Table 2.
Response variables used for phenological analysis and their derivations.
| response variable | derivation | units | tests |
|---|---|---|---|
| TDD |  |
°d | accumulation of heat sums |
| βDOY_x_YEAR | slope of date of phenological event versus year of measurement | d yr−1 | temporal trends in timing of phenological events |
| βTDD_x_YEAR | slope of TDD at phenological event versus year of measurement | °d yr−1 | temporal trends in heat sums of phenological events |
| βDOY_x_TAIRSPRING | slope of date of phenological event versus spring air temperature (April–May) | d °C−1 | sensitivity of timing of phenological event to spring air temperature |
| βDOY_x_TAIRSUMMER | slope of date of phenological event versus summer air temperature (June–August) | d °C−1 | sensitivity of timing of phenological event to summer air temperature |