There are two chapters in the story of Crater Lake: One, that relating to the geological history of the region – how the mountain was made; the other tells the story of the plant cover – how this originally bare region came to be clothed with vegetation. It is this second chapter which we shall here consider.

It is a fact which we may all observe that nearly any region which has a good soil will have a covering of vegetation. This vegetation, or plant community, is directly under the influence of the weather. The species which go to make up this plant community are dictated largely by the temperature and humidity. Alexander von Humboldt, many years ago, observed that as one climbed the high mountains of South America, the vegetable covering came more and more to resemble the polar forms. In other words, altitude and latitude acted similarly upon the forest covering – the prime factor being temperature. More recently this zonation has been painstakingly investigated on the high mountains in our own country. Not only does the plant community change with temperature differences, but as one goes from wet to dry climate, there will be a change from forest to prairie to desert, though the average temperature may remain about constant. From these observations, we may draw the conclusion that our final forest covering at Crater Lake is determined principally by the climate and that the soil, provided it is adequately rich and deep, is not great factor.

But there is a long and fascinating history to the soil and its formation from the bare lava flows of which Garfield Peak was originally composed. Trees will not grow on bed rock, nor will bushes nor grass. What then was the first vegetable covering?

Let us then examine the plant covering of Garfield Peak to see if we can unravel the history of the forest. As we stand on the switchbacks we note that where bare lava is exposed, there is only one plant to be found – the lichen. Here is the plant which is able to grow on the recent flows, and which preceded all other plants in this volcanic region. This small organism encrusts the cliffs around the Lake and is responsible for the green patches on Dutton Cliff and Sentinel Point. Its functions are several: it conserves soil by collecting dust in the same manner as does a carpet; it sends tiny rootlets down into the rock and hastens the breaking down of the stone; and it also enriches the soil by contributing its dead carcass to form humus or leaf mould.

But we will notice that where the soil formed by the lichens has collected into crevasses and depressions, the mosses have invaded. Because of their greater efficiency in wresting a living from the soil they are able to predominate over the lichens in all but the exposed places. The mosses, like the lichen collect, form, and enrich the soil. Because of their size, they carry on these processes at greater speed. And it is that which is their own undoing, for if we look carefully, we will see the lowly moss yield to the fern – its superior in height and complexity. The mosses remain only in the less favorable situations.

It is not until the cliffs give way to the steep talus slope that the ferns bow to the sedges and grasses. The more efficient seeding of the latter plants coupled with ability to endure dryer soil give them the upper hand on these slopes. The perennial flowering plants such as the various forms of wild buckwheat, arnica, bleeding heart, and Indian paint-brush may bee seen to grow in the grassy places and so they share this stage of succession. The inroads made by the shrubs into this plant community may well be seen near the foot of the peak in the region of the first switch-back, for there the Ocean Spray, Squaw Carpet, pine mat, and currant grows in profusion and apparently to detriment of the lower forms.

The final plant community, or the climax community as it may properly be called, is the forest. The first forest may be seen on the steep hillsides as a mixture of white bark pine and hemlock. Before optimum conditions were reached one or the other of these species is thinned out and we find that near the crest of the ridge the white barked pine exists in almost pure stands, while below it are unmixed hemlock forests.

What a complicated bit of machinery Nature puts into motion in order to build a forest! We are inclined to be impatient when we see that the first stages may well take hundreds of years. Let us not forget that years mean nothing in the workings of the universe, and that the human life is but the flicker of a candle compared to the life of old Mt. Mazama. We are also distressed that this machinery does not seem to be as precise as the polished automatons which run our ships or grind out shoes or automobiles. One thing does not follow another as the textbooks would have it. Many of the stages are overlapping or run together. A most excellent example of this is to be seen on the large rock the second switch-back from the summit. Here we may see lichen, or six varieties, in the greatest of profusion, while in the crevices the rest of the life history of the forest is written in complete form. Mosses, ferns, sedges, grasses, flowers, shrubs, pines, and hemlocks grow all within an area ten feet square. This rock stands as a summary of the second story of Crater Lake and refreshes the memory of the traveler on Garfield Peak.

 

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