9/23/11 A LITTLE EXCITEMENT ON THE FIRST DAY OF FALL

TOWN BEAR

MOUNTAIN MAPLE

SUGAR MAPLE

Friday, 8:00 AM.  38.5 degrees, wind WSW, calm.  The sky is mostly overcast but the barometer predicts sunshine and the it will probably clear up by noon. Geese are flying high, heading south.
    We had a little excitement on our morning walk.  Roxy, the neighbor’s black lab, was with us and scented a bear in the woods on 9th St., got on its trail and flushed it out on the corner at  Wilson St.  I could hear it just off the road and did manage to keep up with it and get a photo as it ran out.  It was either a very large cub or a small yearling, probably a hundred and twenty pounds or so.  Anyway, mama was not with it, which was probably a good thing.  Lucky doesn't see or hear well enough anymore to have sensed it.
    Although it occurs right on schedule every year, I am still always more than a little amazed at the way vegetation begins to turn to fall coloration and then dormancy right on cue, just before or even on the very first day of fall.
    Red maples started to color perhaps a week or so ago, maple and birch virtually  yesterday or today. each species in the temperate flora following its own slightly different time table.
     Fall leaf coloration is a complex process, dependent upon rainfall, temperature and other contributing factors, but the primary determinant is shortening day length, which makes sense, since it is the most, virtually the only one of many factors which is absolutely consistent every year.   When the sun crosses the equator at the fall equinox in its apparent journey south, deciduous plants in the earth’s northern temperate zone “know,” through their genetic evolutionary development, that the cold and drought of winter is  imminent.  Of course it is actually the earth tipping on its axis as it orbits the sun that actually, rather than apparently, determines day length.   
    We are fortunate that we have gotten some moisture recently, and that should prolong the retention of fall leaf color, and if we get a period of night temperatures approaching but above freezing the colors will intensify.  But day length is the boss.