Tuesday, April 26, 2016

On the Verge of Spring

The advance guard of spring—first the silver maples and then the red maples and quaking aspens—seem to have got out front alone.  I had thought spring was arriving a full month early, but it seems the other trees paid no attention to these three, and have been adhering to their own, more cautious, calendars.  The demonstrative Norway maples began to bloom in earnest this week, casting a green light over city and suburb, while the shy sugar maples are opening delicate green flowers here and there.  Paper birch catkins stiff and contracted all winter are stretching out and dangling as they prepare to drop loads of pollen, and some are beginning to leaf out, as well.  Ashes—the males, at least—are just beginning to bloom, and black oaks have buds poised to display their long, dangling flower clusters from every twig.  All in all, so many things are about to pop that we are on the verge of “spring”—the beginning of the growing season.  

Buds of black oak (Quercus velutina) breaking over a week or so
to unleash a fountain of flowers and leaves.

Other black oaks around the neighborhood getting ready to pop.

 White oaks (Quercus alba) won't be far behind.

With the foliage coming in, spotting the morning musical performers
like this black-capped chickadee is about to get much harder.

Thr little pussy willow at the high school is nearly finished.  Here it was a couple of weeks ago.

The green you've already seen is mostly Norway maple (Acer psuedoplatanus). 
It has at least a week's head-start over the earliest oaks.

Norway maple leafing-out.

White ash (Fraxinus americana) is beginning to flower, but so far only the males.

Ash-leaved maple (Acer negundo) is a rather strange tree
that flowers differently from other maples, dangling long, unruly red stamens.
These are around an abandoned parking lot by Palmer Avenue

Paper birch (like other birches) have their flowers ready to go in tough, compact catkins in fall,  
In spring, these relax, lengthen, and begin dropping pollen just before the leaves emerge.

I only discovered that we have sassafras (Sassafras albidum) at West Middle School
a few weeks ago, just before the flowers emerged.

Larch, or tamarack (Larix laricina) is gradually lengthening its tufts of soft, green needles.
The larches at the VA must be planted, they are so far from their sub-arctic home.

 Sugar maple (Acer saccharum) is not as demonstrative as its foreign cousin, Norway maple.  The flowers emerge here and their, small and demure, and are gradually hidden by expanding leaves.

Silver maple (Acer saccharinum) got the jump on everyone,
and had expanding leaves almost before any other buds were broken.

Flowering dogwood (Cornus florida) is preparing to justify its name.

Leaves of the one witchhazel bush I know in the neighborhood are beginning to unfold.

Quaking aspen (Populus tremuloides) has long since finished flowering,
but is only now beginning to spread its leaves.

Saturday, April 23, 2016

Spoke too soon...

 This week it became clear that I was wrong in describing how well the red maple flowers had weathered snow and temperatures that plunged into the twenties.  Because this week most of the female flowers have dropped from the trees, virtually ending their chance of having any kids this year. 

 April 2nd, just before the snow. 
 female red maple flowers.

 male red maple flowers.
I missed the signs of trouble on April 5th. And the
male flowers (bottom) were on their way out, anyway.

 On the 9th & 13th the flowers were blackening & shrivelling.

By the 21st so many had fallen that I wonder if any will survive at all.

Red maple’s flowering so early appears to have been a bad “decision.”  Of course, seasonal weather from year to year varies quite a bit, and so mistakes will be made—sometimes growth will begin later than is optimal for taking full advantage of the frost-free growing season, while some years—such as this one—growth will begin too early and a year of reproduction will be lost.  We can expect that the genes of these trees are optimized to split the difference between these two timing risks; that is what natural selection does. 

On the other hand, climate change is making warmer winters more common, and too-early blooming more common as well: what then?  Probably there are variations in timing among red maple trees--I know of one near my house that was weeks later in blooming than the others—and if this tree and others like it reproduce more successfully year after year, it’s more-successful, late-timing genes will spread through the red maple population: in other words, red maples will evolve to better fit the new conditions.  That, too, is what natural selection does!

The silver maples (Acer saccharinum) bloomed earlier and were farther along when the snow and freezing weather hit, and may have fared better.  Time will tell, but it looks like some developing fruit survived. 

Silver maple ice-rimed on the 3rd.

Silver maple beginning to leaf out a few days ago,
and with some maturing fruit (bottom)