Plant cold hardiness - It's the extremes, people!

When it comes to plant distributions based on temperature, it's the extremes that determine the limits.  Unfortunately, there also is a lot of misinformation, some might call it fraud, in the nursery business.  Now understand, there's a big difference between a plant that is hardy to zone 6 versus one that is hardy in zone 5, about 10 degrees (F) of cold tolerance.  And a lot more territory in which to sell a plant labeled zone 5.  TPP remarked in a workshop presentation that cedars (Cedrus) are not reliably hardy in zone 5.  A woman replied that she bought a Cedrus libani (cedar of Lebanon) that was labeled zone 5, oh yes, and it had died this year. According to a very authoritative source, one variety (var. stenocoma) is supposedly hardy "in the warmer parts of zone 5", which ain't here!  There is a lot of north-south territory in this part of zone 5 in the great Midwest.  The tree in question had been planted 4 years ago, and for the past three winters our minimum temperature has been about 0 F (32 degrees F below freezing for the rest of the world), but this year we've had temperatures below zero weekly for two months reaching a minimum of -17 F, nearly two cold hardiness zones, near the minimum expected temperature for zone 5 (-20 F), and certainly not in keeping with being the warmer part of zone 5, which is probably about 100 miles south of here. Even then how confident can you be that the tree in question was the "hardy variety"?  To label such a tree as hardy in zone 5 is a fraud.  This species of cedar prefers a zone 7 climate, but can handle zone 6, and with little exception, is not hardy in zone 5.  Now TPP regularly plants things that are zone 6 plants, and just as regularly some of them die, but not all.  Unfortunately because cedars are wonderful trees, cedars don't appear to be one of the tough ones. This winter will sort out the real cold hardiness.  One of TPP's range extension plants is Helianthemum (Cistaceae), a good Mediterranean shrub. Hopefully the snow cover has protected this low-growing plant, and the bunnies have ignored it. Some plants will die back and re-sprout from the base (e.g., Vitex). A sweet bay magnolia was struggling, and was replaced by a hardier variety, and hopefully it will survive.  Generally, it's best to select plants grown north of your area.  Plants grown further south are a poor bet; northwestern grown plants are nearly always losers.  It's like Californians that move to Chi-town. It is to laugh. Always ask about the nursery source. So while really cold winters are becoming less frequent, as you would expect with global warming, the extremes have not shifted northward as yet, so you pays you money and you takes you chances.

Climate change "facts"?

Bob Carter is a geologist and a global warming denier. His recent opinion piece in The Age titled "An inconvenient fallacy" shows him using his own facts. Not being an expert on most of the issues, the Phactor will confine his criticism to just one fact. "Fact 3. Atmospheric carbon dioxide is beneficial. In increasing quantity it causes mild though diminishing warming (useful at a time of a quiet sun and likely near-future planetary cooling) and acts as a valuable plant fertiliser. Extra carbon dioxide helps to shrink the Sahara Desert, green the planet and feed the world. Ergo, carbon dioxide is neither a pollutant nor dangerous, but an environmental benefit."
First of all, does this guy think the Sahara is a desert because of the lack of CO2? OK, well, guess he doesn't garden or have house plants. Probably just a pet rock, and it seldom needs watering.
Next, the stuff about CO2 and plants is sort of OK, but when temperature gets added to the equation things change, and not only won't the Sahara get greener, the Amazonian rainforest might get a lot grassier, i.e., tree death may lead to a grassland savana replacing tropical rain forest. This change-over releases more CO2 because all those woody stems are store houses of CO2 that begin decomposing after the tree dies. This happens all the time, but if there are fewer trees to make wood, more CO2 will be released than taken up. Trees die because the rate of plant respiration continues to go up as temperature goes up, but photosynthetic rate tops out and then begins to decline. This means at higher temps more respiration, less photosynthesis. In one of the few long term studies, tropical tree mortality and average temperatures are negatively correlated; trees just respire themselves to death at higher temperatures. So our geologist is only correct if temperatures remain steady, but average temperatures are positively correlated to atmospheric CO2. Now of course the biologists who have been doing the study, my friends the Clarks, get their salaries and research money from grants, and their data and analyses that get published all have to get by lots of reviewers taking critical looks at their data, ideas, methodology, analyses, knowledge of science, etc., and they've been very successful for nearly 3 decades now. And in just 10 mins the Phactor let the air our of one of Prof. Carter's "facts". So who you gonna go with?

New Record - 85 degree shift

Mrs. Phactor set a new record on Friday. At 5:30 AM when she departed it was -5 degrees F (-20.5 C) and by noon she was in southern Florida at 80 F (26.6 C), an 85 degree temperature shift in a matter of hours. But although not as drastic, the return from tropical to arctic is always much harder, and that comes from having returned from tropical field work into our winter on several occasions. No fun it that what so ever, however the worst aspect is not the temperature shift but the difference in humidity and the horrible things that does to my aging dermis.

Global warming denial made easy

An anonymous benefactor has presented the Phytophactor with a gift, the Skeptic’s Handbook on global warming by Joanne Nova. Uh, thanks. Make no doubts about it, the Phactor is a card-carrying skeptic from way back, but Joanne No-go isn’t a skeptic, she’s a denier. And her charming little booklet is just full of misinformation (you can get your own copy online, but I’ll not promote it by providing the link). The Smog Blog as debunked the main claims in this booklet as easy as 1, 2, 3.

The Phactor is no expert on climate, but he knows enough to say that we have reason for concern because the carbon dioxide data, the temperature data, and the tree growth/mortality data coincide very closely in one of the few well done long term studies. Yes, correlation is not causation, but it strongly suggests a connection. The worrisome part is that trees are massive storehouses of carbon. If rising temperatures lead to more tree mortality, that carbon is returned to the atmosphere as the trees decay. Why would increasing temperature cause tree mortality? Well, the rate of photosynthesis increases with temperature only to a point and then the rate declines quickly. However, the rate of respiration continues to increase with temperature. So beyond a critical temperature, trees respire faster than they capture carbon dioxide in photosynthesis, literally metabolizing themselves to death. If increased carbon dioxide leads to an increase in temperature, then the whole system is off to the races. The resulting climatic impact on agricultural regions would be disastrous especially for those of our species who have been living close to the edge of starvation. So the choice is to act now, while we can, to make what changes we can, or to wait until there is more certainty, and maybe as a result of waiting, have no chance for or choice of actions. For whatever their reasons deniers are willing to gamble with everyone’s future because they advocate doing nothing. This is neither wise nor pragmatic. It's OK to be skeptical, but don't be foolish.