
Cupressaceae, time lag, water storage, tall tree, inner bark
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