Studies On Photosynthetic Physiological Characteristics Of Larix Gmelinii In Great Xingan Mountains Of Inner Mongolia

In this paper, Larix gmelinii in Greet Xingan Mountains forest ecosystem fixed research was selected to the test materials. The experiments were carried out by using portable photosynthetic measuring system LI-6400 form June to September in 2008. Monthly variation and Diurnal variation of eco-physiological factors were researched. It studied the effect of monthly variation of LMA, K content, P content N content and Pn of L. gmelinii. This paper also analyzed the correlation between Pn, Tr and eco-physiological factors. and then studied that Needle of L. gmelinii response to doubled CO₂ concentration. We last estimated the net photosynthesis at the level of unit leaf area (m2) in a day.The results are as follows:1. Diurnal variation of Pn and monthly variation of day average Pn of L. gmelinii present the trend of single-peak curve form June to September. The day average Pn was highest on 17th June while lowest on 13th August. The correlations between Pn and eco-physiological factors has different among different months, the correlations between RH, PAR, Ta, Gs and Pn achieve significant.as a whole.2. Diurnal variation of Tr and monthly variation of day average Tr of Dahurian larch present the trend of single-peak curve form June to September. The day average Pn was highest on 2th August while lowest on 14th September. The correlations between Gs, PAR and Tr among different months present positive relation. The correlations between RH, Ci and PAR among different months present negative correlation. The correlations between Ta, Tl, VpdL and Tr present positive relation.as a whole.3. Compared to others months, the daily assimilation, daily transpiration and transpiration efficiencyof L. gmelinii at August is the lowest of all months and that at June is the lowest. The highest of the daily assimilation is 2.6 times than the lowest; the highest of daily transpiration is 2.3times than the lowest.4. Under two CO₂ concentration, the average Pn Gs and Tr of L. gmelini increased separately 87.07%, 89.17%, 26.01%, 46.89%, 40.07%, 52.87% on July and August.5. The correlations between monthly variation of K content and the day average Pn of L. gmelinii does achieve significant, presenting multinomial correlation.