One of the issues is grass fires. There were grass fires after the successful launch of EO-1 from Vandenberg. So no one, except the fire fighters, were allowed to go closer for quite some time. Not surprisingly, according to the link below, this is quite common. Also, even with a water sound abatement system, the launch is really, really loud--not good for nearby instrumentation or wildlife.
See: https://www.facebook.com/spaceheadnews/photos/pcb.493904570803006/493900457470084/?type=3