I received following answer to one of my questions

Have a look at the Green Heart of Holland ("Groene hart") between the four largest cities of the country. Maybe you find a base for further discussion.

Any ideas/writings on "Making middle landscape" to prevent conurbations? - ResearchGate. Available from: https://www.researchgate.net/post/Any_ideas_writings_on_Making_middle_landscape_to_prevent_conurbations2 [accessed Sep 18, 2015].

and Vienna Austria has a good example with the Viennesse Woods...

also 

A good example of tying together the city is http://www.paisajetransversal.org/2015/03/nuevos-retos-creacion-ciudad-integrar-paisajes-previos-ordenacion-territorio-urbanismo-planeamiento-urbano.html

 Identify and giving to peri-urban areas of importance the status of "natural reserve area" or "wildlife sanctuary", then, the urban development cannot ignore its existence.

Hi, I think that may be interesting for you to consult the FAO toolbox about urban and peri-urban forestry. You can find interesting papers aand publications about  urban forestry and green buffers (qualification, quantification, case studies...): http://www.fao.org/sustainable-forest-management/toolbox/modules/forest-management-planning/basic-knowledge/en/

Regards from Spain. 

 so many thanks Prof. Pedro.

 Another source can be

 https://www.researchgate.net/publication/30438587_Les_jardins_de_la_nostalgie

Article Les jardins de la nostalgie

Article Peri-Urban to Urban Landscape Patterns Elucidation through S...