Before revision:  Empirical studies of the vegetation cover of drylands and semiarid regions have revealed the existence of vegetation patches of broadly diverse sizes , such that the probability distribution of their sizes can be fitted by a power law, i.e. vegetation patches are approximately scale free.
After revision:  Empirical studies of the vegetation cover in some areas such as drylands and semiarid regions have revealed the existence of vegetation patches of broadly diverse sizes , such that the probability distribution of their sizes can be fitted by a power law, i.e. vegetation patches are approximately scale free.