Any good outcomes of winter cold?

It's been 35 years since the upper midwest has had a winter this cold.  Since December began there have been 20 days (nights) where the temperature has been below zero, and for those of you using a sensible C scale, water freezes at 32 on the F scale, so below zero is more than 32 F below freezing.  As the Phactor wonders how some of his semi-hardy, maybe-not-quite-zone 5 plants will do, a neighbor asked if anything good could come of such cold?  Last winter there may not have been any days with below zero temperatures, and the frequency of really cold winters has been decreasing (yes, as expected if the climate is warming).  Well, among the good possible outcomes might be if the emerald ash borer proves to be not so winter hardy.  Wouldn't it be great if a really cold winter knocked out the population!  Wow, that would be great. Some other insect populations might get reduced for a while too like the Japanese beetle, but all the snow cover this year may insulate those things that overwinter in the ground from the cold.  Same is true for some of the low-growing shrubs and other perennials. Snow is a great insulator.  So all we can do is hope for the best.  For example, the aerial portions of our Vitex are not winter hardy at these temperatures, but the basal portions will survive and resprout, so the dead upper portions must just be pruned off.  The last few mild winters had allowed it to become a 2.5 m tree, so for 2014 it will have to start over. 

On the sunny side of the street - the problem with monocultures

Three years ago three large white ash trees lined the street in front of my house and my neighbors spaced about 60 feet apart (all over 3 foot diameter trunks).  The city just removed the last one; it was clearly moribund.  Thank you emerald ash borer.  Three really big trees make a lot of shade and when you remove all three essentially at once you notice the difference.  The lesson here is simple: monocultures don't work.  They are inherently unstable and unworkable ecologically.  Someone about 70 years ago decided to plant a monoculture of white ash trees down our side of the street.  They were getting old, but you expect as they age, one by one, for them to be replaced, and someone chose white ash trees.  No imagination.  The newest trees are more diverse, red oaks, white oaks, new elms, and some smaller ornamentals.  The problem with monocultures is when one is susceptable to something, they all are, and they all die at once, and at about the same stage of life rather than being staggered.  There are virtually no exceptions, and yet is this not the most common of human cultivational strategies?  Our landscaping in part reflects the sun-shade environment as it was a decade ago with healthy shade trees.  A few of our beds suffered in last summer's heat and drought made worse by they more open exposure.  Fortunately our city arborist is being more proactive diversifying plantings and planning ahead and getting replacements going a few years before trees in decline are removed.  That's the way to do it.

Ash Bored

Our street, our neighborhood, our yard is a bit more impoverished because a large (4' diam) white ash tree was taken down this week.  It's the city's tree, a boulevard tree, and two years ago they took down it's mate in size and species from the other corner of our lot.  For the last 50 or so years these trees have shaded our street, and they would have lasted considerably longer, but they fell prey to the emerald ash borer introduced to the USA right here in Lincolnland.  Even worse an up and comer boulevard tree planted some15 years ago, sort of mid-way between these two big ashes, which were about 120 feet apart (it's a big lot), was also a white ash, so rather than come back a year from now, this much smaller tree was removed as well.  It bothers your perception when such a big landmark is suddenly removed, and it comes as a shock to actually be able to tell if there is oncoming traffic before actually entering the street (not an altogether bad thing), and it's hard to locate the driveway when such a big landmark is removed.  Our city is being proactive and planting a lot of trees interspersing the young ones with all of the ash trees that have been or will be removed.  Over reliance on one species is always a dangerous thing whether your staple food or a street tree.  Two replacements appeared last year, a swamp white oak and a new elm cultivar, a replacement for the elms lost the last time we introduced a fatal disease that decimated a wide spread and common street tree, but they as yet do not make a presence.  This is the terrible thing about trees; you do not replace a large tree except with time, decades. Unfortunately, the utility wires, cable and such are on poles on our side of the street, so big trees right on the boulevard are a bit of a problem.  Although a big tree is going to be missed, a large tree isn't actually needed or wise in this general location, so a smaller, doesn't-get-in-the-wires tree is a better choice, perhaps a Chinese lilac, but only if the city nursery has one available.  Now our yard only has three trees with trunks in the 4 foot diameter category.  So think carefully about cutting down and planting trees; you choice now is one you have to live with for quite awhile.