First bud or first leaf

Does it matter? Michael Knaggs, one of our recorders contacted us with an interesting question...

'Hello there,

I am enjoying my early recording for 2012 and wanted to ask a question about budburst. Why is it important? To me, it seems to be merely an event two weeks before the trees come into leaf and is only significant because it is earlier and gives people an early event to look forward to.
However, I am sure I'm missing something!

I look forward to reading your answer.

Best wishes

Michael'

Prof Tim Sparks, science advisor to the Nature’s Calendar team says:

'There are a number of reasons why we ask recorders to note both budburst and first leaf.

1. Being able to match current data against past records is vitally important for us to help monitor how the seasons are changing. Some of our long-term recorders eg. 
Jean Combes have recorded budburst. Others have recorded first leaf, so it is very helpful for us to have modern records for both.


2. Budburst is an important measure of the first activity of trees. For some species, such as rowan, budburst can occur well before first leaf if the conditions turn cool.
 

3. The gap in time between budburst and first leaf records allows us to assess how quickly spring is advancing in a particular year.'

What do we mean by budburst?

What do we mean by first leaf?