Counting Things

I once heard it said that a scientist who didn't know what to do next would count things.  There's no telling what might turn up in the data!  But the saying needs to be taken with a grain of salt: scientists count (measure) things because quantitative (numerical) data has several advantages over qualitative data: it's more exact and less open to misinterpretation, it's open to powerful statistical analyses, and it can be applied more closely to real-world issues.  I'd guess it's been over a century since science could be done without quantitative data.

I long ago noticed that the samaras (winged seeds*) that fall from sugar maple trees often have bite marks in them.  Many of these have been eaten, leaving an empty shell.  A few minutes' research brought forth the likeliest culprit: squirrels.  The gray squirrel, far from being an acorn specialist, is actually broadly omnivorous, eating a variety of nuts and berries, buds and bark, and not passing up an undefended, nestling bird, either.  The menu specifically includes maple samaras, buds and bark.  How serious is the damage to maple reproduction?  A little half-vast science would provide a clue.

On my walks over the last few days I brought plastic bags and a sharpie marker.  Under three different trees varying distances apart I picked up fistfuls of fallen samaras and put them into labeled bags.  Under a particular tree I've been watching I collected three bags--to get an idea how much random variation there was.  Then home I went to count things. 

 

Science is messy!  Or it that just me?

 I saved the samaras that had at least one intact seed.  Hmm--if half of them germinate,

I only need an acre or so of land to plant them all!

Probably the hardest job doing this sort of science is deciding what to count.  For example, if I decided that every samara was either eaten (seed gone) or alive, what about those I'd seen with a bit mark that might or might not be dead? or the samaras damaged by insects? or those I simply couldn' decide on?  So first I emptied a bag on the kitchen table, pawed through it, and decided on categories.  Even, then, I can't pretend there weren't judgement calls, and my judgement may well have changed as I worked.  For this and other reasons (chiefly about my sampling method and the small number of trees I looked at), I call this "half-vast science."**  Nevertheless, I think I learned some things. 

There was variability between samples taken from under the same tree, but that was probably because of where the samples came from: the two that were alike were seeds that had fallen in the street, rather than on the lawn.  

Less than half of the seeds were intact in any sample, and it was more typically about one-quarter.  

There was very little insect damage: the enemy of sugar maple (at least here in the 'burbs) is the squirrel.  Period!***  

+++++++++++++++++++++++++

Oh, did I forget to mention that THE SUGAR MAPLES ARE HERE!  I noticed samaras falling from the first one in the neighborhood at the end of July, but more trees became involved and the pace really picked up in the last two weeks.  I guess we're now in the middle of it.

Sugar maples are easy to tell by their samaras.  When still joined together, samaras appear squared-off, with plump, rounded seeds.  The only other maple that might be shedding samaras right now is the common (invasive alien) Norway maple, with its nearly straight samaras with flattened seeds.

One of the sugar maples I collected samaras under.  Majestic tree!

Sugar maple samaras have plump seeds and sharply-angled wings, while Norway maples 

(few of which have yet dropped many samaras) are larger, have flat seeds, and wings nearly in line.  (Image below from www.farfromloam.wordpress.com)

Sugar maple is uncommon in southern New England, but is commonly planted as a yard tree here in the city.  It is the same tree of northern New England forests whose sap, boiled down to about 1/40th its original volume, makes maple syrup.  In recent years it has become harder for New Englanders who "tap" the sugar maple to get enough sap to make the work profitable, since the necessary conditions (days reaching about 45 degrees F with nights well below freezing, ending with leaf bud break) have been shortened, probably by climate change.

Even if it is planted, it's nice to have native maples in our yards and by out streets. 


*Really, fruit: the actual seed is inside the samara.
**aka pretty good middle school science fair project.
***Automobiles are another danger here in the city: many samaras, acorns, etc are ground to mush beneath tires.

Acer sacharum, Rest in Peace

Did the one-mile walk with dogs yesterday for the first time in a few days, and looked in on on my plant acquaintances.  

The red maple down the block and round the corner has now shed most of her children, though--since she lives in a narrow strip of turf between street and sidewalk--nearly all will inevitably come to a bad end.  Even so, I expect she will probably get a few surviving offspring over her lifetime--and that's enough (on average) to keep the red maple population stable. 

The red oak on Chatham is doing fine; his male catkins are long since fallen, and, from the ground, I can't see his female flowers nor any beginning of acorns.  For awhile I thought he might be a black oak rather than a red, but I'm still inclined to think I got the ID right the first time.

The sugar maple on the corner of Nancy Lane that I've been following since last fall is--gone.  I stand in sunlight where sunlight shouldn't be, and look at a low, modest mound of wood chips on an otherwise blank stretch of suburban lawn.  Trees do get old, and sometimes endanger homes, but this tree seemed hale and hearty to me.  And even when a tree this old must come down, it should be an event, a drama.  My first thought, after the shock, was that someone should have posted a notice, a sentence of condemnation, preferably at least a month before sentence was to be carried out.  

On the day itself, neighbors should have gathered, somberly dressed and reminiscing in quiet voices.  There should be an earth-shaking crash, the earth gashed by the tons of falling trunk and the scattering of shattered limbs.  The aftermath--as in any execution--would inevitably be brutal, tears falling as whining chainsaws rip into living flesh, smell of tree's blood heavy on the air.  Trucks would come to carry away the logs (hopefully to end on a cheerful hearth rather than buried in a landfill).  Neighbors would disperse, lost in thought.  The evidence of what has happened should be everywhere, signs of disaster, wilted leaves betokening death.  

Instead, this blank lawn and its wood chips are as if the half-century-old tree had never been at all.  

It is obscene. 

I can only wonder whether the homeowner's decision was the occasion of prolonged struggle and anguish, or only a matter of engineering, of dollars and cents.

In his journal on October 7, 1857, Thoreau wrote:

It is monstrous when one cares but little about trees but much about Corinthian columns, and yet this is exceedingly common.