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Effects of clear‐cutting, meteorological, and physiological factors on evapotranspiration in the Kamabuchi experimental watershed in northern Japan
Author(s) -
Kubota Tayoko,
Kagawa Akira,
Abe Toshio,
Hosoda Ikuhiro
Publication year - 2021
Publication title -
hydrological processes
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.222
H-Index - 161
eISSN - 1099-1085
pISSN - 0885-6087
DOI - 10.1002/hyp.14111
Subject(s) - cryptomeria , environmental science , watershed , evapotranspiration , transpiration , japonica , hydrology (agriculture) , atmospheric sciences , interception , photosynthesis , ecology , botany , geology , biology , computer science , geotechnical engineering , machine learning
This study investigated the effects of clear‐cutting and the meteorological and physiological factors on forest evapotranspiration ( ET ), by using the water‐budget method in the Kamabuchi experimental watershed (KMB; 38° 56′ 21″ N, 140° 15′ 58″ E) in northern Japan. Meteorological and discharge data collected during no‐snow periods (from June to October) from 1939 were used to compare ET in three sub‐watersheds: No. 1, where the forest had been left undisturbed, and No. 2 and No. 3, where Cryptomeria japonica was planted after clear‐cutting. Paired watershed experiments revealed that clear‐cutting caused ET to decrease by approximately 100 mm yr −1 , and this reduction continued for more than 20 years, even after C. japonica was planted. ET fluctuated similarly across all watersheds, regardless of clear‐cutting or planting. This fluctuation is mainly caused by solar radiation and temperature. Intrinsic water‐use efficiency ( iWUE ) calculated using δ 13 C of tree‐ring cellulose in C. japonica increased due to elevated atmospheric CO 2 concentration. We estimated annual carbon fixation in a single tree as the annual net photosynthesis ( A ). Subsequently, transpiration ( E ) was calculated from the relationship between iWUE and A . The results showed that A and E per tree increased as the tree grew older; however, the trees' responses to increasing c a suppress the increase in ET . Moreover, the fluctuation of ET from the watershed was small compared to the fluctuation of P during the observation periods because the increase and decrease in E and interception loss complemented each other.