Soil aggregate structure is an important factor affecting soil fertility and erodibility． Ｒeports have suggested that
vegetation restoration may affect water-stable soil aggregates，but few studies have assessed vegetation restoration in the
mining area on the Loess Plateau． This study was performed in the Heidaigou opencast coal mine dump of the Loess
Plateau，which has been restored by vegetation reconstruction for 18 years． To study the effects of vegetation types and
landforms on dump soil aggregate characteristics，we assessed three vegetation types ( grassland，shrubland，and bare land)
and two landforms ( platform and slope) with 6 treatments and 126 samples． The water-stable soil aggregate composition was
analyzed by wet sieving． The aggregates were separated into six size classes: ＞ 5 mm，5—2 mm，2—1 mm，1—0． 5 mm，
0． 5—0． 25 mm，and ＜ 0． 25 mm． Macro-aggregate content ( Ｒ0． 25
) ，mean weight diameter ( MWD) ，geometric mean
diameter ( GMD) ，and fractal dimension ( D) were used as evaluation indexes． Soil particle size distribution was
determined by an MS2000 laser granularity analyzer． Soil organic carbon ( SOC) content was determined by potassium
dichromate volumetry． Ｒesults showed that vegetation restoration promoted the formation of water-stable soil aggregates． The
Ｒ0． 25
，MWD，and GMD of the 0—20 cm soil layer were significantly higher in revegetated land than in bare land on both
platforms and slopes． The Ｒ0． 25
，MWD，GMD，and D in the 0—20 cm soil layer of revegetation land were 31． 1%，0． 70
mm，0． 26 mm，and 2． 91，respectively，on platforms，and 13． 3%，0． 37 mm，0． 17 mm，and 2． 96，respectively，onslopes． The soil aggregate quality on the plat form was better than on the slope． Artificial grassland had more significant
improvement in soil aggregate quality than the shrubland on the platform of the dump，but the shrubland was better on the
slope． The soil aggregate quality was lower in the surface layer than sub-surface layer on the platform． SOC content and soil
clay content were significantly related to soil aggregate quality． Higher SOC content was noted with vegetation restoration on
the platform than on the slope． The distribution of SOC content changed in the order grassland ＞ shrubland ＞ bare land on
the platform，but in the order shrubland ＞ grassland ＞ bare land on the slope． The clay，slit，and sand contents，
respectively，averaged 10． 52%，54%，and 35． 48% on the platform and 7． 68%，42． 82%，and 49． 50% on the slope．
Significant correlations were noted between SOC content and soil aggregate indexes aswellas between soil clay content and
soil aggregate indexes． Correlation analysis showed that water-stable soil aggregate properties were positively correlated with
SOC and soil clay． Further，soil clay promoted the formation of water-stable soil aggregates，while the high SOC increased
the particle size of water-stable soil aggregates and changed their size distribution． Our results suggested that soil aggregate
quality improved significantly after 18 years of vegetation restoration，and vegetation types and landforms had significant
influences on soil aggregate properties in this mining area on the Loess Plateau． In addition，our results showed the positive
effects of vegetation restoration on water stability and soil structure of an opencast coal mine dump on the Loess Plateau，
which reduced soil erosion and improved soil quality in this region．
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