Robinia pseudoacacia is one of the main afforestation tree species in the Loess Plateau, and the soil water law is of great significance in the area of ​​afforestation and even water and soil conservation. In the northern part of the Loess Plateau, the amount of precipitation is relatively small, and the contradiction between supply and demand of soil moisture in forest land is particularly prominent. Based on the long-term observation of the soil moisture of Robinia pseudoacacia forest in the northwestern Shanxi, we used a soil moisture tester to analyze the spatial distribution of soil moisture, compensation, consumption and regulation of soil moisture, and dynamic changes of water storage. .
The determination of the soil moisture tester found that the skewness coefficient was greater than zero, indicating that the distribution of variables larger than the average value of soil moisture was more dispersed, and the larger the skewness coefficient, the more dispersed the variable distribution. The above characteristics of soil moisture in this area are due to the characteristics of compensation and consumption of soil moisture. Because the only supplemental source of soil moisture in the test site is atmospheric precipitation, the consumption of soil moisture is soil evaporation and forest transpiration. The amount of precipitation determines the infiltration depth of precipitation, which determines the soil moisture content.
The soil moisture tester found that the average soil moisture was greater than 6%, the standard deviation was greater than 3, and the coefficient of variation was greater than 50%. The upper and lower bounds of the 95% confidence zone ranged from greater than 2; 80 to 200 cm was the secondary active layer. The change of soil moisture is obvious, the same precipitation and evapotranspiration, but only the larger precipitation can infiltrate into this layer, the average value of soil moisture is between 5.5% and 6%, the standard deviation is 2 to 3, and the coefficient of variation is 15% to 50%. The upper and lower bounds of the 95% confidence zone ranged from 1 to 2; the stable layer below 200 cm showed little change in soil moisture. Only soil moisture was affected during the special year. The moisture average is greater than 5.5%, the standard deviation is less than 1, the coefficient of variation is less than 15%, and the range of variation in the upper and lower bounds of the 95% confidence zone is less than 0.5.
The determination of the soil moisture tester found that the skewness coefficient was greater than zero, indicating that the distribution of variables larger than the average value of soil moisture was more dispersed, and the larger the skewness coefficient, the more dispersed the variable distribution. The above characteristics of soil moisture in this area are due to the characteristics of compensation and consumption of soil moisture. Because the only supplemental source of soil moisture in the test site is atmospheric precipitation, the consumption of soil moisture is soil evaporation and forest transpiration. The amount of precipitation determines the infiltration depth of precipitation, which determines the soil moisture content.
The soil moisture tester found that the average soil moisture was greater than 6%, the standard deviation was greater than 3, and the coefficient of variation was greater than 50%. The upper and lower bounds of the 95% confidence zone ranged from greater than 2; 80 to 200 cm was the secondary active layer. The change of soil moisture is obvious, the same precipitation and evapotranspiration, but only the larger precipitation can infiltrate into this layer, the average value of soil moisture is between 5.5% and 6%, the standard deviation is 2 to 3, and the coefficient of variation is 15% to 50%. The upper and lower bounds of the 95% confidence zone ranged from 1 to 2; the stable layer below 200 cm showed little change in soil moisture. Only soil moisture was affected during the special year. The moisture average is greater than 5.5%, the standard deviation is less than 1, the coefficient of variation is less than 15%, and the range of variation in the upper and lower bounds of the 95% confidence zone is less than 0.5.
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