DOI: 10.57707/fmi-b2share.7ph7y-czd26
title: Bioclimate change across the protected area network of Finland

description: 11 key bioclimatic variables over Finland during the period 1961–2020 based on a gridded climatology. Mean values for periods 1961-1990 and 1991-2020, difference between mean_9120 and mean_6190 and significance (0/1) for the change.

Variable list :
- Annual mean air temperature (°C)	Average of daily mean air temperatures between 1 January and 31 December. 
  Energy availability - species richness relationship, ranges and abundances of warm- vs. cold-adapted species3; completion of annual life cycle.
- Annual precipitation sum (mm)	Sum of daily precipitation levels between 1 January and 31 December.	
  Key factor for water-limited and water-dependent communities, joint driver with temperature to ecosystem productivity
- Growing season length (days)	Count of days between the onset and termination dates of the thermal growing season. 
  Thermal growing season is defined based on a daily mean threshold temperature of 5 °C following the methodology by Ruosteenoja et al. (2016) with 
  an additional criterion that snow depth equals to 0 cm on the onset date of the thermal growing season.	Completion of life cycle and successful population 
  regeneration, key determinant of plant growth8; multiple insect species generations within a year
- Growing degree-day (GDD) sum (°C days)	The cumulative sum of daily mean temperatures exceeding 5 °C during the growing season. 
  Ranges and abundances of warm- vs. cold-adapted species, completion of life cycle and successful population regeneration.
- Number of drought days 	Count of days when daily precipitation level has been below 1 mm for more than 10 consecutive days between 1 April and 1  
  October.	
  Increased plant drought stress and mortality, declined food and habitat resources for animals.
- Water balance (mm)	Precipitation minus evapotranspiration between 1 April and 30 September.	
  Moisture resources for vegetation and insect host and nectar plants, alteration of top-down effects on animal food webs.
- Heat sum (°C days)	The cumulative sum of 5-day running means of daily maximum temperatures exceeding 25 °C between 1 April and 1 October.	
  Increased plant drought stress and mortality, declined food and habitat resources for animals.
- Number of frost days in spring	Count of days with minimum temperature < 0 °C when snow depth equals to 0 cm between 1 April and 30 June.	
  Energetic costs and cold injury due to lack of snow cover, changes in spring phenological events.
- Number of zero-crossing days	Count of days with maximum temperature > 0 °C and minimum temperature < 0 °C between 1 January and 30 June.	
  Increased frequency of biological thresholds crossing freeze - thaw cycling, energetic costs and cold injury,
- Number of snow-covered days	Count of days with snow depth ≥ 1 cm between 1 September and 31 August.	
  Duration of insulating snow cover, earlier vs. delayed warm-season resource gathering.
- Number of rain-on-snow days	Count of days with daily mean temperature ≥ 0.5 °C, snow depth ≥ 1 cm and precipitation level ≥ 1 mm between 1 September and
  30 June.	
  Limited resource availability to mammals and birds, energetic costs and vegetation damage.