Summer World_ A Season of Bounty - Bernd Heinrich [100]
Presumably, trees that are fully acclimatized to a generally stable climate shed their leaves at the optimum time, which is, by definition, when they get the best economic return over the long term. Their evolutionary calculation has balanced the appropriate amount of “insurance”—the cost of not gathering energy when the leaves are either shed early or delayed in being deployed, and the risk of the rare but severe injury. It seems that most of the time, many trees must shut down as though the summer has ended, long before it actually does end.
23
The Last Peep
25 September 2005. IT IS A CRYSTAL-CLEAR DAY AND bees are bringing in pollen from the goldenrod, which is now fading fast. The purple and blue New England asters are still going strong, but the American ash are starting to shed their now purplish leaves. The sedges in the bog are brown and a few sugar maples are turning yellow. The first frost is forecast for tonight, so technically we’re now beginning Indian summer. But we passed the fall equinox two days ago, when the sun spent twelve hours above and twelve hours below the horizon at every latitude on Earth. Here it is defined as the first day of fall (and it is the first day of spring in the southern hemisphere). From now on our days here will be gradually getting shorter than the nights, and that changing photoperiod will affect the physiology of trees, birds, and many mammals, to turn off growth and reproduction. It is therefore curious indeed that some spring-blooming plants are again showing signs of life—even our pear tree has a few blossoms. Dandelions are once again raising yellow flower heads. The phoebe sang briefly this morning after two months of silence, and spring peepers sometimes sound off with isolated calls at night.
19 October 2005. Windy, cool weather makes me feel restless and I’m looking forward to going to Maine tomorrow. The leaves are now falling thickly. Despite the cold and overcast weather a few more “spring” flowers have started to bloom—common blue violets (Viola sororia), self-heal (Prunella vulgaris), cranesbill (Geranium maculatum). I had been startled to see the spring-blooming pear and a crab apple tree that I transplanted in May again put out a few blossoms in late September. Now a wild honeysuckle in our driveway burst several of its hundreds of buds to grow twigs with leaves and flowers. A cottony white fluff ball drifts by on feeble wing beats—it’s the migrating form of the woolly alder aphid. I don’t know where it’s going, but it is of the summer’s last generation from wingless parents. I heard geese calling in the night. This morning about fifty of them sit quiet, like decoys, on the beaver pond. Suddenly, at about eight AM, they splash off toward the east; then they circle toward the north; and then the assembled flock heads west. A dozen remain on the pond. Only a few white-crowned sparrows—migrants passing through—are left here. A grouse drummed. I had not heard one since spring.
The beavers in our bog are again felling poplar trees, gnawing off the branches, and dragging them into the water to store them in their food cache next to their lodge, where the ice will soon cover them. Chipmunks gather acorns and with their cheek pouches stuffed full they scurry to and from their dens to top off larders in their previously prepared underground storerooms. I stock the woodpile, harvest the honey, and insulate the house and hives, while Rachel obsessively cans vegetables and makes apple pies. Meanwhile, overhead the geese honk on their way south, and in the nearby woods the rutting of moose and deer is timed so that the young will be born early enough in the spring to grow up and withstand the next winter. As always when summer ends, most of what I see (and try to do)