Table 1 List of climate variables calculated to describe frost events (Tmin < 0 °C), the weather conditions surrounding frost events occurring outside winter months (Nov-Feb), and annual and seasonal variables that describe the climate of the trial sites
Acronym | Explanation of the variable |
|---|---|
Extreme climate variable: late frost (May–June) | |
  LF1 | Number of late frost days with daily minimum temperatures < 0 °C |
  LF3 | Absolute late frost temperature minimum |
  LF4 | Mean temperature of the day on which LF3 occurred |
  LF5 | Maximum number of late frost events within a single year within the inventory period |
  LF6 | Sum of precipitation across the seven 7 days before LF3 occurred |
  LF7 | Number of vegetation days > 5 °C from 1. January until LF3 |
  LF8 | Number of vegetation days > 10 °C from 1. January until LF3 |
  LF9 | Temperature difference between LF3 date and the minimum temperature of the preceding day |
  LF10 | Temperature difference between LF3 date and the mean temperature of the preceding day |
  LF11 | Temperature difference between LF3 date and the minimum temperature of the seven preceding days |
  LF12 | Temperature difference between LF3 date and the mean temperature of the seven preceding days |
Extreme climate variable: early frost (July–Sep) | |
  EF1 | Number of early frost days with daily minimum temperatures < 0 °C |
  EF3 | Absolute early frost temperature minimum |
  EF4 | Mean temperature of the day on which EF3 occurred |
  EF5 | Maximum number of late frost events within a single year within the inventory period |
  EF6 | Sum of precipitation across the seven 7 days before EF3 occurred |
  EF7 | Number of vegetation days >5 °C from 1. January until EF3 |
  EF8 | Number of vegetation days >10 °C from 1. January until EF3 |
  EF9 | Temperature difference between EF3 date and the minimum temperature of the preceding day |
  EF10 | Temperature difference between EF3 date and the mean temperature of the preceding day |
  EF11 | Temperature difference between EF3 date and the minimum temperature of the seven preceding days |
  EF12 | Temperature difference between EF3 date and the mean temperature of the seven preceding days |
Seasonal and annual climate variables | |
  MAT | Mean annual temperature (°C) |
  MWMT | Mean warmest month temperature (°C) |
  MCMT | Mean coldest month temperature (°C) |
  TD | Continentality, i.e. temperature difference between MWMT and MCMT (°C) |
  MAP | Mean annual precipitation (mm) |
  MSP | Mean summer (May to Sept.) precipitation (mm) |
  AHM | Annual heat: moisture index (MAT+10)/(MAP/1000)) |
  SHM | Summer heat: moisture index ((MWMT)/(MSP/1000)) |
  DD < 0 | Degree-days below 0 °C, chilling degree-days |
  DD > 5 | Degree-days above 5 °C, growing degree-days |
  DD < 18 | Degree-days below 18 °C, heating degree-days |
  DD > 18 | Degree-days above 18 °C, cooling degree-days |
  NFFD | The number of frost-free days |
  FFP | Frost-free period |
  bFFP | The Julian date on which FFP begins |
  eFFP | The Julian date on which FFP ends |
  PAS | Precipitation as snow (mm) between August in previous year and July in current year |
  EMT | Extreme minimum temperature over 30 years |
  Eref | Hargreaves reference evaporation |
  CMD | Hargreaves climatic moisture deficit |
Demographic factor | |
  Tree age | Age of the surviving trees of a given provenance at a given planting site |