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CSO statistical release, , 11am

Plant Phenology

2020

Table A: Number of observations by garden by phenophase 1966-2020
Number of observations
StationBeginning of leaf unfoldingMay shootBeginning of floweringGeneral floweringFirst ripe fruitsAutumn colouringLeaf fall Total
Enniscoe House517484345157 261
Glenveagh National Park1611856324160169 600
John F. Kennedy Arboretum4851243417723210328 1,588
Johnstown Castle39810217814655317402 1,598
National Botanic Gardens4391011083..314428 1,393
Valentia Observatory5668430822229360496 2,065
          
Total2,1004361,0395231151,4121,880 7,505
.. Not available

Wide variability in timing and length of phenological season

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The length of the phenological season for Downy Birch (Betula pubescens) at Valentia Observatory in Kerry during the period 1969-2020 varied from 168 days in 1979 to 236 days in 2014 (see Figure 1). The length of the phenological season is defined as the number of days between beginning of leaf unfolding in the Spring and leaf fall in the Autumn. The Met √Čireann observers at Valentia Observatory have a full record for this plant species for the 51 year period.

The earliest date for leaf unfolding of Downy Birch at Valentia Observatory was day 72 or the 13th March 1975. The latest date for beginning of leaf unfolding was 24th April in both 1979 and 1986. For leaf fall, the earliest date at Valentia Observatory for Downy Birch was day 268 or 25th September 1983 and the latest date was day 330 or 26th November 2014. The earliest dates for each phenophase stage for Downy Birch in each garden are given in Table 1.02.

The length of the phenological season for Alpine Currant (Ribes alpinum) at the National Botanic Gardens in Dublin varied from 202 days in 2016 to 258 days in 1997 (see Figure 2).

The earliest date for beginning of leaf unfolding of Small-leaved Lime (Tilia cordata) at Johnstown Castle in Wexford was day 70 or the 11th March 2019 (see Figure 3). The latest date for beginning of leaf unfolding of Small-leaved Lime (Tilia cordata) at Johnstown Castle was day 132 or the 12th May 1979. For leaf fall, the earliest date at Johnstown Castle for Small-leaved Lime was day 273 or 30th September 2015 and the latest date was day 321 or the 16th November 2016 (see Table 1.10).

The earliest date for general flowering for Wild Cherry (Prunus avium) at Enniscoe House in County Mayo was at 103 days or 13th April in both 2015 and 2019 (see Figure 4 and Table 1.07). 

Phenology is the study of annual seasonal changes in plants and animals. Plant phenology has been proposed as an indicator of climate change by the Intergovernmental Panel on Climate Change.
The data used for this release were provided by Met √Čireann and the National Botanic Gardens.

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The earliest date for beginning of leaf unfolding of European Larch (Larix decidua) at Glenveagh National Park in Donegal was day 86 on the 27th March 2009 and the 26th March 2012 (see Figure 5). The latest date for beginning of leaf unfolding was day 114 or the 24th April 2018. For leaf fall, the earliest date at Glenveagh National Park for European Larch was day 299 or 26th October 2018 and the latest date was day 321 or the 17th November 2009 (see Table 1.01).

The earliest date for beginning of leaf unfolding of European Beech (Fagus sylvatica (Trippstadt)) at John F. Kennedy Arboretum in Wexford was day 110 on the 20th April 1993 (see Figure 6). The latest date for beginning of leaf unfolding was day 137 or the 17th May 1970 and 17th May 1974. For leaf fall, the earliest date at John F. Kennedy Arboretum for European Beech was day 277 or 4th October 1991 and the latest date was day 322 or the 17th November 1976 and the 18th November 1985 (see Table 1.05).