RE: Flowering time : latitudinal relationships?

Chris,
(This response is to widen the discussion slightly)

Temperature (latitude/altitude/microclimate/macro climatically influenced) 
and  photoperiod (day length) all influence when a certain plant begins 
many of its biological functions such ending or beginning of dormancy and 
flower bud initiation as well as actual bloom.

What is highly predictable is the sequence of these activities. 
 Phenological (time sequence) studies have been done in some local areas. 
 IN Vancouver, B.C. for example a decade or so ago there was published a 
Phenology of Rhododendrons.  This showed that while the calendar date may 
vary by as much as 3 weeks year to year, the ORDER in which the flowering 
occurred was quite consistent.  Though the length or brevity of the bloom 
for a single species or a region could be changed by weather patterns. 
 Such as a compressed bloom season caused by an extended cold spring with 
sudden fast warming.

A couple of other area of work where such useful information has been 
researched and data collected.

* A great deal of information has been collected regarding fruit trees and 
their flowering in relation to  such parameters as heating degree days. 
 This is widely published information.

* The term "co-incide" or maybe "coin-cide"(I think that is the spelling) 
was coined was coined 20 years ago or so by an entomologist who was looking 
at ways of predicating pest insect emergence.  He noted that regardless of 
location, when forsythia bloomed, a certain aphid for example was within 
days or emergence.  This way spraying could be managed rather than 
blanketing everything all the time, you could target spray.

A long reply with no specific answers except to say that the data is out 
there, scattered about for those willing to hunt for it.  It will be 
interesting to see if our widely flung companions have found anything where 
the data is compiled to answer you specific question.

It is safe to say that when a particular cultivar or species is say in full 
bloom in Chicago, that point in time for that specific location, 
corresponds to the same point of time where ever that plant is in bloom in 
that region.

Best Regards,
Scott

Scott Vergara
R&D for a commercial nursery
Forest Grove, OR (west of Portland)
USDA Zone 7b


-----Original Message-----
From:	Christopher P. Lindsey [SMTP:lindsey@mallorn.com]
Sent:	Saturday, December 04, 1999 7:50 PM
To:	woodyplants@lorien.mallorn.com
Subject:	Flowering time : latitudinal relationships?

Does anyone know if any work has been done to establish a relationship
between degrees of latitude and and flowering times?

I have lots of documented flowering times for the Chicagoland area, but I'd
like to make this extensible to just about anywhere.   For example,
Champaign-Urbana is about two weeks ahead of Chicago for most everything.
Can I then assume that for each degree of latitude (approx. 69 miles, or
111 km) the flowering time will change by one week?

I'd say the answer is no since solar angles, etc. come into play for
different seasons.  But there's also no doubt in my mind that someone's
already put a lot more thought into this than I have.  :)

So please, any references or pointers would really be appreciated...

Thanks,

Chris

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