Sunday, 17 June 2012

The speed of Spring

This post has been catalysed by a question on QI which we watched last evening (I have no idea when originally broadcast in the UK).  The question was along the lines of
What moves from Lands End to John O'Groats at 0.3mph?
The answer turned out to be "Spring".  As measured by the start of flowering - presumably for standard species - Spring arrives in John O'Groats some 8 weeks after it hauls itself out of the Atlantic at Lands End.
I believe it was also said that every 100 feet of elevation gain delayed the arrival of Spring by 2 days.

At Carwoola, at about 800m AMSL we have noticed that plants flower here about 2 weeks later than they do in Canberra at about 600m AMSL.  A well known local naturalist (and tour guide) has commented that this rate of about 1 week per 100m increase in elevation matches what is observable with the flowering of Daviesia mimosoides when looking at progression up to the main ridge of the Brindabellas.  This is also quite consistent with the elevation component of the UK example.

What I don't have is an Australian equivalent for the 'pure' North - South changes in flowering times.

As a potential alternative I did examine a 4 year  time series of maximum temperatures for Canberra (from the Bureau of Meteorology website) but there was no obvious point of inflexion in the graph.
Thus I didn't think it worth bothering with looking at temperatures as an indicator of "Spring".

Attempting to indicate Spring by flowering dates suffers from the major problem that as far as I am aware there is no precise data on this topic in Australia.  By way of example PlantNet gives the flowering period for   Daviesia mimosoides as September to November, far too wide a range for this purpose.  At a minimum, what is needed is a date - that is actual day - on which the first  flower of a Spring-flowering species is seen at a reasonably widely dispersed range of sites.

Ideally, data for several species should be used to prevent conditions which favour a single species biasing the results.  Equally, several years should be used for the same reason.  However, a start needs to be made somewhere and here is a proposal:

  • Daviesia mimosoides seems to be a suitable first species as it is reasonably widespread and fairly easy to identify.


 

  • Could readers of this blog advise, preferably by comment to this post, of the first date on which they observe this species flowering in a location (and a description of the location such as the name of the nearest road and settlement).

If readers wish to suggest additional species that would also be helpful down the track.

No comments: