| In the Loess Plateau,the slope is a common terrain unit in the process of soil moisture(abbreviated as SM below)accumulation and vegetation construction,and SM affects the ecological construction of the region.SM has typical spatio-temporal variability under the influence of various factors.This paper took four common land-use sunny slopes(Robinia pseudoacacia forest,Pinus tabuliformis forest,barren grassland,and reclaimed terraced fields)in Shanxi Province as research object.Through long-term determination of SM,statistical methods,gray correlation analysis and time stability analysis were used to determine research on temporal and spatial variation law of SM on sunny slopes of four land uses in different hydrological years,temporal stability,consumption and compensation characteristics of each soil layer in vertical section,explore the dynamic change mechanism of SM on sunny slopes,and develop slopes for the loess area.Lay a theoretical foundation for the utilization of surface water and soil resources and the layout of vegetation.The main conclusions were as follows:(1)Different land use SM on sunny slope,the slopes of converted farming terraces in wet years had the largest water content,and the difference in water content between P.tabuliformis forest and barren grassland was not significant from May to October(P>0.05);the water content of the four types of sunny slopes in normal water years had significant differences in May and September(P<0.05).Use of SM in different months on the same land on a sunny slope,water content of R.pseudoacacia forest,P.tabuliformis forest,barren grassland and reclaimed terraced fields showed no significant difference between May and June,July and August(P>0.05).In normal years,the difference in water content of R.pseudoacacia forest and P.tabuliformis forest was not significant between August and October(P>0.05),while there was no significant differerce in the slopes of barren grassland and converted farmland terraces in September and October,August and September(P>0.05).The variation trend of seasonal variation coefficient of SM on the sunny slope of four land uses was similar,and the coefficient of variation of water content of four land uses slope in wet years was higher than that in normal years.(2)From July to September in wet years,the difference in SM of the 100-200 cm soil layer on the sunny slopes was small.P.tabuliformis forest had a better control effect on deep soil moisture in wet years,but that was barren grassland in normal years.Interannual rainfall changes had a greater impact on the active layer range of four land uses slope,and the relatively stable layer was smaller.The active layer range in wet years was larger than that in normal years.(3)According to the criterion of time stability,the representative soil layers of four types of sunny slopes during in wet years were all 80-100 cm,but in normal years,they were 0-20 cm,20-40 cm,0-20 cm and 100-200 cm.SM of the representative soil layers selected on sunny slope of each land use can better reflect the average change of SM on the corresponding slope.(4)The changes in soil water storage and rainfall on the sunny slopes of different land uses were relatively consistent,and soil water storage was highly correlated with monthly average humidity and monthly average water vapor pressure.In wet years,SM on the sunny slopes of different land uses did not appear to be deficient only in July and October,but in normal years,it was always deficient,and R.pseudoacacia had a large monthly deficit.From the perspective of vertical section,the difference in soil deficit changes of P.tabuliformis forest in wet years was small,and the soil deficit in terraced fields of returning farmland was small in normal years.The compensation degree of 0-40 cm soil layer of the two forest lands in wet years was higher than that of barren grassland and converted farmland terraces,but40-100 cm soil layer was opposite. |
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