Hidden Nature -- Trees

Hidden Nature -- Trees

    Nitrogen.  It's all around us, especially in the air, for 78% of what we breathe each minutes is nitrogen.  Even in a hospital, the "oxygen" you'll receive is mostly nitrogen.  It will fill your car tires, and when synthesized, become fertilizer.  So if it's so plentiful, why are trees so deprived of nitrogen (which they need)?  And going back to several earlier posts, what the heck do earthworms have to do with all of this?  As it turns out, trees are rather primitive and just as they did in primal forests, count on fungi and mold spores to break down the fallen leaves and branches slowly, very slowly (even those primitive sow bugs cannot digest a fallen oak leaf, but only those leaves that have over-wintered and have had time to break down).  This all makes a dense carpet on the forest floor and the decomposition allows the nitrogen to slowly seep into the trees' roots.  But the earthworms are too fast, something you can witness in your compost pile or within your own aerated yard; they make the soil loose and aerated and wreck the beneficial fungi; as a result the nitrogen washes away or is converted into a form that the trees are again unable to use (much the same thing happens with farming when the soil is plowed).  So what comes to the rescue besides our human-made fertilizer?...mice (in addition to chowing down on gypsy moths, they transport fungal spores which help the trees) and of all things, our pollution.  As you've gathered, the trees can't use all that nitrogen in the air so they relie on our cars to convert it into a usable form, nitrogen and nitrogen oxide (or NOx as it appears on your vehicle emissions report).  A quick lesson: too little nitrogen and your plants aren't green; too much and your plants die (those yellow spots in the lawn from your dog peeing).  Trees need a balance.  Our pollution goes into the air, the wind and rain wash it down, and voila, the trees are for the most part, nourished and happy.  Okay, that's a bit too simple and sounds as if pollution is a good thing (it isn't)...in fact, trees have been discovered to emit a wax-like coating on their leaves to block pollution (remember acid rain?).

    But trees are way smarter than that.  Imagine if your were stuck and couldn't move or defend yourself against attack and yet still needed to reproduce and feed and otherwise survive?  Trees have been discovered to have an ability called "masting," to pollinate or release excessive amounts of fruit and seeds in a unified way (and to do the opposite and limit the dropping or production of fruit), sometimes synchronzing this release over vast distances (like continents away).  How is this done?  Can the trees and other plants communicate?  Says author Hannah Holmes in her book, Suburban Safari: Most experiments on "talking trees" have been conducted on small, manageable plants like tobacco and sage.  But researchers increasingly suspect that many plants can smell when their neighbors are battling bugs and react to protect themselves.  In one of the few experiments with trees in the open air, researchers played the role of herbivore in a stand of European black alders.  They ripped leaves off some trees, which theoretically stimulated the alders to let out a chemical yell.  Researchers then monitored the amount of natural attack borne by neighboring alders, whose leaves were not ripped.  The trees nearest the wounded alders experienced the least gnawing by bugs...Expieriments with smaller plants have demonstrated all of these steps: A torn sage plant releases a burst of methyl jasmonate.  A tomato or a tobacco plant downwind from the injured sage plant boosts its own defensive chemicals...In one field trial with tobacco plants, researchers set tobacco budworms on some plants, and corn earworms on others.  Each herbivore solicited a different mix of twelve chemicals from the plant it bit.  Right on cue, a species of parasitic wasp that preys on budworms showed up, and those wasps flew to the budworm-infested plants.

    Many plants release a burst of oxygen and even antibiotics into their leaves to repel microorganisms.  Oak trees produce tannins, others produce poisonous alkaloids (once these poisonous defenses are toned down, we seem to somewhat illicitly love these plants and their alkaloids and their resulting nicotine, caffeine, morphine, cocaine and heroin) and pine trees produce terpenes (some terpenes can kill an insect outright).  Come winter, the trees begin a massive effort to send any remaining nutrients into their trunks and roots.  Says author Holmes:  The trees, and all the other overwintering plants in the yard, assembled freeze-resistant molecules to stir into their sap.  Some replaced water with sugars.  Some adjusted their proteins.  Some added fat to their needles.  Some mixed and matched strategies...The mercury drifted down, and my oak tree's twigs chilled along with the air...Crystals have just formed in the spaces between the tree's cells, and that shift from liquid to solid released heat...Each leaf shunted unused nutrients back into the branches.  A layer of cells grew between leaf and limb, cutting off circulation.  The green chlorophyll faded from the dying leaves.  And in mid-November, a big wind knocked down all the dead leaves in one night...Beneath my boots, beneath the soil, the roots of all the perennials are whistling in the dark.  They're not dead, and they're not frozen.  The oak roots and the bamboo roots, the tulip bulbs and the iris tubers, all weatherproofed themselves in the darkening days of fall.  They cast off their green uppers, and withdrew under the protection of the soil.  The earth turned rigid around them, but the antifreeze in their cells buffered them from the cold.  Like the woodchuck, they wait.

    If all of this sounds too scientific (or to an actual botanist, too simplified), the point was just to show how much is right outside your door, whether you live in a crowded urban city or way out in some remote cabin.  Explore just one tiny area and around you are a hundred more.  Dive into the life of one species of tree and there are a hundred more.  Take a peek at one insect and there are thousands more.  Grab a microscope and peer at the soil and well, you're doomed...you're now into the millions.  National Geographic just announced their newest book arrival, a book on "bringing nature into your yard and garden."  But perhaps if you look real closely, it's already there.