TY - JOUR
T1 - Azimuthal variations of sap flux density within Japanese cypress xylem trunks and their effects on tree transpiration estimates
AU - Tsuruta, Kenji
AU - Kume, Tomonori
AU - Komatsu, Hikaru
AU - Higashi, Naoko
AU - Umebayashi, Toshihiro
AU - Kumagai, Tomo'omi
AU - Otsuki, Kyoichi
N1 - Funding Information:
Acknowledgments The authors are grateful to Mr. Yasuki Shiiba, Mr. Hisami Nagasawa and Mr. Kiyohiro Kaji (Kasuya Research Forest, Kyushu University) for their help in felling trees. We are also grateful to members of the Laboratory of Ecohydrology, Kasuya Research Forest, Kyushu University, for their assistance with leaf area measurements. Thanks are also due to two anonymous reviewers whose comments were helpful. This research was supported by the Japanese Ministry of Education, Culture, Sports, Science and Technology (MEXT) through a Grant-in-Aid for Scientific Research (#20780119) and by Global COE Program (Center of excellence for Asian conservation ecology as a basis of human-nature mutualism), MEXT, Japan and by Core Research for Evolution, Science and Technology of the Japan Science and Technology Agency.
PY - 2010/12
Y1 - 2010/12
N2 - Sap flow techniques are practical tools for estimating tree transpiration. Though many previous studies using sap flow techniques did not consider azimuthal variations of sap flux density (Fd) on xylem trunk to estimate tree transpiration, a few studies reported that ignoring the azimuthal variations in Fd could cause large errors in tree transpiration estimates for some tree species. Therefore, examining azimuthal variations in Fd for major plantation tree species is critical for estimating tree transpiration. Using the thermal dissipation method, we examined azimuthal variations in Fd in six trees of Japanese cypress Chamaecyparis obtusa (Sieb. et Zucc.) Endl., which is one of the most common plantation tree species in Japan. We recorded considerable variations among Fd at four different azimuthal directions. The Fd value for one aspect was more than 100% larger than those for the other aspects. We calculated differences between tree transpiration estimates based on Fd for one to three azimuthal directions and those based on Fd for four aspects. The differences relative to tree transpiration estimates based on Fd for four aspects were typically 30, 20, and 10% in accordance with the Fd for one, two, and three measurement aspects, respectively. This finding indicates that ignoring azimuthal variations could cause large errors in tree transpiration estimates for Japanese cypress.
AB - Sap flow techniques are practical tools for estimating tree transpiration. Though many previous studies using sap flow techniques did not consider azimuthal variations of sap flux density (Fd) on xylem trunk to estimate tree transpiration, a few studies reported that ignoring the azimuthal variations in Fd could cause large errors in tree transpiration estimates for some tree species. Therefore, examining azimuthal variations in Fd for major plantation tree species is critical for estimating tree transpiration. Using the thermal dissipation method, we examined azimuthal variations in Fd in six trees of Japanese cypress Chamaecyparis obtusa (Sieb. et Zucc.) Endl., which is one of the most common plantation tree species in Japan. We recorded considerable variations among Fd at four different azimuthal directions. The Fd value for one aspect was more than 100% larger than those for the other aspects. We calculated differences between tree transpiration estimates based on Fd for one to three azimuthal directions and those based on Fd for four aspects. The differences relative to tree transpiration estimates based on Fd for four aspects were typically 30, 20, and 10% in accordance with the Fd for one, two, and three measurement aspects, respectively. This finding indicates that ignoring azimuthal variations could cause large errors in tree transpiration estimates for Japanese cypress.
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U2 - 10.1007/s10310-010-0202-0
DO - 10.1007/s10310-010-0202-0
M3 - Article
AN - SCOPUS:78149496374
SN - 1341-6979
VL - 15
SP - 398
EP - 403
JO - Journal of Forest Research
JF - Journal of Forest Research
IS - 6
ER -