Table 5.

Description of basic information of large old Z. serrata and growth space data collected by field survey.

Data item		Description of variables
Tree information	DBHa	Mean 143.8 ± 37.6 cm
	Tree height	Mean 14.4 ± 2.6 m
	Tree crown width	South–North: mean 17.4 ± 4.8 m, East–West: mean 17.3 ± 5.1 m
Growth space	Mean separation Distance from the roadb	< 0.5 m (4.2%), 0.5–1 m (25.0%), 1–2 m (12.5%), 2–3 m (16.7%), ≥ 3 m (41.7%)
	Growth space ratioc	0–100% (16.0%), 100–200% (76.0%), 200% (8.0%)
	Surface coverage type	Bare land (37.8%), concrete (31.1%), gravel (13.3%), others (8.9%), woodchip (6.7%), grass (2.2%)
	Impervious surface ratiod	0–20 (16.0%), 21–49 (16.0%), 50–79 (36.0%),  ≥ 80 (32.0%)
	Depth of soil covering	≤ 20 (16.0%), 50–60 (68.0%), ≥ 100 (16.0%)
	Presence of reinforcing stone walls	Present (40.0%), absent (60.0%)

^aDiameter at breast height (1.2 m above ground level) were measured.

^bMean separation distance from the tree to the nearest road.

^cRatio of growth space area relative to the crown width area (if the growth space is smaller than the crown width area, “ − 1” was multiplied by the decreased ratio to convert it to a negative number).

^dRatio of impervious surface within the crown width area.