Budburst sensitivity to March temperature
Rachel Abernethy (GIS Analyst, Met Office), 13/10/2017
Budburst is an important indicator of spring, which, although a few months away, might end up happening earlier (or later) than we expect!
Understanding the relationship between climate variability and timing of budburst can help us determine when spring will occur.
State of the UK Climate 2016 report - phenology supplement
The Phenology Supplement to the State of the UK Climate 2016 report presents observations of budburst for 11 tree species across the UK. Over 100 000 Nature's Calendar budburst observations, recorded from 2000 to 2016, were used in this research.
We looked at the relationships between temperature, precipitation and hours of sunshine, and the timing of budburst. To understand how trees in different areas respond to changes in these climate variables, we split the UK into 9 regions. Having lived in Northern Ireland, Scotland and now Devon I know that the weather can be very different between the north and south!
What did we find out?
- In 2016 the UK average date of budburst for all 11 species was 12th April. European larch was earliest on 2nd April, and ash was latest on 1st May.
- Relative to the 2000 to 2016 average, UK average budburst for all species (except pedunculate oak) was later in 2016 by between 1 day (sessile Oak) and 5 days (rowan).
- 10 out of 11 species showed greatest sensitivity to March or April temperature. A 1 °C lower or higher temperature during these months was associated with later or earlier budburst of between 3 days, for alder in the South East, and 6 days, for European larch in the North East.
- The later than average budburst of most species was associated with cooler March and April temperatures in the UK. The 2016 March temperature was 0.3 °C below the 2000-2016 average and the 2016 April temperature was 1.5 °C below the 2000-2016 average.
- European Larch showed the greatest sensitivity to March temperature in the North East. A 1 °C rise in March temperature in this region is associated with earlier budburst of European larch by 5.5 days.
Important points to remember:
- Different species respond in different ways and responses will vary between regions.
- Year to year changes are important. We do not always see a rise in temperature from one year to the next and this variability means that sometimes budburst will happen earlier and sometimes later which leads on to saying....
- 17 years is a very short time when studying climate change – keep recording your observations so long-terms trends can be investigated in the future
Your observations have been extremely useful in understanding the relationship between budburst and climate. Although some years it may be a bit cooler in spring, historical records show that as temperatures rise, spring will start earlier.
Read the full report to find out more about the relationship between budburst and climate.