On the sheer declivities where the surface soils were held by chaparral, there is no chaparral.
The mechanism is most likely to be operative on steep, humid, forested hillslopes with very permeable surface soils.
It lacks intermediate transition layer between the lower parent rock and the surface soils.
In the soil and agricultural sciences, infiltration improvement usually involves cultivation to soften the surface soils.
Surface soils at footslope had the highest ammonium and nitrate concentrations in summer and autumn.
Surface soils at footslope had slightly higher moisture over seasons (Table 1).
This lasting cation rise is reflected by ammonium (NH4) displacement from surface soils.
Second, surface soils are being replenished by decaying plant matter, which has low levels of aluminum and is essentially diluting the concentration of the metal in soil.
Moreover, the surface soils of the grazing land had shown relatively higher OC content than the surface soils of the forest (where no grasses were observed on the surface of this field) (Table 5).
It has the ability to extract water from deep to surface soils, which can benefit other tree species.
These results might be helpful for future monitoring of further increase of heavy metal concentrations in surface soils along highways.
