"When we think of public space in an urban context we tend to think of its grander manifestations - a city square, an esplanade, a park. However, in Hong Kong these openings are few and far between," writes art curator Marc Feustel, in the introductory essay to Hong Kong-based photographer Michael Wolf's new book. "Instead, one of the main forms of public space is a vast network of narrow back alleys running between the city's buildings. Often no more than a few feet wide, they act as channels of circulation - shortcuts through the congested urban fabric - while also offering locals the opportunity to claim a few extra square metres as their own."

Informal Solutions - the title refers to coping mechanisms devised by the residents of Hong Kong to deal with high-density living - is a collection of pictures the German photographer has taken in our back alleys - or "scavenger lanes" - since he arrived in the city, in 1994.

Scavenger lanes, as heritage academics Lynne D. DiStefano and Lee Ho-yin explain in another essay included in the book, were originally drawn into the urban blueprint to facilitate the removal of household detritus, "especially nightsoil and pig swill from the back of buildings". However, write the scholarly pair, "Hong Kong's back alleys are about more than daylight and fresh air, more than shortcuts and access points, more than garbage and seeming accumulations of junk. Indeed, over time, Hong Kong's back alleys have assumed a unique character, a distinctive identity."

And it is that character and identity Wolf has sought to capture in these photographs, many of which have been seen in exhibitions and small books before but have now been collected in what Feustel calls "a visual encyclopedia of this extraordinarily rich, diverse and ever-changing urban ecosystem".

Presented here are just a few of Michael Wolf's "informal solutions".

Informal Solutions (WE Press) is in bookshops now