Exploring soil particle size fraction and spatial redistribution of 137Cs in sloping landscapes with different lynchet height of terracing hedgerows in the remote mountain region, southwestern China

Soil erosion is a global environmental problem related to anthropogenic activities, as well as being influenced by natural factors. The sloping cultivated lands, which have serious soil erosion, constitute a major proportion of landscape in the remote mountain region. The traditional soil conservation strategy, referred as certain height of lynchets on the edge of the terracing hedgerows of the sloping lands, plays an effective part in soil and water conservation. A typical sloping landscape with lynchet of terracing hedgerows was chosen in this study. The results showed that fine-grained sediment was deposited in front of the lynchet of terracing hedgerows, especially particle size grouped at < 0.002mm and 0.002-0.02mm. The profiles 137 Cs concentration of the lynchet from the upper to the lower sloping landscape showed first increased then decreased trends as the soil depth increased. 137 Cs inventory generally increased along the whole sloping landscapes. And the results suggested that the mean 137 Cs inventory and erosion rate could be represented by the average value of the middle slope position. The highest value of annual erosion modulus reached to 4917.06 tkm − 2 a − 1 on the upper site of the sloping lands. While the annual erosion modulus were synchronous reduced from the upper to the lower of the slope landscape, the erosion rate had the similar trends. Meanwhile, K values of soil erodibility changed from 0.0338 thm 2 h (hm − 2 MJ − 1 mm − 1 ) to 0.0375 thm 2 h (hm − 2 MJ − 1 mm − 1 ) along the slope length. There existed the logarithmic relationship between K value and 137 Cs inventory in the correspondent slope position. Therefore, it is useful to study spatial patterns of soil erosion in different slope positions with the different height of lynchet of terracing hedgerows of the whole sloping landscape. Also it is important for implementing soil conservation strategy in the remote mountain region, China.