| Eco-economic forest has both economic and social benefits as well as outstanding ecological benefits.It is a suitable model to solve the current ecological environment improvement and sustainable economic and social development.jujube,as a kind of eco-economic forest species,is widely planted in southern Xinjiang.In this paper,jujube stands with different ages(8a,13 a,17a)planted in the 224 th Regiment of Southern Xinjiang were taken as the research object.and the protection benefits of jujube forests of different ages were studied in combination with field investigation and indoor experiments.The purpose was to reveal the difference of planting years on wind prevention and sand fixation,climate improvement,soil protection of jujube forests.It was expected to provide relevant theoretical basis and practical guidance for the ecological governance of desert in Southern Xinjiang.The result were as follows:(1)Tree height,crown width and leaf area index(LAI)of jujube stands at different ages increased rapidly from April to July,and the growth trend tended to be gentle after July.With the increase of stand age,the overall performance was 17 a > 13 a > 8a.However,there were differences in the growth status of each index among different forest ages.There were significant differences in tree height between 13-year-old jujube forest,17-year-old and 8-year-old jujube forest.From April to October,there was a significant difference in the crown width of jujube stands at different ages.There was no significant difference in leaf area index between 13-year-old and 17-year-old jujube forest.(2)On the horizontal gradient,the windproof efficiency of jujube stands at different ages showed the order of middle area > front area > edge area.Moreover,there were significant differences between the edge region and the leading edge region,the middle region in April and May.In terms of months,the windproof efficiency of the full leaf stage(From July to September)of Jujube forest was significantly higher than that of the non-leaf stage(April),leaf expansion stage(May)and deciduous stage(October).From April to October,the windproof efficiency of jujube stands at different ages was 17 a > 13 a > 8a,and there was no significant difference between jujube forest 17 a and 13 a.In addition,the sediment transport of jujube stands at different ages was 8a > 13 a > 17 a,and there was no significant difference among different ages,which was significantly lower than that of bare area.(3)Jujube stands at different ages could effectively reduce air temperature and soil surface temperature,increase air relative humidity,and the improvement effect was more significant in summer(from July to September).The improvement effect of jujube stands at different ages was 17 a > 13 a > 8a.On the vertical gradient,with the increase of the height above the ground,the air temperature in jujube forest decreased gradually,and the air relative humidity increased gradually.The soil temperature decreased with the increase of soil depth.The soil water content of jujube stands at different ages was 13 a > 8a > 17 a.(4)Compared with bare soil,the soil bulk density,p H value and water-soluble salt content in 0-60 cm soil layer of jujube stans at different ages decreased by 0.55%-6.98%,10.99%-11.95% and 80.4%-83.31%,respectively,and soil total porosity and organic matter content were increased by 1.52%-4.9% and 77.69%-250.91%.Among them,the p H,water-soluble salt content and organic matter content were significantly different from bare soil.With the increase of stand age,soil bulk density and water-soluble salt showed a trend of "first decreasing and then increasing",with the order of 13 a < 17 a < 8a.However,the total porosity and p H of soil showed a trend of "rising first and then falling",with the order of 8 years old<17 years old<13years old;The content of soil organic matter is 8a<13a<17a. |
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