As Lee said, for the landscape urbanism, ‘It is the combination of landscape infrastructure, functional infrastructure and social needs of the city’. Actually, I`ve read a relevant paper named Landscape as Urbanism. The author said that ‘Landscape urbanism offers an implicit critique of architecture and urban design’s inability to offer coherent, competent, and convincing explanations of contemporary urban conditions … as a disciplinary realignment in which landscape supplants architecture’s historical role as the basic building block of urban design.’  And I also drew a simple diagram to describe this process, as follows.
(picture is drawn by the author)
Therefore, in my opinion, I think landscape urbanism can be understood as a method to describe the rapidly increasing sprawl and change in contemporary urban development. Because it presents the temporal mutability and horizontal extensivity of current city.
And for the three models Lee proposed at last, I can get a general understanding by different form of city landscape from the perspective of history. In fact, the birth of landscape urbanism can be traced back to the criticism of modern architecture and urban planning. Charles Jencks thought modernism can`t provide a “meaningful” or “livable” public realm, as it overlooked the fact that city as a historical construction of collective consciousness. Therefore, we can see obviously that the scenographic mean of postmodern architecture can`t reveal real structure of industrialized modernity. And thus, we can say contemporary landscape urbanism advocates using infrastructure and landscapes to model an ordered mechanism for city itself. Just as Lee brought, ‘landscape is also a variety of functions “carrier”, it has spawned and the coordination between the natural environment and infrastructure integration and mutual exchange flow interface’.
Finally, I want to use a sentence from the paper I mentioned, ‘landscape urbanism has become a disciplinary framework for reconceiving the contemporary urban field.’
 Charles Waldheim, Landscape as Urbanism, 2006. The landscape urbanism reader, Princeton Architectural Press, New York. P. 35-53
 See note 1