Study on photosynthetic characteristics ofLarix olgensis Henry at Erlongshan Forest Farm

Net photosynthetic rate (Pn) and respiration rate (R) of different directions and levels of crownof Larix olgensis Henry, growing at Erlongshan Forest Farm, were different. Pn of 14-year-oldL. olgensis was the biggest at the west of crown, and the lowest at the east of crown. Diurnal process of Pn of the south of crown showed monopeak curve pattern. Diurnal processes of Pn and R of 7-year-old and 16-year-oldL. olgensis showed bipeak curve pattern. Seasonal process of Pn ofL. ol-gensis showed monopeak curve pattern. Light compensation and saturation points ofL. olgensis were 18 and 1080 μ molm⁻² s⁻¹ respectively. Chlorophyll content of different directions and levels of crown ofL. olgensis were different. Chlorophyll content increased with the passage of time (May 22 – September 13), and reached its biggest content at August, then decreased. Seasonal process of chlorophyll content, like that of Pn, showed monopeak curve pattern. Chlorophyll content related to Pn positively.