Sounds kind of simple to assume that just considering the crop cover will have an impact on the accumulation of salts and desertification of the land. Trees and grasses work in cooperation with each depending on environmental conditions. Depending on rainfall, and the original components of the soils matrix could definetely change the composition of the vegetation growing up the land. (Grasses, shrubs and small trees and larger trees. )
Soils with low permeability and low rainfall will more likely tent to accumulate salts. One factor to consider is the long term changes in the amount of total rainfall and natural erosion and percolation over large portions of the land. Many tropical areas in South America ( and I assume Australia also) are being changed from forested land to pastures and finally to desert in a short period of time ( less than 100 years)
The removal of vegetation either trees or pastures will definetely affect the salinity levels in the soil profile. So, it is safe to assume that the changes on salinity mentioned on the study can not be associated exclusively with the change on vegeetative cover but also to large scale changes in rainfall and humidity and temperature.
Pretending to revert the changes by reintroducing large numbers of trees into a pasture or semi-desertic area will not likely change the current soil conditions back to what it was one to two hundred years back.
The soils profiles have changed too much over time due to natural normal evolution and consolidation and they are not likely to be reverted to its natural state.
Nice article Ekka!
