| This paper,based on the theoiy of continuous development and the idea of continuous.expansion with forest ecology and management, disusses the basic economic and ecological features of the forest and fannland net in Zhangye Irrigation Area. - Aiming at the following 6 elements: target of social and economic development, Social and economic development, target of ecological and social function, target of policy, techonology and the environmental bearing, the author with a mathematic method, provides the esfimate target system of the continuous developmnt of the forest net and farmlomd in Zhangye li-rigation Area. It results that the farget of continuous develpoment in this area is o.4780 which indicates the discontinuous development. The following reasons prevent the discontinuous development in Zhangye fan7nland: unitary tree Variety , Lack of stability,unefficient water consumption, stortage of the govenmental iveestment ,disadvantage of the science and rechonoogy: bad ecological environment, degeneration of natural vegetation, the recession of sandbreak forest, dis contiunous e cological development, ecotogical discontinuation, discontinuous of forest shelter belt, dilema existed in further exploit, etc. For these reasons, some managable strategies are 7 I attached to improve the vegetation resources and consolidate sandbreak forest protedion and replaceable systems; at the same time, to popularize the water--saving irrigation systemso: 1.. The sand storm Lasted less time eveiy year because the forest shelter belt was built around the Thrmland. The area of the sand stom disaster is reduced to 65.1% and the wind speed is reduced to 42.6%. 2.. The better proportion of the farmland forest shelter belt and economic forest is 4:1 The propoitiom of farmland,forest shelter, forest windbreak and pasture forest shelter should be 1:6:3. The best vanety of the trees are: D. alba var. pyranidalis.. H.amnodendron.. D.euphratica.. T. chinensis .. A.fruticosu .. R.pseudoacacia .. E.angustifolia .. D. gansuensis.. D.nigra Var therestino.. U.pumila.. S.japonica.. Salix matsudana.. Fraxinus bungeana. P.X beijingensis. Pinus sylvesfris pinus mongolica. plantation should be popularized on the most important forest shelter belt. 3.. Some strategies Like攑oplar trees in big net, fruit trees in small net?are practical in the distribution of forest trees.According to the experimental result, close distribution of forest with O.25----O.3 which has an effestion of windbreak is the better distribntion. The windbreak offecf will be increased to 19--54.6% when leaves remain on trees. 4 ~. The vertical section shaped like an square, the space between lines is 1.5X 1.5m or IX lm with more officient wind-break offect. Grown-up forest trees consumed Lot of water in the area of 0-1 H near the forest. The water consumption of the forest trees influences the water capacity in the soil. The water level remains the lowest level of the year. The production of wheat in the forest tree net depends on the water capacity in the soil. Every 100% increase of wat... |
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