Browsing by Author "Yoshiko Kosugi"

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    Assessing the changes in river water quality across a land-use change (forest to oil palm plantation) in peninsular Malaysia using the stable isotopes of water and nitrate
    (Elsevier, 2023) Masayuki Itoh; Ken'ichi Osaka; Kotaro Iizuka; Yoshiko Kosugi; Marryanna Lion; Satomi Shiodera
    Land conversion from natural forests to plantations (e.g., oil palm) in Southeast Asia is one of the most intensive land-use changes occurring worldwide. To clarify the effects of oil palm plantations on water quality, we conducted multipoint river and stream water sampling in peninsular Malaysia at the end of the rainy season over a 3-year period (2013-2015).
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    CO2 exchange of a tropical rainforest at Pasoh in Peninsular Malaysia
    (Elsevier, 2008) Yoshiko Kosugi; Satoru Takanashi; Shinjiro Ohkubo; Naoko Matsuo; Makoto Tani; Tomonori Mitani; Daizo Tsutsumi; Abdul Rahim Nik
    An obvious inhibition of canopy CO2 exchange in the afternoon coupling with increases in VPD and air temperature was observed year-round. In the case of nighttime NEE, a slight increase in wet period was observed. Diurnal pattern of CO2 exchange revealed that obvious restriction of canopy photosynthesis in the afternoon was occurred in this forest irrespective of soil moisture. Seasonal and annual patterns of CO2 exchange reveal that one of the main causes which induce the difference in NEE pattern between Amazonian and Southeast Asian rainforests was not the difference in daytime photosynthesis but the difference in ecosystem respiration related with dry and rainy seasons. The decrease of CO2 uptake (increase of NEE) at wet period was also observed at this site, but did not form an obvious seasonality such as in Amazonian forests.