Local phenological subtlety ?

[Graham]

Noticed it on some semi-mature roadside beech a few days ago. One in particular was at least two weeks ahead. I find it's most noticeable in hawthorn. Native stock hedges dating from the early enclosures always seems fairly consistent whereas later hedges seem inconsistent with a variation in flushing times.

 

I remember discussing this with my old college lecturer and his theory was that the later hedges included a lot of stock of Irish provenance which he thought flushed earlier and was more variable.

[David Humphries]

The difference is amazing in bud burst but especially leaf fall - around 4-5 weeks. Must be genetic variation?

 

Or perhaps provenance variation.

 

Do you know if the 96 oaks came from the same nursery and were also from the same seed source?

 

I saw Peter Thomas (Trees: their natural history) talk at a Barchams seminar last year and he talked around the phenology of leaf and flower bud burst and the timing of leaves shutting down in autumn.

Interestingly while speaking around temperature and day light length being factors for deciduous trees waking up and gong into dormancy he mentioned that there hadn't been any phd's on why it is that temperature is the driving force on this as opposed to hours of light.

 

Could be a good dissertation for somebody.

 

 

The range of flushing dates in this bud burst model for oak, is worth a look

 

 

Forest Research - Oak budburst model

 

 

 

 

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[Tony Croft aka hamadryad]

Health can play a part in bud burst too, stressed trees will always be a week or two behind the others IME, interesting subject David.

 

if it was temperature dependent and not light affected we would not see those odd branches around street lights persist all winter. Hours of daylight play critical roles in many phenological aspects, flowering in particular.

 

like you say, be an interesting one for somebody to play with

[sloth]

Just to nitpick and be fussy bugger I'm reading Colin Judge how trees live and why they matter at the moment, and he states its not how many hours of daylight that count, its how few hours of night. eg (I may be remembering this wrong) when under controlled conditions strawberry plants will set flowers with just a few hours of darkness, regardless of daylight length. I can't quite remember the ins and outs of it, it involved hormones. I may have to roll back a chapter or two and re-read!

[David Humphries]

An interesting situation that was noted by one of our team at the weekend.

 

 

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[Amelanchier]

The end of dormancy is a heady blend of genetics and environment for sure.

 

Genes get switched on and off by a plethora of triggers - climate, ambient light, nutrient availability, maturity, stress, disease; but you can add another layer of complexity to that when you know that they can be triggered by whether other genes have been triggered (which can be triggered by other genes being triggered, etc.). Recursive causation at its most opaque.

[David Humphries]

The end of dormancy is a heady blend of genetics and environment for sure.

 

What I didn't complete on the above post, is that these two are both subject to hosting Meripilus.

 

To what extent, I dunno ?

 

 

 

 

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[Baxter]

Another example I have seen, on an avenue of Lime in Shaftesbury, Dorset.

 

Photo is taken straight from Google street view so its not present day. The four limes on the left (on the far side of the entrance) are always two weeks behind the rest of the avenue (on the right). Both in Spring and Autumn.

 

I can't see how any of them would have different micro-climates. My only thought is that they may have been planted a year or two later and therefore from a different nursery. Only a guess though!

Edited April 29, 2013 by Baxter