Diurnal and seasonal variations in photosynthetic rates of dwarf pine <i>Pinus pumila</i> at the treeline in central Japan

It is important to develop a convenient method for predicting photosynthetic rates in cold regions such as high elevations. Dwarf pine Pinus pumila representative treeline species Japan. In this study, we investigated how environmental factors affect diurnal and seasonal variations of the situ rate P. pumila. Five (photosynthetic photon flux density [PPFD], air temperature [Ta], soil [Ts], vapor pressure deficit [VPD], water content [SWC]) were examined. Photosynthetic measurements conducted four needle ages at hourly intervals on fifteen days from July October 2018. The net decreased with age changed seasonally diurnally each age. showed unimodal patterns Ta, Ts, SWC. changes related (PPFD, SWC); mid-summer when PPFD due decrease Seasonal could be reproduced by multiplicative model Therefore, can explained predicted using these This information will useful effects climate change production plants regions.