I suppose it would be forest because in order to have organic matter the soil needs to be rich and fertile,therefore it is forest.
The degree of polarity of diatomic molecule is related to the difference of electronegativity of the two atoms. If the difference is very large, i.e. one atom is highly electronegative and the other atom is highly electropostive then, the covalent bond is formed. But if the difference between the electronegativities is very less, then its likely that ionic bond is formed.