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Heading back toward Broadway, we came upon a giant mural on the side of an apartment building featuring male and female hooded warblers perched on a bird’s-foot violet plant.

By varying the steepness of the table, they created miniature mountain streams disgorging into fan-shaped flood plains and bird's-foot deltas.

Seven years on, it is starting to look respectable, filled with fritillaries, oxeye daisies, devil’s-bit scabious, and bird’s-foot trefoil.

The summer of 2002 revealed wildflowers with delightful names such as bird’s-foot trefoil and lady’s bedstraw that hadn’t been seen in such numbers for a generation, along with a profusion of insects, which produced a continuous thrum – “something”, in Tree’s words, “we hadn’t even known we’d been missing”.

Much has been made of the methane emissions of livestock, but these are lower in biodiverse pasture systems that include wild plants such as angelica, common fumitory, shepherd’s purse and bird’s-foot trefoil because they contain fumaric acid – a compound that, when added to the diet of lambs at the Rowett Institute in Aberdeen, reduced emissions of methane by 70%.