Thanks @kaydee. I am actually a teacher.

Yes, bush burning could degrade soil seed bank, it can as well promote the emergence of some otherwise dormant seeds in the seed bank. A large percentage of herbaceous plant's seeds are very sensitive to fire, hence, they are the first to be cleared off during fire. However, fire can be a stimulant for dormancy breaking of some seeds of woody species, example is found in the Pinus's seeds.

Wind and water erosion sure do have effects on seed banks. Seedbank of vegetation in a windward side of slope has been found to be smaller than that of the leeward side of the slope. Run-offs in form of erosions also deplete seeds that are not deeply buried within the soil.