The Toona sinensis plantation in Zhenning County of Guizhou Province were classified according to the age as class I(8~13a)

classⅡ(15~25a)and classⅢ(>25a).Indicators such as the content of soil organic matter

particle size composition

content of dry soil aggregates(>0.25mm)

content of waterstable aggregates

and soil structure destruction rate were determined for erosion resistance evaluation of the soils under the plantations.The results show that

the average contents of soil organic matter were 4.56%

5.02%and 5.35%

the contents of dry soil aggregates(>0.25mm)were 92.19%

96.72%and 98.07%

and the contents of water-stable aggregates were 65.83%

70.72% and 75.29%in class I

classⅡ

and classⅢ

respectively.Correlation analysis showed that the contents of soil organic matter and water-stable aggregate

and structure destruction rate were the best indicators for evaluating soil resistance to erosion. The erosion resistance of soil was influenced by forest age significantly according to variance analysis;soils from older forests showed stronger resistance to erosion.As expected

soil erosion resistance in Toona sinensis plantation was stronger than that in non-forest lands.