A MOUNTAIN PARK IN THE SAN JUAN MOUNTAINS
During one of his early exploring expeditions, John C. Frémont visited North Park and wrote of it as follows: "The valley narrowed as we ascended and presently degenerated into a gorge, through which the river passed as through a gate—a beautiful circular valley of thirty miles in diameter, walled in all around with snowy mountains, rich with water and with grass, fringed with pine on the mountain sides below the snow line and a paradise to all grazing animals. We continued our way among the waters of the park over the foothills of the bordering mountains."
Hayden Valley in the Yellowstone National Park is another large grassy opening in a mountain forest. This valley apparently was once a vast arm of Yellowstone Lake.
Estes Park, in Colorado, is one of the most attractive as well as the best known of the mountain parks. Although much smaller than Middle or South Park, it is much larger than hundreds of the other beautiful mountain parks. The Estes Park region embraces about one hundred square miles, though only one third of this is open. The approximate altitude of the ragged lowland park is a trifle less than eight thousand feet. This is entirely surrounded by high mountains which uphold a number of rocky, snowy peaks. In 1875 Dr. F. V. Hayden, father of the Yellowstone Park, wrote of this region: "Within the district treated we will scarcely be able to find a region so favorably distinguished as that presented by Estes Park. Not only has nature amply supplied this valley with features of rare beauty and surroundings of admirable grandeur, but it has thus distributed them that the eye of an artist may rest with perfect satisfaction on the complete picture presented." Erosion and glacial action have given this region its form, while fire made the beautiful opening or park within a forest.
The majority of parks or meadow gardens which decorate the forests of the Rocky Mountains probably owe their existence to fire. Trees and grass are endlessly contending for the possession of the earth. In this incessant silent struggle a sweeping fire is generally of advantage to the grass. Trees suffer more from fire than does grass. It is probable that repeated fires enable the grass to hold the plains and prairies against the encroachments of the trees. Each forest fire commonly gives the grass possession of a part of the area formerly dominated by the forest. Usually both grass and trees are prompt to seize any fire-cleared area. The grass may be first to come, or some space may be wet or in some other way unfavorable to tree seed but encouraging to grass seed.
While forest fires bring many of these parks, others are glacier meadows, lake-basins which time has filled with sediment and sodded with grass. Many are due to the presence of water, either outspreading surface water or an excess of underground water just beneath the surface,—to streams visible or invisible. A few result from boggy places which result from impaired drainage caused by landslips or fallen trees. Thousands were made by beaver dams,—are old beaver ponds that filled with sediment and then grassed over.
Most parks that owe their origin to forest fires have charcoal beneath the surface. A little digging commonly reveals charred logs or roots. Occasionally, too, a blackened tree-snag stands suggestively in these treeless gardens. In the competition for this territory, in which grass, spruces, aspens, and kinnikinick compete, grass was successful. Just what conditions may have been favorable to grass cannot be told, though probably one point was the abundance of moisture. Possibly the fire destroyed all near-by seed trees, or trees not destroyed may not have borne seed until the year following the fire. Anyway, grass often seizes and covers fire-cleared areas so thickly and so continuously with sod that tree seeds find no opening, and grass thus holds possession for decades, and, in favorable places, possibly for a century.
Trees grow up around these areas and in due time the grassy park is surrounded by a forest. The trees along the edge of this park extend long limbs out into it. These limbs shade and kill the grass beneath. Tree seeds sprout where the grass is killed, and these seedlings in turn produce trees with long limbs reaching into the park. These shade and smother more grass and thus advance the forest another limb's length. Slowly but surely the park is diminished.
Struggling trees may sometimes obtain a place in advance of the others or a start in the centre of the park, and thus hasten the death of the park and speed the triumph of the trees. A mere incident may shorten the life of a park. A grizzly bear that I followed one day, paused on a dry point in a park to dig out some mice. In reaching these he discovered a chipmunk burrow. By the time he had secured all these he had torn up several square yards of sod. In this fresh earth the surrounding trees sowed triumphant seeds, from which a cluster of spruces expanded and went out to meet the surrounding advancing forest. Fighting deer sometimes cut the sod and thus allow a few tree seeds to assert themselves. Wind may blow down a tall tree which lands in the edge of the park. Along its full length grows a line of invading forest. Occasionally the earth piled out by a gopher, or by a coyote in digging out a gopher, offers an opportunity that is seized by a tree seed. An ant-hill in a meadow may afford a footing for invading tree seeds. On one occasion a cliff tumbled and a huge rock-fragment bounded far into the sloping meadow. Trees sprang up in each place where the rock tore the sod and also around where it came to rest in the grass.
These breaks in the sod made by animals or other agencies do not always give triumph to the trees. Seedlings may eagerly start in these openings, but, being isolated, they are in greater danger, perhaps, than seedlings in the forest. Rabbits may nibble them, woodchucks devour, or insects overrun them. The surrounding grass may smother them and reclaim the temporarily lost opening.