Table 2.

Year 1—Effect of backfill amending and of size of the paved surface on leaf dry weight (g), net photosynthesis (Pn tømol/m⁻²/s⁻¹ di CO₂]), transpiration rate (E [mmol/m⁻²/s⁻¹ di H₂O]), on water use efficiency (WUE [Pn/transpiration rate]), and on chlorophyll content (mg/cm⁻²) of Acer platanoides L. trees (first year).^{^z}

	Leaf dry weight	Pn	E	WUE	Chlorophyll
Substrate
Topsoil + compost 25%	10.46 a	6.29 a	1.25 b	5.77 a	16.78 a
Topsoil + compost 50%	9.25 a	5.53 a	1.09 b	5.92 a	15.23 a
Topsoil + compost 75%	10.63 a	5.94 a	1.32 a	5.31 a	16.44 a
Topsoil (control)	8.7 a	6.43 a	1.49 a	5.21 a	16.78 a
P	0.642	0.166	0.001	0.454	0.624
Size of nonpaved surface
1 m² (10.8 ft²) + metal grate	10.23 a	5.84 a	1.37 a	4.99 b	16.73 a
6.25 m² (67.5 ft²) + pine bark and groundcover	9.20 a	6.37 a	1.29 a	5.92 a	16.10 a
P	0.422	0.166	0.256	0.009	0.440
Interactions substrate × size
P	0.793	0.000	0.003	0.005	0.000

↵^zData on leaf gas exchange are the average of three sampling dates, chlorophyll of two sampling dates. Values differ significantly when followed by different letters at P ≤ 0.05 (least significant difference test).