Study On Ecophysiological Adaptability Of Picea Crassifolia And Sabina Przewalskii At Different Altitudes

Growth of plant needs numerous environment factors. When the environmental factors, which are plants need(including physical, chemical, or biological environmental factors), beyond the normal level of plant or in deficit and the injury effect of plant growth, are called adversity. At this time, plants are injured because of adversity. The various ecological factors in environment have changed with the change of altitude, plants which are growing there have formed a complete set of physical adaptation mechanisms by the genetic constraints, to withstand harm caused by adverse environmental.The experiment studied on the antioxidase activities and characteristics of leaf morphological structure of Picea crassifolia and Sabina przewalskii leaves along an altitudinal gradient (2765m -3565m) in Sidalong forests, in order to discuss the mechanism of evergreen xylophyte in mountain extreme environment. The results are summarized below:1. With increasing altitude, content of MDA, soluble protein and the activities of peroxidase (POD) and catalase (CAT) in Picea crassifolia obviously increased except the activities of superoxide dismutase (SOD), while those in Sabina przewalskii tended to increase. The content of MDA in Picea crassifolia was higher than Sabina przewalskii, but the content of soluble protein was lower than the later at the same altitude. So both trees could adapt low temperature and strong radiation stress, Picea crassifolia injured seriously in the process of low temperature, and the ability of resisting strong radiation stress was weaker than Sabina przewalskii.2. With increasing altitude, cutin thickness, epidermis thickness, palisade tissue thickness, spongy tissue thickness, cell thickness rate, palisade cell rate, intercellular space and stomatal density of Sabina przewalskii obviously increased, while stomatal size decreased. All these change of Sabina przewalskii showed strong adaptive ability in different altitudes.3. Leaf length and width, cutin thickness, mesophyll cell width, epidermis thickness and width, vascular bundle diameter, phloem thickness, xylem thickness, transfusion tissue thickness, epidermis cell size, and stomatal density of Picea crassifolia obviously increased with increasing altitude from 2765m to 3065m, and then came to maximum at about 3000m, while those decreased with increasing altitude from 3065m to 3465m. But stomata width firstly decreased, then increased. All these change of Picea crassifolia above 3000m and below 3000m showed strong adaptive ability in dry environment at low altitude and cold environment at high altitude.