The Optimization Of Structure Of Farmland Shelterbelt As Well As Shelterbelt Nets Based On The Objective Of Protecting Fruit Trees In The Southern Xinjiang

Xinjiang is the famous " the town of melon fruit",and the southern Xinjiang is a important base of fruit production for Xinjiang and the country.Not only the fruit planted area is 65% of the region,but also the market of dry fruit is a leading position at home and abroad for the total output value of 28 billion yuan per year.However,It has important effect that there are drought arid,less rainfall,windy,fragile ecological environment and desertization for daily life,the agricultural production and economic development of the people.Therefore,the construction and optimization of farmland shelterbelt network not only has the ecological significance to improve farmland ecosystem,but also protects and improves the economic benefit of fruit production,and has important political significance to the stable development of society in southern Xinjiang.However,the previous research mainly focused on the protective effect of single shelterbelt and gridding,and rarely considered the target crop and the accumulation effect of multi-layer shelterbelt.This led to reduce crop benefits for the excessive shelterbelt-net planted areas.Therefore,this paper puts forward a new evaluation model of protective effect of farmland shelterbelt-nets to provides the basis for further optimization of farmland shelterbelt-nets by combining wind tunnel simulation and field observation base on the protective effect of crop.The main findings are as follows:By comparing protective effect of wheather has jujube to find: The protective effect of no jujube shelterbelt decreased with the increase in wind speed;the protective effect decreased by 71.73%,65.62%,64.61% and 61.89% in wind fields with 8,10,12 and 14m/s,respectively,but the protective effect of jujube shelterbelt increased little with the increase in wind speed;the protective effect increased by 88.9%,89.26%,89.91 and 90.94%,respectively.However,the increment of productive effects that jujube shelterbelt than no jujube shelterbelt increased with the increase in wind speed,and increased by 16.40%,23.65%,25.29% and 29.05% in wind fields with 8,10,12 and 14 m/s speeds,respectively.It follows that the protective effect of jujube crops is very significant,and with the increase of wind speed,jujube to play the wind effect is greater.The protective effect of no jujube shelterbelt increased with the decrease in porosity;the protective effect increased by 66.54%,73.47% and 85.57% in porosity with 30.12%,25.01% and 20.92%,respectively,but the protective effect of jujube shelterbelt changed little with the decrease in porosity;the protective effect changed by 89.26%,88.69% and 86.86%,respectively.And,the increment of productive effects that jujube shelterbelt than no jujube shelterbelt decreased with the decreased in porosity,and decreased by 22.72%,15.22% and 1.28% in porosity with 30.12%,25.01% and 20.92%,respectively.By comparing after protective effect of shelterbelt and shelterbelt-nets to find: The protective effect of shelterbelt-nets decreased little with the increase in wind speed;the protective effect decreased by 95.21%,89.61%,89.69% and 90.23% in wind fields with 8,10,12 and 14m/s,respectively,but the increment of productive effects that shelterbelt-nets than shelterbelt decreased with the increase in wind speed,and decreased by 17.99%,3.05%,2.83% and 2.38% in wind fields with 8,10,12 and 14 m/s speeds,respectively.The protective effect of shelterbelt-nets became constant after increasing with the decrease in porosity;the protective effect changed by 84.44%,95.21 % And 94.93% in porosity with 30.12%,25.01% and 20.92%,respectively,and the increment of productive effects has same trend,changed by 6.29%,7.99% and 7.65% in porosity with 30.12%,25.01% and 20.92%,respectively.By constructing the protective effect model of shelterbelt-nets to find: We can get needful protection effect of jujube under the 25m/s wind speed when considered not only the effect of sheltering crops such as jujube and so on,but also the accumulation effect of multi-layer shelterbelt-nets.In the southern Xinjiang farmland shelterbelt-nets,if jujube economic benefit is 20,000 yuan / mu,it will increase the annual economic benefits of 756 million yuan for the southern Xinjiang 700 million mu of jujube.Therefore,this study considers the protective effect of tall crops and the accumulation effect of multi-layer shelterbelt-nets,the decreased shelterbelt areas,and increased crop areas and promotes the economic effect of crops,when one creates a shelterbelt with a tall crop,like jujube,with the development of intensive and precision agriculture.