Fig. 1. Schematic figure of silver birch seedlings in climatecontrolled closedtop chambers in 2002. A) randomized placement of seedlingtrays in each chamber; B) location of chambers in the field.
Fig. 2. Placement of differently treated silver birch seedlings in the built environments in 2003 (figure is not drawn to scale). Within each climate treatment, all the seedlings were located randomly, and their positions rerandomized each week. The distance between the seedlings was 20 cm.
Table 1. Summary of cross tabulations for survived and dead seedlings. The term “survived” refers to overwintered seedlings and “dead” to seedlings that were winterkilled or suffered from broken stems. The percentage (%) of each group indicates the proportion of all the 384 seedlings in the 2003 experiment. 
Treatment 
 Amb. T and amb. CO_{2}  Amb. T and elev. CO_{2}  Elev. T and amb. CO_{2}  Elev. T and elev. CO_{2}  Total 
 Number  %  Number  %  Number  %  Number  %  Number  % 
Survived  32  8.3  46  12.0  41  10.7  47  12.2  166  43.2 
Dead  64  16.7  50  13.0  55  14.3  49  12.8  218  56.8 
Total  96  25.0  96  25.0  96  25.0  96  25.0  384  100.0 

 Fertilized    Unfertilized    Total 
 Number  %    Number  %    Number  % 
Survived  90  23.4    76  19.8    166  43.2 
Dead  102  26.6    116  30.2    218  56.8 
Total  192  50.0    192  50.0    384  100.0 

 Control  25% defoliated  50% defoliated  75% defoliated  Total 
 Number  %  Number  %  Number  %  Number  %  Number  % 
Survived  49  12.8  41  10.7  40  10.4  36  9.4  166  43.2 
Dead  47  12.2  55  14.3  56  14.6  60  15.6  218  56.8 
Total  96  25.0  96  25.0  96  25.0  96  25.0  384  100.0 
Fig. 3. Absolute height increment (cm) of silver birch seedlings during the growing season 2003. The plot results are based on untransformed data, where mean values of different treatment combinations with the standard errors are presented. The trend line is based on the least squares means (LS means) provided by SAS/MIXED. Abbreviations: Amb. T = ambient temperature; Elev. T = elevated temperature; Amb. CO_{2} = ambient CO_{2}; Elev. CO_{2} = elevated CO_{2}.
Fig. 4. Root: shoot ratios (biomass of roots in proportion to biomass of stems + leaves) of silver birch seedlings in different treatment combinations at the end of the experiment. The plot results are based on untransformed data, where mean values of different treatment combinations with the standard errors are presented. The trend line is based on the least squares means (LS means) provided by SAS/MIXED. Abbreviations: Amb. T = ambient temperature; Elev. T = elevated temperature; Amb. CO_{2} = ambient CO_{2}; Elev. CO_{2} = elevated CO_{2}.