For the "Sping Pastoral," the first "season" in the series, I used only the flutes 8' & 4' of the Great against the same stops on the Choir, in a kind of dialogue. The Swell 8'4'2' and the tremulant, provide the shimmer of light on water.
In the middle section, the stings of the Solo and Swell, plus sub & super couplers provide what I took as the outgrowth of nature... ;-)