Evolution of soil properties under artificial and natural revegetation in loess gully coal mining subsidence area

Vegetation restoration is the basis for ecological restoration to coal mining subsidence areas,and the improvement of soil quality is one of the important indexes for vegetation restoration benefits evaluation.It is of great significance to reveal the effects of natural and artificial revegetation on soil properties for guiding vegetation construction after disturbance.At present,the comparison on the dynamic evolution laws of soil properties is still insufficient after artificial and natural vegetation restoration at the coal mining subsidence area in the semi-arid ecologically fragile region in western China.Therefore,the dynamic evolution laws of soil physical,chemical,and biological properties were analyzed during 1-15 years under artificial and natural revegetation area in loess gully area in the Yushenfu mining area,and the evolution mechanism of soil properties was explored combining with the characteristics of plant communities.The results showed that:① With the increase of revegetation time,indexes in duding soil moisture,organic matter,effective nutrient content,enzyme activity,and fungi number increased.The improvement of topsoil physical,chemical and biological properties in artificial revegetation area was better than that in natural revegetation area.② In terms of the recovery rate of soil properties,the soil moisture and biological characteristics can reached the level before the subsidence,but the soil organic matter and available nutrients content were still lower than that in the unsubsidence area after 10 years restoration in natural revegetation areas,while the soil properties can reached or even exceed the level of the unsubsidence area after 6 years restoration in artificial revegetation areas.③ Soil bulk density,water content,available nutrients and fungi are all closely correlated with plant community diversity and vegetation coverage.Soil water content and organic matter were the main factors affecting the soil quality in revegetation area.This study indicated that the artificial revegetation can improve the soil properties better than the natural revegetation in degree and speed in semi-arid coal mining subsidence area,but the interference of the artificial revegetation on the vegetation and soil system should be minimized in the initial artificial restoration;appropriate artificial tending measures can promote the development of vegetation,accelerate the improvement of soil quality,and achieve a better ecological benefits in semi-arid subsided area.