Thursday, July 30, 2015

My Year of Observation

My neighborhood.

--is what Henry David Thoreau wrote in his journal in July 1852, as he sought to pay special attention to the animals and plants he encountered.  This from a man who observed continually in his own community, once wryly observing, “I have traveled a good deal in Concord.”  For much longer than a year he meticulously recorded the flowering and leafing-out of hundreds of flowers, shrubs and trees.  (So meticulously, that his recorded observations have been profitably mined for comparison with modern data, documenting the changing climate.)

In the year or so since I began to track the phenology of some of my local trees, I have also been more careful, patient, and observant.  Lately I have mulled over how different this year feels from last year, and the reasons for it.  Last year I was often confused, often waiting for things that did not occur, and simply ignorant of basic facts—an amazing thing, considering how much information is just a few clicks away. 

Red maple in bloom last year.  

 Sugar maple April 28 & May 3 of last year.

 Once the leaves have expanded, samaras seem to disappear.
Only the occasional fallen twig or aborted samara shows they're still up there somewhere.

Last year I watched the red maples flower, leaf out, set fruit, and scatter its offspring in a neat sequence that you could almost set your calendar by.  Looking at sugar maples a bit later, I watched them flower and leaf out, then wondered why I didn’t see samaras.  Perhaps these were male trees.  When samaras began to appear on the ground a few at a time, I considered that the sugar maple, which is a northern tree, might be too near its ecological limits to reproduce efficiently. 

Same sugar maple branch a year later.
Samaras ripening on July 23.

This year I have learned to find samaras buried among the leaves if branches are low enough and you look for the right angle to show them up.  And this year there are a lot of samaras up there.  I also learned that sugar maple, unlike red maple, has male and female flowers on the same tree.

Last year I didn’t discover silver maple until the spring was well underway, and did not know when it flowered.  Now I know that it is among the first trees to do so; I watched it flower this year, along with quaking aspen, which also wasn’t on my radar screen last year.

Silver maple began to bloom on April 6th.
I discovered ash-leaved maple, already with well-grown samaras, on May 23rd.

This year I am watching two maple species I didn’t even know about last year: the weedy native Ash-leaved Maple, and the alien Sycamore Maple.  It was well along in the growing season before I discovered them, and next year I will be able to put them in their place when I see them flower.  I also have more individuals of each species to keep an informal eye on.

I saw sycamore maple only on June 5th.  Besides having toothed and more
strongly-ribbed leaves than Norway maple, this alien has samaras are often in threes.

Ashes had me even more confused.  I have never seen any samaras under the stately white ash in my back yard.  Yet there are several white ash saplings in the woods only a few yards away.  Last year I watched carefully when it began to spring, but could never say what happened to those flowers, or even their gender.  Sure they were up there somewhere, I waited in vain in fall for samaras to appear on the ground; they never did. 

This year I discovered a couple of ashes at the high school with branches low enough to look at closely.  These were male trees.  Early in the summer I happened upon a prolific female ash directly across the street from other trees I was observing.  Although the branches are a bit higher, they’re well within reach of my camera, and show me what I might expect from a healthy female.  I found a couple more recently, but these new females are in poor health—another issue to watch.  
My beloved white ash right now;
The female ash a few blocks away with some of her many, many babies.

Last year I watched male catkins erupt on all the oaks, but had no idea what the female flowers looked like, and never saw any acorns on the branches I was watching.  Again, I wondered why, and speculated that city living wasn’t good for oaks. 

This year nearly every oak in the neighborhood is laden with acorns.  Although this is a real change, it’s also true that I’ve learned how to look for them: acorns are nearly invisible when branches are viewed from the side, but from the ends and especially from beneath they can be spotted.  Lighting is also important. 

 These black and white oaks have low enough branches
 to track the growth of acorns easily.

More commonly, I take zoom photos of higher branches,
and then enlarge them further (red oak).

Oaks of the red oak group (those with bristle-tipped leaves, among other distinguishing features) have been transforming before my eyes this year.  Last year I believed that most of these oaks were hybrids among several species, and that true examples of pure red, black and scarlet oaks were rare in the neighborhood.  I thought so because I found scarlet oak leaves on trees with black oak buds, and so on.  This year I learned that hybrids are relatively rare among oaks, but their features can vary quite a bit.  Now I believe my neighborhood oaks are probably all card-carrying members of their respective species, but I still lack the confidence to assign them to those species.  In particular, the neighborhood may be full of black oaks and empty of scarlet, or the reverse—I simply don’t know.  The crop of acorns coming up may help distinguish them. 

Those acorns have been another part of my education.  Oaks of the red group differ from those of the white oak group in having acorns that take two seasons to mature.  Now I have seen this development up close: the female flowers are very small and borne in pairs in the axils of the leaves, looking at first much like buds.  Meanwhile, fruit begun last year is developing and growing on last year’s twigs, looking more and more acorn-like as the summer progresses.

One further change.  I began by observing a one-mile route, and made the bulk of my observations on trees I was watching for Nature's Notebook.  Branching out, I discovered other species and--just as important--found new individuals of trees I thought locally rare.  I began observing just two silver maples, one ash-leaved maple, and one shagbark hickory.  Now I have three or four silver maples to compare, three stands of ash-leaved maple spread over a mile, and several shagbark hickories in neighborhoods almost a mile apart, and several fertile female white ash trees among the dozen white ashes I know.  I now walk three different routes with the dogs, each taking us in a different direction.  By walking them in order, I ensure that most plants get a good look about every three days.

Overall, I know so much more than I did a year ago, and with that knowledge comes a certain confidence.

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