Study On The Major Tree Species For Arid And Barren Land Afforestation In Shandong Province And Drought Resistance Of Some Non-timber Tree Species

Based on referring a large amount of information and analysing of tree species compositions of main forest farmes of Shandong provionce. According to such as trees of Shandong Science and Technology Information, to collect statistics of Shandong Prrovince. This paper made an inventory of trees species resources resisting to drought and barren conditions and selected the major drought resistant tree species which adapted to Shandong Province. In includes 23 familiy, 53 genus, and 84 forest trees species and 20 familiy,40 genus, 53 shrubs species. Based their economic importance ,elected for four tree species to drought experiment. The potted one-year-old seedlings of four economic tree species were used to study their characteristics of response to drought stress. With continuous controlled water control method were taken the growth, physiological and biochemical indices of these seedlings, were measured .Evaluation indices system of drought resistance was established to provide scientific and theoretic basis for tree species selation for afforestation in arid mountain areas.The test results showed as followings:1. The under continuous water-controlling conditions,height growth of all seedings was signiticanting reduced enhancement of drought stress intensity increased degree of inhibition. The biomass production of seedlings appeared a decreasing trend with the declining of content of soil water. The ratio of root to stem was increasing obviously with the enhancement of drought stress intensity.2. The stomatal inhibition was the major limiting factor to photosynthesis of Castanea mollissima BL.and Juglans regia L. under slight and moderate water stress condition the limiting factor was non-stomatal inhibition.The major limiting factor of photosynthesis of Zanthoxylum bungeanum Maxim was stomatal inhibition under water stress. The photosynthesis reduction of and Gleditsia sinensis Lam was caused by stomatal inhibition factors under the slight and moderate drought stress conditions, and then changed into non-stomatal inhibition under severe stress condition. These phenomena show that stomatal inhibition of photosynthesis generally occurred under slight water stress condition. However, as the intensity of drought stress was enhanced, the non-stomatal inhibition of photosynthesis becomed the major factor.3.Trends in the contents of chlorophyll, carotenoids and the ratio of chlorophylla over chlorophyllb appeared similar under the continuous water controlled treatment conditions. Drought stress inhibited the composition of chlorophyll of Juglans regia however it enhanced the chlorophyll composition of other tree species. Drought stress also enhanced the production of carotenoids.4. As the intensity of drought stress was enhanced, the contents of proline of all seedlings were increased significantly. More contents of proline in seedlings of Gleditsia sinensis Lam and Zanthoxylum bungeanum Maxim were accumulated under the continuous water controlled treatment conditions. Under the gradient water control condition, the contents of soluble sugar were basically higher than that of the check group. Under the same water gradient and as the lengthening of stress time, the increasement of soluble sugar played certain role of osmosis. The soluble protein contents of all four tree seedlings under the same resistant gradient level were appeared decreasing tirst and then increasing trend.5. The cell membrane conductance, MDA content and generating rate of of the seedlings appeared an increasing trend as the intensity of stress enhanced under continuous water controlled conditions. This meaned that the membrane system of seedlings were all damaged. And this damage probably was closely related with the extra oxidation of membrane grease. The four protective enzymes, SOD, POD, CAT and APX integrated cooperately to eliminate the extra free radical, and hence increaed the seedling adaptibility to drought stress.6. The adaptability and production capacity of tree seedlings were compared by subordination function method of vague mathematics. Transpiration rate water-absorbing ability, osmotic adjustment, anti-oxidant system, net photosynthesis rate, water utilization efficiency, biomass production were selected as evaluation index in the drought-resistant assessment of tree species. The ability of drought resistant of the tree species were in descending order as following: Zanthoxylum bungeanum Maxim,Gleditsia sinensis Lam.,Castanea mollissima BL.andJuglans regia L.