Factors influencing soil texture

Xin, you are correct that texture naturally changes very slow, and that management generally does not affect texture. Bio-chemical weathering of soil particles to change texture, as you suggest, is slow. Thus I am unclear what specifically you are thinking of with respect to roots.

Topography, i.e. slope, in a wet climate can result in erosion and downslope deposition of fines. As was discussed for UBC Farm forest site (this site is a lower slope position which is very wet in winter). In general management has limited impact on texture. However, depending on the site(s) you have chosen, activities such as road building, construction etc. can greatly disturb sites. Thus in many urban areas the upper soil horizons in particularly are changed.

Hope this helps, Sandra