Abstract
The farm-shelter forest network is a complex grid protection system, with a windbreak that is distinctly different from that of the single shelterbelt. We selected the farm-shelter forest network of a jujube field in the Tarim Basin of northwest China and used a combination of field measurements and wind tunnel tests to determine the optimal spacing interval between principal shelterbelts. The wind speed reductive curve of the farm-shelter forest network showed a gradual wind speed tendency to stability. Therefore, a model was established based on the energy transfer balance between the upper and the lower airflows for a steady wind speed. The prediction error of the model was found to be < 1%. The model results indicated that increasing the spacing interval between principal shelterbelts from 10 to 20 H, where H is the shelterbelt height, maintained more than 70% of the windbreak effect of the farm-shelter forest network. If the spacing interval between principal shelterbelts were to be increased from 10 to 20 H, the jujube planting area would be increased by 0.54%. Therefore, a thorough consideration of the windbreak effect of each shelterbelt, the synergistic effects of shelterbelts, the windbreak effects of tall crops, and the effects of temperature and humidity in farm-shelter forest networks indicates that increasing the spacing interval will not only maintain the windbreak effect, but it will also reduce the side effects of shelterbelts, increase the planting area, favor mechanized operation, and improve planting efficiency.
Highlights
Farm-shelter forest networks play an important role in producing stable and high crop yields, stabilizing the farmland ecosystem, and improving the microclimate of agriculturalResponsible Editor: Philippe GarriguesQinming Sun and Bo Zheng contributed to this work and should be considered co-first authors.Agricultural College, Shihezi University, Shihezi 832003, ChinaCollege of Life Sciences, Shihezi University, Shihezi 832003, ChinaKey Laboratory of Special Fruits & Vegetables Cultivation Physiology and Germplasm Resources Utilization of Xinjiang Production and Construction Corps, Shihezi 832003, China fields, primarily through the reduction of windstorm disasters (Kowalchuk and Jong, 1995; Zheng et al, 2016a, b; Zhu et al, 2017; He et al, 2017)
The results revealed that the height of the shelterbelt was 10 m, the length of the principal shelterbelt was 500 m, the length of secondary shelterbelt was 100 m, the principal shelterbelt was perpendicular to the wind direction, the height of wind speed observation was 2 m, and the roughness was 0.003 m in the wilderness (Guan et al, 2001)
The wind speed was very low, and eventually stabilized in the farm-shelter forest network (Maki, 1982; Cao, 1983; Bao et al, 2020). These results provided a database for the construction of the windbreak effect model used in this study, since the momentum flux was transmitted from the upper layer to the lower layer in order to maintain wind speed stability in the model
Summary
Farm-shelter forest networks play an important role in producing stable and high crop yields, stabilizing the farmland ecosystem, and improving the microclimate of agriculturalResponsible Editor: Philippe GarriguesQinming Sun and Bo Zheng contributed to this work and should be considered co-first authors.Agricultural College, Shihezi University, Shihezi 832003, ChinaCollege of Life Sciences, Shihezi University, Shihezi 832003, ChinaKey Laboratory of Special Fruits & Vegetables Cultivation Physiology and Germplasm Resources Utilization of Xinjiang Production and Construction Corps, Shihezi 832003, China fields, primarily through the reduction of windstorm disasters (Kowalchuk and Jong, 1995; Zheng et al, 2016a, b; Zhu et al, 2017; He et al, 2017). The basic principles of wind control indicate that windbreaks planted or placed in the path of air flow act as surface barriers, causing an upward diversion of the air current, and this diversion is accompanied by a drag on the wind at certain heights of the windbreaks (Woodruff, 1956; Maki, 1985; Zhu, 2013). These combined effects lessen the force of wind on the original ground surface, lower the prevailing surface velocity, and create an area of relatively calm airflow within the zone of influence of the windbreaks. The most common design parameter for a system of windbreaks is the spacing interval (Cao, 1983; Zhu, 2013)
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