Table 6 Greening strategy matrix of the study area

Square, vacant land

1. Open space (H/D < 0.5)

2. Tourist gathering areas, high density, long stay duration.

Area-based greening

1. Umbrella-shaped trees (H = 7 m, coverage rate 50–75%);

2. Linear layout;

3. Permeable pavement with low reflectivity.

4. Unobstructed area at the entrance and exit with width of 4 m.

Main street

1. Radial pattern around the central square, with width of ≥10 m and H/D ratio of 0.8–1.5.

2. The width of the fire escape lane on each side is ≥4 m.

Linear greening.

1. A 2 m-high shrub belt arranged along the arcade colonnade;

2. Movable potted plants added in between.

3. The width of the shrub belt is ≤2 m, and the spacing between potted plants is ≥6 m.

Branch streets and alleys

1. The road width is ≥5 m, and H/D ≥ 2.

2. The width of the fire escape lane is ≥4 m.

Vertical greening

1. Wall climbing plants, wall planting bags, and hanging plants suspended from eaves.

2. Avoid ground trees and plants.

Surrounding areas of buildings

The area within a 1-m= radius around the heritage buildings is a no-planting zone.

Shallow- rooted greening

1. Shallow-rooted herbaceous plants planted in flower box.

2. The planting area shall not be adjacent to the external wall.