I added a shape here, which can be refined later.
https://www.openstreetmap.org/way/1488064259

natural=wood
 + leaf_type=mixed was found on this proposal in the wiki, about Miyawaki method of planting.
https://wiki.openstreetmap.org/wiki/Proposal:Urban_Overheating

Raphael is right, we may not copy information directly from the website, e.g. if there was a map or other details.

Everything was drawn from aerial imagery.  The website says the forest has an area of 770 m².  Despite my efforts to make it as small as possible the OSM object is larger, with 874 m².

Can we close this note?