A nationwide analysis in the Netherlands suggests that feelings of social safety are generally higher in areas with larger amounts of vegetated space. Highly urban areas are the exception, where reduced visibility from "closed" vegetated space is associated with criminal activity.
Maas, Jolanda, Peter Spreeuwenberg, Marijke Van Winsum-Westra, Robert A. Verheij, Sjerp de Vries, and Peter P. Groenewegen. (2009). Is green space in the living environment associated with people’s feelings of social safety? Environment and Planning, A 41(7), 1763-1777.