Wizard Island: It's Succession Of Life
By Dr. Wm. G. Vinal, Ranger-Naturalist
Wizard Island is never the same twice. As the same moment no two people see it the same and it is only by continuous observation and accretion of ideas that the complete story of its origin and life can be unfolded.
It is evident to an observer on the Watchman, Hillman Peak or Llao Rock, looking down on the island, that it is made up of the three zones of volcanic contributions, namely blocks of rough andesitic lava at the base along the shore line, a coarse undulating lava flow along the intermediate slopes and the symmetrical conical slopes of ash and cinders above. Disintegration and decomposition have not contributed much to the breaking down of these lava slopes. The volcano is so young geologically that very little progress has been made in converting the raw slaggy slopes into a soil with humus. A slight covering of volcanic dust co-mingled with organic material has filled the more gentle slopes and irregular crevices as the base. It is evident that there is not sufficient soil nor is the humidity sufficient to invite the growth of such shade plants as the coral root, trailing raspberry and a host of other deep wood plants.
Darwin's classical earthworms have not arrived nor could they find any subsoil to bring up to the surface. The plants on Wizard Island, therefore, are limited to those forms whose structure allows them to suffer drought.
The stages in the vegetal conquest of Wizard Island may be the key to the many successive revegetations of the slopes of Mt. Mazama. What were the first plants to land and how did they come? After the last swirling flow of lava and the vanishing of steam there were, as always before, prevailing westerlies wafting spores of lichens, fungi, and eric mosses and perhaps the winged seeds of conifers from the Rim. The water currents undoubtedly floated seeds. Probably 99% of these germs of life were born for naught as is the great mass of pollen that washes to and fro today. Many would-be colonizers were destined to land on such barren, sterile places that they were inevitably doomed to perish.
The only plants today that are succeeding in the glare of light on the lower rock blocks are the lichens. The golden lichen is a crustose form which can stand a certain amount of direct sun but must have shade a part of the day. The gray lichens could also have been early arrivals. It must have been eons before any crannied wall accumulated dust particles enough to encourage a moss plant. The lace fern (Chelianthes gracilliam) grows in pockets on the lower rock ledges, Woodsie (Woodsia oregana) pokes its rusty fronds from protected spots on the rocky summit, and the rock brake (Cryptogramma acrtostichoides) is found in rock clefts in the crater. Those are the only members of the fern tribe that have succeeded in mastering the situation. Untold ages had to follow before seed plants could anchor long enough to send their rootlets down to the water table.
In the meantime what could have been going on in the way of seed arrivals on the ash pile above the cone? It is a mile from the west rim across Skell Channel to the crater of Wizard Island. It must have been a strong west wind that enabled the first mono-planed seeds of the conifers and the ballooms of the composites and figworts to flutter from the rim of Crater Lake to the sides of the island cone. There had to be at least one from each conifer, the mountain hemlock (Tsuga mertensiana), the white bark pine (Pinus albicaulis), the western white pine (Pinus monticola), the lodgepole pine (Pinus contorta), and the shasta red fir (Abies magnifica shastensis). It may not be sheer accident that the greatest growth of evergreens is on the west side of the island, that the largest and possibly oldest western white pines and Shasta red firs are at least five hundred feet above the lake, or that the best stand (of) lodgepole and white bark pine is at the summit. In other words, did not the colonizers come by the air route and land as they would, hit or miss, but mostly miss? The seeds successful in growing. The ash cone proved to be the best of the three areas. It was these veterans that lived to perpetuate each its own kind. They remained to shake their seeds downward that the forest might grow upward to eventually cover the cone.
The five conifers had a most difficult time in establishing themselves. The remarkably few evergreen seedlings on the ash slope are mute testimony to the fate of most seeds which are unfortunate enough to cast their lot on such a dry, sterile environment. Those which succeeded in reaching a goodly size still had to fight. About 500 feet up the cone lava rocks from a fissure flow have imbedded themselves eighteen inches above the slope in the trunk of a Shasta red fir and at a still higher altitude a lava rock as large as a man's head has become wedged between the upright trunks of a white bark pine. Such land slides are denuding agents for seedlings and surely handicaps to veteran tree. In one of the larger gullies the larger trees have had their heads snapped off about twenty feet above ground. The fact that they held fast with their root systems indicates a deep root system, or that they were broken by a wind storm which whirled up the valley when the trees were braced by deep snow. Many a wind-blown tree has lost its main trunk to start again. The battle is with the elements and not with each other.
And what of the antecedent herbs? The shade-requiring plants of the deep forest are few indeed. The small-leaved penstemon, the pine-mat manzanita and the wintergreens represented by the one-sided pyrola, the toothed wintergreen and pipsissewa are practically the only arrivals. The representatives of the open woods are the white hawkweed and the elephant's head. The few herb and shrubs of the forest indicate that the stand must be young in its development.
The colonizers of the ash slope are the strong-stemmed, creeping perennials that are able to battle alone. The amount of heat on the slope is much greater than on the wooded plateau below. Any plant growing there must be drought resistant, capable of anchoring tightly, and able to stand punishment when bombarded by pumicite or when buried alive by miniature sand dunes. Theirs is a terrific punishment. The typical plants of this area are arenaria, chalice cup, white buckwheat, and Newberry's knotweed. All of these hardy pioneers send runners into the bare ash and are often exposed by the drift of the soil. Their offshoots, rhizomes, or stolons are controlled by gravity and swing like cables down the slope. This may be thought of as a linear migration (as opposed to radial migration) and new plants spring up just below the parent plant. As many as eight successive offspring were counted on one cable which had been sent out by white buckwheat (Eriogonum ovalifolium).
Interspersed with the "cable" growths are such hoary and stemless plants as the silver leafed senecio, and sulphur flower, and the root-storing carrot (Cogswellia martindalei). In protected spots the fireweed, Englemann's aster, the alpine, false dandelion, arnica, and wood rush have made appearance and stand ready to furnish the strands of crosswise vegetation as soon as the "cable" plants get stabilized. The vegetation on the ash lope has hardly reached the stage of being able to weave a mat or turf.
A third zone of herbaceous plants appears near the top of the island. Although the island does not reach into alpine heights it has a few plants which are typically montane in character. At the crater a few yellow mountain daisies (Hulsea nana) grow just outside the rim on the south side in loose red cinders. A few feet across the crest, but within the crater and on the north facing slope, is the heart-leafed arnica (Arnica cordifolia) and the more widely spread alpine saxifrage (Saxifraga tolmei). This little saxifrage starts as a tuft in back of a rock and in due time forms a dense mat. The silver-leafed senecio (Raillardella argentea) grows on the dry ash of the north slope outside the cone and penstemons adorn the inner slope. While in the "cable" plant district it is largely ability to adapt to a small amount of moisture and shifting soils around the crater it is a matter of little moisture and direct or indirect sunlight.
The trees are herbaceous plants listed are those whose seeds could have been brought by the wind. The shrub plants with berried fruits also came by the air route except that they borrowed their wings. Only two shrubs of red berried elder (Sambucus racemosa) were noted on the cone. One was at an altitude of 6650 feet and the other at the bottom of the crater. Four little offspring are growing near the base of the crater specimen. A solitary gooseberry bush was found at an altitude of 6250 feet in the forest. The scattered appearance of the many-stemmed mountain ash (Sorbus sitchensis) with its berry-like apple, the pine-mat manzanita, and the mazama currant have all appeared above the encroaching forest. The pine mistletoe (Arcenthobium) could well have taken the bird express to the white bark and lodgepole pines on the rim of the crater.
The pine mistletoe could not arrive before its host. The same is true of parasitic paint brushes. The aphids in the rolled red-leaves of manzanita had to wait for the hosts' arrival. The tiny craters of the "doodlebugs" (Ant Lions) found at such widely separated stations as the first trees above shoreline (6207 feet), the upper limit of the shady forest (6437 feet), the fissure flow at 6610 feet in altitude and the top of the rim (6940 feet) show that such barriers as Skell Channel, bare lava rocks, or ash deserts are not insurmountable. These carnivorous insects must have followed the advent of required food as was the case of the dozens of dragon flies hovering over the crater (August 10, 1993). And how about the toads sitting patiently in the crater waiting for food to pass by? Were they and the dragonflies and the mosquitoes crater-born or channel-born? Wizard Island may thus be compared to the House-That-Jack-Built, for this is the ant lion that ate the ant that lived in the tree that came from the seed that grew in the pumice that was blown out of the crater that Wizard Island built. Or, this is the egg, laid by the beetle that came from the grub, that infested the bar, that belonged to the lodgepole, that had the "rumor", caused by the spores that came from the parasite that lived on the paintbrush (for four generations) that grew on the slope, beside the trail that Jack built. And so one may go on ad liberatum.
An abundant insect life readily invites bird inhabitants. The mountain blue bird family on the rim would indicate that a pair had nested thereabouts. The redbreasted nuthatches and Oregon Juncos appeared busy and happy. The Calliope humming-bird was observed sipping nectar from phacelia and fireweed, the Clark nutcracker probing the cones of the white bark pine on the rim, the marks of the sapsucker on a white bark pine, and the Cassin purple finch and Audubon warbler feeding along the evergreened base, the toads near the snow bank, the coney making hay in the rock slide at the bottom of the crater, the three golden-mantled ground squirrels near the domicile of the coney were all dependent "on things" that must have come before.
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