A wireless sensor network for monitoring one or more selected environmental characteristics. Multiple wireless signal transceivers, disposed in respective portions of a selected environment, respond to one or more wireless beacon signals by selectively collecting, processing and storing data corresponding to one or more characteristics of such portions of the selected environment, and by selectively transmitting respective wireless response signals containing selected portions of such data. Alternatively, multiple wireless signal transceivers, disposed in respective sub-networks in portions of a selected environment, collect and convey data corresponding to one or more characteristics of such selected environment portions.