Study On Sustainable Forestry In HeXi Irrigated Area

Study on protective forest system of desert-oases in Hexi irrigated area showed that, inside the oases, the annual average velocity of wind ,the annual average days of wild wind and the annual average days of sand-storm decreased Zby 42.6%, 66.6% and 65.1% respectively, while with the rate of forest coverage increasing from 2.8% to 7.8%. Contrastive observation has shown that, inside the network of shelter belts, the velocity of wind and the evaporation of water decreased by 25.6% and 18.7% respectively, while the soil water and the yield of crops increased by 19.2% and 23.4% respectively. By calculating, it was concluded that, one month in vigorous growth season (from May to September), 30mm water inside one network of shelt belts, and totally 100 million m3 water in the 330.000 hm2 farmland networked by shelter belts in Hexi irrigated area, could be saved. Mulching with straw could enhance the soil water by 41.4%. The productivity of dry matter in agroforestry compound system was 25.5- 30t/hm2, the efficiency of solar energy utilization was 1.2-2.7%, and the output per m3 water increased from 2.14 to 3.79. To develop economic plantation is the practicable path for improving the economic profit of sustainable forestry in Hexi irrigated area. 59 species of fruit trees were transplanted, from which 2 apple species, 2 plum species and 2 apricot species were selected for economic plantation development in Hexi irrigated area. The ratio structure of apples Pear and other fruit trees (such as plum, apricot etc.) should be 1:1:0.5. The effect of integrated planting techniques was prominent in increasing yield and improving quality of fruit. Branch-pushing(t~)fj~) could make fruit-bearing time 1 year ahead and the early yield (in the first 3,4 or 5 years of a fruit tree) enhanced by 100%. Pest integrated management techniques could decrease the pest density by 82.8% and enhance the commercial value of fruits by 1500- 6000 Yuan/hm2. A multiple-indicators system was put forward for evaluating the development of sustainable forestry in Hexi irrigated area. The result of evaluation is that the index of sustainable forestry development, A0.609, a weakly sustainable level, that is to say, it is sustainable but not strong.