TY - JOUR
T1 - Effects of tree-to-tree and radial variations on sap flow estimates of transpiration in Japanese cedar
AU - Kumagai, Tomo'omi
AU - Aoki, Sayaka
AU - Nagasawa, Hisami
AU - Mabuchi, Tetsuya
AU - Kubota, Katsuyoshi
AU - Inoue, Sachiko
AU - Utsumi, Yasuhiro
AU - Otsuki, Kyoichi
N1 - Funding Information:
This work was supported in part by a Grant-in-Aid for Scientific Research (Nos. 14360088, 17380096 and 17510011) from the Ministry of Education, Science and Culture, Japan. Tomo’omi Kumagai is grateful to A. Christopher Oishi, Joshua Uebelherr and Ram Oren for giving instructions in Granier-type sap flow sensor.
PY - 2005/12/14
Y1 - 2005/12/14
N2 - To scale sap flux density (Fd) measurements of individual trees to stand level transpiration (E), the mean stand Fd (JS) is among the most important factors, because E is frequently estimated as a product of JS and stand sapwood area. Major uncertainties in J S estimations are caused by tree-to-tree and radial variations in Fd. Thus, by using the Monte Carlo sampling technique with original tree-to-tree Fd data measured at several depths, we examined how many trees and radial depths need to be sampled for calculation of appropriate JS. In this study, Fd was measured in 14 mature Japanese cedar (Cryptomeria japonica) trees at several radial depths, 0-2, 2-4 and 4-6 cm, using Granier-type sensors. The results revealed that the potential error in JS with the largest available sample size was not stable even though radial profiles in Fd for all sample trees were measured. They also showed that to consider radial variation in Fd it might be necessary to sample at least six trees, but not necessarily more than this. The results imply that, for E estimations, there is more tree-to-tree variation in F d than in radial variation in Fd.
AB - To scale sap flux density (Fd) measurements of individual trees to stand level transpiration (E), the mean stand Fd (JS) is among the most important factors, because E is frequently estimated as a product of JS and stand sapwood area. Major uncertainties in J S estimations are caused by tree-to-tree and radial variations in Fd. Thus, by using the Monte Carlo sampling technique with original tree-to-tree Fd data measured at several depths, we examined how many trees and radial depths need to be sampled for calculation of appropriate JS. In this study, Fd was measured in 14 mature Japanese cedar (Cryptomeria japonica) trees at several radial depths, 0-2, 2-4 and 4-6 cm, using Granier-type sensors. The results revealed that the potential error in JS with the largest available sample size was not stable even though radial profiles in Fd for all sample trees were measured. They also showed that to consider radial variation in Fd it might be necessary to sample at least six trees, but not necessarily more than this. The results imply that, for E estimations, there is more tree-to-tree variation in F d than in radial variation in Fd.
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U2 - 10.1016/j.agrformet.2005.11.007
DO - 10.1016/j.agrformet.2005.11.007
M3 - Article
AN - SCOPUS:33144469664
SN - 0168-1923
VL - 135
SP - 110
EP - 116
JO - Agricultural and Forest Meteorology
JF - Agricultural and Forest Meteorology
IS - 1-4
ER -