Luxembourg: greenery per inhabitant in Luxembourg City 2018

The source adds the following information:

Criteria Definitions
Forest & Woodland: Forest: managed forest or woodland plantation, wood: forest, sometimes considered to have restricted meaning "Woodland with no forestry".
Nature Reserve: A nature reserve (also called a natural reserve, bioreserve, (natural/nature) preserve, or (national/nature) conserve) is a protected area of importance for wildlife, flora, fauna or features of geological or other special interest, which is reserved and managed for conservation and to provide special opportunities for study or research.
Park: A public green space, managed by the city or state. Often includes areas of recreation, rest and sports, such a playgrounds, stadiums and benches.
Maintained Grass: An area of mown and managed grass.
Public Garden: A garden which maintains and collects plants for the purposes of enjoyment and education, such as botanical gardens, zoological gardens and sculpture gardens. Public gardens can be both managed by both the city and private institutions.
Golf Course: A golf course is the grounds where the game of golf is played.
Orchard: Intentional planting of trees or shrubs maintained for food production.
Vineyard: A piece of land where grapes are grown.
Farmland: An area of farmland used for tillage and pasture (animals, crops, vegetables, flowers, fruit growing).