Rarity and Abundance - the Have's and the Have-nots

[following is only a start, a partial small bit of the whole picture]

The issue of relative abundance vs. rarity in the plant and animal worlds invites an easy analogy with the fortunes of humans, whether at the level of the individual, the family, the nation, whatever.

Some are languishing at the edge of starvation, others bask in a perpetual summer of wealth and privilege.  Individuals, like families and nations, can run the whole gamut of fortune in a lifetime, from an unpromising hardscrabble beginning to a gold-plated middle age, and sometimes right back to the poor house by some cruel reversal of fate.

We in the fortunate U.S. of A, who at present make up about 4% of the world’s population, have managed to garner to ourselves something like 40% of the world’s annual output of resources—in other words, the average American consumes 10 times as much in energy and goods as the average non-American.  And even so, most of us would gladly grab an even bigger slice of the pie if we could.  The more we have, the more we seem to want.

The situation is almost exactly the same among, for example, our greatest earthly benefactors, the plants.  Take a look at almost any grassy field or vacant lot in your neighborhood and you will see that the great majority of the space (and consequently the water, light, and soil nutrients—in other words, all things plants consider valuable) are monopolized by a very few kinds of plants, sometimes only one or two, begrudging only a little room to all the other kinds of plants in the neighborhood.  It hasn’t always been so [explain, expand].

The greatest modern problem among our fellow animals and plants is, possibly by coincidence and possibly not, amazingly parallel to our own worldwide human problem: the rich are getting richer and the poor poorer.  This is nothing new of course, either among humans or other creatures; but whereas this problem, if you see it as such (which for the sake of justice?  I hope you do), has often been localized, intermittent, and occasionally reversible, but now it is universal and accelerating and more severe than ever?? (at least among plants if not humans).  [Give extreme example of a statewide shift from high-diversity to near-monoculture, i.e. the annual grasslands of California, which are now a nearly unbroken sea of stickers, belonging to a mere handful of species, all of which are foreign invaders.]

Rarity is increasing rapidly.  There have always been extinctions (as well as new species evolving) but the rate now . . . bla bla bla presumably exceeds the rate of speciation instead of vice versa as in the past.

Even under “natural” conditions, most of the biomass in a typical California landscape is made up of a relatively few species, and sometimes that preponderance is astronomical/ overwhelming, as in the case of a redwood forest, for example, where only one species can account for close to 100% of the total cover and biomass.  This sort of thing is not at all uncommon on a relatively limited, local scale.

However, in the entire flora of California, consisting of at least x thousand species of plants, only a small percentage of those species could be considered “common” or “abundant,” while the great majority range from somewhat uncommon? to rare, with a large and ever-increasing number qualifying as extremely rare, many in imminent danger of extinction. [Try to show the trend, then vs. now, by bell-curve graphs, common at left end and rare at right].

Nature follows a very complicated (with checks and balances) system of laissez-faire (now more laissez-unfaire).  Until the extinction of the Pleistocene megafauna, the system worked well, maintaining a high diversity of both plants and animals.  After that event, and the arrival of humans (Indians) in the Western Hemisphere, a different system was worked out, based on human management (by fire etc.), which served to maintain the high plant diversity, plus what was left of the animal diversity (minus most of the large mammals).  Now we have a new system (laissez-unfaire?) . . . [expand/explain as clearly/succinctly as possible].