Year 3—Effect of backfill amending and of size of 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% | 9.85 a | 5.27 b | 1.88 b | 2.99 a | 10.81 b |
| Topsoil + compost 50% | 8.20 a | 5.25 b | 1.84 b | 3.14 a | 12.59 a |
| Topsoil + compost 75% | 8.40 a | 4.74 b | 1.97 ab | 2.59 a | 12.32 a |
| Topsoil (control) | 7.90 a | 6.15 a | 2.23 a | 2.98 a | 12.68 a |
| P | 0.860 | 0.004 | 0.010 | 0.222 | 0.000 |
| Size of nonpaved surface 1 m2 (10.8 ft2) + metal grate | 6.50 a | 3.70 b | 1.41 b | 2.74 b | 9.59 b |
| 6.25 m2 (67.5 ft2) + pine bark and groundcover | 9.433 a | 6.74 a | 2.43 a | 3.09 a | 13.89 a |
| P | 0.057 | 0.000 | 0.000 | 0.039 | 0.000 |
| Interactions substrate x size | |||||
| P | 0.606 | 0.000 | 0.000 | 0.014 | 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).