An Ecological Paradox
The Presidential Address of Dr. Theodore M. Sperry to the Kansas Academy of Science.
Sperry, Theodore M. 1960. An ecological paradox. Transactions of the Kansas Academy of Science. 63(4):215-227.
The text reprinted below is used with permission of the Kansas Academy of Science. The subsections were not highlighted this way in the original, but were added for clarity in this web version.
I had an Ecological Idea.
I don't know where it came from, but I imagine it had been present in outer space for millennia and had first entered the earth's magnetic field sometime after the development of higher life on the earth's surface.
Its orbit first crossed my awareness, as I recall, many years ago while I was wading the waters of Bacon's Swamp at Indianapolis, even before the time ecologist Stanley Cain was describing this area in his earliest papers. But it wasn't trapped during this transit and presumably went into an elliptical orbit around the sun.
During its irregular recurrence in succeeding years, I had fleeting glimpses of it while at the University of Illinois, but in graduate school individual ideas are as difficult to keep track of as flies around a manure pile. The very richness of such a medium makes it difficult for individual ideas to develop well (except a few saprobiotic forms) and, as with its biological counterpart, the graduate training must subsequently be spread thinly over a considerable area in order to produce its most effective yields. The flowering and fruiting of ideas often occur after the academic infusion has decomposed and is no longer recognizable.
By the time I had become influenced by Aldo Leopold at the University of Wisconsin, I was enabled to grasp the Idea as it whizzed by on one of its transits and retain it within my own sphere long enough to examine it.
Its general description is that of a wild area, within the encompassment of a western civilization. I was engaged at the time in the development of the University of Wisconsin Arboretum, located on the edge of the city of Madison within easy view of the State Capitol building. Here, where the corn stalks of earlier crops were still present, was restored a wild area of hardwood and evergreen forests, prairie, and marshland, around the shores of Lake Wingra. Within this area were deer, fox, mink, swans, orchids of several kinds, and hundreds of other species in uncounted variety, both common and rare, all living under natural, wild conditions. The past had not yet disappeared even with the present very much with us.
The buzzing of an Idea
Unlike our more conventional satellitic hardware in the atmosphere, ideas seldom create much friction in passing through the relatively empty reaches of the mind, but occasionally they get hot if trapped within the cerebrum, where they buzz around like a, fly in a bottle.
One such buzzing of this Idea produced a feverish development on a small lot in Decatur, Illinois, where numerous wild species were restored for a few years, with considerable success in spite of some errors of management which were introduced. Like the fly, the Idea subsequently escaped and cooled off during a few more solar orbits.
It again became trapped in December, 1949, when approaching Pittsburg, Kansas, from the south, becoming deflected by the attraction of a lot just over one acre in size, in the southwestern part of the city – a lot which is herewith identified by the name Paradocs.
This area, was formerly underlain at the depth of a few feet by the Pittsburg-Weir vein of coal. This coal was removed around the turn of the century by team and scoop, and the area left rough, with a shallow open pit in its eastern half. Building lots were sold all around it, but it remained for a pair of biologists in1954 finally to build a residence on this acre, one of the last remaining undeveloped lots in the vicinity.
The Idea determined that the lot, for the most part, should remain "undeveloped", with the residence confined to the southwestern corner. This is the highest part of the acre, and there is a definite, although not steep, slope to the northeast. During the fifty-odd years following the removal of the coal, the lot was relatively undisturbed, allowing a number of cottonwoods, elms, wild cherries, and silver maples to reach maturity, and various other woody species to become introduced. Repeated burning had left its effects upon the vegetation, and an overnight cabin had been built at the eastern edge of the lot, with a drive from the street leading to it.
The wild areas suggested by the Idea consist of a border of forest along the northern edge of the lot, with a central area of prairie between the forest and the residence. The shallow pit in the eastern part remains as a pond. Shrubby borders bound the area on the east, south, and west, and a small mown lawn surrounds the house. Small rocky ledges interrupt some of the slopes of the lawn. Paths and trails provide access to the various areas of Paradocs, as well as serving as emergency fire breaks. These are used extensively by various species of mammals and birds, as well as providing the small openings needed as ecological niches in any general habitat.
Maintenance of the area is kept to a minimum. Not only did this Idea not like lots of work, but it was more a matter of a principle which insists that wild areas are the result of the actions of the environment, the reactions of the organisms to that environment, and the normal interactions of these organisms with each other. Mowing maintains the lawns and trails, and trimming is necessary along the paths and wooded edges.
Watering is limited to recently transplanted introductions, and to the retention of a small drinking pool for the fauna during periods of drought. Burning of the prairie area, in early spring every two or three years was introduced as a result of various observations, especially the studies by Albertson and his colleagues. Dead trees are not cut, nor are dead leaves or down timber removed except from the lawn areas. In this way, many additional ecological niches are added for fungi, insects and insect predators, hole nesters, etc.
The absence of the large native mammals (bison, deer, badger, coyote, etc.) prevents the development of a completely balanced biocoenose, but this can be compensated in part by the disturbing influence of Homo sapiens. The Idea insists that it is less important as to how a disturbance is introduced than that some disturbance is repeatedly introduced. Thus Baptisia or Silphium become established in a prairie soil equally well whether the sod has been broken by the pawing of a bison, the burrowing of a badger, or digging by man. It might require fifty years, or a century, for a. combination of squirrel, raccoon, and Indian to bring a pecan to a particular acre of ground, or an ecologist can do it in one season, but time is of no importance to either pecans or ideas, as long as the establishment is at some time accomplished.
Uniformity and variation
A uniformity of environment yields a uniformity of biota. This is extremely difficult to maintain. The greater the diversity of the environment, the richer the biotic yield from it. No richness of harvest or soil ever resulted from a uniformity of treatment. Witness the decreasing yields consistently obtained from the uniformly cropped agricultural plots of the Rothamstead Agricultural Station at Horpenden, in England, or the Morrow Plots on the University of Illinois campus. This is an important genetic allele of the Idea, that continual and varied changes be introduced by the ecologist wherever the limited size of the area prevents normal biotic reactions (especially of the larger mammals) within the area.
One variant which has been recently introduced is the development of a small sand prairie within the restored grassland. In spite of its small size of only fifteen or twenty feet, with a depth of one to two feet, it should still be sufficient to provide an ecological niche for the cacti Opuntia and Mamillaria, for Oenothera missouriensis, for a lizard or two, such as Crotaphytus collaris, and for numerous insects and smaller biotic species.
A contrasting variant also recently introduced has been an equally small depression of wet prairie for Spartina and some sedges, perhaps with some attendant temporary fauna during migration, since resident species generally prefer substantially larger areas.
The pond is mostly shaded by some of the old trees of Paradocs, but the northern and western edges are being kept as open as possible for some shorebirds and heliophilic plants. Time has not yet cooperated with the Idea to introduce a greater variety of borders for the pond. These borders at present are rather uniformly steep, but some gentler slopes will result from a recontouring job of the now nearly level bottom.
Additional ecological niches are added in the form of stone and brush piles in the wooded areas and elsewhere. An earth mound is located in the southwest corner. A plum thicket, already present in the area, is being retained between the prairie area and the pond, while a small juniper spinney is developing at the northwestern edge of the prairie area. Landscaping effects are considered in the establishment of the various ecological areas and niches, and each view from the residence presents a different vegetational aspect.
"Listen," said the Idea, "just what do you consider as native species on this Paradocs of yours? I have a distinct recollection that that acre was solid prairie before the coal miners came in to demolish a biocoenose which required thousands of years to establish."
"Agreed," replied the ecologist, "but even their worst efforts didn't entirely destroy all of that vegetation. Look! Here are a number of prairie species still remaining on the area: big and little bluestem, the sunflower Helianthus mollis, several goldenrods and asters, Baptisia leucantha, Viola sagittata, and even a number of plants of the orchid Spiranthes cernua. We are, however, working on an old mine spoil bank, and must consider what might be called native to such a spoil bank, rather than native to an undisturbed prairie. As we said a few minutes ago, this disturbance should produce a much greater variety than would occur on the original prairie itself, and an examination of the spoil banks here in the Pittsburg area seems to confirm this. Note, for example, the many beavers and occasional deer which now occur here. Would you have found them on our original prairies?"
"Well! They could have wandered through from time to time, even if they hadn't remained long," answered the Idea,
"That's the point," said the ecologist. "Even occasional or rare species may still be considered native to an area if they come in by natural causes. Let's count as native species any which occur within the vicinity, or which might migrate by natural means into such a disturbed any time within a century or so. Known introductions which have become naturalized must also be included in our lists. And let's not get stiff-necked about the horticultural lilac and spiraea, and narcissus left here by the previous owner. They are no more out of place than the residential structure itself. We shall confine such horticultural species to the lawn around the house or to the south border, where they should have little effect on the rest of the area."
Lists of plants
The Idea has been buzzing around Paradocs for a decade now, apparently departing frequently on a series of 92-minute global orbits during lectures, exams, seminars, paper grading, innumerable committee meetings, organizational presidencies, N.S.F. conferences, and kindred interruptions. But what has it accomplished during its buzzing? Perhaps a series of lists would give some enlightenment.
The Idea lapsed momentarily into one of its reveries. It recalled the war between the Oak trees and the Squirrels.
It seems that one day the head of the tribe of Sciurus was feeling proud and a bit conceited at having elevated himself and his offspring above the other rodents by dint of the hard work of climbing a tree (and as a result of having forgotten to trim his toenails). He lay sprawled out in the sun on the horizontal limb of a large Oak tree, with his legs dangling on either side of the branch and his chin testing on a small knot.
"The nerve of some people!" thought the Oak tree, "making me work holding his lazy weight out there when it's job enough just to support this family of ripening acorns these autumnal months. Here's a big acorn that is already ripe. Watch me fix that Squirrel." Whereupon the Oak Tree, with unerring ,aim, plopped the acorn squarely on top of the Squirrel's head.
"About those lists," interrupted the ecologist, bringing the, Idea back with a start.
First, let us look at the arboreal plants now established on Paradocs – some 35 species. Of these, 10 may be listed as horticultural. Of the native or naturalized species, 5 have been deliberate introductions, while the remaining 20 have come in under their own powers. Elm, silver maple, and pin oak are dominant, with black cherry a sub-dominant. These and the subsequent: figures, by the way, are not necessarily complete as of the time of writing, and are usually in need of revision.
The shrubs and vines comprise another 30 species. these, 6 are horticultural, 10 are deliberately introduced native or naturalized species, and 14 are naturally seeded species. Unfortunately, the European honeysuckle is dominant along with the native coralberry and blackberries. Wild grape is a, sub-dominant.
Some 50 forest forbs and grasses have thus far been identified, of which 30 have been brought in by the ecologist and 20 are self-seeded. Among these, the blue violets and dayflower are conspicuous. A number of transplanted vernal natives are now becoming quite at home since the arboreal species are now tall enough to give some open air beneath their leafy canopy.
The Idea had wandered back to the story of the Squirrel.
"Well! Of all the mean tricks! I'll get even with that acorn," barked the Squirrel, not recognizing that it was the Oak tree which had been offended. Whereupon the Squirrel retrieved the acorn from the ground, carried it to a convenient limb, and promptly proceeded to devour it.
"He can't get away with an insult like that," snapped the Oak tree, and promptly popped him with another acorn. The Squirrel ate that one, too.
The Oak tree dropped two more acorns and missed, then scored a bull's-eye with twin acorns at the same time.
"The lists!" persisted the ecologist, seeing that the Idea had wandered again.
Unfortunately, from the point of view of the ecologist, the prairie, as the original biome of the area, was somewhat short-changed on space, but there seemed to be no choice without sacrificing some of the mature trees on the area, and this it seemed prudent not to do. In spite of its crowded quarters, the prairie has been quite successful, as indicated by its floristic list. The sand prairie and the wet prairie areas have been too recently developed to add their share to this list, and that part already established still shows some conspicuous floristic gaps.
Among the graminoids, the big blue-stem and Indian grass are dominant, with the broom sedge (Andropogon virginicus), a. relict of the former annual burning, a sub-dominant. Tridens and Setaria might also be included among the sub-dominants. Of this list of 20 grasses and sedges, 7 are intentional transplants to the prairie, and the remainder naturally seeded.
Of the 60 prairie forbs, 25 have been brought in by the ecologist. Helianthus mollis, and the Solidagos and Asters, constitute the dominants in this list.
Statistics bored the Idea. The Squirrel story was more interesting.
"Cheou!" chattered the Squirrel. "Two acorns on the inside are making me feel as uncomfortable as the lumps on my head on the outside. I need some help to combat these pests."
So he called together the members of his tribe and announced that as a result of an unprovoked attack, a state of war existed between the Squirrels and the Acorns. The offended Oak tree said nothing, pleased that the jumpy Squirrels didn't even realize who it was that they were actually trying to conquer. The Squirrels also didn't realize how much acornition the Oak tree had in reserve, and it wasn't long before every Squirrel in the tribe was fed up with the war. A truce was called for the night.
The ecologist, however, was concerning himself with aquatic plants.
Of the plants around the pond, the sub-aquatic willow and sycamore and buttonbush have already been listed among the woody plants. The list of 20 grasses and forbs which have been identified to date is an entirely naturally-seeded group. Development of this group awaits the recontouring job mentioned earlier.
With the exception of the fern Cystopteris fragilis which has been introduced into the wooded area, the cryptogams have had to shift for themselves. No naturally occurring Pteridophytes have been found on the area. There are more than half a dozen species of mosses, several of them growing luxuriously and abundantly, but none of them has yet been determined. No liverworts have been noted.
The next morning, the Idea recollected, a smart young Squirrel had a plan. "If we go out to the ends of the branches and bite off those acorns, it will be impossible for them to attack us. Furthermore, instead of trying to destroy them all at once, we can carry them off and bury them now, then take care of them at our leisure during the winter.
Incidentally, their protein production is prodigious and their tempting taste is terrific if one doesn't stuff the stomach to satiety.
Lists of fungi
The ecologist was now down to the Thallophytes.
A mycologist could have a field day, or many of them, on Paradocs. The bracketed cellulose digesters abound on the dead and down timber. There are a variety of gilled mushrooms and puffballs among the more conspicuous forms, as well as the fascinating phalloids and many smaller forms. There are a number of rusts and smuts among the parasites as well as the interminable leaf spots and many others equally difficult.
Among the ascos is the always recognizable Morchella esculenta. Some alcohol-producing yeasts were discovered in some bee-stung grapes. Penicillium and Aspergillus occur in the kitchen from time to time, and doubtless occur outdoors as well. There are powdery mildews and wilts and black rots and brown rots and leaf curls and blights to make one's head swim. With fare exceptions, even bacteriologists can tell one almost nothing about the "wild" bacteria, even when they are sufficiently abundant to photograph without a microscope (on the surface of the pond). And let's not forget the capillitia of the slime molds among the mycological observations.
The algae are less numerous, and the Paradocs species even less known. Protococcus abounds on the sandstone rock ledges and on the bark of the various trees, less frequently elsewhere. Lyngbia has been identified from the pond, and a number of other greens and diatoms are known to occur.
Several lichens, especially the corticolous forms, are common, but there are also some soil forms which compete with the mosses for space. Anybody want to name them?
The Idea mused.
Not only was this plan adopted, but the Squirrels called in the deer, bear, raccoon and other mast feeders, including the woodpeckers, jays, and grackles, for help. Acorns broken by the hoofed mammals were also used as food by rabbits, mice, rats, and many of the smaller winter birds, such as the bobwhites, cardinals, titmice, chickadees, juncos, etc. But the Oak tree sighed contentedly in the wind, covered the buried acorns with a layer of weather-resistant leaves, and planned its buds with an even larger acorn crop for the following year.
The ecologist continued with scientific persistence.
Lists of invertebrates
For the most part, the Invertebrates of Paradocs are even less known than the Cryptogams. Protozoa have been noted in the pond, and they also doubtless occur elsewhere, but thus far their identification has not been attempted. The same is true for the roundworms. Perhaps other helminths also occur, but none has yet been noted. (They haven't even been looked for.) One or more species of the Lumbricidae among the annelids are present, and these seem to be slowly increasing in numbers. The only mollusks yet noted include a snail of the genus Planorbis, and one or two species of small slugs. All of these are moderately common in some seasons.
Even the most tantalizing menu eventually becomes monotonous, thought the Idea, and by the time the elm buds began to swell late in February, the Squirrels neglected their war with the acorns in favor of this new taste sensation. Elm flowers and fruits quickly followed. The militant leaders among the Squirrels, following the advice of their War Office for Research and Scientific Techniques (WORST), tried to renew the attack in April by advising a diet of Oak tree catkins, but this plan fell flat. The Oak tree production plants were too large and efficient, and the acorn-producing pistil manufacturers were too small and well hidden for the spring-fevered Squirrels.
The ecologist was now considering the arthropods.
One species of crayfish is fairly common over the area, and some of the tiny crustacea have remained in the pond still unidentified. Spiders of a dozen or more genera abound over the area, just waiting for some¡one to pull a book off the shelf and get busy on them. A few ticks have been found, and the larval Trombicula (the well-known "chigger", and sometimes a little too common) is a representative of the mites. No scorpions have yet been added to the list.
A limited amount of work has been done by a graduate student on the insects, and a list of some 40 species represents a rudimentary start. As Professor Lutz has aptly said, there are "a lot of insects," – perhaps some of them never yet named. The association of certain insects with their particular preferred host plants is sometimes quite noticeable.
The Idea knew well that in May, the secret timing mechanism hidden in the acorns, and subsequently described to the press as the Delayed Nutritional Action (DNA), was released, and the now forgotten food stores hidden by the Squirrels themselves quietly developed new acorn-producing plants in locations at far greater distances than the Oak tree, even at its stormiest, could have accomplished. Their true nature was not even suspected by the Squirrels for several years, by which time they were too well established to be displaced.
Lists of vertebrates
The vertebrate record, continued the ecologist, is much more satisfactory. There are no fish in the pond, which dries up during our drought seasons. Its catchment basin is much too small, scarcely more than an acre, and the soil is somewhat more porous than some of our old spoil bank soils.
Although Paradocs is more than half a mile east of Cow Creek, and there are no permanent ponds in the vicinity closer than this almost intermittent stream, seven species of anurans and one salamander have all come in on their own legs, crossing at least two streets and several lawns to reach this pond. The anuran calls fill the night air during the spring mating season, as each one seems to attempt to prove its dominance.
Fortunately, the reptiles are silent, and we, too, remain silent about them, so far as the neighbors and visitors are concerned. There are four species of turtles, six snakes, and two lizards on this list, but most of these seem to be transients. Two snakes, one lizard, and the box turtles may be listed as permanent residents. The Scaled Lizard has been the only introduced species, and it did not persist.
And so the feud continues, observed the Idea, with the Squirrels getting fat each year while they try to prevent the shower of acorns, and the Oak trees continually expanding into new territories with the able assistance of these Squirrels.
The enthusiasm of the ecologist had now reached its peak.
None of the 163 species of birds may be said to be permanent residents of this restricted acre, although certainly a number of them are residents of this vicinity. There are perhaps fifteen on the list which have only been sighted as they flew over the area, such as the geese, for example, but the remainder have paid personal visits to the lot, including such wild forms as a Mallard on the pond and the Pileated Woodpecker insect-hunting on the dead trees. A Lark Sparrow, brought in by a student, is the only introduced species on the list, and of course it didn't stay long. The banding program has yielded 87 species from this list in the traps or nets.
Not counting cats, dogs, or men, some 18 species of mammals have occurred natively on Paradocs. The Cottontails and Fox Squirrels are the dominant permanent residents above ground and the Mole below ground. The Opossum, Deer Mouse, Cotton Rat, and Big Brown Bat, are also usually in residence, while the remainder are less frequent, although some, like the Woodchuck, may remain a year or two at a time.
"Wait!" said the Idea. "I've just thought of a moral. Symbiosis makes simple sense to the sophisticated."
"Whatever called forth that remark?" exclaimed the ecologist. "And yet," he continued without waiting for a reply, "you are right. In fact, I was about to make a similar suggestion myself, but in a more detailed manner, of course."
Climate and change
In examining these lists, we have noted the large number of species naturally-occurring on the area. Many of these have come in within the decade that the Idea has been operative on Paradocs, and as a direct result of the ecological management producing the various habitats. From what we know of the distribution of biotic species generally, there can be no doubt that most of the native species which have recently been reintroduced would also have come in by natural means if they had been given enough time. The principal influence of the ecologist has been to speed up the process sharply, and to ensure the appropriate kind of disturbance to keep the varied habitats available for the incoming disseminules as they arrive, instead of waiting for the slow processes of flood and drought, fire and epidemic disease, insect depredations and grazing mammals and native Indian to produce, eventually, similarly favorable areas over the years.
Such changes, commented the Idea, make fossils of some species and relicts of others, while at the same time providing new ecological niches available for occupancy by chance generic mutants.
Yes, agreed the ecologist, but of more immediate concern is that such variations keep each of the various species in check. Let any one get out of bounds as a population explosion and it soon kills itself off. Usually not to the point of extermination, of course, but to such a low level that it may take. it many years to recover. In such cases, those species previously held in check by the exploding species then have a chance to move in while they repair the damage caused by the explosion,.
Normal climatic variations, thanks to sunspot cycles among other causes, are ordinarily effective in keeping most species within reasonable limits, although within recent years these have not been very effective with Homo sapiens. Flood and famine kept this species under control for many thousands of years until he learned to use his brain, but recently not even his diabolically clever devices for warfare have been effective in controlling his numbers. He is even talking now about ways to limit the weather extremes, to keep these controls, weak as they now are in his case, from being effective. What does the guy want, anyway?
The gene-pool and an urban acre
Something definitive will have to be done, and soon, stated the Idea. But just now, our job is to keep a gene-pool in reserve to repair the wastage now being produced by man. No damage is so great that it cannot eventually be repaired by the proper combination of genes, selected from among the two million organisms we presently have available. No one species, least of all man with his photosynthetic and socio-psychological limitations, can accomplish much repair by itself. It requires the coordinated action of a rather large number of species, each producing its own particular effect, to obtain the high level of biological productivity – "richness", we like to say – which we idealize as the basis of a good life. The oak needs the ant and the earthworm to loosen the soil. The rabbit needs the coyote to prevent a population explosion, and the bluestem needs the bison for the same reason. Bees and orchids, rails and ostracods, diatoms and nematodes and termites and prairie anemones. What else can do what the combined action of these can do?
When large areas of the earth's surface are cleared by the plow and the saw and the bulldozer, how can the richness be restored if there are not gene-pools held in reserve, like an insurance policy in a time of need?
In the days of forests and savannas and deserts, there was no need for gene-pools. There were gene-oceans, then. In these days of fields and cities and defense developments, the wild areas are numbered and measured. There are National Forests, National Parks, and National Wildlife Refuges, generally in thin soil or marshy areas unsuitable for economic development. These are rich gene-pools, as far as they go. But even these need to be assured by the establishment of a National Wilderness System as outlined by the bill now under consideration by Congress, in view of the increasingly heavy human usage of our present natural areas. Such natural areas are already rare in grassland soils and along our seashores. Congressional bills introduced to provide such areas have not yet attracted sufficient backing to permit their enactment.
Mountain Lion, Timber Wolf, Bison, and Wolverine ate, by their nature, largely restricted to these large natural reserves. So are such wild species as the Whooping Crane, California Condor, and Bighorn. But what about the smaller species, especially the small migrants, or those which wander with the variations in climate? Their survival rests upon their ability to move from one favorable habitat to the next. How close together must these habitat's be? No one knows for most of our species. Favorable habitats one hundred miles from the normal range are often found occupied by a species. This distance may be much too great, however, for some species to cross – moles, for example.
Is it not an Ecological Idea to establish a series of small gene-pools across the land to protect our diminishing genetic reserves? Who is in a position to say that this gene, or that, is not worth jealously guarding? Would you have recognized the value of the genes of Penicillium, or Neurospora, or Drosophila, which made possible the research leading to the Nobel prize awards?
Let the governments protect our few scattered large reserves. Let citizen organizations, like the Audubon Society or the Nature Conservancy, supplement these with smaller choice sites between the large reserves. But to bond these together, we need the individual enlightened citizen to establish the many little gene-pools within the length of the stride of the Mourning Cloak and Partridge Pea, and Spirogyra. The farm pond and Conservation Reserve specialists can do this in our agricultural areas. But so can the more numerous dwellers in our spreading Suburbia.
It is an Ecological Paradox how many genes one can keep, with appropriate management, on an urban acre.
– Kansas State College of Pittsburg