中文摘要：

通过分析庞泉沟国家级自然保护区不同海拔（1600～2800m）梯度华北落叶松针叶中3种抗氧化酶及光合色素含量的变化，探讨了高山林木适应环境的生理机制．结果表明，华北落叶松针叶中超氧化物歧化酶、过氧化物酶和过氧化氢酶的活性随海拔梯度的变化规律相一致，即中海拔区（1900～2400m）的3种抗氧化酶活性相对较低，而低海拔区（1600～1800m）和高海拔区（2500～2800m）活性相对较高．低海拔区3种酶活性分别比中海拔区提高62．79％、42．13％和7．87％，高海拔区分别提高75．20％、14．49％和63．38％，但临近森林垂直分布上限活性降低．膜脂过氧化产物丙二醛含量在低海拔区和高海拔区分别达9．27和14．06μmol·g^-1FM，而在中海拔区平均含量为5．58μmol·g^-1FM．叶绿素和类胡萝卜素含量随海拔梯度升高而降低，相关系数分别为-0．969和-0．986；但叶绿素a／b比值及Car的相对含量（Car／Chl）随海拔梯度升高而增加，相关系数分别为0．962和0．877．

英文摘要：

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 （1 900-2 400 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, malon- dialdehyde （MDA） content was up to 9.27 and 14.06 μmol·g^-1 FM, respectively, while at middie altitude, it was 5.58 μmol· g^-1 FM 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.