How to reference multiple authors of a chapter from a book [APA]?
From the APA blog this is what you need to site in APA


  Author, A. A. (Year). Title of chapter. In B. B. Editor (Ed.), Title
  of book [E-reader version, if applicable] (pp. xxx–xxx). Retrieved
  from http://xxxxx


You will see in the purdue OWL that you should only list seven authors. So your chapter citation should look like this. I'm assuming this is the chapter you are referring to at this link.


  De Groot, R, Ramakrishnan, P.S, Van De Berg, A,  Kulenthran,, T, Muller, S, Pitt, D, ... Rossler, M. (2005). 
  Chapter 17 Cultural and Amenity Services (Xu Jianchu and Hebe
  Vessuri Ed.). In  Rashid Hassan, Robert Scholes, and Neville Ash (Ed.), Ecosystems and Human Well-being: Current State and Trends (Vol. 1, The Millennium Ecosystem Assessment, pp. 455-476). Washington: Island Press.


For in text citations use the following link


  Six or More Authors: Use the first author's name followed by et al. in the signal phrase or in parentheses.
  
  Harris et al. (2001) argued...
  
  (Harris et al., 2001)