[Obiective] Investigating the distribution of soil calcium on natural slope under the influences of integrated factors in order to better understand the structure and evolution of soil in karst area.[Methods] Typical karst peak-cluster in Yanbei Town

Yingde City

Northern Guangdong Province

was selected as the research area. The contents of total calcium

exchangeable calcium

water calcium and organic matter were measured

and correlation analysis were used.[Results] At the peak cluster

the average content of total calcium

exchangeable calcium and water soluble calcium was 4.172

1.050 and 0.026 g/kg

respectively. Exchangeable calcium accounted for 22.29% of the total calcium

while water soluble calcium accounted for 0.56% of total calcium. The contents of total calcium

exchangeable calcium and organic matter reduced with the decrease of slope gradient. Contents of soil calcium in steep slope were obviously higher than that in the gentle one. The contents of water soluble calcium showed little changes with the slope variation. The correlation analysis showed that the total calcium and exchangeable calcium was positively related with altitude

slope and coverage of rock

while negatively related with soil thickness. There were no significant correlations between water soluble calcium and the topographical factors.[Conclusion] The topographical change and soil development influences the contents of total calcium and exchangeable calcium

while it has no significant influence on the contents of water soluble calcium. On the natural slope of karst peak-cluster

both total calcium and exchangeable calcium migrate with the slope descending

but the vertical migration is not obvious. The migration of water soluble calcium is not obvious

but it is sensitive to local hydrological conditions.