Table 3.
Correlation of the four first principal components resulting from principal component analysis (PCA) of the whole data set (46 Quercus ilex samples collected in 42 locations) with individual seed traits, climatic and microtopographic variables
| Factor | PC1 | PC2 | PC3 | PC4 |
|---|---|---|---|---|
| Seed dry mass | –0·279 | –0·041 | 0·146 | –0·723 (52·3) |
| Seed water content | 0·703 (49·4) | –0·251 | 0·606 (36·7) | –0·059 |
| Germination | 0·661 (43·7) | –0·338 | 0·583 (34·0) | 0·021 |
| Rainfall | 0·888 (78·8) | –0·120 | –0·159 | –0·200 |
| Tmin | 0·409 | 0·837 (70·1) | 0·087 | –0·148 |
| Tmin aver | 0·485 | 0·861 (74·2) | 0·027 | 0·051 |
| Tmax aver | –0·738 (54·5) | 0·407 | 0·178 | –0·337 |
| Taver | –0·079 | 0·948 (89·8) | 0·131 | –0·172 |
| T°C range | –0·823 (67·8) | –0·412 | 0·087 | –0·246 |
| Days rain <2 mm | –0·675 (45·6) | 0·075 | 0·561 (31·5) | 0·198 |
| Days rain <5 mm | –0·701 (49·1) | 0·260 | 0·349 | 0·464 |
| Slope | –0·014 | –0·179 | 0·359 | –0·450 |
| Exposure | –0·209 | –0·014 | –0·782 (61·2) | –0·131 |
| Shade* | 0·106 | –0·063 | 0·566 (32·0) | –0·017 |
| Soil cover* | –0·359 | 0·171 | –0·317 | 0·008 |
| Eigen value | 4·419 (33·99) | 2·975 (22·88) | 1·996 (15·35) | 1·269 (9·77) |
All variables were active, with the exception of two qualitative variables, shade and soil cover, which were supplementary variables and are indicated by an asterisk.
Percentage contributions of variables to the principal components are indicated in parentheses for significant correlations. The Eigen value of each PC and the corresponding percentage of total variance explained (in parentheses) are also indicated in the bottom row.
Tmin, absolute minimum temperature; Tmin aver, average minimum temperatures; Tmax aver, average maximum temperatures; Taver, average daily temperatures; T°C range, average daily temperature range; Days rain <2 mm, number of consecutive days with <2 mm daily rainfall; Days rain <5 mm, number of consecutive days with <5 mm daily rainfall.