| Soil moisture is the main limiting factor of vegetation growth in rocky mountain area in Beijing,which is the key factor affecting the growth and development of vegetation.It is of great significance to grasp the spatiotemporal variation characteristics of soil moisture in the slope of in Rocky mountain area in Beijing,which is of great importance to the precision analysis and management of forest and soil moisture relationship in Beijing.In this experiment,the Beijing Jiufeng National Forest Park slope forest of Platyeladus orientalis as the objiect of study.Based on the detailed investigation on the terrain,forest,soil and water conservation engineering measures,30 soil moisture observation points were arranged on the natural slope of 40×50m in this study.The observation of soisture is divided into 10cm intervals and the observation depth ranges from 50 to 70cm.We conducted a total of 38 soil moisture observation from August 2014 to March 2016.The Spatiotemporal changes of soil moisture and its influencing factors were studied by classical statistics and geo-statistical methods.The main results were as follows.(l)The mean soil moisture at different depths was froml2.84±6.8%to 24.8%±6.0%and significantly increased with the increasing depth of soil layer,and the average soil water storage was 21.97%±5.9.A linear negative correlation can be well describe between the average soil water content and the coefficient of variation in space.(2)Soil moisture varied with rainfall,but its spatial distribution pattern shows strong temporal stability characteristic,with the increase of soil depth the spatial distribution pattern tends to be more stable,the average rank correlation coefficient of soil moisture in different soils layers varied from 0.72 to 0.83,and whole profile was 0.75.By using the relative difference analysis method,the representative observation points were selected,the correlation between the soil water content of representative observation points and the average soil water content in different soil layers was strong r2 was 0.94+0.03,thus it can be accurately predict average soil water content.(3)Based on the the data of soil water content before and after the rainstorm in summer of 2015,analyse the response of soil moisture spatial pattern to preciptition.the results show,Before and afer rainfall,The structural ratio of soil water content range are varied from 0.05 to 18.23%,indicatied soil water content had a strong spatial autocorrelation in different layers,spatial variation pattern of soil moisture is mainly eaused by structural factors.The scale of spatial autocorrelation of soil water contents increases with the increase of soil depth during the summer drought period,0?10cm layer was the minimum,8.87m,10?50cm layer of soil changes increased to 13.33 ± 1.04m.The scale of spatial autocorrelation of soil water contents of 0?10cm increased to 21.33m after heavy rain,and the strong precipitation significantly increased the spatial autocorrelation scale of surface soil moisture.(4)Based on the statistical analysis of the average of 38 times data during observations period,it was shown that soil water storage of top slope>middle slope>bottom slope,the soil water storage was 144.12±31.10mn,136.84±45.59mm,and 128.53±19.01mm,respectively,However there was no significant difference in soil water storage at different slope positions(P<0.05),but micro-topography has a significant effect on the spatial distribution of soil water storage,The soil soil water storage of level bench,gentle slope,steep slope and scrap was 152.85±26.46mm,92.38± 1.84mm,137.45±23.99mm and 118.73± 10.23mm,respectively.The soil water storage of level bench and gentle slope is significantly larger than steep slope and scrap(P<0.05).Soil and water conservation engineering measures have important influence on the spatial distribution pattern of soil moisture.The closer the distance to the trees,the lower the soil water storage,When distance between the soil moisture observation point and tree trunk was 0.5m,1.0m,1.5m,the soil water storage was 128.11 ±24.87mm,134.87±31.59mm,149.56±44.31mm,however there was no significant difference in soil water storage at different distance from tree trunk(P>0.05). |
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