Monday, May 30, 2011

Mini-essay for June 2011

In June birds are in full abundance. They are on the ground, in the trees and flying here and there. But why in the air? Why do birds fly at all? One good reason is that they escape ground-dwelling predators. Another is that the air is filled with nutritious insects. Here is a whole new environment available to whomever can enter it. Over time any slight hereditary modification in a bird ancestor, which at first enables soaring from a tree or a brief taleoff while running, when further enhanced leads to flight.

What about insects, most of which fly? What advantages does an aerial capability confer upon them? One great advantage is faster locomotion. It would take a fly a long time to walk from Saratoga Springs to Ballston Spa, but in flight it could be done in 20 minutes. The great advantage of fast flight is the ability to disperse over large areas which in turn means a greater chance of surviving abrupt environmental changes. In the fossil record wings first appear in insects as a double pair and many existing kinds of insects still have four wings (beetles, bees, butterflies). Some insects have lost a pair of wings and now have only two (flies) and a few kinds of insects have lost flying wings altogether (fleas, bedbugs). There is a hitch in flight as a way of escaping predators. Some birds have evolved as predators (hawks) and among their prey are their fellow birds. The same thing occurred among insects. Dragonflies feed upon many kinds of insects.

The only other truly flying animals are bats and they serve us well by eating enormous numbers of night-flying insects, especially mosquitoes. All those other animals described as flying (flying squirrels, flying fish) do not truly fly, they soar and glide. If we sometimes imagine how delightful it might be to fly lke a bird, we should keep in mind to look over our shoulder for the flying predator always lurking nearby.

Wednesday, May 4, 2011

Miniessay for May 2011

In May with leaves emerging, we think of that vast amount of leaf surface accomplishing photosynthesis, making food for those leaf-producing plants. We also know that the process is valuable in that it helps reduce carbon dioxide in the atmosphere and supplies oxygen. It is much less well known that photosynthesis occurs in the oceans as well, though not so much the shoreside seaweeds or those in the Sargasso Sea. Instead, there are minute photosynthetic bacteria (cyanobacteria) in the oceans that produce as much as 20% of the oxygen we breathe, but this was not known until the late 1980's. The discovery was made by a Skidmore College Biology Department graduate, Sally (Penny) Chisholm, and others, working at the Woods Hole Oceanographic Institute and MIT.

Of such small size that it would take 1000 to line up across the head of a pin, there might be a million of these oxygen-producing bacteria in a thimbleful of seawater. It is hard to believe that such important organisms were unknown for so long, but in fact the whole world of tiny creatures drifting in the oceans (and in lakes and ponds) was not known until 1828 and was not called plankton until 1887. When creatures are large, we easily recognize differences (an elephant is roughly 100 times longer than a mouse), but we tend to think of tiny organisms as pretty much alike and sommetimes group them under the same name, microbe. In this Lilliputian world, however, slowly opened up to us in the 1600's by the microscope, there are great differences in structure, size, chemical composition and function. Some bacteria are 150 times larger than others. Bacteria in our gut synthesize vitamin K, others cause disease, bacteria in the oceans help degrade oil from oil spills and now we know that other ocean bacteria make a sizeable portion of the oxygen we breathe.

How much there is that we would not know except for the instruments of modern day science. Pure science and technology are a productively matched pair.

Wednesday, March 30, 2011

Seasonal Essay for April

April showers give us a chance once again to ponder the cycle of water as it moves from sky to earth and back to sky again, but through such a tortuous route! Surplus rain, collected in numerous streams, Kayaderosseras, Bog Meadow, Spring Run, pours into lakes Lonely and Saratoga. From here Fish Creek takes water to the Hudson which wends its way to the sea. Evaporation from the sea returns water to the sky once again, a cycle repeated over and over through many millions of years. Particles, eroded from the land and transported in our rivers have a different fate. Some, reaching the mouth of the Hudson, may be carried out to sea, slowly falling to the bottom as the current slows and over the course of many centuries a thick carpet of sediments piles up on the ocean floor reaching as far as 200 miles from shore. Dissolved solids carried in streams don't settle out directly, each kind having a different fate. Silica, upon reaching the sea, may be taken up by minute photosynthetic cells called diatoms and used to build glassy shells within which they live. When these cells die, their houses rain down upon the ocean floor and over great spans of time some deposits of these may be raised above sea level where we can mine them. The resulting fine abrasive is used in silver polish and even toothpaste. When we watch raindrops falling, we can think of their different fates. Some will soak into the earth and be taken up into the tallest trees where they will participate in the making of leaves. Others will evaporate back into the air to fall somewhere else. Still others will be embarking on that long journey to the sea.

Monday, February 28, 2011

Seasonal Essay for March

Some years ago I descended Spuce Mountain with windblown sleet splattering my back. The trail was wide and open making movement easy, freeing my mind and senses for other occupations. At a turn, a valley extended to one side and through it came wind which, added to that already blowing, set the trees into violent swaying, even the larger trunks moving almost to ground level. And the noise! The big trunks creaked and groaned. On top of them the smaller branches, hitting against each other cracked and rattled, and above it all the rushing sound of the wind provided the continuo.

It was too compellintg a scene to leave, so I pulled my square of insulated pad from my shoulder bag and sitting on it, leaned my back against a tree. Dark branches against a uniformly grey sky had their own fast beat, but in addition, each tree crown swayed as an entity, each tree size having its own resonant frequency. The effect was that of rows of dancers, arms upraised, each row bending first right andf then left, but in a direction opposite to that of the rows in front of and behind it, each tree-dancer having not two arms but many. I watched until a lull in the wind signaled intermission and as darkness fell I plodded homeward to offer a review of the performance.

Saturday, January 29, 2011

February Seasonal Essay

Winter offers us a chance to note again that among living organisms, each act of creation has its destructive counterpart. each great tree, rising out of the forest floor, finds many of its building materials among the ruins of former plants and animals. In addition, each forest creature throughout its life, sheds its used and worn-out parts onto the ground to be broken into its chemical constituents and recycled once again. We are fully aware of this in the fall when the great mass of leaves, generated through spring and early summer, having fulfilled their task of food manufacture, are cast free. But we are not so aware that this process of shedding continues in some degree throughout the year. In winter we see this especially clearly.

However pure the white new-fallen snows of February may be, in the woods they quickly lose their virginity. Soon they become littered with myriad dark fragments, some formless, others with clear and recognizable form repeated again and again. The last-remaining portions of birch catkins litter the snow and open cones of hemlocks and pines, shaken by the wind, shed the last of their more tenacious seeds. Strong wind loosens some of the last remaining leaves of oaks and beeches. A pile of wood chips at the base of a tree is readily explained by looking upward at the squared hole made by a Pileated Woodpecker. Masses of tiny black specks in snow hollows are jumping! They are insect-like springtails. And everywhere are fragments of bark, loosened by growth in girth of trees. The whiteness of snow gives the perfect background on which to display the products of the never-ending process of shedding, of life and death.

Monday, December 27, 2010

January Seasonal Essay

It is a great pleasure to walk in snowy woods, but if the snow is deep it is hard work. The answer? More flotation, walk on top of the snow the way snowshoe hares do, get a pair of snowshoes and poles. Snowshoeing has become a popular winter activity. Even 15 years ago there were over 600,000 people involved in it in the USA. Snowshoes were in use by Native Americans when Europeans first arrived and were quickly adopted by them. These ingenious snow-walking implements may well have come from Siberia as the first people to inhabit the Americas crossed Bering Straight, and probably were invented in Asia many thousands of years ago.

There are several sizes and shapes of snowshoes and if you are thinking about getting into this activity, in order to choose wisely I suggest that you look at any of the several books on the subject in the Saratoga Springs Public Library. Search nonfiction call number 796.92 which is where I obtained the information above. This will help you to match the snowshoes you buy to the kind of snowshoeing you contemplate: flat ground on trails, racing, or taking off into the woods. You could also rent a pair for the day and see how it goes.

There are some fine areas around Saratoga Springs for this recreation. You could begin hiking in the State Park or at the Saratoga Battlefield. In many trailless areas snow travel is much easier than going through summer woods littered with a tangle of brush and fallen branches. If you can navigate with map and compass, try the plateau that lies west of us, its slopes are not steep. Start at Lake Desolation and head northward to Spruce Mountain, descending the trail to the parking lot which requires someone to pick you up there. I have snowshoed on the Tongue Mountain penninsula where there are beautiful views of Lake George. A good way to do this is to have two people or groups of people, one group starting at one end of the trek and the other at the opposite end. They pass each other somewhere near the middle of the roughly four-hour hike and then drive home in each other's cars.

It is especially rewarding to walk in the woods in new fallen snow, untroddden by anyone before us. The silence is complete and that white covering is the very image of purity. One time, while snowshoeing in January, with snow falling steadily in windless deep woods, I came to a thin branch across my path on which snowflakes were accumulating. With hand raised to push it aside, I stopped, suddenly aware that in this thin line of snow perhaps an inch or so high, each flake was intact, its six sculptured arms unbroken. The whole was a naturally formed vitrine of cut glass.

Monday, November 29, 2010

Seasonal Essay for December

For us, this is the month of our shortest day. Our tilted earth in its yearly passage around the sun is at the place where the North Pole is furthest from the sun and where we, looking up at that sun, see it at its southmost point. It therefore takes less time for those of us north of the equator on our rotating earth to pass by it. While we're having shorter days of winter, our neighbors south of the equator are having their long days of summer.

Day length has its effects on both plants and animals. Increasing day length brings about enlargement of the gonads in birds in preparation for the breeding season, and decreasing day length is a cue for migratory northern birds to head south. Some plants exhibit short day flowering while others are long day plants.

Dark days can have dark effects on our psyche and so it is the season of festivals, of ways to lighten the spirit. Peoples of antiquity in regions of Romania saw the bright side of the darkest day and called it, "the birthday of the invincible sun," the beginning of longer days.

No wonder ancient people worshipped the sun and struggled to plot its varying paths through the sky. It gives us warmth and that wonderful light that makes possible this chromatic world in which we live.