Year 2—Effect of backfill amending and of size of paved surface on leaf dry weight (g), net photosynthesis (Pn (μmol/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% | 17.23 a | 4.333 a | 1.146 a | 3.74 a | 9.61 b |
| Topsoil + compost 50% | 17.94 a | 3.930 a | 1.090 a | 3.48 a | 11.59 a |
| Topsoil + compost 75% | 16.46 a | 2.975 a | 1.185 a | 2.66 a | 10.91 a |
| Topsoil (control) | 17.48 a | 4.806 a | 1.401 a | 3.53 a | 11.48 a |
| P | 0.951 | 0.191 a | 0.131 a | 0.410 | 0.007 |
| Size of nonpaved surface | |||||
| 1 m2 (10.8 ft2) + metal grate | 15.812 b | 2.774 b | 1.08 b | 2.63 b | 9.07 b |
| 6.25 m2 (67.5 ft2) + pine bark and groundcover | 18.667 a | 5.437 a | 1.36 a | 4.14 a | 12.72 a |
| P | 0.048 | 0.000 | 0.006 | 0.001 | 0.000 |
| Interactions substrate × size | |||||
| P | 0.805 | 0.000 | 0.084 | 0.000 | 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).