Well essentially reading as a landscape photographer is "Yi Fu Tuan - A Sense of Place, or preferably if you can find it Topophilia". Although a geographer his writings are about how we use the space around us. All my own landscape work is about man's impact on the landscape and Tuan's books are very useful helping contextualise my photography.
Of course he writes heavily about the social landscape.
A writer I've found helpful on social landscape (although perhaps in an oblique way) is Barry Lopez. There's a wonderful essay in 'About this life - journey's on the threshold of memory' about the relationship between place, and photographs.