| In recent years, the ecological safety and food security have become a key issuewhich is closely related to human survival quality. Farmland shelterbelt plays an importantrole in agricultural and ecological construction. The Yellow River floodplain is an importantgrain producing area in China. It has great significances to increase agricultural production bycontrolling the hazards of sand storms effectively. In this study, we reveal the spatial andtemporal variation in wind speed, temperature and humidity by the method of real-timesynchronous observation in a240m×150m farmland shelterbelt network based on ecologicalfield theory. Its aim is to illustrate the spatial heterogeneities of various ecological factors inthe forest network, and provide theoretical basis and technological guidance for sustainablemanagement of farmland shelter forest construction. The main conclusions are as follows:(1) In three sample line perpendicular to the main belt (48m,120m,192m respectively tothe side belt), The wind field under different wind angles (75.8o,60o,45.4o)in forest protectionarea is not the regular pattern, and the overall average wind speed is significantly lower thanthe control (P<0.05) under different wind angles. The average efficiency of wind prevention is51.3%,49.5%and48.2%which are fitted by exponential model and the spatialautocorrelation is more than0.738.When control wind velocity increases gradually with same wind direction and angle ofwind deflection in the same forest (wind speed mean0.74m/s,1.48m/s and2.23m/s,respectively), three different wind speed were decreased44.3%,44.6%and47.5%byshelterbelt network. The change of wind speed through the shelterbelt network in thissituation shown significant difference (P<0.05). The size and shape of the protection zone arebasically same, and sequence of continuous space distribution of wind speed in the shelterbeltnetwork is0.74m/s<1.48m/s<2.23m/s. With the increasing of the control wind speedgradually, the spatial grid autocorrelation, continuity and heterogeneity are strong andincreasing gradually.(2) The function to regulate the temperature. Compared with the control, the temperaturedifference between day and night is shortened about2℃in forest network.In three sample line perpendicular to the main belt (48m,120m,192m respectively to the side belt), thetemperature variation is similar: regularity of heterogeneous, significantly smaller than that ofthe control (P<0.05). Temperature at forest margins is lower and air temperature is higher atthe central area of forest. Temperature reaches the maximum value around14:00o ’clock.Change of temperature appears U-shape. From12:00to16:00, temperature increasing rangeis the biggest. It gradually stabilizes near21:00night. This is conducive to crop growth. At3different moment (11:00,14:00,17:00), temperature in the grid averagely decreased by3.3%,4.4%and3.3%, the effective temperature regulation zone are irregular graphics, adjustabletemperature effect will tend to be consistent.(3) The regulation of the humidity. Variation of humidity is similar. The humidity in theshelterbelt network is obviously higher than that of the control and the difference issignificant (P<0.05). The humidity is higher near the forest edge and the humidity is graduallyreduced from the shelterbelt edge to the center of shelterbelt network..At3moments, discrete degree of frequency chart of air humidity gradually increased.From11:00,14:00to17:00, frequency of high humidity values obviously gradually increasedand relative humidity averagely increases respectively4.56%,4.25%and4.73%comparedwith the control area. Furthermore, humidity reaches the minimum value and the extent ofhumidification is relative minimum at14:00in the afternoon. The changes of air humiditywithin the grid have a strong correlation, little influence by random factors and strong spacecontinuity. |
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