Abstract: To study the physiological mechanisms in environment adaptation of alpine trees, the antioxidase activities and photosynthetic pigment contents in Larix principis-rupprechtii leaves along an altitudinal gradient from 1 600 m to 2 800 m at Pangquangou National Nature Reserve were investigated. The results showed that the superoxide dismutase (SOD), peroxidase (POD) and catalase (CAT) activities in L. principis-rupprechtii leaves had the same change pattern along the altitudinal gradient, i. e. , relatively lower at middle altitude (1900-2400 m) and relatively higher at lower (1 600-1 800 m) and higher altitudes (2 500-2 800 m). Comparing with those at middle altitude, the SOD, POD and CAT activities were 62.79%, 42.13% and 7.87% higher at lower altitude and 75.20%, 14.49% and 63.38% higher at higher altitude, respectively, but decreased at the altitude near the upper limit of forest vertical distribution. At lower and higher altitudes, malondialdehyde (MDA) content was up to 9.27 and 14.06 μmol·g^-1 FM, respectively, while at middle altitude, it was 5.58 μmol·g^-1FM on average. Chlorophyll and carotinoid contents tended to decrease with increasing altitude, while chlorophyll a/b ratio and relative carotinoid content (Car/Chl) were in adverse, with the relative coefficients being -0.969 and -0.986, and 0.962 and 0.877, respectively.

Key words: Kalimeris integrifolia, Cone plant, Ramet, Bomass allocation, Allometry, Srategy of growth