On a trip to the New Museum several months back I encountered the sculpture of Urs Fisher
The physicality of these pseudo-organic large objects and voids I passed thru evoked images of a surreal garden with these masses of space representing the hanging limbs of trees, shrubs, man-cured hedges or topiary as positive spaces to the negative i passed through.
One begins to notice that Installation art is going some way towards re-integrating sculpture with its surroundings as sculptors have for years taking an interest in garden design.

Perhaps this finds its suggestion in japanese garden design with an emphasis on abstract compositional harmonies, rusticity,  borrowed views and  assymetrical configuration of design elements.  patterns and textures play their part as well.. a Shinto shrine exists as a space in nature.

However, It could be argued that "traditional" sculpture is considered three-dimensional, yet landscape design or gardens are more complex in that they have a fourth dimension... time. 
Perhaps there is a category, somewhere in-between the two disciples, where you place installation art, experimental gardens, etc., where  they truly merge? Herbert Bayer was perhaps one of the first to merge multiple visual disciplines.

The Marble Garden, 1955.  Slabs of unpolished white marble, found in a nearby quarry are arranged on a 38' square platform with interesting spacial relationships created due to shadows, shifting wind patterns and a fountain jet of water in the center. 

Bayer's influence is evidenced in successive modernists such as Ernst Cramer's "Poet's Garden".  Within a decade after this garden was exhibited at the 1959 garden Exposition in Zurich Switzerland it had a profound effect, maybe a "tipping point" on landscape designers and architects who then began incorporating landforms + earth sculptures into their body of work.