Reconstruction of soil erosion rates from exposed roots in southeast China

ABSTRACT Southeast China, characterized by a humid subtropical climate, is dominated by dense evergreen broad-leaved forests with the exception for the Changting area, which is one of the most eroded areas in southern China. Various methods have been employed to investigate regional soil erosion dynamics, yet these studies are limited to short periods and few sites. Dendrogeomorphological methods can alleviate this problem due to the long duration of tree rings and easy implementation for many sites. We present the first tree-ring-based soil erosion study in southeastern China, based on 123 exposed roots from 85 Pinus massoniana trees at six sites in Changting. The distinct reduction of cell lumen area of earlywood tracheids of exposed roots is a good bio-indicator for the first year of exposure due to soil erosion for this hot and humid area. The reconstructed soil erosion rates ranged from 4.26 to 43.50 mm/year with an average of 14.14 ± 8.05 mm/year. Soil erosion rate is the highest at the slopes of 10°–30°. This is in line with previous findings using other methods over the study area. In addition, soil erosion in this area is found to be closely related to vegetation types and summer precipitation.