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[Phys-l] Fwd: "Hardiness zones" as global warming canary?



This is bad news for the fruit trees that require low temps to fruit.

Chill Requirements for Fruit Trees | eHow.com

and many others.

Chill Map

bc has a peach and a pear tree.

p.s. Some years they have almost no fruit. The year we had sno, wow. Branches broke from the weight -- every year for the apricot.

p.p.s. An interestring trivium:

Another approach to increasing the low-temperature tolerance of plants is by eliminating ice-nucleating bacteria (INB) from leaf surfaces. Recent research has demonstrated that some plants, which usually succumb at 30° F can be supercooled to 24° F without damage if these bacteria are eliminated from the plant's surfaces. As explained in the literature, these bacterial promote the formation of ice crystals that pierce plant cell walls, leading to desiccation and death. While not a completely accepted method, these bacteria can be killed by spraying plant surfaces with a bactericide such as Kocide 101 (cupric hydroxide).

Backyard Frost Protection

A friend has built a wood overhang for their dwarf lemon tree. We just cover ours w/ a frost cloth.

Begin forwarded message:

From: John Mallinckrodt <ajm@csupomona.edu>
Date: 2011, January 01, 22:03:42 PST
To: "Phys-L: Forum for Physics Teachers" <phys-l@carnot.physics.buffalo.edu>
Subject: [Phys-l] "Hardiness zones" as global warming canary?
Reply-To: Forum for Physics Educators <phys-l@carnot.physics.buffalo.edu>

I suspect that most Phys-L'ers may be unaware of the remarkable northward shift of the so-called plant-hardiness zones in maps published in 1990 by the USDA and again in 2006 by the Arbor Day Foundation. The hardiness zones are defined by the average annual minimum temperature and each zone spans a 10 Fahrenheit degree range. The following web page allows you to scrub between the 1990 and 2006 maps for the U.S.

http://www.usatoday.com/weather/climate/2008-04-23-gardening-map_N.htm

You will notice that in the west the zones are rather chaotic, but in the midwest, where the zones arrange themselves largely in an east west direction, the zones have shifted about one half of a zone northward between 1990 and 2006, implying about a 5 degree increase over 16 years, an astonishingly quick increase.

To be sure, there is some controversy about the Arbor Day map that you can read about in the accompanying story, but it does seem to me that the most noticeable effect of increased CO2 in the atmosphere *ought* to be increasing minimum temperatures (perhaps much more so than increasing *average* temperatures) because of the insulating effect of the greenhouse blanket on cold winter nights. It leads to me wonder why we don't hear more about studies that look at trends in minimum temperatures.

John Mallinckrodt
Cal Poly Pomona


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